Example #1
0
        private SimpleASTNode Multiplicative(TokenReader tokens)
        {
            SimpleASTNode child1 = Primary(tokens);
            SimpleASTNode node   = child1;

            while (true)
            {
                Token token = tokens.Peek();
                if (token != null && (token.GetType() == TokenType.Star || token.GetType() == TokenType.Slash))
                {
                    token = tokens.Read();
                    SimpleASTNode child2 = Primary(tokens);
                    if (child2 != null)
                    {
                        node = new SimpleASTNode(ASTNodeType.Multiplicative, token.GetText());
                        node.AddChild(child1);
                        node.AddChild(child2);
                        child1 = node;
                    }
                    else
                    {
                        throw new Exception("invalid multiplicative expression, expecting the right part.");
                    }
                }
                else
                {
                    break;
                }
            }
            return(node);
        }
Example #2
0
        public static void TextCalculator()
        {
            SimpleCalculator calculator = new SimpleCalculator();

            string script = "int a = b+3";

            Console.WriteLine("解析变量声明语句:" + script);
            SimpleLexer lexer  = new SimpleLexer();
            TokenReader tokens = lexer.Tokenize(script);

            try
            {
                SimpleASTNode node = calculator.InitDeclare(tokens);
                calculator.DumpAST(node, "");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }

            // script = "2 + 3*5";
            //Console.WriteLine("\n计算:" + script + ",看上去一切正常");
            script = "2 + 3 + 4";
            calculator.Evaluate(script);
        }
Example #3
0
        /// <summary>
        /// 基础表达式
        /// </summary>
        /// <param name="tokens"></param>
        /// <returns></returns>
        private SimpleASTNode Primary(TokenReader tokens)
        {
            SimpleASTNode node  = null;
            Token         token = tokens.Peek();

            if (token.GetType() == TokenType.IntLiteral)
            {
                token = tokens.Read();
                node  = new SimpleASTNode(ASTNodeType.IntLiteral, token.GetText());
            }
            else if (token.GetType() == TokenType.Identifier)
            {
                token = tokens.Read();
                node  = new SimpleASTNode(ASTNodeType.Identifier, token.GetText());
            }
            else if (token.GetType() == TokenType.LeftParen)
            {
                tokens.Read();
                node = Additive2(tokens);
                if (node != null)
                {
                    token = tokens.Peek();
                    if (token != null && token.GetType() == TokenType.RightParen)
                    {
                        tokens.Read();
                    }
                }
                else
                {
                    throw new Exception("expecting an additive expression inside parenthesis");
                }
            }
            return(node);
        }
Example #4
0
        /// <summary>
        /// 解析加法表达式
        /// </summary>
        /// <param name="tokens"></param>
        /// <returns></returns>
        private SimpleASTNode Additive(TokenReader tokens)
        {
            SimpleASTNode child1 = Multiplicative(tokens);
            SimpleASTNode node   = child1;

            Token token = tokens.Peek();

            if (child1 != null && token != null)
            {
                if (token.GetType() == TokenType.Plus || token.GetType() == TokenType.Minus)
                {
                    token = tokens.Read();
                    SimpleASTNode child2 = Additive(tokens);
                    if (child2 != null)
                    {
                        node = new SimpleASTNode(ASTNodeType.Additive, token.GetText());
                        node.AddChild(child1);
                        node.AddChild(child2);
                    }
                    else
                    {
                        throw new Exception("invalid additive expression, expecting the right part.");
                    }
                }
            }
            return(node);
        }
Example #5
0
        private SimpleASTNode Additive2(TokenReader tokens)
        {
            SimpleASTNode child1 = Multiplicative(tokens);
            SimpleASTNode node   = child1;

            if (child1 != null)
            {
                while (true)
                {
                    Token token = tokens.Peek();
                    if (token != null && (token.GetType() == TokenType.Plus || token.GetType() == TokenType.Minus))
                    {
                        token = tokens.Read();
                        SimpleASTNode child2 = Multiplicative(tokens);
                        node = new SimpleASTNode(ASTNodeType.Additive, token.GetText());
                        node.AddChild(child1);
                        node.AddChild(child2);
                        child1 = node;
                    }
                    else
                    {
                        break;
                    }
                }
            }
            return(node);
        }
Example #6
0
        /// <summary>
        /// 根节点
        /// </summary>
        /// <param name="tokens"></param>
        /// <returns></returns>
        private SimpleASTNode Prog(TokenReader tokens)
        {
            SimpleASTNode node  = new SimpleASTNode(ASTNodeType.Program, "Caculator");
            SimpleASTNode child = Additive2(tokens);

            if (child != null)
            {
                node.AddChild(child);
            }
            return(node);
        }
Example #7
0
        /// <summary>
        /// 声明变量
        /// int a
        /// int b = 2 * 3
        /// </summary>
        /// <param name="tokens"></param>
        /// <returns></returns>
        private SimpleASTNode IntDeclare(TokenReader tokens)
        {
            SimpleASTNode node  = null;
            Token         token = tokens.Peek();

            if (token != null && token.GetType() == TokenType.Int)
            {
                token = tokens.Read();
                if (tokens.Peek().GetType() == TokenType.Identifier)
                {
                    token = tokens.Read();
                    node  = new SimpleASTNode(ASTNodeType.IntDeclaration, token.GetText());
                    token = tokens.Peek();
                    if (token != null && token.GetType() == TokenType.Assignment)
                    {
                        tokens.Read();
                        SimpleASTNode child = Additive(tokens);
                        if (child == null)
                        {
                            throw new Exception("invalid variable iniialization, expecting an expression.");
                        }
                        else
                        {
                            node.AddChild(child);
                        }
                    }
                }
                else
                {
                    throw new Exception("Variable name expected.");
                }
            }
            if (node != null)
            {
                token = tokens.Peek();
                if (token != null && token.GetType() == TokenType.SemiColon)
                {
                    tokens.Read();
                }
                else
                {
                    throw new Exception("invalid statement, expecting semicolon");
                }
            }
            return(node);
        }
Example #8
0
        private SimpleASTNode AssignmentStatement(TokenReader tokens)
        {
            SimpleASTNode node  = null;
            Token         token = tokens.Peek();

            if (token != null && token.GetType() == TokenType.Identifier)
            {
                token = tokens.Read();
                node  = new SimpleASTNode(ASTNodeType.AssignmentStmt, token.GetText());
                token = tokens.Peek();
                if (token != null && token.GetType() == TokenType.Assignment)
                {
                    tokens.Read();
                    SimpleASTNode child = Additive(tokens);
                    if (child == null)
                    {
                        throw new Exception("invalid assignment statement, expecting an expression");
                    }
                    else
                    {
                        node.AddChild(child);
                        token = tokens.Peek();
                        if (token != null && token.GetType() == TokenType.SemiColon)
                        {
                            tokens.Read();
                        }
                        else
                        {
                            throw new Exception("invalid statement, expecting semicolon");
                        }
                    }
                }
                else
                {
                    tokens.UnRead();
                    node = null;
                }
            }
            return(node);
        }
Example #9
0
 public void AddChild(SimpleASTNode child)
 {
     children.Add(child);
     child.parent = this;
 }