#if NET20 || NET30 || !NET_4_6

// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System.Collections.Generic;
using System.Diagnostics;
using System.Dynamic.Utils;
using System.Globalization;
using System.IO;
using System.Reflection;

namespace System.Linq.Expressions.Reimplement
{
    internal sealed class DebugViewWriter : ExpressionVisitor
    {
        [Flags]
        private enum Flow
        {
            None,
            Space,
            NewLine,

            Break = 0x8000      // newline if column > MaxColumn
        };

        private const int _tab = 4;
        private const int _maxColumn = 120;

        private readonly TextWriter _out;
        private int _column;

        private readonly Stack<int> _stack = new Stack<int>();
        private int _delta;
        private Flow _flow;

        // All the unique lambda expressions in the ET, will be used for displaying all
        // the lambda definitions.
        private Queue<LambdaExpression> _lambdas;

        // Associate every unique anonymous LambdaExpression in the tree with an integer.
        // The id is used to create a name for the anonymous lambda.
        //
        private Dictionary<LambdaExpression, int> _lambdaIds;

        // Associate every unique anonymous parameter or variable in the tree with an integer.
        // The id is used to create a name for the anonymous parameter or variable.
        //
        private Dictionary<ParameterExpression, int> _paramIds;

        // Associate every unique anonymous LabelTarget in the tree with an integer.
        // The id is used to create a name for the anonymous LabelTarget.
        //
        private Dictionary<LabelTarget, int> _labelIds;

        private DebugViewWriter(TextWriter file)
        {
            _out = file;
        }

        private int Base
        {
            get { return _stack.Count > 0 ? _stack.Peek() : 0; }
        }

        private int Delta
        {
            get { return _delta; }
        }

        private int Depth
        {
            get { return Base + Delta; }
        }

        private void Indent()
        {
            _delta += _tab;
        }

        private void Dedent()
        {
            _delta -= _tab;
        }

        private void NewLine()
        {
            _flow = Flow.NewLine;
        }

        private static int GetId<T>(T e, ref Dictionary<T, int> ids)
        {
            if (ids == null)
            {
                ids = new Dictionary<T, int>
                {
                    { e, 1 }
                };
                return 1;
            }
            else
            {
                int id;
                if (!ids.TryGetValue(e, out id))
                {
                    // e is met the first time
                    id = ids.Count + 1;
                    ids.Add(e, id);
                }
                return id;
            }
        }

        private int GetLambdaId(LambdaExpression le)
        {
            Debug.Assert(string.IsNullOrEmpty(le.Name));
            return GetId(le, ref _lambdaIds);
        }

        private int GetParamId(ParameterExpression p)
        {
            Debug.Assert(string.IsNullOrEmpty(p.Name));
            return GetId(p, ref _paramIds);
        }

        private int GetLabelTargetId(LabelTarget target)
        {
            Debug.Assert(string.IsNullOrEmpty(target.Name));
            return GetId(target, ref _labelIds);
        }

        internal static void WriteTo(Expression node, TextWriter writer)
        {
            Debug.Assert(node != null);
            Debug.Assert(writer != null);

            new DebugViewWriter(writer).WriteTo(node);
        }

        private void WriteTo(Expression node)
        {
            var lambda = node as LambdaExpression;
            if (lambda != null)
            {
                WriteLambda(lambda);
            }
            else
            {
                Visit(node);
                Debug.Assert(_stack.Count == 0);
            }

            //
            // Output all lambda expression definitions.
            // in the order of their appearances in the tree.
            //
            while (_lambdas != null && _lambdas.Count > 0)
            {
                WriteLine();
                WriteLine();
                WriteLambda(_lambdas.Dequeue());
            }
        }

        #region The printing code

        private void Out(string s)
        {
            Out(Flow.None, s, Flow.None);
        }

        private void Out(Flow before, string s)
        {
            Out(before, s, Flow.None);
        }

        private void Out(string s, Flow after)
        {
            Out(Flow.None, s, after);
        }

        private void Out(Flow before, string s, Flow after)
        {
            switch (GetFlow(before))
            {
                case Flow.None:
                    break;

                case Flow.Space:
                    Write(" ");
                    break;

                case Flow.NewLine:
                    WriteLine();
                    Write(new string(' ', Depth));
                    break;
            }
            Write(s);
            _flow = after;
        }

        private void WriteLine()
        {
            _out.WriteLine();
            _column = 0;
        }

        private void Write(string s)
        {
            _out.Write(s);
            _column += s.Length;
        }

        private Flow GetFlow(Flow flow)
        {
            var last = CheckBreak(_flow);
            flow = CheckBreak(flow);

