コード例 #1
0
ファイル: Parser.cs プロジェクト: collenirwin/Loxish
        /// <summary>
        /// Consumes an if statement.
        /// </summary>
        private IfStatement IfStatement()
        {
            Consume(TokenType.LeftParen, "Expected '(' after 'if'.");
            var condition = Expression();

            Consume(TokenType.RightParen, "Expected ')' after 'if' condition.");

            var           thenBranch = Statement();
            StatementBase elseBranch = null;

            if (NextTokenMatches(TokenType.Else))
            {
                elseBranch = Statement();
            }

            return(new IfStatement(condition, thenBranch, elseBranch));
        }
コード例 #2
0
ファイル: Statements.cs プロジェクト: collenirwin/Loxish
 public IfStatement(ExpressionBase condition, StatementBase thenBranch, StatementBase elseBranch)
 {
     Condition  = condition;
     ThenBranch = thenBranch;
     ElseBranch = elseBranch;
 }
コード例 #3
0
ファイル: Statements.cs プロジェクト: collenirwin/Loxish
 public WhileStatement(ExpressionBase condition, StatementBase body)
 {
     Condition = condition;
     Body      = body;
 }
コード例 #4
0
 /// <summary>
 /// Runs the statement's <see cref="StatementBase.Accept(IStatementVisitor)"/> method.
 /// </summary>
 /// <param name="statement">Statement to execute.</param>
 private void Execute(StatementBase statement)
 {
     statement.Accept(this);
 }
コード例 #5
0
ファイル: Parser.cs プロジェクト: collenirwin/Loxish
        /// <summary>
        /// Consumes a for statement (desugars into a block-enclosed while loop).
        /// </summary>
        private StatementBase ForStatement()
        {
            Consume(TokenType.LeftParen, "Expected '(' after 'for'.");

            StatementBase initializer = null;

            if (!NextTokenMatches(TokenType.SemiColon))
            {
                initializer = NextTokenMatches(TokenType.Var)
                    ? VarDeclaration()
                    : ExpressionStatement();
            }

            ExpressionBase condition = null;

            if (!PeekMatches(TokenType.SemiColon))
            {
                condition = Expression();
            }

            Consume(TokenType.SemiColon, "Expected ';' after for loop condition.");

            ExpressionBase increment = null;

            if (!PeekMatches(TokenType.RightParen))
            {
                increment = Expression();
            }

            Consume(TokenType.RightParen, "Expected ')' after for loop clauses.");

            try
            {
                _loopDepth++;
                var body = Statement();

                if (increment != null)
                {
                    // wrap the body in a block with the increment executing at the end
                    body = new BlockStatement(new[]
                    {
                        body,
                        new ExpressionStatement(increment)
                    });
                }

                // wire up a while loop using the condition and body
                condition ??= new LiteralExpression(true);
                body = new WhileStatement(condition, body);

                if (initializer != null)
                {
                    // wrap the body in another block with the increment executing first
                    body = new BlockStatement(new[]
                    {
                        initializer,
                        body
                    });
                }

                return(body);
            }
            finally
            {
                _loopDepth--;
            }
        }