.clang-format

@@ -63,7 +63,7 @@ BreakBeforeTernaryOperators: true
 BreakConstructorInitializers: AfterColon
 BreakInheritanceList: AfterColon
 BreakStringLiterals: false
-ColumnLimit: 120
+ColumnLimit: 80
 CommentPragmas: "^ IWYU pragma:"
 CompactNamespaces: false
 ConstructorInitializerAllOnOneLineOrOnePerLine: true
@@ -167,7 +167,7 @@ RawStringFormats:
       - PROTO
     CanonicalDelimiter: pb
 ReferenceAlignment: Left
-ReflowComments: false
+ReflowComments: true
 RemoveBracesLLVM: false
 SeparateDefinitionBlocks: Always
 ShortNamespaceLines: 0

doc/doxygen.conf.in

@@ -2237,7 +2237,9 @@ SEARCH_INCLUDES        = YES
 
 INCLUDE_PATH           = @TOP_SRCDIR@/src \
                          @TOP_SRCDIR@/src/ast \
-                         @TOP_SRCDIR@/src/models
+                         @TOP_SRCDIR@/src/lib \
+                         @TOP_SRCDIR@/src/lib/models \
+                         @TOP_SRCDIR@/src/lib/include
 
 # You can use the INCLUDE_FILE_PATTERNS tag to specify one or more wildcard
 # patterns (like *.h and *.hpp) to filter out the header-files in the

meson.build

@@ -1,4 +1,5 @@
 project('obelisk',
+    'c',
     'cpp',
     version : '1.0.0',
     license : 'BSD-3-Clause',
@@ -9,6 +10,8 @@ project('obelisk',
     ]
 )
 
+project_version_lib = '0'
+
 llvm = dependency('llvm', version: '>= 14.0.0', modules : ['core', 'target', 'mcjit', 'nativecodegen'], required : true, method: 'config-tool')
 
 cdata = configuration_data()

src/ast/ast.h

@@ -11,9 +11,28 @@
 
 namespace obelisk
 {
+    /**
+     * @brief The LLVM context.
+     *
+     */
     static std::unique_ptr<llvm::LLVMContext> TheContext;
+
+    /**
+     * @brief The LLVM module.
+     *
+     */
     static std::unique_ptr<llvm::Module> TheModule;
+
+    /**
+     * @brief The LLVM IR builder.
+     *
+     */
     static std::unique_ptr<llvm::IRBuilder<>> Builder;
+
+    /**
+     * @brief The LLVM named values.
+     *
+     */
     static std::map<std::string, llvm::Value *> NamedValues;
 } // namespace obelisk
 

src/ast/call_expression_ast.h

@@ -9,25 +9,74 @@
 
 namespace obelisk
 {
+    /**
+     * @brief The call AST expression node used to call functions.
+     *
+     */
     class CallExpressionAST : public ExpressionAST
     {
         private:
+            /**
+             * @brief The function being called.
+             *
+             */
             std::string callee_;
+
+            /**
+             * @brief The arguments passed to the function.
+             *
+             */
             std::vector<std::unique_ptr<ExpressionAST>> args_;
 
+            /**
+             * @brief Get the callee.
+             *
+             * @return std::string Returns the name of the function being
+             * called.
+             */
             std::string getCallee();
+
+            /**
+             * @brief Set the callee.
+             *
+             * @param[in] callee The name of the function.
+             */
             void setCallee(std::string callee);
 
+            /**
+             * @brief Get the arguments being used by the function.
+             *
+             * @return std::vector<std::unique_ptr<ExpressionAST>> Returns an
+             * AST expression containing the args.
+             */
             std::vector<std::unique_ptr<ExpressionAST>> getArgs();
+
+            /**
+             * @brief Set the arguments to be used by the function.
+             *
+             * @param[in] args The args to set.
+             */
             void setArgs(std::vector<std::unique_ptr<ExpressionAST>> args);
 
         public:
-            CallExpressionAST(const std::string &callee, std::vector<std::unique_ptr<ExpressionAST>> args) :
+            /**
+             * @brief Construct a new CallExpressionAST object.
+             *
+             * @param[in] callee The function to call.
+             * @param[in] args The args to pass into the function.
+             */
+            CallExpressionAST(const std::string &callee,
+                std::vector<std::unique_ptr<ExpressionAST>> args) :
                 callee_(callee),
                 args_(std::move(args))
             {
             }
 
+            /**
+             * @brief Generate the calle IR code.
+             *
+             * @return llvm::Value*
+             */
             llvm::Value *codegen() override;
     };
 } // namespace obelisk

src/ast/error.h

@@ -7,8 +7,22 @@
 
 namespace obelisk
 {
-    std::unique_ptr<ExpressionAST> LogError(const char *Str);
-    llvm::Value *LogErrorV(const char *Str);
+    /**
+     * @brief Log an AST expression error.
+     *
+     * @param[in] str The error message.
+     * @return std::unique_ptr<ExpressionAST> Returns the AST expression that
+     * caused the error.
+     */
+    std::unique_ptr<ExpressionAST> LogError(const char *str);
+
+    /**
+     * @brief Log an AST value error.
+     *
+     * @param[in] str The error message.
+     * @return llvm::Value* Returns the AST value that caused the error.
+     */
+    llvm::Value *LogErrorV(const char *str);
 } // namespace obelisk
 
 #endif

src/ast/expression_ast.h

@@ -5,10 +5,25 @@
 
 namespace obelisk
 {
+    /**
+     * @brief A generic AST expression which other expression will inherit from.
+     *
+     */
     class ExpressionAST
     {
         public:
-            virtual ~ExpressionAST()       = default;
+            /**
+             * @brief Destroy the ExpressionAST object.
+             *
+             */
+            virtual ~ExpressionAST() = default;
+
+            /**
+             * @brief Generate LLVM IR code based on the AST expression.
+             *
+             * @return llvm::Value* Returns the LLVM code value from the
+             * expression.
+             */
             virtual llvm::Value *codegen() = 0;
     };
 } // namespace obelisk

src/ast/function_ast.cpp

@@ -17,7 +17,8 @@ llvm::Function *obelisk::FunctionAST::codegen()
         return nullptr;
     }
 
-    llvm::BasicBlock *bB = llvm::BasicBlock::Create(*TheContext, "entry", theFunction);
+    llvm::BasicBlock *bB
+        = llvm::BasicBlock::Create(*TheContext, "entry", theFunction);
     Builder->SetInsertPoint(bB);
 
     NamedValues.clear();

src/ast/function_ast.h

@@ -8,22 +8,58 @@
 
 namespace obelisk
 {
+    /**
+     * @brief A Funcion AST node.
+     *
+     */
     class FunctionAST
     {
         private:
+            /**
+             * @brief The prototype of the function.
+             *
+             */
             std::unique_ptr<PrototypeAST> prototype_;
+
+            /**
+             * @brief The body of the function.
+             *
+             */
             std::unique_ptr<ExpressionAST> body_;
 
+            /**
+             * @brief Get the prototype.
+             *
+             * @return std::unique_ptr<PrototypeAST> Returns the prototype AST.
+             */
             std::unique_ptr<PrototypeAST> getPrototype();
+
+            /**
+             * @brief Set the prototype.
+             *
+             * @param[in] prototype Set the prototype.
+             */
             void setPrototype(std::unique_ptr<PrototypeAST> prototype);
 
         public:
-            FunctionAST(std::unique_ptr<PrototypeAST> prototype, std::unique_ptr<ExpressionAST> body) :
+            /**
+             * @brief Construct a new FunctionAST object.
+             *
+             * @param[in] prototype The prototype of the function.
+             * @param[in] body The body of the function.
+             */
+            FunctionAST(std::unique_ptr<PrototypeAST> prototype,
+                std::unique_ptr<ExpressionAST> body) :
                 prototype_(std::move(prototype)),
                 body_(std::move(body))
             {
             }
 
+            /**
+             * @brief Generate LLVM IR code.
+             *
+             * @return llvm::Function* Returns the LLVM IR function code.
+             */
             llvm::Function *codegen();
     };
 } // namespace obelisk

src/ast/number_expression_ast.h

@@ -5,20 +5,49 @@
 
 namespace obelisk
 {
+    /**
+     * @brief A number expression AST node.
+     *
+     */
     class NumberExpressionAST : public ExpressionAST
     {
         private:
+            /**
+             * @brief The number.
+             *
+             */
             double number_;
 
+            /**
+             * @brief Get the number.
+             *
+             * @return double Returns the number.
+             */
             double getNumber();
+
+            /**
+             * @brief Set the number.
+             *
+             * @param[in] number The number.
+             */
             void setNumber(double number);
 
         public:
+            /**
+             * @brief Construct a new NumberExpressionAST object.
+             *
+             * @param[in] number The number.
+             */
             NumberExpressionAST(double number) :
                 number_(number)
             {
             }
 
+            /**
+             * @brief Generate LLVM IR code for the number.
+             *
+             * @return llvm::Value* Returns the genrated IR code.
+             */
             llvm::Value *codegen() override;
     };
 } // namespace obelisk

src/ast/prototype_ast.cpp

@@ -3,10 +3,17 @@
 
 llvm::Function *obelisk::PrototypeAST::codegen()
 {
-    std::vector<llvm::Type *> doubles(args_.size(), llvm::Type::getDoubleTy(*TheContext));
-    llvm::FunctionType *FT = llvm::FunctionType::get(llvm::Type::getDoubleTy(*TheContext), doubles, false);
+    std::vector<llvm::Type *> doubles(args_.size(),
+        llvm::Type::getDoubleTy(*TheContext));
+    llvm::FunctionType *FT
+        = llvm::FunctionType::get(llvm::Type::getDoubleTy(*TheContext),
+            doubles,
+            false);
 
-    llvm::Function *F = llvm::Function::Create(FT, llvm::Function::ExternalLinkage, name_, obelisk::TheModule.get());
+    llvm::Function *F = llvm::Function::Create(FT,
+        llvm::Function::ExternalLinkage,
+        name_,
+        obelisk::TheModule.get());
 
     unsigned idx = 0;
     for (auto &arg : F->args())

src/ast/prototype_ast.h

@@ -8,30 +8,76 @@
 
 namespace obelisk
 {
+    /**
+     * @brief The prototype AST node.
+     *
+     */
     class PrototypeAST
     {
         private:
+            /**
+             * @brief The name of the prototype.
+             *
+             */
             std::string name_;
+            /**
+             * @brief The arguments the protype accepts.
+             *
+             */
             std::vector<std::string> args_;
 
+            /**
+             * @brief Set the name of the prototype.
+             *
+             * @param[in] name The name.
+             */
             void setName(const std::string& name);
+
+            /**
+             * @brief Get the arguments the prototype accepts.
+             *
+             * @return std::vector<std::string> Returns the arguments.
+             */
             std::vector<std::string> getArgs();
+
+            /**
+             * @brief Set the arguments the prototype accepts.
+             *
+             * @param[in] args The arguments.
+             */
             void setArgs(std::vector<std::string> args);
 
         public:
-            PrototypeAST(const std::string& name, std::vector<std::string> args) :
+            /**
+             * @brief Construct a new PrototypeAST object.
+             *
+             * @param[in] name The name of the prototype.
+             * @param[in] args The arguments the prototype accepts.
+             */
+            PrototypeAST(const std::string& name,
+                std::vector<std::string> args) :
                 name_(name),
                 args_(std::move(args))
             {
             }
 
+            /**
+             * @brief Get the name of the prototype.
+             *
+             * @return const std::string& Returns the name of the prototype.
+             */
             const std::string& getName() const
             {
                 return name_;
             }
 
+            /**
+             * @brief Generate LLVM IR code for the prototype.
+             *
+             * @return llvm::Function* Returns IR code for the prototype.
+             */
             llvm::Function* codegen();
     };
-} //namespace obelisk
+} // namespace obelisk
 
 #endif

src/ast/variable_expression_ast.h

@@ -7,21 +7,51 @@
 
 namespace obelisk
 {
+    /**
+     * @brief The variable expression AST node.
+     *
+     */
     class VariableExpressionAST : public ExpressionAST
     {
         private:
+            /**
+             * @brief The name of the variable.
+             *
+             */
             std::string name_;
+
+            /**
+             * @brief Get the name of the variable.
+             *
+             * @return std::string Returns the name of the variable.
+             */
             std::string getName();
+
+            /**
+             * @brief Set the name of the variable.
+             *
+             * @param[in] name The name of the variable.
+             */
             void setName(const std::string name);
 
         public:
+            /**
+             * @brief Construct a new VariableExpressionAST object.
+             *
+             * @param[in] name The name of the variable.
+             */
             VariableExpressionAST(const std::string &name) :
                 name_(name)
             {
             }
 
+            /**
+             * @brief Generate the variable LLVM IR code.
+             *
+             * @return llvm::Value* Returns the generated IR code.
+             */
             llvm::Value *codegen() override;
     };
-} //namespace obelisk
+} // namespace obelisk
 
 #endif

src/knowledge_base.cpp

@@ -1,167 +0,0 @@
-#include "knowledge_base.h"
-#include "models/action.h"
-#include "models/entity.h"
-#include "models/error.h"
-#include "models/fact.h"
-#include "models/rule.h"
-#include "models/suggest_action.h"
-#include "models/verb.h"
-
-#include <cstring>
-#include <filesystem>
-#include <iostream>
-#include <string>
-
-obelisk::KnowledgeBase::KnowledgeBase(const char* filename, int flags)
-{
-    filename_ = std::move(filename);
-    flags_    = std::move(flags);
-
-    std::filesystem::path path {filename};
-    auto dbExists = std::filesystem::exists(path);
-
-    auto result = sqlite3_open_v2(filename, &dbConnection_, flags, NULL);
-    if (result != SQLITE_OK)
-    {
-        throw new KnowledgeBaseException("database could not be opened");
-    }
-
-    enableForeignKeys();
-
-    if (!dbExists)
-    {
-        createTable(obelisk::Action::createTable);
-        createTable(obelisk::Entity::createTable);
-        createTable(obelisk::Verb::createTable);
-        createTable(obelisk::Fact::createTable);
-        createTable(obelisk::Rule::createTable);
-        createTable(obelisk::SuggestAction::createTable);
-    }
-}
-
-obelisk::KnowledgeBase::~KnowledgeBase()
-{
-    if (dbConnection_)
-    {
-        sqlite3_close_v2(dbConnection_);
-    }
-}
-
-void obelisk::KnowledgeBase::enableForeignKeys()
-{
-    char* errmsg;
-    int result = sqlite3_exec(dbConnection_, "PRAGMA foreign_keys = ON;", NULL, NULL, &errmsg);
-    if (result != SQLITE_OK)
-    {
-        if (errmsg)
-        {
-            throw obelisk::KnowledgeBaseException(errmsg);
-        }
-        else
-        {
-            throw obelisk::KnowledgeBaseException();
-        }
-    }
-}
-
-void obelisk::KnowledgeBase::createTable(std::function<const char*()> function)
-{
-    char* errmsg;
-    int result = sqlite3_exec(dbConnection_, function(), NULL, NULL, &errmsg);
-    if (result != SQLITE_OK)
-    {
-        if (errmsg)
-        {
-            throw obelisk::KnowledgeBaseException(errmsg);
-        }
-        else
-        {
-            throw obelisk::KnowledgeBaseException();
-        }
-    }
-}
-
-void obelisk::KnowledgeBase::addEntities(std::vector<obelisk::Entity>& entities)
-{
-    for (auto& entity : entities)
-    {
-        try
-        {
-            entity.insertEntity(dbConnection_);
-        }
-        catch (obelisk::DatabaseConstraintException& exception)
-        {
-            // ignore unique constraint error
-            if (std::strcmp(exception.what(), "UNIQUE constraint failed: entity.name") != 0)
-            {
-                throw;
-            }
-        }
-    }
-}
-
-void obelisk::KnowledgeBase::addVerbs(std::vector<obelisk::Verb>& verbs)
-{
-    for (auto& verb : verbs)
-    {
-        try
-        {
-            verb.insertVerb(dbConnection_);
-        }
-        catch (obelisk::DatabaseConstraintException& exception)
-        {
-            // ignore unique constraint error
-            if (std::strcmp(exception.what(), "UNIQUE constraint failed: verb.name") != 0)
-            {
-                throw;
-            }
-        }
-    }
-}
-
-void obelisk::KnowledgeBase::addFacts(std::vector<obelisk::Fact>& facts)
-{
-    for (auto& fact : facts)
-    {
-        try
-        {
-            fact.insertFact(dbConnection_);
-        }
-        catch (obelisk::DatabaseConstraintException& exception)
-        {
-            // ignore unique constraint error
-            if (std::strcmp(exception.what(),
-                    "UNIQUE constraint failed: fact.left_entity, fact.right_entity, fact.verb")
-                != 0)
-            {
-                throw;
-            }
-        }
-    }
-}
-
-void obelisk::KnowledgeBase::getEntity(obelisk::Entity& entity)
-{
-    entity.selectEntity(dbConnection_);
-}
-
-void obelisk::KnowledgeBase::getVerb(obelisk::Verb& verb)
-{
-    verb.selectVerb(dbConnection_);
-}
-
-void obelisk::KnowledgeBase::getFact(obelisk::Fact& fact)
-{
-    fact.selectFact(dbConnection_);
-}
-
-void obelisk::KnowledgeBase::getFloat(float& result1, float& result2, double var)
-{
-    result1 = (float) var;
-    result2 = (float) (var - (double) result1);
-}
-
-void obelisk::KnowledgeBase::getDouble(double& result, float var1, float var2)
-{
-    result = (double) ((double) var2 + (double) var1);
-}

src/lexer.cpp

@@ -7,7 +7,8 @@ obelisk::Lexer::Lexer(const std::string& sourceFile)
     fileStream_.open(sourceFile, std::ifstream::in);
     if (!fileStream_)
     {
-        throw obelisk::LexerException("could not open source file " + sourceFile);
+        throw obelisk::LexerException(
+            "could not open source file " + sourceFile);
     }
 }
 
