if command

alib2cli/src/ast/command/IfCommand.h

+#ifndef _CLI_IF_COMMAND_H_
+#define _CLI_IF_COMMAND_H_
+
+#include <ast/Command.h>
+#include <environment/Environment.h>
+#include <ast/Statement.h>
+#include <common/CastHelper.h>
+
+namespace cli {
+
+class IfCommand : public Command {
+	std::unique_ptr < Expression > m_condition;
+	std::unique_ptr < Command > m_thenBranch;
+	std::unique_ptr < Command > m_elseBranch;
+
+public:
+	IfCommand ( std::unique_ptr < Expression > condition, std::unique_ptr < Command > thenBranch, std::unique_ptr < Command > elseBranch ) : m_condition ( std::move ( condition ) ), m_thenBranch ( std::move ( thenBranch ) ), m_elseBranch ( std::move ( elseBranch ) ) {
+	}
+
+	CommandResult run ( Environment & environment ) const override {
+		std::shared_ptr < abstraction::Value > conditionResult = m_condition->translateAndEval ( environment );
+
+		std::shared_ptr < abstraction::Value > castedResult = abstraction::CastHelper::eval ( environment, conditionResult, "bool" );
+
+		if ( std::static_pointer_cast < abstraction::ValueHolderInterface < bool > > ( castedResult )->getValue ( ) )
+			return m_thenBranch->run ( environment );
+		else if ( m_elseBranch != nullptr )
+			return m_elseBranch->run ( environment );
+
+		return cli::CommandResult::OK;
+	}
+};
+
+} /* namespace cli */
+
+#endif /* _CLI_IF_COMMAND_H_ */

alib2cli/src/parser/Parser.cpp

@@ -33,6 +33,7 @@
 #include <ast/command/BlockCommand.h>
 #include <ast/command/EvalCommand.h>
 #include <ast/command/InterpretCommand.h>
+#include <ast/command/IfCommand.h>
 #include <ast/expression/BinaryExpression.h>
 #include <ast/expression/PrefixExpression.h>
@@ -450,6 +451,24 @@ std::unique_ptr < Command > Parser::command ( ) {
 		match ( cli::Lexer::TokenType::FILE, cli::Lexer::TokenType::STRING );
 		return std::make_unique < InterpretCommand > ( std::move ( fileName ) );
+	} else if ( check_nonreserved_kw ( "if" ) ) {
+		if ( globalScope ( ) )
+			throw exception::CommonException ( "Statement not available in global scope." );
+		match_nonreserved_kw ( "if" );
+		match ( cli::Lexer::TokenType::LEFT_PAREN );
+		std::unique_ptr < Expression > condition = assign_expression ( );
+		match ( cli::Lexer::TokenType::RIGHT_PAREN );
+
+		match_nonreserved_kw ( "then" );
+		std::unique_ptr < Command > thenBranch = semicolon_command ( );
+
+		std::unique_ptr < Command > elseBranch;
+		if ( check_nonreserved_kw ( "else" ) ) {
+			match_nonreserved_kw ( "else" );
+			elseBranch = semicolon_command ( );
+		}
+
+		return std::make_unique < IfCommand > ( std::move ( condition ), std::move ( thenBranch ), std::move ( elseBranch ) );
 	} else {
 		throw exception::CommonException ( "Mismatched set " + ext::to_string ( getCheckOptions ( ) ) + " while expanding parse rule. Token is " + ( ( std::string ) m_current ) + "." );
 	}

alib2cli/src/parser/Parser.h

@@ -149,6 +149,10 @@ public:
 		-- m_forceLexerReadNext;
 	}
+	bool globalScope ( ) {
+		return m_forceLexerReadNext == 0;
+	}
+
 	std::unique_ptr < Expression > assign_expression ( );
 	std::unique_ptr < Expression > or_expression ( );