            // Get the biggest flow that is requested None < Space < NewLine
            return (Flow)Math.Max((int)last, (int)flow);
        }

        private Flow CheckBreak(Flow flow)
        {
            if ((flow & Flow.Break) != 0)
            {
                if (_column > (_maxColumn + Depth))
                {
                    flow = Flow.NewLine;
                }
                else
                {
                    flow &= ~Flow.Break;
                }
            }
            return flow;
        }

        #endregion The printing code

        #region The AST Output

        private void VisitExpressions<T>(char open, IList<T> expressions) where T : Expression
        {
            VisitExpressions(open, ',', expressions);
        }

        private void VisitExpressions<T>(char open, char separator, IList<T> expressions) where T : Expression
        {
            VisitExpressions(open, separator, expressions, e => Visit(e));
        }

        private void VisitDeclarations(IList<ParameterExpression> expressions)
        {
            VisitExpressions('(', ',', expressions, variable =>
            {
                Out(variable.Type.ToString());
                if (variable.IsByRef)
                {
                    Out("&");
                }
                Out(" ");
                VisitParameter(variable);
            });
        }

        private void VisitExpressions<T>(char open, char separator, IList<T> expressions, Action<T> visit)
        {
            // NOTICE this method has no null check
            Out(open.ToString());

            if (expressions != null)
            {
                Indent();
                var isFirst = true;
                foreach (var e in expressions)
                {
                    if (isFirst)
                    {
                        if (open == '{' || expressions.Count > 1)
                        {
                            NewLine();
                        }
                        isFirst = false;
                    }
                    else
                    {
                        Out(separator.ToString(), Flow.NewLine);
                    }
                    visit(e);
                }
                Dedent();
            }

            char close;
            switch (open)
            {
                case '(':
                    close = ')';
                    break;

                case '{':
                    close = '}';
                    break;

                case '[':
                    close = ']';
                    break;

                case '<':
                    close = '>';
                    break;

                default:
                    throw ContractUtils.Unreachable;
            }

            if (open == '{')
            {
                NewLine();
            }
            Out(close.ToString(), Flow.Break);
        }

        protected internal override Expression VisitBinary(BinaryExpression node)
        {
            if (node.NodeType == ExpressionType.ArrayIndex)
            {
                ParenthesizedVisit(node, node.Left);
                Out("[");
                Visit(node.Right);
                Out("]");
            }
            else
            {
                var parenthesizeLeft = NeedsParentheses(node, node.Left);
                var parenthesizeRight = NeedsParentheses(node, node.Right);

                string op;
                var isChecked = false;
                var beforeOp = Flow.Space;
                switch (node.NodeType)
                {
                    case ExpressionType.Assign:
                        op = "=";
                        break;

                    case ExpressionType.Equal:
                        op = "==";
                        break;

                    case ExpressionType.NotEqual:
                        op = "!=";
                        break;

                    case ExpressionType.AndAlso:
                        op = "&&";
                        beforeOp = Flow.Break | Flow.Space;
                        break;

                    case ExpressionType.OrElse:
                        op = "||";
                        beforeOp = Flow.Break | Flow.Space;
                        break;

                    case ExpressionType.GreaterThan:
                        op = ">";
                        break;

                    case ExpressionType.LessThan:
                        op = "<";
                        break;

                    case ExpressionType.GreaterThanOrEqual:
                        op = ">=";
                        break;

                    case ExpressionType.LessThanOrEqual:
                        op = "<=";
                        break;

                    case ExpressionType.Add:
                        op = "+";
                        break;

                    case ExpressionType.AddAssign:
                        op = "+=";
                        break;

                    case ExpressionType.AddAssignChecked:
                        op = "+=";
                        isChecked = true;
                        break;

                    case ExpressionType.AddChecked:
                        op = "+";
                        isChecked = true;
                        break;

                    case ExpressionType.Subtract:
                        op = "-";
                        break;

                    case ExpressionType.SubtractAssign:
                        op = "-=";
                        break;