@@ -40,7 +41,7 @@ int obelisk::Lexer::getToken()
 
         if (getIdentifier() == "rule")
         {
-            return Token::kTokenFact;
+            return Token::kTokenRule;
         }
 
         if (getIdentifier() == "action")

src/lib/include/obelisk.h

@@ -0,0 +1,82 @@
+#ifndef OBELISK_INCLUDE_OBELISK_H
+#define OBELISK_INCLUDE_OBELISK_H
+
+#include "knowledge_base.h"
+
+#include <memory>
+#include <string>
+
+/**
+ * @brief The obelisk namespace contains everything needed to compile obelisk
+ * code.
+ *
+ */
+namespace obelisk
+{
+    /**
+     * @brief The obelisk library provides everything needed to consult the
+     * KnowledgeBase.
+     *
+     */
+    class Obelisk
+    {
+        private:
+            std::unique_ptr<obelisk::KnowledgeBase> kb_;
+
+        public:
+            /**
+             * @brief Construct a new Obelisk object.
+             *
+             */
+            Obelisk(std::string filename);
+
+            /**
+             * @brief Destroy the Obelisk object.
+             *
+             */
+            ~Obelisk() = default;
+
+            /**
+             * @brief Get the obelisk version.
+             *
+             * @return std::string The version.
+             */
+            std::string getVersion();
+
+            /**
+             * @brief Get the obelisk library so version.
+             *
+             * @return int The version.
+             */
+            int getLibVersion();
+
+            /**
+             * @brief Query the obelisk KnowledgeBase to see if a Fact is true
+             * or not.
+             *
+             * @param[in] p_obelisk The obelisk object pointer.
+             * @param[in] left_entity The left entity.
+             * @param[in] verb The verb.
+             * @param[in] right_entity The right entity.
+             * @return double Returns whether or not the Fact is true.
+             */
+            double query(const std::string& leftEntity,
+                const std::string& verb,
+                const std::string& rightEntity);
+
+            /**
+             * @brief Query the Obelisk KnowledgeBase and return the suggested
+             * action to take.
+             *
+             * @param[in] leftEntity The left entity.
+             * @param[in] verb The verb.
+             * @param[in] rightEntity The right entity.
+             * @return std::string Returns the suggested action.
+             */
+            std::string queryAction(const std::string& leftEntity,
+                const std::string& verb,
+                const std::string& rightEntity);
+    };
+} // namespace obelisk
+
+#endif

src/lib/include/obelisk_c.h

@@ -0,0 +1,80 @@
+#ifndef OBELISK_INCLUDE_OBELISK_PROGRAM_H
+#define OBELISK_INCLUDE_OBELISK_PROGRAM_H
+
+/**
+ * @brief Struct wrapper around Obelisk class.
+ *
+ */
+typedef struct CObelisk CObelisk;
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /**
+     * @brief Create an obelisk object.
+     *
+     * @param[in] filename The obelisk KnowledgeBase file to use.
+     * @return CObelisk* Returns an obelisk object.
+     */
+    extern CObelisk* obelisk_open(const char* filename);
+
+    /**
+     * @brief Delete an obelisk object.
+     *
+     * @param[in] obelisk The obelisk object.
+     */
+    extern void obelisk_close(CObelisk* obelisk);
+
+    /**
+     * @brief Get the obelisk version.
+     *
+     * @param[in] obelisk The obelisk object.
+     * @return const char* Returns a string containing the version. This must be
+     * freed by the caller.
+     */
+    extern char* obelisk_get_version(CObelisk* obelisk);
+
+    /**
+     * @brief Query the obelisk KnowledgeBase to see if a Fact is true or false.
+     *
+     * @param[in] obelisk The obelisk object.
+     * @param[in] left_entity The left entity.
+     * @param[in] verb The verb.
+     * @param[in] right_entity The right entity.
+     * @return double Returns whether the Fact is true or false.
+     */
+    extern double obelisk_query(CObelisk* obelisk,
+        const char* left_entity,
+        const char* verb,
+        const char* right_entity);
+
+    /**
+     * @brief Query the obelisk KnowledgeBase to get a suggested Action to do.
+     *
+     * @param[in] obelisk The obelisk object.
+     * @param[in] left_entity The left entity.
+     * @param[in] verb The verb.
+     * @param[in] right_entity The right entity.
+     * @return char* Returns the Action to do or an empty string if there is no
+     * action.
+     */
+    extern char* obelisk_query_action(CObelisk* obelisk,
+        const char* left_entity,
+        const char* verb,
+        const char* right_entity);
+
+    /**
+     * @brief Get the obelisk library so version.
+     *
+     * @param[in] obelisk The obelisk object.
+     * @return int Returns the so version.
+     */
+    extern int obelisk_get_lib_version(CObelisk* obelisk);
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif

src/lib/knowledge_base.cpp

@@ -0,0 +1,284 @@
+#include "knowledge_base.h"
+#include "models/error.h"
+
+#include <cstring>
+#include <filesystem>
+#include <iostream>
+#include <string>
+
+obelisk::KnowledgeBase::KnowledgeBase(const char* filename, int flags)
+{
+    filename_ = std::move(filename);
+    flags_    = std::move(flags);
+
+    std::filesystem::path path {filename};
+    auto dbExists = std::filesystem::exists(path);
+
+    auto result = sqlite3_open_v2(filename, &dbConnection_, flags, NULL);
+    if (result != SQLITE_OK)
+    {
+        throw new KnowledgeBaseException("database could not be opened");
+    }
+
+    enableForeignKeys();
+
+    if (!dbExists)
+    {
+        createTable(obelisk::Action::createTable);
+        createTable(obelisk::Entity::createTable);
+        createTable(obelisk::Verb::createTable);
+        createTable(obelisk::Fact::createTable);
+        createTable(obelisk::Rule::createTable);
+        createTable(obelisk::SuggestAction::createTable);
+    }
+}
+
+obelisk::KnowledgeBase::~KnowledgeBase()
+{
+    if (dbConnection_)
+    {
+        sqlite3_close_v2(dbConnection_);
+    }
+}
+
+void obelisk::KnowledgeBase::enableForeignKeys()
+{
+    char* errmsg;
+    int result = sqlite3_exec(dbConnection_,
+        "PRAGMA foreign_keys = ON;",
+        NULL,
+        NULL,
+        &errmsg);
+    if (result != SQLITE_OK)
+    {
+        if (errmsg)
+        {
+            throw obelisk::KnowledgeBaseException(errmsg);
+        }
+        else
+        {
+            throw obelisk::KnowledgeBaseException();
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::createTable(std::function<const char*()> function)
+{
+    char* errmsg;
+    int result = sqlite3_exec(dbConnection_, function(), NULL, NULL, &errmsg);
+    if (result != SQLITE_OK)
+    {
+        if (errmsg)
+        {
+            throw obelisk::KnowledgeBaseException(errmsg);
+        }
+        else
+        {
+            throw obelisk::KnowledgeBaseException();
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addEntities(std::vector<obelisk::Entity>& entities)
+{
+    for (auto& entity : entities)
+    {
+        try
+        {
+            entity.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: entity.name")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addVerbs(std::vector<obelisk::Verb>& verbs)
+{
+    for (auto& verb : verbs)
+    {
+        try
+        {
+            verb.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: verb.name")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addActions(std::vector<obelisk::Action>& actions)
+{
+    for (auto& action : actions)
+    {
+        try
+        {
+            action.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: action.name")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addFacts(std::vector<obelisk::Fact>& facts)
+{
+    for (auto& fact : facts)
+    {
+        try
+        {
+            fact.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: fact.left_entity, fact.right_entity, fact.verb")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addSuggestActions(
+    std::vector<obelisk::SuggestAction>& suggestActions)
+{
+    for (auto& suggestAction : suggestActions)
+    {
+        try
+        {
+            suggestAction.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: suggest_action.fact, suggest_action.true_action, suggest_action.false_action")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::addRules(std::vector<obelisk::Rule>& rules)
+{
+    for (auto& rule : rules)
+    {
+        try
+        {
+            rule.insert(dbConnection_);
+        }
+        catch (obelisk::DatabaseConstraintException& exception)
+        {
+            // ignore unique constraint error
+            if (std::strcmp(exception.what(),
+                    "UNIQUE constraint failed: rule.fact, rule.reason")
+                != 0)
+            {
+                throw;
+            }
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::getEntity(obelisk::Entity& entity)
+{
+    entity.selectByName(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::getVerb(obelisk::Verb& verb)
+{
+    verb.selectByName(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::getAction(obelisk::Action& action)
+{
+    action.selectByName(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::getFact(obelisk::Fact& fact)
+{
+    fact.selectById(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::getSuggestAction(
+    obelisk::SuggestAction& suggestAction)
+{
+    suggestAction.selectById(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::getRule(obelisk::Rule& rule)
+{
+    rule.selectById(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::checkRule(obelisk::Fact& fact)
+{
+    std::vector<obelisk::Rule> rules;
+    obelisk::Rule::selectByReason(dbConnection_, fact.getId(), rules);
+    for (auto& rule : rules)
+    {
+        auto reason = rule.getReason();
+        getFact(reason);
+        if (reason.getIsTrue() > 0)
+        {
+            auto updateFact = rule.getFact();
+            updateFact.setIsTrue(1.0);
+            updateFact.updateIsTrue(dbConnection_);
+        }
+    }
+}
+
+void obelisk::KnowledgeBase::updateIsTrue(obelisk::Fact& fact)
+{
+    fact.updateIsTrue(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::queryFact(obelisk::Fact& fact)
+{
+    fact.selectByName(dbConnection_);
+}
+
+void obelisk::KnowledgeBase::querySuggestAction(obelisk::Fact& fact,
+    obelisk::Action& action)
+{
+    fact.selectActionByFact(dbConnection_, action);
+}
+
+void obelisk::KnowledgeBase::getFloat(float& result1,
+    float& result2,
+    double var)
+{
+    result1 = (float) var;
+    result2 = (float) (var - (double) result1);
+}
+
+void obelisk::KnowledgeBase::getDouble(double& result, float var1, float var2)
+{
+    result = (double) ((double) var2 + (double) var1);
+}

src/lib/knowledge_base.h

@@ -1,8 +1,11 @@
 #ifndef OBELISK_KNOWLEDGE_BASE_H
 #define OBELISK_KNOWLEDGE_BASE_H
 
+#include "models/action.h"
 #include "models/entity.h"
 #include "models/fact.h"
+#include "models/rule.h"
+#include "models/suggest_action.h"
 #include "models/verb.h"
 
 #include <sqlite3.h>
@@ -23,7 +26,7 @@ namespace obelisk
     {
         private:
             /**
-             * @brief The filename of the opened knowledge base.
+             * @brief The filename of the opened KnowledgeBase.
              *
              */
             const char* filename_;
@@ -61,7 +64,7 @@ namespace obelisk
              *
              * @param[in] filename The name of the file to save the knowledge
              * base as.
-             * @param[in] flags The flags to open the knowledge base with.
+             * @param[in] flags The flags to open the KnowledgeBase with.
              */
             KnowledgeBase(const char* filename, int flags);
 
@@ -72,19 +75,20 @@ namespace obelisk
              * base as.
              */
             KnowledgeBase(const char* filename) :
-                KnowledgeBase(filename, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE)
+                KnowledgeBase(filename,
+                    SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE)
             {
             }
 
             /**
              * @brief Destroy the KnowledgeBase object.
              *
-             * This will close the opened knowledge base before destroying it.
+             * This will close the opened KnowledgeBase before destroying it.
              */
             ~KnowledgeBase();
 
             /**
-             * @brief Add entities to the knowledge base.
+             * @brief Add entities to the KnowledgeBase.
              *
              * @param[in,out] entities The entities to add. If the insert is
              * successful it will have a row ID, if not the ID will be 0.
@@ -92,7 +96,7 @@ namespace obelisk
             void addEntities(std::vector<obelisk::Entity>& entities);
 
             /**
-             * @brief Add verbs to the knowledge base.
+             * @brief Add verbs to the KnowledgeBase.
              *
              * @param[in,out] verbs The verbs to add. If the insert is
              * successful it will have a row ID, if not the ID will be 0.
@@ -100,7 +104,15 @@ namespace obelisk
             void addVerbs(std::vector<obelisk::Verb>& verbs);
 
             /**
-             * @brief Add facts to the database.
+             * @brief Add actions to the KnowledgeBase.
+             *
+             * @param[in,out] actions The actions to add. If the insert is
+             * successful it will have a row ID, if nto the ID will be 0.
+             */
+            void addActions(std::vector<obelisk::Action>& actions);
+
+            /**
+             * @brief Add facts to the KnowledgeBase.
              *
              * @param[in,out] facts The facts to add. If the insert is
              * successful it will have a row ID, if not the ID will be 0.
@@ -108,7 +120,25 @@ namespace obelisk
             void addFacts(std::vector<obelisk::Fact>& facts);
 
             /**
-             * @brief Get an entity object based on the ID it contains.
+             * @brief Add suggested actions to the KnowledgeBase.
+             *
+             * @param[in,out] suggestActions The suggested actions to add. If
+             * the insert is successful it will have a row ID, if not the ID
+             * will be 0.
+             */
+            void addSuggestActions(
+                std::vector<obelisk::SuggestAction>& suggestActions);
+
+            /**
+             * @brief Add rules to the KnowledgeBase.
+             *
+             * @param[in,out] rules The rules to add. If the insert is
+             * successful it will have a row ID, if not the ID will be 0.
+             */
+            void addRules(std::vector<obelisk::Rule>& rules);
+
+            /**
+             * @brief Get an Entity object based on the ID it contains.
              *
              * @param[in,out] entity The Entity object should contain just the
              * ID and the rest will be filled in.
@@ -116,7 +146,7 @@ namespace obelisk
             void getEntity(obelisk::Entity& entity);
 
             /**
-             * @brief Get a verb object based on the ID it contains.
+             * @brief Get a Verb object based on the ID it contains.
              *
              * @param[in,out] verb The Verb object should contain just the ID
              * and the rest will be filled in.
@@ -124,20 +154,76 @@ namespace obelisk
             void getVerb(obelisk::Verb& verb);
 
             /**
-             * @brief Get a fact object based on the ID it contains.
+             * @brief Get an Action based on the ID it contains.
              *
-             * @param[in,out] fact The fact object should contain just the ID
+             * @param[in] action The Action object should contain just the ID
+             * and the rest will be filled in.
+             */
+            void getAction(obelisk::Action& action);
+
+            /**
+             * @brief Get a Fact object based on the ID it contains.
+             *
+             * @param[in,out] fact The Fact object should contain just the ID
              * and the rest will be filled in.
              */
             void getFact(obelisk::Fact& fact);
 
+            /**
+             * @brief Get a SuggestAction based on the ID it contains.
+             *
+             * @param[in,out] suggestAction The SuggestAction object should
+             * contain just the ID and the rest will be filled in.
+             */
+            void getSuggestAction(obelisk::SuggestAction& suggestAction);
+
+            /**
+             * @brief Get a Rule based on the ID it contains.
+             *
+             * @param[in,out] rule The Rule object should  contain just the ID
+             * and the rest will be filled in.
+             */
+            void getRule(obelisk::Rule& rule);
+
+            /**
+             * @brief Check if a rule looks for this Fact, if so update its
+             * truth.
+             *
+             * @param[in,out] fact The Fact to check for existing rules.
+             */
+            void checkRule(obelisk::Fact& fact);
+
+            /**
+             * @brief Update the is true field in the KnowledgeBase.
+             *
+             * @param[in,out] fact The fact to update.
+             */
+            void updateIsTrue(obelisk::Fact& fact);
+
+            /**
+             * @brief Query the KnowledgeBase to see if a Fact is true or false.
+             *
+             * @param[in] fact The Fact to check.
+             */
+            void queryFact(obelisk::Fact& fact);
+
+            /**
+             * @brief Query the KnowledgeBase to get a suggested action based
+             * on a Fact.
+             * If a SuggestAction doesn't exist, it will return an empty Action.
+             *
+             * @param[in] fact The Fact to search for.
+             * @param[out] action The Action that is suggested to take.
+             */
+            void querySuggestAction(obelisk::Fact& fact,
+                obelisk::Action& action);
+
             /**
              * @brief Take a float and divide it into 2 floats.
              *
              * This is useful to store doubles in SQLite since SQLite doesn't
-             * have a double type.
-             * Instead just store the 2 floats in the database. Then after
-             * selecting them combine them.
+             * have a double type. Instead just store the 2 floats in the
+             * database. Then after selecting them combine them.
              *
              * @param[out] result1 The first float generated from the double.
              * @param[out] result2 The second float generated from the double.

