Click here to Skip to main content
13,354,605 members (66,181 online)
Click here to Skip to main content


248 bookmarked
Posted 22 Oct 2011

Implementing Programming Languages Using C# 4.0

, 12 Jul 2012
An introduction to creating programming language tools using C# 4.0.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;

namespace Diggins.Jigsaw
    public class JavaScriptExpressionCompiler : ExpressionCompiler
        public static Delegate CompileLambda(string s)
            var nodes = JavaScriptGrammar.AnonFunc.Parse(s);
            return CompileLambda(nodes[0]);

        public static Delegate CompileLambda(Node n)
            n = JavaScriptTransformer.Transform(n);
            var compiler = new JavaScriptExpressionCompiler();
            var expr = (LambdaExpression)compiler.ToExpr(n);
            if (expr == null) return null;
            return expr.Compile();

        /// <summary>
        /// The node has to be transformed before being passed
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        public Expression ToExpr(Node n)
            switch (n.Label)
                case "Empty":
                    return Noop;
                case "Return":
                    return (n.Count > 0)
                        ? Expression.Return(GetReturnTarget(), ToExpr(n[0]), typeof(Object))
                        : Expression.Return(GetReturnTarget(), Expression.Constant(typeof(Object), null));
                case "If":
                    return n.Count > 2
                        ? Expression.IfThenElse(Expression.Convert(ToExpr(n[0]), typeof(Boolean)), ToExpr(n[1]), ToExpr(n[2]))
                        : Expression.IfThen(Expression.Convert(ToExpr(n[0]), typeof(Boolean)), ToExpr(n[1]));
                case "Else":
                    return ToExpr(n[0]);
                case "For":                    
                    return CompileForLoop(ToExpr(n[0]), ToExpr(n[1]), ToExpr(n[2]), ToExpr(n[3]));
                case "VarDecl":
                        var r = AddBinding(Expression.Variable(typeof(object), n[0].Text));
                        if (n.Count > 1)
                            r = Expression.Assign(r, ToExpr(n[1]));
                        return r;
                case "Block":
                    return ScopedExpr(() => Expression.Block(n.Nodes.Select(ToExpr)));
                case "TertiaryExpr":
                    return Expression.Condition(ToExpr(n[0]), ToExpr(n[1]), ToExpr(n[2]));
                case "BinaryExpr":
                    return Expression.Call(null, Primitives.GetMethodFromBinaryOperator(n[1].Text), ToExpr(n[0]), ToExpr(n[2]));
                case "AssignExpr":
                    return Expression.Assign(ToExpr(n[0]), ToExpr(n[2]));
                case "FieldExpr":
                    return Expression.Field(ToExpr(n[0]), n[1].Text);
                case "IndexExpr":
                    return CompileIndexExpr(ToExpr(n[0]), ToExpr(n[2]));
                case "CallExpr":
                    return CompileCallExpr(ToExpr(n[0]), n[1].Nodes.Select(ToExpr));
                case "MethodCallExpr":
                        var self = ToExpr(n[0]);
                        var func = Expression.Field(self, n[1].Text);
                        var args = new List<Expression>() { self };
                        return CompileCallExpr(func, args);
                case "PrefixExpr":
                    switch (n[0].Text)
                        case "!": return Expression.Not(ToExpr(n[1]));
                        case "~": return Expression.OnesComplement(ToExpr(n[1]));
                        case "-": return Expression.Negate(ToExpr(n[1]));
                        default: throw new Exception("Unrecognized prefix operator " + n[0].Text);
                case "NewExpr":
                    return ScopedExpr(() => 
                            AddBinding("this", Expression.Constant(new JsonObject()));
                            return ToExpr(n[0]);
                case "ParenExpr":
                    return ToExpr(n[0]);
                case "AnonFunc":
                        var ps = n[0].Nodes.Select(x => Expression.Parameter(typeof(Object), x.Text));
                        return CreateStatementLambda(ps, () => ToExpr(n[1]));
                case "Object":
                    throw new NotImplementedException();
                case "Array":
                    return Expression.NewArrayInit(typeof(object), n.Nodes.Select(ToExpr));
                case "Identifier":
                    return Lookup(n.Text);
                case "String":
                    return Expression.Constant(Utilities.Unquote(n.Text));
                case "Integer":
                    return Expression.Convert(Expression.Constant(int.Parse(n.Text)), typeof(Object));
                case "Float":
                    return Expression.Convert(Expression.Constant(float.Parse(n.Text)), typeof(Object));
                case "True":
                    return Expression.Convert(Expression.Constant(true), typeof(Object));
                case "False":
                    return Expression.Convert(Expression.Constant(false), typeof(Object));
                case "Null":
                    return Expression.Constant(null);
                    throw new Exception("Unrecognized node type " + n.Label);

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.


This article, along with any associated source code and files, is licensed under The MIT License


About the Author

Christopher Diggins
Software Developer Autodesk
Canada Canada
This article was written by Christopher Diggins, a computer science nerd who currently works at Autodesk as an SDK specialist.

You may also be interested in...

Permalink | Advertise | Privacy | Terms of Use | Mobile
Web02 | 2.8.180111.1 | Last Updated 12 Jul 2012
Article Copyright 2011 by Christopher Diggins
Everything else Copyright © CodeProject, 1999-2018
Layout: fixed | fluid