                    case ExpressionType.SubtractAssignChecked:
                        op = "-=";
                        isChecked = true;
                        break;

                    case ExpressionType.SubtractChecked:
                        op = "-";
                        isChecked = true;
                        break;

                    case ExpressionType.Divide:
                        op = "/";
                        break;

                    case ExpressionType.DivideAssign:
                        op = "/=";
                        break;

                    case ExpressionType.Modulo:
                        op = "%";
                        break;

                    case ExpressionType.ModuloAssign:
                        op = "%=";
                        break;

                    case ExpressionType.Multiply:
                        op = "*";
                        break;

                    case ExpressionType.MultiplyAssign:
                        op = "*=";
                        break;

                    case ExpressionType.MultiplyAssignChecked:
                        op = "*=";
                        isChecked = true;
                        break;

                    case ExpressionType.MultiplyChecked:
                        op = "*";
                        isChecked = true;
                        break;

                    case ExpressionType.LeftShift:
                        op = "<<";
                        break;

                    case ExpressionType.LeftShiftAssign:
                        op = "<<=";
                        break;

                    case ExpressionType.RightShift:
                        op = ">>";
                        break;

                    case ExpressionType.RightShiftAssign:
                        op = ">>=";
                        break;

                    case ExpressionType.And:
                        op = "&";
                        break;

                    case ExpressionType.AndAssign:
                        op = "&=";
                        break;

                    case ExpressionType.Or:
                        op = "|";
                        break;

                    case ExpressionType.OrAssign:
                        op = "|=";
                        break;

                    case ExpressionType.ExclusiveOr:
                        op = "^";
                        break;

                    case ExpressionType.ExclusiveOrAssign:
                        op = "^=";
                        break;

                    case ExpressionType.Power:
                        op = "**";
                        break;

                    case ExpressionType.PowerAssign:
                        op = "**=";
                        break;

                    case ExpressionType.Coalesce:
                        op = "??";
                        break;

                    default:
                        throw new InvalidOperationException();
                }

                if (parenthesizeLeft)
                {
                    Out("(", Flow.None);
                }

                Visit(node.Left);
                if (parenthesizeLeft)
                {
                    Out(Flow.None, ")", Flow.Break);
                }

                // prepend # to the operator to represent checked op
                if (isChecked)
                {
                    op = string.Format(
                            CultureInfo.CurrentCulture,
                            "#{0}",
                            op
                    );
                }
                Out(beforeOp, op, Flow.Space | Flow.Break);

                if (parenthesizeRight)
                {
                    Out("(", Flow.None);
                }
                Visit(node.Right);
                if (parenthesizeRight)
                {
                    Out(Flow.None, ")", Flow.Break);
                }
            }
            return node;
        }

        protected internal override Expression VisitParameter(ParameterExpression node)
        {
            // Have '$' for the DebugView of ParameterExpressions
            Out("$");
            if (string.IsNullOrEmpty(node.Name))
            {
                // If no name if provided, generate a name as $var1, $var2.
                // No guarantee for not having name conflicts with user provided variable names.
                //
                var id = GetParamId(node);
                Out("var" + id);
            }
            else
            {
                Out(GetDisplayName(node.Name));
            }
            return node;
        }

        protected internal override Expression VisitLambda(LambdaExpression node)
        {
            Out(
                string.Format(CultureInfo.CurrentCulture,
                    "{0} {1}<{2}>",
                    ".Lambda",
                    GetLambdaName(node),
                    node.Type.ToString()
                )
            );

            if (_lambdas == null)
            {
                _lambdas = new Queue<LambdaExpression>();
            }

            // N^2 performance, for keeping the order of the lambdas.
            if (!_lambdas.Contains(node))
            {
                _lambdas.Enqueue(node);
            }

            return node;
        }

        private static bool IsSimpleExpression(Expression node)
        {
            var binary = node as BinaryExpression;
            if (binary != null)
            {
                return !(binary.Left is BinaryExpression || binary.Right is BinaryExpression);
            }