src/lib/meson.build

@@ -0,0 +1,36 @@
+conf_data = configuration_data()
+conf_data.set('version', meson.project_version())
+conf_data.set('so_version', project_version_lib)
+configure_file(input : 'version.h.in',
+    output : 'version.h',
+    configuration : conf_data
+)
+
+subdir('models')
+
+obelisk_lib_sources = files(
+    'obelisk.cpp',
+    'obelisk.c',
+    'obelisk_wrapper.cpp',
+    'knowledge_base.cpp'
+)
+
+obelisk_lib_sources += obelisk_model_sources
+
+sqlite3 = dependency('sqlite3')
+
+incdirs = include_directories(['.', 'include'])
+lib = library('obelisk',
+    obelisk_lib_sources,
+    include_directories: incdirs,
+    dependencies : [sqlite3],
+    version : meson.project_version(),
+    soversion : project_version_lib,
+    install : true
+)
+
+libobelisk = declare_dependency(
+    include_directories : incdirs,
+    link_with : lib,
+    sources : obelisk_lib_sources
+)

src/lib/models/action.cpp

@@ -0,0 +1,168 @@
+#include "models/action.h"
+#include "models/error.h"
+
+const char* obelisk::Action::createTable()
+{
+    return R"(
+        CREATE TABLE "action" (
+            "id"   INTEGER NOT NULL UNIQUE,
+            "name" TEXT NOT NULL CHECK(trim(name) != '') UNIQUE,
+            PRIMARY KEY("id" AUTOINCREMENT)
+        );
+    )";
+}
+
+void obelisk::Action::selectByName(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT id, name FROM action WHERE name=?",
+        -1,
+        &ppStmt,
+        nullptr);
+
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_STATIC);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // no rows in the database
+            break;
+        case SQLITE_ROW :
+            setId(sqlite3_column_int(ppStmt, 0));
+            setName((char*) sqlite3_column_text(ppStmt, 1));
+            break;
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Action::insert(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "INSERT INTO action (name) VALUES (?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result
+        = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_TRANSIENT);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            setId((int) sqlite3_last_insert_rowid(dbConnection));
+            sqlite3_set_last_insert_rowid(dbConnection, 0);
+            break;
+        case SQLITE_CONSTRAINT :
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+int& obelisk::Action::getId()
+{
+    return id_;
+}
+
+void obelisk::Action::setId(int id)
+{
+    id_ = id;
+}
+
+std::string& obelisk::Action::getName()
+{
+    return name_;
+}
+
+void obelisk::Action::setName(std::string name)
+{
+    name_ = name;
+}

src/lib/models/action.h

@@ -1,6 +1,8 @@
 #ifndef OBELISK_MODELS_ACTION_H
 #define OBELISK_MODELS_ACTION_H
 
+#include <sqlite3.h>
+
 #include <string>
 
 namespace obelisk
@@ -14,7 +16,7 @@ namespace obelisk
     {
         private:
             /**
-             * @brief The ID of the Action in the knowledge base.
+             * @brief The ID of the Action in the KnowledgeBase.
              *
              */
             int id_;
@@ -71,7 +73,7 @@ namespace obelisk
             }
 
             /**
-             * @brief Create the Action table in the knowledge base.
+             * @brief Create the Action table in the KnowledgeBase.
              *
              * @return const char* Returns the query used to create the table.
              */
@@ -104,6 +106,22 @@ namespace obelisk
              * @param[in] name The name of the Action.
              */
             void setName(std::string name);
+
+            /**
+             * @brief Select an Action from the datbase based on the object
+             * name.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectByName(sqlite3* dbConnection);
+
+            /**
+             * @brief Insert an Action into the KnowledgeBase based on the
+             * object's fields.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void insert(sqlite3* dbConnection);
     };
 } // namespace obelisk
 

src/lib/models/entity.cpp

@@ -12,7 +12,7 @@ const char* obelisk::Entity::createTable()
     )";
 }
 
-void obelisk::Entity::selectEntity(sqlite3* dbConnection)
+void obelisk::Entity::selectByName(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -21,7 +21,11 @@ void obelisk::Entity::selectEntity(sqlite3* dbConnection)
 
     sqlite3_stmt* ppStmt = nullptr;
 
-    auto result = sqlite3_prepare_v2(dbConnection, "SELECT id, name FROM entity WHERE name=?", -1, &ppStmt, nullptr);
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT id, name FROM entity WHERE name=?",
+        -1,
+        &ppStmt,
+        nullptr);
 
     if (result != SQLITE_OK)
     {
@@ -76,7 +80,7 @@ void obelisk::Entity::selectEntity(sqlite3* dbConnection)
     }
 }
 
-void obelisk::Entity::insertEntity(sqlite3* dbConnection)
+void obelisk::Entity::insert(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -85,13 +89,18 @@ void obelisk::Entity::insertEntity(sqlite3* dbConnection)
 
     sqlite3_stmt* ppStmt = nullptr;
 
-    auto result = sqlite3_prepare_v2(dbConnection, "INSERT INTO entity (name) VALUES (?)", -1, &ppStmt, nullptr);
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "INSERT INTO entity (name) VALUES (?)",
+        -1,
+        &ppStmt,
+        nullptr);
     if (result != SQLITE_OK)
     {
         throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
     }
 
-    result = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_TRANSIENT);
+    result
+        = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_TRANSIENT);
     switch (result)
     {
         case SQLITE_OK :
@@ -118,7 +127,8 @@ void obelisk::Entity::insertEntity(sqlite3* dbConnection)
             sqlite3_set_last_insert_rowid(dbConnection, 0);
             break;
         case SQLITE_CONSTRAINT :
-            throw obelisk::DatabaseConstraintException(sqlite3_errmsg(dbConnection));
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
         case SQLITE_BUSY :
             throw obelisk::DatabaseBusyException();
             break;

src/lib/models/entity.h

@@ -16,10 +16,11 @@ namespace obelisk
     {
         private:
             /**
-             * @brief The ID of the Entity.
+             * @brief The ID of the Entity in the KnowledgeBase.
              *
              */
             int id_;
+
             /**
              * @brief The name of the Entity.
              *
@@ -72,7 +73,7 @@ namespace obelisk
             }
 
             /**
-             * @brief Create the table in the knowledge base.
+             * @brief Create the table in the KnowledgeBase.
              *
              * @return const char* Returns the query used to create the table.
              */
@@ -107,20 +108,20 @@ namespace obelisk
             void setName(std::string name);
 
             /**
-             * @brief Select an Entity from the database based on the object's
-             * ID.
+             * @brief Select an Entity from the KnowledgeBase based on the
+             * object's name.
              *
              * @param[in] dbConnection The database connection to use.
              */
-            void selectEntity(sqlite3* dbConnection);
+            void selectByName(sqlite3* dbConnection);
 
             /**
-             * @brief Insert an Entity into the database based on the object's
-             * fields.
+             * @brief Insert an Entity into the KnowledgeBase based on the
+             * object's fields.
              *
              * @param[in] dbConnection The database connection to use.
              */
-            void insertEntity(sqlite3* dbConnection);
+            void insert(sqlite3* dbConnection);
     };
 } // namespace obelisk
 

src/lib/models/error.h

@@ -0,0 +1,193 @@
+#ifndef OBELISK_MODELS_ERROR_H
+#define OBELISK_MODELS_ERROR_H
+
+#include <exception>
+#include <string>
+
+namespace obelisk
+{
+    /**
+     * @brief Exception thrown by database models.
+     *
+     */
+    class DatabaseException : public std::exception
+    {
+        protected:
+            /**
+             * @brief The error message describing the exception.
+             *
+             */
+            std::string errorMessage_;
+
+        public:
+            /**
+             * @brief Construct a new DatabaseException object.
+             *
+             */
+            DatabaseException() :
+                errorMessage_("an unknown error ocurred")
+            {
+            }
+
+            /**
+             * @brief Construct a new DatabaseException object.
+             *
+             * @param[in] errorCode The error code that came from sqlite.
+             */
+            DatabaseException(const int errorCode) :
+                errorMessage_(
+                    "database error " + std::to_string(errorCode) + " ocurred")
+            {
+            }
+
+            /**
+             * @brief Construct a new DatabaseException object.
+             *
+             * @param[in] errorMessage The error message to describe the
+             * exception.
+             */
+            DatabaseException(const std::string& errorMessage) :
+                errorMessage_(errorMessage)
+            {
+            }
+
+            /**
+             * @brief Retreive the exception message as a C type string.
+             *
+             * @return const char* The error message.
+             */
+            virtual const char* what() const noexcept
+            {
+                return errorMessage_.c_str();
+            }
+
+            /**
+             * @brief Set the error message.
+             *
+             * @param[in] errorMessage The error message.
+             */
+            virtual void setErrorMessage(const std::string errorMessage)
+            {
+                errorMessage_ = errorMessage;
+            }
+    };
+
+    /**
+     * @brief Exception thrown if the string or blob size exceeds sqlite's
+     * limits.
+     *
+     */
+    class DatabaseSizeException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseSizeException object.
+             *
+             */
+            DatabaseSizeException()
+            {
+                setErrorMessage("size of string or blob exceeds limits");
+            }
+    };
+
+    /**
+     * @brief Exception thrown if the index used it out of range.
+     *
+     */
+    class DatabaseRangeException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseRangeException object.
+             *
+             */
+            DatabaseRangeException()
+            {
+                setErrorMessage("parameter index is out of range");
+            }
+    };
+
+    /**
+     * @brief Exception thrown if there is not enough memory to perform the
+     * operation.
+     *
+     */
+    class DatabaseMemoryException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseMemoryException object.
+             *
+             */
+            DatabaseMemoryException()
+            {
+                setErrorMessage("not enough memory for operation");
+            }
+    };
+
+    /**
+     * @brief Exception thrown if the database was busy.
+     *
+     */
+    class DatabaseBusyException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseBusyException object.
+             *
+             */
+            DatabaseBusyException()
+            {
+                setErrorMessage(
+                    "database was busy and operation was not performed");
+            }
+    };
+
+    /**
+     * @brief Exception thrown if there is a misuse of the databse.
+     *
+     */
+    class DatabaseMisuseException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseMisuseException object.
+             *
+             */
+            DatabaseMisuseException()
+
+            {
+                setErrorMessage("misuse of the database routine");
+            }
+    };
+
+    /**
+     * @brief Exception thrown if a constraint was violated.
+     *
+     */
+    class DatabaseConstraintException : public obelisk::DatabaseException
+    {
+        public:
+            /**
+             * @brief Construct a new DatabaseConstraintException object.
+             *
+             */
+            DatabaseConstraintException()
+            {
+                setErrorMessage("a constraint exception occurred");
+            }
+
+            /**
+             * @brief Construct a new DatabaseConstraintException object.
+             *
+             * @param[in] errorMessage The error message to send when the
+             * constraint is violated.
+             */
+            DatabaseConstraintException(const std::string& errorMessage)
+            {
+                setErrorMessage(errorMessage);
+            }
+    };
+} // namespace obelisk
+
+#endif

src/lib/models/fact.cpp

@@ -0,0 +1,600 @@
+#include "models/error.h"
+#include "models/fact.h"
+
+const char* obelisk::Fact::createTable()
+{
+    return R"(
+        CREATE TABLE "fact" (
+            "id"           INTEGER NOT NULL UNIQUE,
+            "left_entity"  INTEGER NOT NULL,
+            "verb"         INTEGER NOT NULL,
+            "right_entity" INTEGER NOT NULL,
+            "is_true"      INTEGER NOT NULL DEFAULT 0,
+            PRIMARY KEY("id" AUTOINCREMENT),
+            UNIQUE("left_entity", "right_entity", "verb")
+            FOREIGN KEY("verb") REFERENCES "verb"("id") ON DELETE RESTRICT,
+            FOREIGN KEY("right_entity") REFERENCES "entity"("id") ON DELETE RESTRICT,
+            FOREIGN KEY("left_entity") REFERENCES "entity"("id") ON DELETE RESTRICT
+        );
+    )";
+}
+
+void obelisk::Fact::selectById(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    const char* query;
+    if (getId() == 0)
+    {
+        query
+            = "SELECT id, left_entity, right_entity, verb, is_true FROM fact WHERE (left_entity=? AND right_entity=? AND verb=?)";
+    }
+    else
+    {
+        query
+            = "SELECT id, left_entity, right_entity, verb, is_true FROM fact WHERE (id=?)";
+    }
+    auto result = sqlite3_prepare_v2(dbConnection, query, -1, &ppStmt, nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    if (getId() == 0)
+    {
+        result = sqlite3_bind_int(ppStmt, 1, getLeftEntity().getId());
+        switch (result)
+        {
+            case SQLITE_OK :
+                break;
+            case SQLITE_TOOBIG :
+                throw obelisk::DatabaseSizeException();
+                break;
+            case SQLITE_RANGE :
+                throw obelisk::DatabaseRangeException();
+                break;
+            case SQLITE_NOMEM :
+                throw obelisk::DatabaseMemoryException();
+                break;
+            default :
+                throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+                break;
+        }
+
+        result = sqlite3_bind_int(ppStmt, 2, getRightEntity().getId());
+        switch (result)
+        {
+            case SQLITE_OK :
+                break;
+            case SQLITE_TOOBIG :
+                throw obelisk::DatabaseSizeException();
+                break;
+            case SQLITE_RANGE :
+                throw obelisk::DatabaseRangeException();
+                break;
+            case SQLITE_NOMEM :
+                throw obelisk::DatabaseMemoryException();
+                break;
+            default :
+                throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+                break;
+        }
+
+        result = sqlite3_bind_int(ppStmt, 3, getVerb().getId());
+        switch (result)
+        {
+            case SQLITE_OK :
+                break;
+            case SQLITE_TOOBIG :
+                throw obelisk::DatabaseSizeException();
+                break;
+            case SQLITE_RANGE :
+                throw obelisk::DatabaseRangeException();
+                break;
+            case SQLITE_NOMEM :
+                throw obelisk::DatabaseMemoryException();
+                break;
+            default :
+                throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+                break;
+        }
+    }
+    else
+    {
+        result = sqlite3_bind_int(ppStmt, 1, getId());
+        switch (result)
+        {
+            case SQLITE_OK :
+                break;
+            case SQLITE_TOOBIG :
+                throw obelisk::DatabaseSizeException();
+                break;
+            case SQLITE_RANGE :
+                throw obelisk::DatabaseRangeException();
+                break;
+            case SQLITE_NOMEM :
+                throw obelisk::DatabaseMemoryException();
+                break;
+            default :
+                throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+                break;
+        }
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // no rows in the database
+            break;
+        case SQLITE_ROW :
+            setId(sqlite3_column_int(ppStmt, 0));
+            getLeftEntity().setId(sqlite3_column_int(ppStmt, 1));
+            getRightEntity().setId(sqlite3_column_int(ppStmt, 2));
+            getVerb().setId(sqlite3_column_int(ppStmt, 3));
+            setIsTrue(sqlite3_column_int(ppStmt, 4));
+            break;
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Fact::selectByName(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT fact.id, fact.left_entity, fact.right_entity, fact.verb, fact.is_true FROM fact LEFT JOIN entity le ON le.id = fact.left_entity LEFT JOIN entity re ON re.id = fact.right_entity LEFT JOIN verb v ON fact.verb = v.id WHERE (le.name=? AND v.name=? AND re.name=?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_text(ppStmt,
+        1,
+        getLeftEntity().getName().c_str(),
+        -1,
+        SQLITE_STATIC);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_text(ppStmt,
+        2,
+        getVerb().getName().c_str(),
+        -1,
+        SQLITE_STATIC);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_text(ppStmt,
+        3,
+        getRightEntity().getName().c_str(),
+        -1,
+        SQLITE_STATIC);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // no rows in the database
+            break;
+        case SQLITE_ROW :
+            setId(sqlite3_column_int(ppStmt, 0));
+            getLeftEntity().setId(sqlite3_column_int(ppStmt, 1));
+            getRightEntity().setId(sqlite3_column_int(ppStmt, 2));
+            getVerb().setId(sqlite3_column_int(ppStmt, 3));
+            setIsTrue(sqlite3_column_int(ppStmt, 4));
+            break;
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Fact::selectActionByFact(sqlite3* dbConnection,
+    obelisk::Action& action)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT CASE f.is_true WHEN 0 THEN (SELECT name FROM action WHERE id = fa.id) WHEN 1 THEN (SELECT name from action WHERE id = ta.id) END action FROM suggest_action LEFT JOIN action ta ON ta.id = suggest_action.true_action LEFT JOIN action fa ON fa.id = suggest_action.false_action LEFT JOIN fact f ON f.id = suggest_action.fact WHERE (f.id = ?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // no rows in the database
+            break;
+        case SQLITE_ROW :
+            action.setName((char*) sqlite3_column_text(ppStmt, 0));
+            break;
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Fact::insert(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "INSERT INTO fact (left_entity, right_entity, verb, is_true) VALUES (?, ?, ?, ?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, getLeftEntity().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 2, getRightEntity().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 3, getVerb().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 4, getIsTrue());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            setId((int) sqlite3_last_insert_rowid(dbConnection));
+            sqlite3_set_last_insert_rowid(dbConnection, 0);
+            break;
+        case SQLITE_CONSTRAINT :
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Fact::updateIsTrue(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "UPDATE fact SET is_true=? WHERE id=?",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, getIsTrue());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 2, getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // Row updated
+            break;
+        case SQLITE_CONSTRAINT :
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+int& obelisk::Fact::getId()
+{
+    return id_;
+}
+
+void obelisk::Fact::setId(int id)
+{
+    id_ = id;
+}
+
+obelisk::Entity& obelisk::Fact::getLeftEntity()
+{
+    return leftEntity_;
+}
+
+void obelisk::Fact::setLeftEntity(obelisk::Entity leftEntity)
+{
+    leftEntity_ = leftEntity;
+}
+
+obelisk::Entity& obelisk::Fact::getRightEntity()
+{
+    return rightEntity_;
+}
+
+void obelisk::Fact::setRightEntity(obelisk::Entity rightEntity)
+{
+    rightEntity_ = rightEntity;
+}
+
+obelisk::Verb& obelisk::Fact::getVerb()
+{
+    return verb_;
+}
+
+void obelisk::Fact::setVerb(obelisk::Verb verb)
+{
+    verb_ = verb;
+}
+
+double& obelisk::Fact::getIsTrue()
+{
+    return isTrue_;
+}
+
+void obelisk::Fact::setIsTrue(double isTrue)
+{
+    isTrue_ = isTrue;
+}