            return false;
        }

        protected internal override Expression VisitConditional(ConditionalExpression node)
        {
            if (IsSimpleExpression(node.Test))
            {
                Out(".If (");
                Visit(node.Test);
                Out(") {", Flow.NewLine);
            }
            else
            {
                Out(".If (", Flow.NewLine);
                Indent();
                Visit(node.Test);
                Dedent();
                Out(Flow.NewLine, ") {", Flow.NewLine);
            }
            Indent();
            Visit(node.IfTrue);
            Dedent();
            Out(Flow.NewLine, "} .Else {", Flow.NewLine);
            Indent();
            Visit(node.IfFalse);
            Dedent();
            Out(Flow.NewLine, "}");
            return node;
        }

        protected internal override Expression VisitConstant(ConstantExpression node)
        {
            var value = node.Value;

            if (value == null)
            {
                Out("null");
            }
            else if ((value is string) && node.Type == typeof(string))
            {
                Out(string.Format(
                    CultureInfo.CurrentCulture,
                    "\"{0}\"",
                    value));
            }
            else if ((value is char) && node.Type == typeof(char))
            {
                Out(string.Format(
                    CultureInfo.CurrentCulture,
                    "'{0}'",
                    value));
            }
            else if ((value is int) && node.Type == typeof(int)
              || (value is bool) && node.Type == typeof(bool))
            {
                Out(value.ToString());
            }
            else
            {
                var suffix = GetConstantValueSuffix(node.Type);
                if (suffix != null)
                {
                    Out(value.ToString());
                    Out(suffix);
                }
                else
                {
                    Out(string.Format(
                        CultureInfo.CurrentCulture,
                        ".Constant<{0}>({1})",
                        node.Type.ToString(),
                        value));
                }
            }
            return node;
        }

        private static string GetConstantValueSuffix(Type type)
        {
            if (type == typeof(uint))
            {
                return "U";
            }
            if (type == typeof(long))
            {
                return "L";
            }
            if (type == typeof(ulong))
            {
                return "UL";
            }
            if (type == typeof(double))
            {
                return "D";
            }
            if (type == typeof(float))
            {
                return "F";
            }
            if (type == typeof(decimal))
            {
                return "M";
            }
            return null;
        }

        protected internal override Expression VisitRuntimeVariables(RuntimeVariablesExpression node)
        {
            Out(".RuntimeVariables");
            VisitExpressions('(', node.Variables);
            return node;
        }

        // Prints ".instanceField" or "declaringType.staticField"
        private void OutMember(Expression node, Expression instance, MemberInfo member)
        {
            if (instance != null)
            {
                ParenthesizedVisit(node, instance);
                Out("." + member.Name);
            }
            else
            {
                // For static members, include the type name
                Out(member.DeclaringType + "." + member.Name);
            }
        }

        protected internal override Expression VisitMember(MemberExpression node)
        {
            OutMember(node, node.Expression, node.Member);
            return node;
        }

        protected internal override Expression VisitInvocation(InvocationExpression node)
        {
            Out(".Invoke ");
            ParenthesizedVisit(node, node.Expression);
            VisitExpressions('(', node.Arguments);
            return node;
        }

        private static bool NeedsParentheses(Expression parent, Expression child)
        {
            Debug.Assert(parent != null);
            if (child == null)
            {
                return false;
            }

            // Some nodes always have parentheses because of how they are
            // displayed, for example: ".Unbox(obj.Foo)"
            switch (parent.NodeType)
            {
                case ExpressionType.Increment:
                case ExpressionType.Decrement:
                case ExpressionType.IsTrue:
                case ExpressionType.IsFalse:
                case ExpressionType.Unbox:
                    return true;
            }

            var childOpPrec = GetOperatorPrecedence(child);
            var parentOpPrec = GetOperatorPrecedence(parent);

            if (childOpPrec == parentOpPrec)
            {
                // When parent op and child op has the same precedence,
                // we want to be a little conservative to have more clarity.
                // Parentheses are not needed if
                // 1) Both ops are &&, ||, &, |, or ^, all of them are the only
                // op that has the precedence.
                // 2) Parent op is + or *, e.g. x + (y - z) can be simplified to
                // x + y - z.
                // 3) Parent op is -, / or %, and the child is the left operand.
                // In this case, if left and right operand are the same, we don't
                // remove parenthesis, e.g. (x + y) - (x + y)
                //
                switch (parent.NodeType)
                {
                    case ExpressionType.AndAlso:
                    case ExpressionType.OrElse:
                    case ExpressionType.And:
                    case ExpressionType.Or:
                    case ExpressionType.ExclusiveOr:
                        // Since these ops are the only ones on their precedence,
                        // the child op must be the same.
                        Debug.Assert(child.NodeType == parent.NodeType);
                        // We remove the parenthesis, e.g. x && y && z
                        return false;