src/lib/models/fact.h

@@ -0,0 +1,247 @@
+#ifndef OBELISK_MODELS_FACT_H
+#define OBELISK_MODELS_FACT_H
+
+#include "models/action.h"
+#include "models/entity.h"
+#include "models/fact.h"
+#include "models/verb.h"
+
+#include <string>
+
+namespace obelisk
+{
+    /**
+     * @brief The Fact model represents truth in the releationship between two
+     * entities separated by a verb.
+     *
+     */
+    class Fact
+    {
+        private:
+            /**
+             * @brief The ID of the Fact in the KnowledgeBase.
+             *
+             */
+            int id_;
+
+            /**
+             * @brief The Entity from the left side of the expression.
+             *
+             */
+            obelisk::Entity leftEntity_;
+
+            /**
+             * @brief The Entity from the right side of the expression.
+             *
+             */
+            obelisk::Entity rightEntity_;
+
+            /**
+             * @brief The Verb that represents the relationship in the
+             * expression.
+             *
+             */
+            obelisk::Verb verb_;
+
+            /**
+             * @brief Whether or not the fact is considered true or not.
+             *
+             */
+            double isTrue_;
+
+        public:
+            /**
+             * @brief Construct a new Fact object.
+             *
+             */
+            Fact() :
+                id_(0),
+                leftEntity_(),
+                rightEntity_(),
+                verb_(),
+                isTrue_(0)
+            {
+            }
+
+            /**
+             * @brief Construct a new Fact object.
+             *
+             * @param[in] id The ID of the Fact in the KnowledgeBase.
+             */
+            Fact(int id) :
+                id_(id),
+                leftEntity_(),
+                rightEntity_(),
+                verb_(),
+                isTrue_(0)
+            {
+            }
+
+            /**
+             * @brief Construct a new Fact object.
+             *
+             * @param[in] leftEntity The Entity on the left side of the
+             * expression.
+             * @param[in] rightEntity The Entity on the right side of the
+             * expression.
+             * @param[in] verb The Verb separating the entities.
+             * @param[in] isTrue Whether or not the fact is true.
+             */
+            Fact(obelisk::Entity leftEntity,
+                obelisk::Entity rightEntity,
+                obelisk::Verb verb,
+                double isTrue = 0) :
+                id_(0),
+                leftEntity_(leftEntity),
+                rightEntity_(rightEntity),
+                verb_(verb),
+                isTrue_(isTrue)
+            {
+            }
+
+            /**
+             * @brief Construct a new Fact object.
+             *
+             * @param[in] id The ID of the Fact in the KnowledgeBase.
+             * @param[in] leftEntity The Entity on the left side of the
+             * expression.
+             * @param[in] rightEntity The Entity on the right side of the
+             * expression.
+             * @param[in] verb The Verb separating the entities.
+             * @param[in] isTrue Whether or not the fact is true.
+             */
+            Fact(int id,
+                obelisk::Entity leftEntity,
+                obelisk::Entity rightEntity,
+                obelisk::Verb verb,
+                double isTrue = 0) :
+                id_(id),
+                leftEntity_(leftEntity),
+                rightEntity_(rightEntity),
+                verb_(verb),
+                isTrue_(isTrue)
+            {
+            }
+
+            /**
+             * @brief Create the Fact table in the KnowledgeBase.
+             *
+             * @return const char* Returns the query used to create the table.
+             */
+            static const char* createTable();
+
+            /**
+             * @brief Get the ID of the Fact
+             *
+             * @return int& Returns the ID.
+             */
+            int& getId();
+
+            /**
+             * @brief Set the ID of the Fact.
+             *
+             * @param[in] id Set the ID of the Fact.
+             */
+            void setId(int id);
+
+            /**
+             * @brief Get the left Entity object.
+             *
+             * @return Entity& The left Entity.
+             */
+            Entity& getLeftEntity();
+
+            /**
+             * @brief Set the left Entity object.
+             *
+             * @param[in] leftEntity The left Entity to set.
+             */
+            void setLeftEntity(obelisk::Entity leftEntity);
+
+            /**
+             * @brief Get the right Entity object.
+             *
+             * @return Entity& The right Entity.
+             */
+            Entity& getRightEntity();
+
+            /**
+             * @brief Set the right Entity object.
+             *
+             * @param[in] rightEntity The right Entity to set.
+             */
+            void setRightEntity(obelisk::Entity rightEntity);
+
+            /**
+             * @brief Get the Verb object.
+             *
+             * @return Verb& The Verb.
+             */
+            Verb& getVerb();
+
+            /**
+             * @brief Set the Verb object.
+             *
+             * @param[in] verb The Verb.
+             */
+            void setVerb(obelisk::Verb verb);
+
+            /**
+             * @brief Gets the isTrue value.
+             *
+             * @return true If the Fact is considered true.
+             * @return false If the Fact is considered false.
+             */
+            double& getIsTrue();
+
+            /**
+             * @brief Set the Fact as true or false.
+             *
+             * @param[in] isTrue Whether or not the Fact is true.
+             */
+            void setIsTrue(double isTrue);
+
+            /**
+             * @brief Select the Fact from the KnowledgeBase by IDs of the
+             * sub-objects.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectById(sqlite3* dbConnection);
+
+            /**
+             * @brief Select the Fact from the KnowledgeBase by the name's of
+             * the entities and verb.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectByName(sqlite3* dbConnection);
+
+            /**
+             * @brief Select an Action from the KnowledgeBase using the provided
+             * Fact.
+             *
+             * @param[in] dbConnection The database connection to use.
+             * @param[out] action The Action to take based on the provided fact.
+             */
+            void selectActionByFact(sqlite3* dbConnection,
+                obelisk::Action& action);
+
+            /**
+             * @brief Insert the Fact into the KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void insert(sqlite3* dbConnection);
+
+            /**
+             * @brief Update whether or not the fact is true in the
+             * KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection.
+             */
+            void updateIsTrue(sqlite3* dbConnection);
+    };
+} // namespace obelisk
+
+#endif

src/lib/models/rule.cpp

@@ -0,0 +1,286 @@
+#include "models/error.h"
+#include "models/rule.h"
+
+const char* obelisk::Rule::createTable()
+{
+    return R"(
+        CREATE TABLE "rule" (
+            "id"     INTEGER NOT NULL UNIQUE,
+            "fact"   INTEGER NOT NULL,
+            "reason" INTEGER NOT NULL CHECK("reason" != "fact"),
+            PRIMARY KEY("id" AUTOINCREMENT),
+            UNIQUE("fact", "reason"),
+            FOREIGN KEY("fact") REFERENCES "fact"("id") ON DELETE RESTRICT,
+            FOREIGN KEY("reason") REFERENCES "fact"("id") ON DELETE RESTRICT
+        );
+    )";
+}
+
+void obelisk::Rule::selectById(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT id, fact, reason FROM rule WHERE (fact=? AND reason=?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, getFact().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 2, getReason().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            // no rows in the database
+            break;
+        case SQLITE_ROW :
+            setId(sqlite3_column_int(ppStmt, 0));
+            getFact().setId(sqlite3_column_int(ppStmt, 1));
+            getReason().setId(sqlite3_column_int(ppStmt, 2));
+            break;
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Rule::insert(sqlite3* dbConnection)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "INSERT INTO rule (fact, reason) VALUES (?, ?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, getFact().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_bind_int(ppStmt, 2, getReason().getId());
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_step(ppStmt);
+    switch (result)
+    {
+        case SQLITE_DONE :
+            setId((int) sqlite3_last_insert_rowid(dbConnection));
+            sqlite3_set_last_insert_rowid(dbConnection, 0);
+            break;
+        case SQLITE_CONSTRAINT :
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
+        case SQLITE_BUSY :
+            throw obelisk::DatabaseBusyException();
+            break;
+        case SQLITE_MISUSE :
+            throw obelisk::DatabaseMisuseException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+void obelisk::Rule::selectByReason(sqlite3* dbConnection,
+    int reasonId,
+    std::vector<obelisk::Rule>& rules)
+{
+    if (dbConnection == nullptr)
+    {
+        throw obelisk::DatabaseException("database isn't open");
+    }
+
+    sqlite3_stmt* ppStmt = nullptr;
+
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT id, fact, reason FROM rule WHERE (reason=?)",
+        -1,
+        &ppStmt,
+        nullptr);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+
+    result = sqlite3_bind_int(ppStmt, 1, reasonId);
+    switch (result)
+    {
+        case SQLITE_OK :
+            break;
+        case SQLITE_TOOBIG :
+            throw obelisk::DatabaseSizeException();
+            break;
+        case SQLITE_RANGE :
+            throw obelisk::DatabaseRangeException();
+            break;
+        case SQLITE_NOMEM :
+            throw obelisk::DatabaseMemoryException();
+            break;
+        default :
+            throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+            break;
+    }
+
+    while ((result = sqlite3_step(ppStmt)) != SQLITE_DONE)
+    {
+        switch (result)
+        {
+            case SQLITE_ROW :
+                rules.push_back(obelisk::Rule(sqlite3_column_int(ppStmt, 0),
+                    obelisk::Fact(sqlite3_column_int(ppStmt, 1)),
+                    obelisk::Fact(sqlite3_column_int(ppStmt, 2))));
+                break;
+            case SQLITE_BUSY :
+                throw obelisk::DatabaseBusyException();
+                break;
+            case SQLITE_MISUSE :
+                throw obelisk::DatabaseMisuseException();
+                break;
+            default :
+                throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+                break;
+        }
+    }
+
+    result = sqlite3_finalize(ppStmt);
+    if (result != SQLITE_OK)
+    {
+        throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
+    }
+}
+
+int& obelisk::Rule::getId()
+{
+    return id_;
+}
+
+void obelisk::Rule::setId(int id)
+{
+    id_ = id;
+}
+
+obelisk::Fact& obelisk::Rule::getFact()
+{
+    return fact_;
+}
+
+void obelisk::Rule::setFact(obelisk::Fact fact)
+{
+    fact_ = fact;
+}
+
+obelisk::Fact& obelisk::Rule::getReason()
+{
+    return reason_;
+}
+
+void obelisk::Rule::setReason(obelisk::Fact reason)
+{
+    reason_ = reason;
+}

src/lib/models/rule.h

@@ -0,0 +1,163 @@
+#ifndef OBELISK_MODELS_RULE_H
+#define OBELISK_MODELS_RULE_H
+
+#include "models/fact.h"
+
+#include <string>
+#include <vector>
+
+namespace obelisk
+{
+    /**
+     * @brief The Rule model represents a truth relation between 2 Facts.
+     *
+     */
+    class Rule
+    {
+        private:
+            /**
+             * @brief The ID of the Rule in the KnowledgeBase.
+             *
+             */
+            int id_;
+
+            /**
+             * @brief The Fact that depends on the Fact reason being true.
+             *
+             */
+            obelisk::Fact fact_;
+
+            /**
+             * @brief The Fact that makes the other Fact true or false.
+             *
+             */
+            obelisk::Fact reason_;
+
+        public:
+            /**
+             * @brief Construct a new Rule object.
+             *
+             */
+            Rule() :
+                id_(0),
+                fact_(),
+                reason_()
+            {
+            }
+
+            /**
+             * @brief Construct a new Rule object.
+             *
+             * @param[in] id The ID of the Rule in the KnowledgeBase.
+             */
+            Rule(int id) :
+                id_(id),
+                fact_(),
+                reason_()
+            {
+            }
+
+            /**
+             * @brief Construct a new Rule object.
+             *
+             * @param[in] fact The Fact.
+             * @param[in] reason The reason Fact.
+             */
+            Rule(obelisk::Fact fact, obelisk::Fact reason) :
+                id_(0),
+                fact_(fact),
+                reason_(reason)
+            {
+            }
+
+            /**
+             * @brief Construct a new Rule object.
+             *
+             * @param[in] id The ID of the Rule.
+             * @param[in] fact The Fact.
+             * @param[in] reason The reason Fact.
+             */
+            Rule(int id, obelisk::Fact fact, obelisk::Fact reason) :
+                id_(id),
+                fact_(fact),
+                reason_(reason)
+            {
+            }
+
+            /**
+             * @brief Create the Rule table in the KnowledgeBase.
+             *
+             * @return const char* Returns the query used to create the table.
+             */
+            static const char* createTable();
+
+            /**
+             * @brief Get the ID of the Rule.
+             *
+             * @return int& The ID.
+             */
+            int& getId();
+
+            /**
+             * @brief Set the ID of the Rule.
+             *
+             * @param[in] id The ID.
+             */
+            void setId(int id);
+
+            /**
+             * @brief Get the Fact object.
+             *
+             * @return obelisk::Fact& The Fact.
+             */
+            obelisk::Fact& getFact();
+
+            /**
+             * @brief Set the Fact object.
+             *
+             * @param[in] fact The Fact.
+             */
+            void setFact(obelisk::Fact fact);
+
+            /**
+             * @brief Get the reason Fact object.
+             *
+             * @return obelisk::Fact& The reason Fact.
+             */
+            obelisk::Fact& getReason();
+
+            /**
+             * @brief Set the reason Fact object.
+             *
+             * @param[in] reason The reason Fact.
+             */
+            void setReason(obelisk::Fact reason);
+
+            /**
+             * @brief Select the Rule from the KnowledgeBase by IDs of the
+             * sub-objects.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectById(sqlite3* dbConnection);
+
+            /**
+             * @brief Get the rules that match the reason.
+             *
+             * @param[in] dbConnection The database connection to use.
+             * @param[out] rules The rules to fill in from the database.
+             */
+            static void selectByReason(sqlite3* dbConnection,
+                int reasonId,
+                std::vector<obelisk::Rule>& rules);
+
+            /**
+             * @brief Insert the Rule into the KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void insert(sqlite3* dbConnection);
+    };
+} // namespace obelisk
+
+#endif

src/lib/models/suggest_action.cpp

@@ -1,25 +1,24 @@
 #include "models/error.h"
-#include "models/fact.h"
+#include "models/suggest_action.h"
 
-const char* obelisk::Fact::createTable()
+const char* obelisk::SuggestAction::createTable()
 {
     return R"(
-        CREATE TABLE "fact" (
+        CREATE TABLE "suggest_action" (
             "id"           INTEGER NOT NULL UNIQUE,
-            "left_entity"  INTEGER NOT NULL,
-            "verb"         INTEGER NOT NULL,
-            "right_entity" INTEGER NOT NULL,
-            "is_true"      INTEGER NOT NULL DEFAULT 0,
+            "fact"         INTEGER NOT NULL,
+            "true_action"  INTEGER NOT NULL,
+            "false_action" INTEGER NOT NULL,
             PRIMARY KEY("id" AUTOINCREMENT),
-            UNIQUE("left_entity", "right_entity", "verb")
-            FOREIGN KEY("verb") REFERENCES "verb"("id") ON DELETE RESTRICT,
-            FOREIGN KEY("right_entity") REFERENCES "entity"("id") ON DELETE RESTRICT,
-            FOREIGN KEY("left_entity") REFERENCES "entity"("id") ON DELETE RESTRICT
+            UNIQUE("fact", "true_action", "false_action"),
+            FOREIGN KEY("fact") REFERENCES "fact"("id") ON DELETE RESTRICT,
+            FOREIGN KEY("true_action") REFERENCES "action"("id") ON DELETE RESTRICT,
+            FOREIGN KEY("false_action") REFERENCES "action"("id") ON DELETE RESTRICT
         );
     )";
 }
 
-void obelisk::Fact::selectFact(sqlite3* dbConnection)
+void obelisk::SuggestAction::selectById(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -29,7 +28,7 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
     sqlite3_stmt* ppStmt = nullptr;
 
     auto result = sqlite3_prepare_v2(dbConnection,
-        "SELECT id, left_entity, right_entity, verb FROM fact WHERE (left_entity=? AND right_entity=? AND verb=?)",
+        "SELECT id, fact, true_action, false_action FROM suggest_action WHERE (fact=? AND true_action=? AND false_action=?)",
         -1,
         &ppStmt,
         nullptr);
@@ -38,7 +37,7 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
         throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
     }
 
-    result = sqlite3_bind_int(ppStmt, 1, getLeftEntity().getId());
+    result = sqlite3_bind_int(ppStmt, 1, getFact().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -57,7 +56,7 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
             break;
     }
 
-    result = sqlite3_bind_int(ppStmt, 2, getRightEntity().getId());
+    result = sqlite3_bind_int(ppStmt, 2, getTrueAction().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -76,7 +75,7 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
             break;
     }
 
-    result = sqlite3_bind_int(ppStmt, 3, getVerb().getId());
+    result = sqlite3_bind_int(ppStmt, 3, getFalseAction().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -103,9 +102,9 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
             break;
         case SQLITE_ROW :
             setId(sqlite3_column_int(ppStmt, 0));
-            getLeftEntity().setId(sqlite3_column_int(ppStmt, 1));
-            getRightEntity().setId(sqlite3_column_int(ppStmt, 2));
-            getVerb().setId(sqlite3_column_int(ppStmt, 3));
+            getFact().setId(sqlite3_column_int(ppStmt, 1));
+            getTrueAction().setId(sqlite3_column_int(ppStmt, 2));
+            getFalseAction().setId(sqlite3_column_int(ppStmt, 3));
             break;
         case SQLITE_BUSY :
             throw obelisk::DatabaseBusyException();
@@ -125,7 +124,7 @@ void obelisk::Fact::selectFact(sqlite3* dbConnection)
     }
 }
 
-void obelisk::Fact::insertFact(sqlite3* dbConnection)
+void obelisk::SuggestAction::insert(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -135,7 +134,7 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
     sqlite3_stmt* ppStmt = nullptr;
 
     auto result = sqlite3_prepare_v2(dbConnection,
-        "INSERT INTO fact (left_entity, right_entity, verb) VALUES (?, ?, ?)",
+        "INSERT INTO suggest_action (fact, true_action, false_action) VALUES (?, ?, ?)",
         -1,
         &ppStmt,
         nullptr);
@@ -144,7 +143,7 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
         throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
     }
 
-    result = sqlite3_bind_int(ppStmt, 1, getLeftEntity().getId());
+    result = sqlite3_bind_int(ppStmt, 1, getFact().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -163,7 +162,7 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
             break;
     }
 
-    result = sqlite3_bind_int(ppStmt, 2, getRightEntity().getId());
+    result = sqlite3_bind_int(ppStmt, 2, getTrueAction().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -182,7 +181,7 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
             break;
     }
 
-    result = sqlite3_bind_int(ppStmt, 3, getVerb().getId());
+    result = sqlite3_bind_int(ppStmt, 3, getFalseAction().getId());
     switch (result)
     {
         case SQLITE_OK :
@@ -209,7 +208,8 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
             sqlite3_set_last_insert_rowid(dbConnection, 0);
             break;
         case SQLITE_CONSTRAINT :
-            throw obelisk::DatabaseConstraintException(sqlite3_errmsg(dbConnection));
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
         case SQLITE_BUSY :
             throw obelisk::DatabaseBusyException();
             break;
@@ -228,42 +228,42 @@ void obelisk::Fact::insertFact(sqlite3* dbConnection)
     }
 }
 
-int& obelisk::Fact::getId()
+int& obelisk::SuggestAction::getId()
 {
     return id_;
 }
 
-void obelisk::Fact::setId(int id)
+void obelisk::SuggestAction::setId(int id)
 {
     id_ = id;
 }
 
-obelisk::Entity& obelisk::Fact::getLeftEntity()
+obelisk::Fact& obelisk::SuggestAction::getFact()
 {
-    return leftEntity_;
+    return fact_;
 }
 
-void obelisk::Fact::setLeftEntity(obelisk::Entity leftEntity)
+void obelisk::SuggestAction::setFact(obelisk::Fact fact)
 {
-    leftEntity_ = leftEntity;
+    fact_ = fact;
 }
 
-obelisk::Entity& obelisk::Fact::getRightEntity()
+obelisk::Action& obelisk::SuggestAction::getTrueAction()
 {
-    return rightEntity_;
+    return trueAction_;
 }
 
-void obelisk::Fact::setRightEntity(obelisk::Entity rightEntity)
+void obelisk::SuggestAction::setTrueAction(obelisk::Action trueAction)
 {
-    rightEntity_ = rightEntity;
+    trueAction_ = trueAction;
 }
 
-obelisk::Verb& obelisk::Fact::getVerb()
+obelisk::Action& obelisk::SuggestAction::getFalseAction()
 {
-    return verb_;
+    return falseAction_;
 }
 
-void obelisk::Fact::setVerb(obelisk::Verb verb)
+void obelisk::SuggestAction::setFalseAction(obelisk::Action falseAction)
 {
-    verb_ = verb;
+    falseAction_ = falseAction;
 }

src/lib/models/suggest_action.h

@@ -0,0 +1,185 @@
+#ifndef OBELISK_MODELS_SUGGEST_ACTION_H
+#define OBELISK_MODELS_SUGGEST_ACTION_H
+
+#include "models/action.h"
+#include "models/fact.h"
+
+#include <string>
+
+namespace obelisk
+{
+    /**
+     * @brief The SuggestAction model representas the actions to take depending
+     * on if the Fact is true or false.
+     *
+     */
+    class SuggestAction
+    {
+        private:
+            /**
+             * @brief The ID of the SuggestAction.
+             *
+             */
+            int id_;
+
+            /**
+             * @brief The Fact to check the truth of.
+             *
+             */
+            obelisk::Fact fact_;
+
+            /**
+             * @brief The Action to take if the Fact is true.
+             *
+             */
+            obelisk::Action trueAction_;
+
+            /**
+             * @brief The Action to take if the Fact is false.
+             *
+             */
+            obelisk::Action falseAction_;
+
+        public:
+            /**
+             * @brief Construct a new SuggestAction object.
+             *
+             */
+            SuggestAction() :
+                id_(0),
+                fact_(),
+                trueAction_(),
+                falseAction_()
+            {
+            }
+
+            /**
+             * @brief Construct a new SuggestAction object.
+             *
+             * @param[in] id The ID of the SuggestAction in the KnowledgeBase.
+             */
+            SuggestAction(int id) :
+                id_(id),
+                fact_(),
+                trueAction_(),
+                falseAction_()
+            {
+            }
+
+            /**
+             * @brief Construct a new SuggestAction object.
+             *
+             * @param[in] fact The Fact.
+             * @param[in] trueAction The true Action.
+             * @param[in] falseAction The false Action.
+             */
+            SuggestAction(obelisk::Fact fact,
+                obelisk::Action trueAction,
+                obelisk::Action falseAction) :
+                id_(0),
+                fact_(fact),
+                trueAction_(trueAction),
+                falseAction_(falseAction)
+            {
+            }
+
+            /**
+             * @brief Construct a new SuggestAction object.
+             *
+             * @param[in] id The ID of the SuggestAction in the KnowledgeBase.
+             * @param[in] fact The Fact.
+             * @param[in] trueAction The true Action.
+             * @param[in] falseAction The false Action.
+             */
+            SuggestAction(int id,
+                obelisk::Fact fact,
+                obelisk::Action trueAction,
+                obelisk::Action falseAction) :
+                id_(id),
+                fact_(fact),
+                trueAction_(trueAction),
+                falseAction_(falseAction)
+            {
+            }
+
+            /**
+             * @brief Create the SuggestAction table in the database.
+             *
+             * @return const char* Returns the query used to create the table.
+             */
+            static const char* createTable();
+
+            /**
+             * @brief Get the ID of the SuggestAction.
+             *
+             * @return int& Returns the ID.
+             */
+            int& getId();
+
+            /**
+             * @brief Set the ID of the SuggestAction.
+             *
+             * @param[in] id The new ID.
+             */
+            void setId(int id);
+
+            /**
+             * @brief Get the Fact object.
+             *
+             * @return obelisk::Fact& Returns the Fact.
+             */
+            obelisk::Fact& getFact();
+
+            /**
+             * @brief Set the Fact object.
+             *
+             * @param[in] fact The new Fact.
+             */
+            void setFact(obelisk::Fact fact);
+
+            /**
+             * @brief Get the true Action object.
+             *
+             * @return obelisk::Action& Returns the true Action.
+             */
+            obelisk::Action& getTrueAction();
+
+            /**
+             * @brief Set the true Action object.
+             *
+             * @param[in] trueAction The new true Action.
+             */
+            void setTrueAction(obelisk::Action trueAction);
+
+            /**
+             * @brief Get the false Action object.
+             *
+             * @return obelisk::Action& Returns the false Action.
+             */
+            obelisk::Action& getFalseAction();
+
+            /**
+             * @brief Set the false Action object.
+             *
+             * @param[in] falseAction The new false Action.
+             */
+            void setFalseAction(obelisk::Action falseAction);
+
+            /**
+             * @brief Select the SuggestAction from the KnowledgeBase by IDs of
+             * the sub-objects.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectById(sqlite3* dbConnection);
+
+            /**
+             * @brief Insert the SuggestAction into the KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void insert(sqlite3* dbConnection);
+    };
+} // namespace obelisk
+
+#endif

src/lib/models/verb.cpp

@@ -14,7 +14,7 @@ const char* obelisk::Verb::createTable()
     )";
 }
 
-void obelisk::Verb::selectVerb(sqlite3* dbConnection)
+void obelisk::Verb::selectByName(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -23,7 +23,11 @@ void obelisk::Verb::selectVerb(sqlite3* dbConnection)
 
     sqlite3_stmt* ppStmt = nullptr;
 
-    auto result = sqlite3_prepare_v2(dbConnection, "SELECT id, name FROM verb WHERE name=?", -1, &ppStmt, nullptr);
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "SELECT id, name FROM verb WHERE name=?",
+        -1,
+        &ppStmt,
+        nullptr);
     if (result != SQLITE_OK)
     {
         throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
@@ -76,7 +80,7 @@ void obelisk::Verb::selectVerb(sqlite3* dbConnection)
     }
 }
 
-void obelisk::Verb::insertVerb(sqlite3* dbConnection)
+void obelisk::Verb::insert(sqlite3* dbConnection)
 {
     if (dbConnection == nullptr)
     {
@@ -85,13 +89,18 @@ void obelisk::Verb::insertVerb(sqlite3* dbConnection)
 
     sqlite3_stmt* ppStmt = nullptr;
 
-    auto result = sqlite3_prepare_v2(dbConnection, "INSERT INTO verb (name) VALUES (?)", -1, &ppStmt, nullptr);
+    auto result = sqlite3_prepare_v2(dbConnection,
+        "INSERT INTO verb (name) VALUES (?)",
+        -1,
+        &ppStmt,
+        nullptr);
     if (result != SQLITE_OK)
     {
         throw obelisk::DatabaseException(sqlite3_errmsg(dbConnection));
     }
 
-    result = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_TRANSIENT);
+    result
+        = sqlite3_bind_text(ppStmt, 1, getName().c_str(), -1, SQLITE_TRANSIENT);
     switch (result)
     {
         case SQLITE_OK :
@@ -118,7 +127,8 @@ void obelisk::Verb::insertVerb(sqlite3* dbConnection)
             sqlite3_set_last_insert_rowid(dbConnection, 0);
             break;
         case SQLITE_CONSTRAINT :
-            throw obelisk::DatabaseConstraintException(sqlite3_errmsg(dbConnection));
+            throw obelisk::DatabaseConstraintException(
+                sqlite3_errmsg(dbConnection));
         case SQLITE_BUSY :
             throw obelisk::DatabaseBusyException();
             break;

src/lib/models/verb.h

@@ -0,0 +1,126 @@
+#ifndef OBELISK_MODELS_VERB_H
+#define OBELISK_MODELS_VERB_H
+
+#include <sqlite3.h>
+
+#include <string>
+
+namespace obelisk
+{
+    /**
+     * @brief The Verb model represents a verb which is used to connnect
+     * entities.
+     *
+     */
+    class Verb
+    {
+        private:
+            /**
+             * @brief The ID of the Verb in the KnowledgeBase.
+             *
+             */
+            int id_;
+
+            /**
+             * @brief The name of the Verb.
+             *
+             */
+            std::string name_;
+
+        public:
+            /**
+             * @brief Construct a new Verb object.
+             *
+             */
+            Verb() :
+                id_(0),
+                name_("")
+            {
+            }
+
+            /**
+             * @brief Construct a new Verb object.
+             *
+             * @param[in] id The ID of the Verb.
+             */
+            Verb(int id) :
+                id_(id),
+                name_("")
+            {
+            }
+
+            /**
+             * @brief Construct a new Verb object.
+             *
+             * @param[in] name The name of the Verb.
+             */
+            Verb(std::string name) :
+                id_(0),
+                name_(name)
+            {
+            }
+
+            /**
+             * @brief Construct a new Verb object.
+             *
+             * @param[in] id The ID of the Verb.
+             * @param[in] name The name of the Verb.
+             */
+            Verb(int id, std::string name) :
+                id_(id),
+                name_(name)
+            {
+            }
+
+            /**
+             * @brief Create the Verb table in the KnowledgeBase.
+             *
+             * @return const char* Returns the query used to create the table.
+             */
+            static const char* createTable();
+
+            /**
+             * @brief Get the ID of the Verb.
+             *
+             * @return int& Returns the ID.
+             */
+            int& getId();
+
+            /**
+             * @brief Set the ID of the Verb.
+             *
+             * @param[in] id Set the ID of the Verb.
+             */
+            void setId(int id);
+
+            /**
+             * @brief Get the name of the Verb.
+             *
+             * @return std::string& The Verb name.
+             */
+            std::string& getName();
+
+            /**
+             * @brief Set the name of the Verb.
+             *
+             * @param[in] name The Verb name.
+             */
+            void setName(std::string name);
+
+            /**
+             * @brief Select a verb by name from the KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void selectByName(sqlite3* dbConnection);
+
+            /**
+             * @brief Insert a new verb into the KnowledgeBase.
+             *
+             * @param[in] dbConnection The database connection to use.
+             */
+            void insert(sqlite3* dbConnection);
+    };
+} // namespace obelisk
+
+#endif

src/lib/obelisk.c

@@ -0,0 +1,41 @@
+#include "obelisk_c.h"
+#include "obelisk_wrapper.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+CObelisk* obelisk_open(const char* filename)
+{
+    return create_obelisk(filename);
+}
+
+void obelisk_close(CObelisk* obelisk)
+{
+    destroy_obelisk(obelisk);
+}
+
+char* obelisk_get_version(CObelisk* obelisk)
+{
+    return call_obelisk_getVersion(obelisk);
+}
+
+int obelisk_get_lib_version(CObelisk* obelisk)
+{
+    return call_obelisk_getLibVersion(obelisk);
+}
+
+double obelisk_query(CObelisk* obelisk,
+    const char* left_entity,
+    const char* verb,
+    const char* right_entity)
+{
+    return call_obelisk_query(obelisk, left_entity, verb, right_entity);
+}
+
+char* obelisk_query_action(CObelisk* obelisk,
+    const char* left_entity,
+    const char* verb,
+    const char* right_entity)
+{
+    return call_obelisk_queryAction(obelisk, left_entity, verb, right_entity);
+}

src/lib/obelisk.cpp

@@ -0,0 +1,47 @@
+#include "include/obelisk.h"
+#include "version.h"
+
+obelisk::Obelisk::Obelisk(std::string filename)
+{
+    kb_ = std::unique_ptr<obelisk::KnowledgeBase> {
+        new obelisk::KnowledgeBase(filename.c_str())};
+}
+
+std::string obelisk::Obelisk::getVersion()
+{
+    return obelisk::version;
+}
+
+int obelisk::Obelisk::getLibVersion()
+{
+    return obelisk::soVersion;
+}
+
+double obelisk::Obelisk::query(const std::string& leftEntity,
+    const std::string& verb,
+    const std::string& rightEntity)
+{
+    obelisk::Fact fact = obelisk::Fact(obelisk::Entity(leftEntity),
+        obelisk::Entity(rightEntity),
+        obelisk::Verb(verb));
+
+    kb_->queryFact(fact);
+
+    return fact.getIsTrue();
+}
+
+std::string obelisk::Obelisk::queryAction(const std::string& leftEntity,
+    const std::string& verb,
+    const std::string& rightEntity)
+{
+    obelisk::Fact fact = obelisk::Fact(obelisk::Entity(leftEntity),
+        obelisk::Entity(rightEntity),
+        obelisk::Verb(verb));
+
+    kb_->queryFact(fact);
+
+    obelisk::Action action;
+    kb_->querySuggestAction(fact, action);
+
+    return action.getName();
+}

src/lib/obelisk_wrapper.cpp

@@ -0,0 +1,61 @@
+#include "obelisk.h"
+#include "obelisk_wrapper.h"
+
+#include <string.h>
+
+extern "C"
+{
+    CObelisk* create_obelisk(const char* filename)
+    {
+        obelisk::Obelisk* obelisk = new obelisk::Obelisk(filename);
+        return reinterpret_cast<CObelisk*>(obelisk);
+    }
+
+    char* call_obelisk_getVersion(CObelisk* p_obelisk)
+    {
+        obelisk::Obelisk* obelisk
+            = reinterpret_cast<obelisk::Obelisk*>(p_obelisk);
+        auto version = strdup(obelisk->getVersion().c_str());
+        return version;
+    }
+
+    int call_obelisk_getLibVersion(CObelisk* p_obelisk)
+    {
+        obelisk::Obelisk* obelisk
+            = reinterpret_cast<obelisk::Obelisk*>(p_obelisk);
+        return obelisk->getLibVersion();
+    }
+
+    double call_obelisk_query(CObelisk* p_obelisk,
+        const char* left_entity,
+        const char* verb,
+        const char* right_entity)
+    {
+        obelisk::Obelisk* obelisk
+            = reinterpret_cast<obelisk::Obelisk*>(p_obelisk);
+        return obelisk->query(std::string(left_entity),
+            std::string(verb),
+            std::string(right_entity));
+    }
+
+    char* call_obelisk_queryAction(CObelisk* p_obelisk,
+        const char* left_entity,
+        const char* verb,
+        const char* right_entity)
+    {
+        obelisk::Obelisk* obelisk
+            = reinterpret_cast<obelisk::Obelisk*>(p_obelisk);
+        auto temp   = obelisk->queryAction(std::string(left_entity),
+            std::string(verb),
+            std::string(right_entity));
+        auto action = strdup(temp.c_str());
+        return action;
+    }
+
+    void destroy_obelisk(CObelisk* p_obelisk)
+    {
+        obelisk::Obelisk* obelisk
+            = reinterpret_cast<obelisk::Obelisk*>(p_obelisk);
+        delete obelisk;
+    }
+};

src/lib/obelisk_wrapper.h

@@ -0,0 +1,76 @@
+#ifndef OBELISK_INCLUDE_OBELISK_WRAPPER_H
+#define OBELISK_INCLUDE_OBELISK_WRAPPER_H
+
+#include "include/obelisk_c.h"
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /**
+     * @brief Create a obelisk object.
+     *
+     * @param[in] filename The name of the obelisk KnowledgeBase file to use.
+     * @return CObelisk* Returns the obelisk object.
+     */
+    CObelisk *create_obelisk(const char *filename);
+
+    /**
+     * @brief Calls the obelisk method getVersion.
+     *
+     * @param[in] p_obelisk The obelisk object pointer.
+     * @return char* Returns the version. This must be freed by the
+     * caller.
+     */
+    char *call_obelisk_getVersion(CObelisk *p_obelisk);
+
+    /**
+     * @brief Calls the obelisk method getLibVersion.
+     *
+     * @param[in] p_obelisk The obelisk object pointer.
+     * @return int Returns the library so version.
+     */
+    int call_obelisk_getLibVersion(CObelisk *p_obelisk);
+
+    /**
+     * @brief Calls the obelisk method query.
+     *
+     * @param[in] p_obelisk The obelisk object pointer.
+     * @param[in] left_entity The left entity.
+     * @param[in] verb The verb.
+     * @param[in] right_entity The right entity.
+     * @return double Returns whether or not the Fact is true.
+     */
+    double call_obelisk_query(CObelisk *p_obelisk,
+        const char *left_entity,
+        const char *verb,
+        const char *right_entity);
+
+    /**
+     * @brief Calls the obelisk method queryAction.
+     *
+     * @param[in] p_obelisk The obelisk object pointer.
+     * @param[in] left_entity The left entity.
+     * @param[in] verb The verb.
+     * @param[in] right_entity The right entity.
+     * @return char* Returns the sugggested action to take or an empty string if
+     * no action is found. This must be freed by the caller.
+     */
+    char *call_obelisk_queryAction(CObelisk *p_obelisk,
+        const char *left_entity,
+        const char *verb,
+        const char *right_entity);
+
+    /**
+     * @brief Delete a obelisk object.
+     *
+     * @param[in] p_obelisk The obelisk object pointer.
+     */
+    void destroy_obelisk(CObelisk *p_obelisk);
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif

src/lib/version.h.in

@@ -0,0 +1,21 @@
+#ifndef OBELISK_VERSION_H
+#define OBELISK_VERSION_H
+
+namespace obelisk
+{
+    /**
+     * @brief The current version of obelisk.
+     *
+     */
+    const std::string version = "@version@";
+
+    /**
+     * @brief The current library version of obelisk.
+     *
+     */
+    // clang-format off
+    const int soVersion = @so_version@;
+    // clang-format on
+} // namespace obelisk
+
+#endif

src/main.cpp

@@ -1,5 +1,6 @@
 #include "knowledge_base.h"
 #include "lexer.h"
+#include "main.h"
 #include "obelisk.h"
 #include "parser.h"
 #include "version.h"
@@ -9,13 +10,15 @@
 #include <limits>
 #include <memory>
 