                    case ExpressionType.Add:
                    case ExpressionType.AddChecked:
                    case ExpressionType.Multiply:
                    case ExpressionType.MultiplyChecked:
                        return false;

                    case ExpressionType.Subtract:
                    case ExpressionType.SubtractChecked:
                    case ExpressionType.Divide:
                    case ExpressionType.Modulo:
                        var binary = parent as BinaryExpression;
                        Debug.Assert(binary != null);
                        // Need to have parenthesis for the right operand.
                        return child == binary.Right;
                }
                return true;
            }

            // Special case: negate of a constant needs parentheses, to
            // disambiguate it from a negative constant.
            if (child != null && child.NodeType == ExpressionType.Constant &&
                (parent.NodeType == ExpressionType.Negate || parent.NodeType == ExpressionType.NegateChecked))
            {
                return true;
            }

            // If the parent op has higher precedence, need parentheses for the child.
            return childOpPrec < parentOpPrec;
        }

        // the greater the higher
        private static int GetOperatorPrecedence(Expression node)
        {
            // Roughly matches C# operator precedence, with some additional
            // operators. Also things which are not binary/unary expressions,
            // such as conditional and type testing, don't use this mechanism.
            switch (node.NodeType)
            {
                // Assignment
                case ExpressionType.Assign:
                case ExpressionType.ExclusiveOrAssign:
                case ExpressionType.AddAssign:
                case ExpressionType.AddAssignChecked:
                case ExpressionType.SubtractAssign:
                case ExpressionType.SubtractAssignChecked:
                case ExpressionType.DivideAssign:
                case ExpressionType.ModuloAssign:
                case ExpressionType.MultiplyAssign:
                case ExpressionType.MultiplyAssignChecked:
                case ExpressionType.LeftShiftAssign:
                case ExpressionType.RightShiftAssign:
                case ExpressionType.AndAssign:
                case ExpressionType.OrAssign:
                case ExpressionType.PowerAssign:
                case ExpressionType.Coalesce:
                    return 1;

                // Conditional (?:) would go here

                // Conditional OR
                case ExpressionType.OrElse:
                    return 2;

                // Conditional AND
                case ExpressionType.AndAlso:
                    return 3;

                // Logical OR
                case ExpressionType.Or:
                    return 4;

                // Logical XOR
                case ExpressionType.ExclusiveOr:
                    return 5;

                // Logical AND
                case ExpressionType.And:
                    return 6;

                // Equality
                case ExpressionType.Equal:
                case ExpressionType.NotEqual:
                    return 7;

                // Relational, type testing
                case ExpressionType.GreaterThan:
                case ExpressionType.LessThan:
                case ExpressionType.GreaterThanOrEqual:
                case ExpressionType.LessThanOrEqual:
                case ExpressionType.TypeAs:
                case ExpressionType.TypeIs:
                case ExpressionType.TypeEqual:
                    return 8;

                // Shift
                case ExpressionType.LeftShift:
                case ExpressionType.RightShift:
                    return 9;

                // Additive
                case ExpressionType.Add:
                case ExpressionType.AddChecked:
                case ExpressionType.Subtract:
                case ExpressionType.SubtractChecked:
                    return 10;

                // Multiplicative
                case ExpressionType.Divide:
                case ExpressionType.Modulo:
                case ExpressionType.Multiply:
                case ExpressionType.MultiplyChecked:
                    return 11;

                // Unary
                case ExpressionType.Negate:
                case ExpressionType.NegateChecked:
                case ExpressionType.UnaryPlus:
                case ExpressionType.Not:
                case ExpressionType.Convert:
                case ExpressionType.ConvertChecked:
                case ExpressionType.PreIncrementAssign:
                case ExpressionType.PreDecrementAssign:
                case ExpressionType.OnesComplement:
                case ExpressionType.Increment:
                case ExpressionType.Decrement:
                case ExpressionType.IsTrue:
                case ExpressionType.IsFalse:
                case ExpressionType.Unbox:
                case ExpressionType.Throw:
                    return 12;