-int obelisk::mainLoop(const std::vector<std::string>& sourceFiles, const std::string& kbFile)
+int obelisk::mainLoop(const std::vector<std::string>& sourceFiles,
+    const std::string& kbFile)
 {
     std::unique_ptr<obelisk::KnowledgeBase> kb;
 
     try
     {
-        kb = std::unique_ptr<obelisk::KnowledgeBase> {new obelisk::KnowledgeBase(kbFile.c_str())};
+        kb = std::unique_ptr<obelisk::KnowledgeBase> {
+            new obelisk::KnowledgeBase(kbFile.c_str())};
     }
     catch (obelisk::KnowledgeBaseException& exception)
     {
@@ -27,7 +30,8 @@ int obelisk::mainLoop(const std::vector<std::string>& sourceFiles, const std::st
     std::shared_ptr<obelisk::Lexer> lexer;
     try
     {
-        lexer = std::shared_ptr<obelisk::Lexer> {new obelisk::Lexer(sourceFiles[file++])};
+        lexer = std::shared_ptr<obelisk::Lexer> {
+            new obelisk::Lexer(sourceFiles[file++])};
     }
     catch (obelisk::LexerException& exception)
     {
@@ -52,14 +56,16 @@ int obelisk::mainLoop(const std::vector<std::string>& sourceFiles, const std::st
         switch (parser->getCurrentToken())
         {
             case obelisk::Lexer::kTokenEof :
-                // end of source file found, create a new lexer and pass it to the parser to use
+                // end of source file found, create a new lexer and pass it to
+                // the parser to use
                 if (file >= sourceFiles.size())
                 {
                     return EXIT_SUCCESS;
                 }
                 try
                 {
-                    lexer = std::shared_ptr<obelisk::Lexer> {new obelisk::Lexer(sourceFiles[file++])};
+                    lexer = std::shared_ptr<obelisk::Lexer> {
+                        new obelisk::Lexer(sourceFiles[file++])};
                     parser->setLexer(lexer);
                     // prime the first token in the parser
                     parser->getNextToken();
@@ -83,13 +89,37 @@ int obelisk::mainLoop(const std::vector<std::string>& sourceFiles, const std::st
                 }
                 break;
             case obelisk::Lexer::kTokenFact :
-                parser->handleFact(kb);
+                try
+                {
+                    parser->handleFact(kb);
+                }
+                catch (obelisk::ParserException& exception)
+                {
+                    std::cout << "Error: " << exception.what() << std::endl;
+                    return EXIT_FAILURE;
+                }
                 break;
             case obelisk::Lexer::kTokenRule :
-                // parser->handleRule();
+                try
+                {
+                    parser->handleRule(kb);
+                }
+                catch (obelisk::ParserException& exception)
+                {
+                    std::cout << "Error: " << exception.what() << std::endl;
+                    return EXIT_FAILURE;
+                }
                 break;
             case obelisk::Lexer::kTokenAction :
-                // parser->handleAction();
+                try
+                {
+                    parser->handleAction(kb);
+                }
+                catch (obelisk::ParserException& exception)
+                {
+                    std::cout << "Error: " << exception.what() << std::endl;
+                    return EXIT_FAILURE;
+                }
                 break;
             default :
                 parser->getNextToken();
@@ -113,7 +143,11 @@ int main(int argc, char** argv)
     while (true)
     {
         int option_index = 0;
-        switch (getopt_long(argc, argv, "k:hv", obelisk::long_options, &option_index))
+        switch (getopt_long(argc,
+            argv,
+            "k:hv",
+            obelisk::long_options,
+            &option_index))
         {
             case 'k' :
                 kbFile = std::string(optarg);

src/main.h

@@ -1,7 +1,10 @@
+#ifndef OBELISK_MAIN_H
+#define OBELISK_MAIN_H
+
 #include <getopt.h>
 
 /**
- * @brief The obelisk namespace contains everything needed to compile obelisk.
+ * @brief The obelisk namespace contains everything needed to compile obelisk
  * code.
  *
  */
@@ -38,9 +41,13 @@ Options:
 
     /**
      * @brief This is the main loop for obelisk.
+     *
      * This loop handles lexing and parsing of obelisk source code.
      *
      * @return int Returns EXIT_SUCCESS or EXIT_FAILURE.
      */
-    int mainLoop(const std::vector<std::string> &sourceFiles, const std::string &kbFile);
+    int mainLoop(const std::vector<std::string> &sourceFiles,
+        const std::string &kbFile);
 } // namespace obelisk
+
+#endif

src/meson.build

@@ -1,15 +1,9 @@
-conf_data = configuration_data()
-conf_data.set('version', meson.project_version())
-configure_file(input : 'version.h.in',
-    output : 'version.h',
-    configuration : conf_data
-)
+subdir('lib')
 
 obelisk_sources = files(
-    'obelisk.cpp',
+    'main.cpp',
     'lexer.cpp',
-    'parser.cpp',
-    'knowledge_base.cpp'
+    'parser.cpp'
 )
 
 sqlite3 = dependency('sqlite3')
@@ -17,9 +11,6 @@ sqlite3 = dependency('sqlite3')
 subdir('ast')
 obelisk_sources += obelisk_ast_sources
 
-subdir('models')
-obelisk_sources += obelisk_model_sources
-
 r = run_command('llvm-config', '--cppflags', check : true)
 cpp_args = ' ' + r.stdout().replace('\n', ' ').replace('-I', '-isystem')
 
@@ -28,7 +19,7 @@ link_args = ' ' + r.stdout().replace('\n', ' ')
 
 executable('obelisk',
     obelisk_sources,
-    dependencies : [sqlite3],
+    dependencies : [libobelisk, sqlite3],
     cpp_args : cpp_args.split(),
     link_args : link_args.split(),
     install : true

src/models/action.cpp

@@ -1,32 +0,0 @@
-#include "models/action.h"
-
-const char* obelisk::Action::createTable()
-{
-    return R"(
-        CREATE TABLE "action" (
-            "id"   INTEGER NOT NULL UNIQUE,
-            "name" TEXT NOT NULL CHECK(trim(name) != '') UNIQUE,
-            PRIMARY KEY("id" AUTOINCREMENT)
-        );
-    )";
-}
-
-int& obelisk::Action::getId()
-{
-    return id_;
-}
-
-void obelisk::Action::setId(int id)
-{
-    id_ = id;
-}
-
-std::string& obelisk::Action::getName()
-{
-    return name_;
-}
-
-void obelisk::Action::setName(std::string name)
-{
-    name_ = name;
-}

src/models/error.h

@@ -1,102 +0,0 @@
-#ifndef OBELISK_MODELS_ERROR_H
-#define OBELISK_MODELS_ERROR_H
-
-#include <exception>
-#include <string>
-
-namespace obelisk
-{
-    class DatabaseException : public std::exception
-    {
-        protected:
-            std::string errorMessage_;
-
-        public:
-            DatabaseException() :
-                errorMessage_("an unknown error ocurred")
-            {
-            }
-
-            DatabaseException(const int errorCode) :
-                errorMessage_("database error " + std::to_string(errorCode) + " ocurred")
-            {
-            }
-
-            DatabaseException(const std::string& errorMessage) :
-                errorMessage_(errorMessage)
-            {
-            }
-
-            virtual const char* what() const noexcept
-            {
-                return errorMessage_.c_str();
-            }
-
-            virtual void setErrorMessage(const std::string errorMessage)
-            {
-                errorMessage_ = errorMessage;
-            }
-    };
-
-    class DatabaseSizeException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseSizeException()
-            {
-                setErrorMessage("size of string or blob exceeds limits");
-            }
-    };
-
-    class DatabaseRangeException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseRangeException()
-            {
-                setErrorMessage("parameter index is out of range");
-            }
-    };
-
-    class DatabaseMemoryException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseMemoryException()
-            {
-                setErrorMessage("not enough memory for operation");
-            }
-    };
-
-    class DatabaseBusyException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseBusyException()
-            {
-                setErrorMessage("database was busy and operation was not performed");
-            }
-    };
-
-    class DatabaseMisuseException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseMisuseException()
-
-            {
-                setErrorMessage("misuse of the database routine");
-            }
-    };
-
-    class DatabaseConstraintException : public obelisk::DatabaseException
-    {
-        public:
-            DatabaseConstraintException()
-            {
-                setErrorMessage("a constraint exception occurred");
-            }
-
-            DatabaseConstraintException(const std::string& errorMessage)
-            {
-                setErrorMessage(errorMessage);
-            }
-    };
-} // namespace obelisk
-
-#endif

src/models/fact.h

@@ -1,72 +0,0 @@
-#ifndef OBELISK_MODELS_FACT_H
-#define OBELISK_MODELS_FACT_H
-
-#include "models/entity.h"
-#include "models/fact.h"
-#include "models/verb.h"
-
-#include <string>
-
-namespace obelisk
-{
-    class Fact
-    {
-        private:
-            int id_;
-            obelisk::Entity leftEntity_;
-            obelisk::Entity rightEntity_;
-            obelisk::Verb verb_;
-
-        public:
-            Fact() :
-                id_(0),
-                leftEntity_(),
-                rightEntity_(),
-                verb_()
-            {
-            }
-
-            Fact(int id) :
-                id_(id),
-                leftEntity_(),
-                rightEntity_(),
-                verb_()
-            {
-            }
-
-            Fact(obelisk::Entity leftEntity, obelisk::Entity rightEntity, obelisk::Verb verb) :
-                id_(0),
-                leftEntity_(leftEntity),
-                rightEntity_(rightEntity),
-                verb_(verb)
-            {
-            }
-
-            Fact(int id, obelisk::Entity leftEntity, obelisk::Entity rightEntity, obelisk::Verb verb) :
-                id_(id),
-                leftEntity_(leftEntity),
-                rightEntity_(rightEntity),
-                verb_(verb)
-            {
-            }
-
-            static const char* createTable();
-
-            int& getId();
-            void setId(int id);
-
-            Entity& getLeftEntity();
-            void setLeftEntity(obelisk::Entity leftEntity);
-
-            Entity& getRightEntity();
-            void setRightEntity(obelisk::Entity leftEntity);
-
-            Verb& getVerb();
-            void setVerb(obelisk::Verb verb);
-
-            void selectFact(sqlite3* dbConnection);
-            void insertFact(sqlite3* dbConnection);
-    };
-} // namespace obelisk
-
-#endif

src/models/rule.cpp

@@ -1,46 +0,0 @@
-#include "models/rule.h"
-
-const char* obelisk::Rule::createTable()
-{
-    return R"(
-        CREATE TABLE "rule" (
-            "id"     INTEGER NOT NULL UNIQUE,
-            "fact"   INTEGER NOT NULL,
-            "reason" INTEGER NOT NULL CHECK("reason" != "fact"),
-            PRIMARY KEY("id" AUTOINCREMENT),
-            UNIQUE("fact", "reason"),
-            FOREIGN KEY("fact") REFERENCES "fact"("id") ON DELETE RESTRICT,
-            FOREIGN KEY("reason") REFERENCES "fact"("id") ON DELETE RESTRICT
-        );
-    )";
-}
-
-int& obelisk::Rule::getId()
-{
-    return id_;
-}
-
-void obelisk::Rule::setId(int id)
-{
-    id_ = id;
-}
-
-obelisk::Fact& obelisk::Rule::getFact()
-{
-    return fact_;
-}
-
-void obelisk::Rule::setFact(obelisk::Fact fact)
-{
-    fact_ = fact;
-}
-
-obelisk::Fact& obelisk::Rule::getReason()
-{
-    return reason_;
-}
-
-void obelisk::Rule::setReason(obelisk::Fact reason)
-{
-    reason_ = reason;
-}

src/models/rule.h

@@ -1,59 +0,0 @@
-#ifndef OBELISK_MODELS_RULE_H
-#define OBELISK_MODELS_RULE_H
-
-#include "models/fact.h"
-
-#include <string>
-
-namespace obelisk
-{
-    class Rule
-    {
-        private:
-            int id_;
-            obelisk::Fact fact_;
-            obelisk::Fact reason_;
-
-        public:
-            Rule() :
-                id_(0),
-                fact_(),
-                reason_()
-            {
-            }
-
-            Rule(int id) :
-                id_(id),
-                fact_(),
-                reason_()
-            {
-            }
-
-            Rule(obelisk::Fact fact, obelisk::Fact reason) :
-                id_(0),
-                fact_(fact),
-                reason_(reason)
-            {
-            }
-
-            Rule(int id, obelisk::Fact fact, obelisk::Fact reason) :
-                id_(id),
-                fact_(fact),
-                reason_(reason)
-            {
-            }
-
-            static const char* createTable();
-
-            int& getId();
-            void setId(int id);
-
-            obelisk::Fact& getFact();
-            void setFact(obelisk::Fact fact);
-
-            obelisk::Fact& getReason();
-            void setReason(obelisk::Fact reason);
-    };
-} // namespace obelisk
-
-#endif

src/models/suggest_action.cpp

@@ -1,58 +0,0 @@
-#include "models/suggest_action.h"
-
-const char* obelisk::SuggestAction::createTable()
-{
-    return R"(
-        CREATE TABLE "suggest_action" (
-            "id"           INTEGER NOT NULL UNIQUE,
-            "fact"         INTEGER NOT NULL,
-            "true_action"  INTEGER NOT NULL,
-            "false_action" INTEGER NOT NULL,
-            PRIMARY KEY("id" AUTOINCREMENT),
-            UNIQUE("fact", "true_action", "false_action"),
-            FOREIGN KEY("fact") REFERENCES "fact"("id") ON DELETE RESTRICT,
-            FOREIGN KEY("true_action") REFERENCES "action"("id") ON DELETE RESTRICT,
-            FOREIGN KEY("false_action") REFERENCES "action"("id") ON DELETE RESTRICT
-        );
-    )";
-}
-
-int& obelisk::SuggestAction::getId()
-{
-    return id_;
-}
-
-void obelisk::SuggestAction::setId(int id)
-{
-    id_ = id;
-}
-
-obelisk::Fact& obelisk::SuggestAction::getFact()
-{
-    return fact_;
-}
-
-void obelisk::SuggestAction::setFact(obelisk::Fact fact)
-{
-    fact_ = fact;
-}
-
-obelisk::Action& obelisk::SuggestAction::getTrueAction()
-{
-    return trueAction_;
-}
-
-void obelisk::SuggestAction::setTrueAction(obelisk::Action trueAction)
-{
-    trueAction_ = trueAction;
-}
-
-obelisk::Action& obelisk::SuggestAction::getFalseAction()
-{
-    return falseAction_;
-}
-
-void obelisk::SuggestAction::setFalseAction(obelisk::Action falseAction)
-{
-    falseAction_ = falseAction;
-}

src/models/suggest_action.h

@@ -1,68 +0,0 @@
-#ifndef OBELISK_MODELS_SUGGEST_ACTION_H
-#define OBELISK_MODELS_SUGGEST_ACTION_H
-
-#include "models/action.h"
-#include "models/fact.h"
-
-#include <string>
-
-namespace obelisk
-{
-    class SuggestAction
-    {
-        private:
-            int id_;
-            obelisk::Fact fact_;
-            obelisk::Action trueAction_;
-            obelisk::Action falseAction_;
-
-        public:
-            SuggestAction() :
-                id_(0),
-                fact_(),
-                trueAction_(),
-                falseAction_()
-            {
-            }
-
-            SuggestAction(int id) :
-                id_(id),
-                fact_(),
-                trueAction_(),
-                falseAction_()
-            {
-            }
-
-            SuggestAction(obelisk::Fact fact, obelisk::Action trueAction, obelisk::Action falseAction) :
-                id_(0),
-                fact_(fact),
-                trueAction_(trueAction),
-                falseAction_(falseAction)
-            {
-            }
-
-            SuggestAction(int id, obelisk::Fact fact, obelisk::Action trueAction, obelisk::Action falseAction) :
-                id_(id),
-                fact_(fact),
-                trueAction_(trueAction),
-                falseAction_(falseAction)
-            {
-            }
-
-            static const char* createTable();
-
-            int& getId();
-            void setId(int id);
-
-            obelisk::Fact& getFact();
-            void setFact(obelisk::Fact fact);
-
-            obelisk::Action& getTrueAction();
-            void setTrueAction(obelisk::Action trueAction);
-
-            obelisk::Action& getFalseAction();
-            void setFalseAction(obelisk::Action falseAction);
-    };
-} // namespace obelisk
-
-#endif

src/models/verb.h

@@ -1,54 +0,0 @@
-#ifndef OBELISK_MODELS_VERB_H
-#define OBELISK_MODELS_VERB_H
-
-#include <sqlite3.h>
-
-#include <string>
-
-namespace obelisk
-{
-    class Verb
-    {
-        private:
-            int id_;
-            std::string name_;
-
-        public:
-            Verb() :
-                id_(0),
-                name_("")
-            {
-            }
-
-            Verb(int id) :
-                id_(id),
-                name_("")
-            {
-            }
-
-            Verb(std::string name) :
-                id_(0),
-                name_(name)
-            {
-            }
-
-            Verb(int id, std::string name) :
-                id_(id),
-                name_(name)
-            {
-            }
-
-            static const char* createTable();
-
-            int& getId();
-            void setId(int id);
-
-            std::string& getName();
-            void setName(std::string name);
-
-            void selectVerb(sqlite3* dbConnection);
-            void insertVerb(sqlite3* dbConnection);
-    };
-} // namespace obelisk
-
-#endif

src/parser.cpp

@@ -1,9 +1,6 @@
 #include "ast/call_expression_ast.h"
 #include "ast/number_expression_ast.h"
 #include "ast/variable_expression_ast.h"
-#include "models/entity.h"
-#include "models/fact.h"
-#include "models/verb.h"
 #include "parser.h"
 
 #include <memory>
@@ -45,13 +42,15 @@ void obelisk::Parser::setCurrentToken(int currentToken)
     currentToken_ = currentToken;
 }
 
-std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::logError(const char* str)
+std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::logError(
+    const char* str)
 {
     fprintf(stderr, "Error: %s\n", str);
     return nullptr;
 }
 
-std::unique_ptr<obelisk::PrototypeAST> obelisk::Parser::logErrorPrototype(const char* str)
+std::unique_ptr<obelisk::PrototypeAST> obelisk::Parser::logErrorPrototype(
+    const char* str)
 {
     logError(str);
     return nullptr;
@@ -85,12 +84,14 @@ std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parsePrimary()
 
 std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseNumberExpression()
 {
-    auto result = std::make_unique<obelisk::NumberExpressionAST>(getLexer()->getNumberValue());
+    auto result = std::make_unique<obelisk::NumberExpressionAST>(
+        getLexer()->getNumberValue());
     getNextToken();
     return result;
 }
 
-std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseParenthesisExpression()
+std::unique_ptr<obelisk::ExpressionAST>
+    obelisk::Parser::parseParenthesisExpression()
 {
     getNextToken();
     auto v = parseExpression();
@@ -107,7 +108,8 @@ std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseParenthesisExpress
     return v;
 }
 
-std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseIdentifierExpression()
+std::unique_ptr<obelisk::ExpressionAST>
+    obelisk::Parser::parseIdentifierExpression()
 {
     std::string idName = getLexer()->getIdentifier();
     getNextToken();
@@ -177,7 +179,8 @@ std::unique_ptr<obelisk::PrototypeAST> obelisk::Parser::parsePrototype()
 
     getNextToken();
 
-    return std::make_unique<obelisk::PrototypeAST>(functionName, std::move(argNames));
+    return std::make_unique<obelisk::PrototypeAST>(functionName,
+        std::move(argNames));
 }
 
 std::unique_ptr<obelisk::FunctionAST> obelisk::Parser::parseDefinition()
@@ -191,7 +194,8 @@ std::unique_ptr<obelisk::FunctionAST> obelisk::Parser::parseDefinition()
 
     if (auto expression = parseExpression())
     {
-        return std::make_unique<FunctionAST>(std::move(prototype), std::move(expression));
+        return std::make_unique<FunctionAST>(std::move(prototype),
+            std::move(expression));
     }
 
     return nullptr;
@@ -202,8 +206,10 @@ std::unique_ptr<obelisk::FunctionAST> obelisk::Parser::parseTopLevelExpression()
     if (auto expression = parseExpression())
     {
         // Make an anonymous prototype
-        auto prototype = std::make_unique<obelisk::PrototypeAST>("__anon_expr", std::vector<std::string>());
-        return std::make_unique<obelisk::FunctionAST>(std::move(prototype), std::move(expression));
+        auto prototype = std::make_unique<obelisk::PrototypeAST>("__anon_expr",
+            std::vector<std::string>());
+        return std::make_unique<obelisk::FunctionAST>(std::move(prototype),
+            std::move(expression));
     }
     return nullptr;
 }
@@ -214,18 +220,416 @@ std::unique_ptr<obelisk::PrototypeAST> obelisk::Parser::parseExtern()
     return parsePrototype();
 }
 
-//action("martin" is "dangerous" then "avoid" or "ignore");
-std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseAction()
+void obelisk::Parser::parseAction(obelisk::SuggestAction& suggestAction)
 {
+    std::stack<char> syntax;
+
+    getNextToken();
+    if (getCurrentToken() != '(')
+    {
+        throw obelisk::ParserException(
+            "expected '(' but got '" + std::to_string(getCurrentToken()) + "'");
+    }
+
+    syntax.push('(');
+
+    getNextToken();
+    if (getLexer()->getIdentifier() != "if")
+    {
+        throw obelisk::ParserException(
+            "expected 'if' but got '" + getLexer()->getIdentifier() + "'");
+    }
+
+    bool getEntity {true};
+    std::string leftEntity {""};
+    std::string rightEntity {""};
+    std::string trueAction {""};
+    std::string falseAction {""};
+    std::string entityName {""};
+    std::string verb {""};
+    getNextToken();
+
+    // get the entity side of statement
+    while (true)
+    {
+        if (getEntity)
+        {
+            if (getCurrentToken() == '"')
+            {
+                if (syntax.top() != '"')
+                {
+                    // open a double quote
+                    syntax.push('"');
+                    getNextToken();
+                }
+                else if (syntax.top() == '"')
+                {
+                    // close a double quote
+                    syntax.pop();
+                    if (verb == "")
+                    {
+                        leftEntity = std::move(entityName);
+                    }
+                    else
+                    {
+                        rightEntity = std::move(entityName);
+                    }
+                    getEntity = false;
+                    getNextToken();
+                    continue;
+                }
+            }
+
+            if (syntax.top() == '"')
+            {
+                if (entityName != "")
+                {
+                    entityName += " ";
+                }
+                entityName += getLexer()->getIdentifier();
+            }
+            getNextToken();
+        }
+        else
+        {
+            if (getCurrentToken() == ')')
+            {
+                throw obelisk::ParserException("unexpected ')'");
+            }
+
+            if (getCurrentToken() == '"')
+            {
+                throw obelisk::ParserException("unexpected '\"'");
+            }
+
+            if (getLexer()->getIdentifier() == "then")
+            {
+                break;
+            }
+            else
+            {
+                verb = getLexer()->getIdentifier();
+                for (const auto& letter : verb)
+                {
+                    if (!isalpha(letter))
+                    {
+                        throw new obelisk::ParserException(
+                            "non alphabetic symbol in verb");
+                    }
+                }
+                getEntity = true;
+                continue;
+            }
+        }
+    }
+
+    // get the action side of statement
+    bool getAction {true};
+    while (true)
+    {
+        if (getAction)
+        {
+            if (getCurrentToken() == '"')
+            {
+                if (syntax.top() != '"')
+                {
+                    // open a double quote
+                    syntax.push('"');
+                    getNextToken();
+                }
+                else if (syntax.top() == '"')
+                {
+                    // close a double quote
+                    syntax.pop();
+                    if (trueAction == "")
+                    {
+                        trueAction = std::move(entityName);
+                    }
+                    else
+                    {
+                        falseAction = std::move(entityName);
+                    }
+                    getAction = false;
+                    getNextToken();
+                    continue;
+                }
+            }
+
+            if (syntax.top() == '"')
+            {
+                if (entityName != "")
+                {
+                    entityName += " ";
+                }
+                entityName += getLexer()->getIdentifier();
+            }
+            getNextToken();
+        }
+        else
+        {
+            if (getCurrentToken() == ')')
+            {
+                // closing parenthesis found, make sure we have everything
+                // needed
+                if (syntax.top() != '(')
+                {
+                    throw obelisk::ParserException("unexpected ')'");
+                }
+                else
+                {
+                    syntax.pop();
+                }
+
+                if (leftEntity == "")
+                {
+                    throw obelisk::ParserException("missing left entity");
+                }
+
+                if (rightEntity == "")
+                {
+                    throw obelisk::ParserException("missing left entity");
+                }
+
+                if (verb == "")
+                {
+                    throw obelisk::ParserException("missing verb");
+                }
+
+                if (trueAction == "")
+                {
+                    throw obelisk::ParserException("missing true action");
+                }
+
+                if (falseAction == "")
+                {
+                    throw obelisk::ParserException("missing false action");
+                }
+
+                getNextToken();
+                if (getCurrentToken() != ';')
+                {
+                    throw obelisk::ParserException("missing ';'");
+                }
+
+                break;
+            }
+
+            if (getCurrentToken() == '"')
+            {
+                throw obelisk::ParserException("unexpected '\"'");
+                break;
+            }
+
+            if (getLexer()->getIdentifier() == "else")
+            {
+                getNextToken();
+                getAction = true;
+                continue;
+            }
+            else
+            {
+                getAction = true;
+                continue;
+            }
+        }
+    }
+
+    suggestAction.setFact(obelisk::Fact(obelisk::Entity(leftEntity),
+        obelisk::Entity(rightEntity),
+        obelisk::Verb(verb)));
+    suggestAction.setTrueAction(obelisk::Action(trueAction));
+    suggestAction.setFalseAction(obelisk::Action(falseAction));
 }
 
-//rule("chris" and "martin" is "happy" if "chris" plays "playstation");
-std::unique_ptr<obelisk::ExpressionAST> obelisk::Parser::parseRule()
+void obelisk::Parser::parseRule(obelisk::Rule& rule)
 {
+    std::stack<char> syntax;
+
+    getNextToken();
+    if (getCurrentToken() != '(')
+    {
+        throw obelisk::ParserException(
+            "expected '(' but got '" + std::to_string(getCurrentToken()) + "'");
+    }
+
+    syntax.push('(');
+
+    bool getEntity {true};
+    bool getReason {false};
+    std::string leftEntity {""};
+    std::string rightEntity {""};
+    std::string verb {""};
+    std::string leftReasonEntity {""};
+    std::string rightReasonEntity {""};
+    std::string reasonVerb {""};
+    std::string entityName {""};
+    getNextToken();
+
+    // get the entity side of statement
+    while (true)
+    {
+        if (getEntity)
+        {
+            if (getCurrentToken() == '"')
+            {
+                if (syntax.top() != '"')
+                {
+                    // open a double quote
+                    syntax.push('"');
+                    getNextToken();
+                }
+                else if (syntax.top() == '"')
+                {
+                    // close a double quote
+                    syntax.pop();
+                    if (!getReason)
+                    {
+                        if (verb == "")
+                        {
+                            leftEntity = std::move(entityName);
+                        }
+                        else
+                        {
+                            rightEntity = std::move(entityName);
+                        }
+                    }
+                    else
+                    {
+                        if (reasonVerb == "")
+                        {
+                            leftReasonEntity = std::move(entityName);
+                        }
+                        else
+                        {
+                            rightReasonEntity = std::move(entityName);
+                        }
+                    }
+                    getEntity = false;
+                    getNextToken();
+                    continue;
+                }
+            }
+
+            if (syntax.top() == '"')
+            {
+                if (entityName != "")
+                {
+                    entityName += " ";
+                }
+                entityName += getLexer()->getIdentifier();
+            }
+            getNextToken();
+        }
+        else
+        {
+            if (getCurrentToken() == ')')
+            {
+                // closing parenthesis found, make sure we have everything
+                // needed
+                if (syntax.top() != '(')
+                {
+                    throw obelisk::ParserException("unexpected ')'");
+                }
+                else
+                {
+                    syntax.pop();
+                }
+
+                if (leftEntity == "")
+                {
+                    throw obelisk::ParserException("missing left entity");
+                }
+
+                if (rightEntity == "")
+                {
+                    throw obelisk::ParserException("missing right entity");
+                }
+
+                if (verb == "")
+                {
+                    throw obelisk::ParserException("missing verb");
+                }
+
+                if (leftReasonEntity == "")
+                {
+                    throw obelisk::ParserException(
+                        "missing left reason entity");
+                }
+
+                if (rightReasonEntity == "")
+                {
+                    throw obelisk::ParserException(
+                        "missing right reason entity");
+                }
+
+                if (reasonVerb == "")
+                {
+                    throw obelisk::ParserException("missing reason verb");
+                }
+
+                getNextToken();
+                if (getCurrentToken() != ';')
+                {
+                    throw obelisk::ParserException("missing ';'");
+                }
+
+                break;
+            }
+
+            if (getCurrentToken() == '"')
+            {
+                throw obelisk::ParserException("unexpected '\"'");
+            }
+
+            if (getLexer()->getIdentifier() == "if")
+            {
+                getReason = true;
+                getEntity = true;
+                getNextToken();
+                continue;
+            }
+            else
+            {
+                if (!getReason)
+                {
+                    verb = getLexer()->getIdentifier();
+                    for (const auto& letter : verb)
+                    {
+                        if (!isalpha(letter))
+                        {
+                            throw new obelisk::ParserException(
+                                "non alphabetic symbol in verb");
+                        }
+                    }
+                    getEntity = true;
+                    continue;
+                }
+                else
+                {
+                    reasonVerb = getLexer()->getIdentifier();
+                    for (const auto& letter : reasonVerb)
+                    {
+                        if (!isalpha(letter))
+                        {
+                            throw new obelisk::ParserException(
+                                "non alphabetic symbol in verb");
+                        }
+                    }
+                    getEntity = true;
+                    continue;
+                }
+            }
+        }
+    }
+
+    rule.setFact(obelisk::Fact(obelisk::Entity(leftEntity),
+        obelisk::Entity(rightEntity),
+        obelisk::Verb(verb)));
+    rule.setReason(obelisk::Fact(obelisk::Entity(leftReasonEntity),
+        obelisk::Entity(rightReasonEntity),
+        obelisk::Verb(reasonVerb)));
 }
 
-// fact("chris cromer" and "martin" and "Isabella" can "program" and "speak english");
-// fact("" and "martin")
 void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
 {
     std::stack<char> syntax;
@@ -233,20 +637,19 @@ void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
     getNextToken();
     if (getCurrentToken() != '(')
     {
-        throw obelisk::ParserException("expected '(' but got '" + std::to_string(getCurrentToken()) + "'");
+        throw obelisk::ParserException(
+            "expected '(' but got '" + std::to_string(getCurrentToken()) + "'");
     }
 
     syntax.push('(');
 
-    // ("
-
     bool getEntity {true};
     std::vector<std::string> leftEntities;
     std::vector<std::string> rightEntities;
     std::string entityName {""};
     std::string verb {""};
     getNextToken();
-    while (true) //left side of fact
+    while (true)
     {
         if (getEntity)
         {
@@ -291,7 +694,17 @@ void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
         {
             if (getCurrentToken() == ')')
             {
-                // closing parenthesis found, make sure we have everything needed
+                // closing parenthesis found, make sure we have everything
+                // needed
+                if (syntax.top() != '(')
+                {
+                    throw obelisk::ParserException("unexpected ')'");
+                }
+                else
+                {
+                    syntax.pop();
+                }
+
                 if (verb == "")
                 {
                     throw obelisk::ParserException("verb is empty");
@@ -299,20 +712,28 @@ void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
 
                 if (leftEntities.size() == 0)
                 {
-                    throw obelisk::ParserException("missing left side entities");
+                    throw obelisk::ParserException(
+                        "missing left side entities");
                 }
 
                 if (rightEntities.size() == 0)
                 {
-                    throw obelisk::ParserException("missing right side entities");
+                    throw obelisk::ParserException(
+                        "missing right side entities");
                 }
+
+                getNextToken();
+                if (getCurrentToken() != ';')
+                {
+                    throw obelisk::ParserException("missing ';'");
+                }
+
                 break;
             }
 
             if (getCurrentToken() == '"')
             {
                 throw obelisk::ParserException("unexpected '\"'");
-                break;
             }
 
             if (getLexer()->getIdentifier() == "and")
@@ -323,8 +744,15 @@ void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
             }
             else
             {
-                verb      = getLexer()->getIdentifier();
-                // TODO: make sure verb is alphabetic
+                verb = getLexer()->getIdentifier();
+                for (const auto& letter : verb)
+                {
+                    if (!isalpha(letter))
+                    {
+                        throw new obelisk::ParserException(
+                            "non alphabetic symbol in verb");
+                    }
+                }
                 getEntity = true;
                 continue;
             }
@@ -335,107 +763,242 @@ void obelisk::Parser::parseFact(std::vector<obelisk::Fact>& facts)
     {
         for (auto& rightEntity : rightEntities)
         {
-            facts.push_back(
-                obelisk::Fact(obelisk::Entity(leftEntity), obelisk::Entity(rightEntity), obelisk::Verb(verb)));
+            facts.push_back(obelisk::Fact(obelisk::Entity(leftEntity),
+                obelisk::Entity(rightEntity),
+                obelisk::Verb(verb),
+                true));
         }
     }
 }
 
 void obelisk::Parser::handleAction(std::unique_ptr<obelisk::KnowledgeBase>& kb)
 {
+    obelisk::SuggestAction suggestAction;
+
+    try
+    {
+        parseAction(suggestAction);
+        insertEntity(kb, suggestAction.getFact().getLeftEntity());
+        insertEntity(kb, suggestAction.getFact().getRightEntity());
+        insertVerb(kb, suggestAction.getFact().getVerb());
+        insertFact(kb, suggestAction.getFact());
+        insertAction(kb, suggestAction.getTrueAction());
+        insertAction(kb, suggestAction.getFalseAction());
+        insertSuggestAction(kb, suggestAction);
+    }
+    catch (obelisk::ParserException& exception)
+    {
+        throw;
+    }
 }
 
 void obelisk::Parser::handleRule(std::unique_ptr<obelisk::KnowledgeBase>& kb)
 {
+    obelisk::Rule rule;
+
+    try
+    {
+        parseRule(rule);
+
+        insertEntity(kb, rule.getReason().getLeftEntity());
+        insertEntity(kb, rule.getReason().getRightEntity());
+        insertVerb(kb, rule.getReason().getVerb());
+        insertFact(kb, rule.getReason());
+
+        // The rule is true, so the fact must be true to.
+        if (rule.getReason().getIsTrue() > 0)
+        {
+            rule.getFact().setIsTrue(1.0);
+        }
+
+        insertEntity(kb, rule.getFact().getLeftEntity());
+        insertEntity(kb, rule.getFact().getRightEntity());
+        insertVerb(kb, rule.getFact().getVerb());
+        insertFact(kb, rule.getFact());
+
+        insertRule(kb, rule);
+    }
+    catch (obelisk::ParserException& exception)
+    {
+        throw;
+    }
 }
 
 void obelisk::Parser::handleFact(std::unique_ptr<obelisk::KnowledgeBase>& kb)
 {
     std::vector<obelisk::Fact> facts;
-    parseFact(facts);
+    try
+    {
+        parseFact(facts);
+    }
+    catch (obelisk::ParserException& exception)
+    {
+        throw;
+    }
 
     int verbId = 0;
     for (auto& fact : facts)
     {
-        std::vector<obelisk::Entity> entities {fact.getLeftEntity()};
-        kb->addEntities(entities);
-        fact.setLeftEntity(entities.front());
-
-        // the id was not inserted, so check if it exists in the database
-        if (fact.getLeftEntity().getId() == 0)
+        try
         {
-            obelisk::Entity entity = fact.getLeftEntity();
-            kb->getEntity(entity);
-            if (entity.getId() == 0)
-            {
-                throw obelisk::ParserException("left entity could not be inserted into the database");
-            }
-            else
-            {
-                fact.setLeftEntity(entity);
-            }
+            insertEntity(kb, fact.getLeftEntity());
+            insertEntity(kb, fact.getRightEntity());
         }
-
-        entities = {fact.getRightEntity()};
-        kb->addEntities(entities);
-        fact.setRightEntity(entities.front());
-
-        if (fact.getRightEntity().getId() == 0)
+        catch (obelisk::ParserException& exception)
         {
-            obelisk::Entity entity = fact.getRightEntity();
-            kb->getEntity(entity);
-            if (entity.getId() == 0)
-            {
-                throw obelisk::ParserException("right entity could not be inserted into the database");
-            }
-            else
-            {
-                fact.setRightEntity(entity);
-            }
+            throw;
         }
 
         if (verbId == 0)
         {
-            std::vector<obelisk::Verb> verbs = {fact.getVerb()};
-            kb->addVerbs(verbs);
-            if (verbs.front().getId() != 0)
+            try
             {
-                fact.setVerb(verbs.front());
-                verbId = fact.getVerb().getId();
+                insertVerb(kb, fact.getVerb());
             }
-            else
+            catch (obelisk::ParserException& exception)
             {
-                obelisk::Verb verb = fact.getVerb();
-                kb->getVerb(verb);
-                if (verb.getId() == 0)
-                {
-                    throw obelisk::ParserException("verb could not be inserted into the database");
-                }
-                else
-                {
-                    fact.setVerb(verb);
-                    verbId = fact.getVerb().getId();
-                }
+                throw;
             }
+            verbId = fact.getVerb().getId();
         }
         else
         {
             fact.getVerb().setId(verbId);
         }
 
-        std::vector<obelisk::Fact> facts {fact};
-        kb->addFacts(facts);
-        fact = facts.front();
+        try
+        {
+            insertFact(kb, fact, true);
+        }
+        catch (obelisk::ParserException& exception)
+        {
+            throw;
+        }
 
+        kb->checkRule(fact);
+    }
+}
+
+void obelisk::Parser::insertEntity(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::Entity& entity)
+{
+    std::vector<obelisk::Entity> entities {entity};
+    kb->addEntities(entities);
+    entity = std::move(entities.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (entity.getId() == 0)
+    {
+        kb->getEntity(entity);
+        if (entity.getId() == 0)
+        {
+            throw obelisk::ParserException(
+                "entity could not be inserted into the database");
+        }
+    }
+}
+
+void obelisk::Parser::insertVerb(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::Verb& verb)
+{
+    std::vector<obelisk::Verb> verbs {verb};
+    kb->addVerbs(verbs);
+    verb = std::move(verbs.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (verb.getId() == 0)
+    {
+        kb->getVerb(verb);
+        if (verb.getId() == 0)
+        {
+            throw obelisk::ParserException(
+                "verb could not be inserted into the database");
+        }
+    }
+}
+
+void obelisk::Parser::insertAction(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::Action& action)
+{
+    std::vector<obelisk::Action> actions {action};
+    kb->addActions(actions);
+    action = std::move(actions.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (action.getId() == 0)
+    {
+        kb->getAction(action);
+        if (action.getId() == 0)
+        {
+            throw obelisk::ParserException(
+                "action could not be inserted into the database");
+        }
+    }
+}
+
+void obelisk::Parser::insertFact(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::Fact& fact,
+    bool updateIsTrue)
+{
+    std::vector<obelisk::Fact> facts {fact};
+    kb->addFacts(facts);
+    fact = std::move(facts.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (fact.getId() == 0)
+    {
+        kb->getFact(fact);
         if (fact.getId() == 0)
         {
-            kb->getFact(fact);
-            if (fact.getId() == 0)
+            throw obelisk::ParserException(
+                "fact could not be inserted into the database");
+        }
+        else
+        {
+            if (updateIsTrue)
             {
-                throw obelisk::ParserException("fact could not be inserted into the database");
+                fact.setIsTrue(1.0);
+                kb->updateIsTrue(fact);
             }
         }
     }
 }
 
-// fact("chris cromer" and "martin" and "Isabella" can "program" and "speak english");
+void obelisk::Parser::insertSuggestAction(
+    std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::SuggestAction& suggestAction)
+{
+    std::vector<obelisk::SuggestAction> suggestActions {suggestAction};
+    kb->addSuggestActions(suggestActions);
+    suggestAction = std::move(suggestActions.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (suggestAction.getId() == 0)
+    {
+        kb->getSuggestAction(suggestAction);
+        if (suggestAction.getId() == 0)
+        {
+            throw obelisk::ParserException(
+                "suggest_action could not be inserted into the database");
+        }
+    }
+}
+
+void obelisk::Parser::insertRule(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+    obelisk::Rule& rule)
+{
+    std::vector<obelisk::Rule> rules {rule};
+    kb->addRules(rules);
+    rule = std::move(rules.front());
+
+    // the id was not inserted, so check if it exists in the database
+    if (rule.getId() == 0)
+    {
+        kb->getRule(rule);
+        if (rule.getId() == 0)
+        {
+            throw obelisk::ParserException(
+                "rule could not be inserted into the database");
+        }
+    }
+}

src/parser.h

@@ -6,73 +6,325 @@
 #include "ast/prototype_ast.h"
 #include "knowledge_base.h"
 #include "lexer.h"
+#include "models/action.h"
+#include "models/entity.h"
 #include "models/fact.h"
+#include "models/rule.h"
+#include "models/suggest_action.h"
+#include "models/verb.h"
 
 #include <memory>
 
 namespace obelisk
 {
+    /**
+     * @brief The Parser is responsible for analyzing the language's key words
+     * and taking action based on its analysis.
+     *
+     */
     class Parser
     {
         private:
+            /**
+             * @brief The Lexer object that the Parser is using to Parse a
+             * specific source file.
+             *
+             */
             std::shared_ptr<obelisk::Lexer> lexer_;
+
+            /**
+             * @brief The current token that the lexer has retrieved.
+             *
+             */
             int currentToken_ = 0;
 
+            /**
+             * @brief Set the current token.
+             *
+             * @param[in] currentToken The token should be ASCII character.
+             */
             void setCurrentToken(int currentToken);
 
+            /**
+             * @brief Log errors from the LLVM parsing.
+             *
+             * @param[in] str The error message.
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the AST
+             * expression that caused the error.
+             */
             std::unique_ptr<obelisk::ExpressionAST> logError(const char* str);
-            std::unique_ptr<obelisk::PrototypeAST> logErrorPrototype(const char* str);
 
+            /**
+             * @brief Log errors from the LLVM parsing involving the prototypes.
+             *
+             * @param[in] str The error message.
+             * @return std::unique_ptr<obelisk::PrototypeAST> Returns the AST
+             * for the prototype.
+             */
+            std::unique_ptr<obelisk::PrototypeAST> logErrorPrototype(
+                const char* str);
+
+            /**
+             * @brief The AST expression parser.
+             *
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the
+             * parsed AST expression.
+             */
             std::unique_ptr<obelisk::ExpressionAST> parseExpression();
+
+            /**
+             * @brief The AST number expression parser.
+             *
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the
+             * parsed AST expression.
+             */
             std::unique_ptr<obelisk::ExpressionAST> parseNumberExpression();
-            std::unique_ptr<obelisk::ExpressionAST> parseParenthesisExpression();
+
+            /**
+             * @brief The AST parenthesis expression parser.
+             *
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the
+             * parsed AST expression.
+             */
+            std::unique_ptr<obelisk::ExpressionAST>
+                parseParenthesisExpression();
+
+            /**
+             * @brief The AST identifier expression parser.
+             *
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the
+             * parsed AST expression.
+             */
             std::unique_ptr<obelisk::ExpressionAST> parseIdentifierExpression();
+
+            /**
+             * @brief The AST primary expression parser.
+             *
+             * @return std::unique_ptr<obelisk::ExpressionAST> Returns the
+             * parsed AST expression.
+             */
             std::unique_ptr<obelisk::ExpressionAST> parsePrimary();
+
+            /**
+             * @brief The AST prototype parser.
+             *
+             * @return std::unique_ptr<obelisk::PrototypeAST> Returns the parsed
+             * AST prototype expression.
+             */
             std::unique_ptr<obelisk::PrototypeAST> parsePrototype();
+
+            /**
+             * @brief The AST definition parser.
+             *
+             * @return std::unique_ptr<obelisk::FunctionAST> Returns the parsed
+             * AST definition expression.
+             */
             std::unique_ptr<obelisk::FunctionAST> parseDefinition();
+
+            /**
+             * @brief The AST top level expression parser.
+             *
+             * @return std::unique_ptr<obelisk::FunctionAST> Returns the parsed
+             * AST top level expression.
+             */
             std::unique_ptr<obelisk::FunctionAST> parseTopLevelExpression();
+
+            /**
+             * @brief The AST external definition parser.
+             *
+             * @return std::unique_ptr<obelisk::PrototypeAST> Returns the parsed
+             * AST external definition.
+             */
             std::unique_ptr<obelisk::PrototypeAST> parseExtern();
-            std::unique_ptr<obelisk::ExpressionAST> parseAction();
-            std::unique_ptr<obelisk::ExpressionAST> parseRule();
+
+            /**
+             * @brief Parse a SuggestAction.
+             *
+             * @param[out] suggestAction The parsed SuggestAction.
+             */
+            void parseAction(obelisk::SuggestAction& suggestAction);
+
+            /**
+             * @brief Parse a Rule.
+             *
+             * @param[out] rule The parsed Rule.
+             */
+            void parseRule(obelisk::Rule& rule);
+
+            /**
+             * @brief Parse Facts.
+             *
+             * @param[out] facts The parsed Facts.
+             */
             void parseFact(std::vector<obelisk::Fact>& facts);
 
         public:
+            /**
+             * @brief Construct a new Parser object.
+             *
+             * @param[in] lexer The lexer the parser uses to retrieve parts of
+             * the language.
+             */
             Parser(std::shared_ptr<obelisk::Lexer> lexer) :
                 lexer_(lexer)
             {
             }
 
+            /**
+             * @brief Get the Lexer.
+             *
+             * @return std::shared_ptr<obelisk::Lexer> Returns the current Lexer
+             * in use by the Parser.
+             */
             std::shared_ptr<obelisk::Lexer> getLexer();
+
+            /**
+             * @brief Set the Lexer to use during the parsing phase.
+             *
+             * @param[in] lexer The Lexer.
+             */
             void setLexer(std::shared_ptr<obelisk::Lexer> lexer);
 
+            /**
+             * @brief Gets the current token held inside the Lexer.
+             *
+             * @return int Returns the current token.
+             */
             int getCurrentToken();
 
+            /**
+             * @brief Instructs the Lexer to retrieve a new token.
+             *
+             * @return int Returns the next token.
+             */
             int getNextToken();
 
-            void handleDefinition();
-            void handleExtern();
-            void handleTopLevelExpression();
+            /**
+             * @brief Parse the SuggestAction and then insert it into the
+             * KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to insert the SuggestAction into.
+             */
             void handleAction(std::unique_ptr<obelisk::KnowledgeBase>& kb);
+
+            /**
+             * @brief Parse the Rule and then insert it into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to insert the Rule into.
+             */
             void handleRule(std::unique_ptr<obelisk::KnowledgeBase>& kb);
+
+            /**
+             * @brief Parse the Fact and then insert it into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to insert the Fact into.
+             */
             void handleFact(std::unique_ptr<obelisk::KnowledgeBase>& kb);
+
+            /**
+             * @brief Helper used to insert an Entity into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to use.
+             * @param[in,out] entity The Entity to insert. It will contain the
+             * ID of the Entity after inserting it.
+             */
+            void insertEntity(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::Entity& entity);
+
+            /**
+             * @brief Helper used to insert a Verb into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledegeBase to use.
+             * @param[in,out] verb The Verb to insert. It will contain the ID of
+             * the Verb after inserting it.
+             */
+            void insertVerb(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::Verb& verb);
+
+            /**
+             * @brief Helper used to insert an Action into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to use.
+             * @param[in,out] action The Action to insert. It will contain the
+             * ID of the Action after inserting it.
+             */
+            void insertAction(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::Action& action);
+
+            /**
+             * @brief Helper used to insert a Fact into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to use.
+             * @param[in,out] fact The Fact to insert. It will contain the ID of
+             * the Fact after inserting it.
+             * @param[in] updateIsTrue If true, it will update the value of
+             * is_true in the KnowledgeBase if the Fact already exists.
+             */
+            void insertFact(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::Fact& fact,
+                bool updateIsTrue = false);
+
+            /**
+             * @brief Helper used to insert a SuggestAction into the
+             * KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to use.
+             * @param[in,out] suggestAction The SuggestAction to insert. It will
+             * contain the ID of the SuggestAction after inserting it.
+             */
+            void insertSuggestAction(
+                std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::SuggestAction& suggestAction);
+
+            /**
+             * @brief Helper usedto insert a Rule into the KnowledgeBase.
+             *
+             * @param[in] kb The KnowledgeBase to use.
+             * @param[in,out] rule The Rule to insert. It will contain the ID of
+             * the Rule after inserting it.
+             */
+            void insertRule(std::unique_ptr<obelisk::KnowledgeBase>& kb,
+                obelisk::Rule& rule);
     };
 
+    /**
+     * @brief The exceptions thrown by the Parser.
+     *
+     */
     class ParserException : public std::exception
     {
         private:
+            /**
+             * @brief The error message.
+             *
+             */
             const std::string errorMessage_;
 
         public:
+            /**
+             * @brief Construct a new ParserException object.
+             *
+             */
             ParserException() :
                 errorMessage_("an unknown error ocurred")
             {
             }
 
+            /**
+             * @brief Construct a new ParserException object.
+             *
+             * @param[in] errorMessage The error message.
+             */
             ParserException(const std::string& errorMessage) :
                 errorMessage_(errorMessage)
             {
             }
 
+            /**
+             * @brief Return the error message as a C style string.
+             *
+             * @return const char* Returns the error message.
+             */
             const char* what() const noexcept
             {
                 return errorMessage_.c_str();

src/version.h.in

@@ -1,8 +0,0 @@
-namespace obelisk
-{
-    /**
-     * @brief The current version of obelisk.
-     *
-     */
-    std::string version = "@version@";
-} // namespace obelisk