                // Power, which is not in C#
                // But VB/Python/Ruby put it here, above unary.
                case ExpressionType.Power:
                    return 13;

                // Primary, which includes all other node types:
                //   member access, calls, indexing, new.
                /*case ExpressionType.PostIncrementAssign:
                case ExpressionType.PostDecrementAssign:*/
                default:
                    return 14;

                // These aren't expressions, so never need parentheses:
                //   constants, variables
                case ExpressionType.Constant:
                case ExpressionType.Parameter:
                    return 15;
            }
        }

        private void ParenthesizedVisit(Expression parent, Expression nodeToVisit)
        {
            if (NeedsParentheses(parent, nodeToVisit))
            {
                Out("(");
                Visit(nodeToVisit);
                Out(")");
            }
            else
            {
                Visit(nodeToVisit);
            }
        }

        protected internal override Expression VisitMethodCall(MethodCallExpression node)
        {
            Out(".Call ");
            if (node.Object != null)
            {
                ParenthesizedVisit(node, node.Object);
            }
            else if (node.Method.DeclaringType != null)
            {
                Out(node.Method.DeclaringType.ToString());
            }
            else
            {
                Out("<UnknownType>");
            }
            Out(".");
            Out(node.Method.Name);
            VisitExpressions('(', node.Arguments);
            return node;
        }

        protected internal override Expression VisitNewArray(NewArrayExpression node)
        {
            if (node.NodeType == ExpressionType.NewArrayBounds)
            {
                // .NewArray MyType[expr1, expr2]
                Out(".NewArray " + node.Type.GetElementType());
                VisitExpressions('[', node.Expressions);
            }
            else
            {
                // .NewArray MyType {expr1, expr2}
                Out(".NewArray " + node.Type, Flow.Space);
                VisitExpressions('{', node.Expressions);
            }
            return node;
        }

        protected internal override Expression VisitNew(NewExpression node)
        {
            Out(".New " + node.Type);
            VisitExpressions('(', node.Arguments);
            return node;
        }

        protected override ElementInit VisitElementInit(ElementInit node)
        {
            if (node.Arguments.Count == 1)
            {
                Visit(node.Arguments[0]);
            }
            else
            {
                VisitExpressions('{', node.Arguments);
            }
            return node;
        }

        protected internal override Expression VisitListInit(ListInitExpression node)
        {
            Visit(node.NewExpression);
            VisitExpressions('{', ',', node.Initializers, e => VisitElementInit(e));
            return node;
        }

        protected override MemberAssignment VisitMemberAssignment(MemberAssignment node)
        {
            Out(node.Member.Name);
            Out(Flow.Space, "=", Flow.Space);
            Visit(node.Expression);
            return node;
        }

        protected override MemberListBinding VisitMemberListBinding(MemberListBinding node)
        {
            Out(node.Member.Name);
            Out(Flow.Space, "=", Flow.Space);
            VisitExpressions('{', ',', node.Initializers, e => VisitElementInit(e));
            return node;
        }

        protected override MemberMemberBinding VisitMemberMemberBinding(MemberMemberBinding node)
        {
            Out(node.Member.Name);
            Out(Flow.Space, "=", Flow.Space);
            VisitExpressions('{', ',', node.Bindings, e => VisitMemberBinding(e));
            return node;
        }

        protected internal override Expression VisitMemberInit(MemberInitExpression node)
        {
            Visit(node.NewExpression);
            VisitExpressions('{', ',', node.Bindings, e => VisitMemberBinding(e));
            return node;
        }

        protected internal override Expression VisitTypeBinary(TypeBinaryExpression node)
        {
            ParenthesizedVisit(node, node.Expression);
            switch (node.NodeType)
            {
                case ExpressionType.TypeIs:
                    Out(Flow.Space, ".Is", Flow.Space);
                    break;

                case ExpressionType.TypeEqual:
                    Out(Flow.Space, ".TypeEqual", Flow.Space);
                    break;
            }
            Out(node.TypeOperand.ToString());
            return node;
        }

        protected internal override Expression VisitUnary(UnaryExpression node)
        {
            switch (node.NodeType)
            {
                case ExpressionType.Convert:
                    Out("(" + node.Type + ")");
                    break;

                case ExpressionType.ConvertChecked:
                    Out("#(" + node.Type + ")");
                    break;

                case ExpressionType.TypeAs:
                    break;

                case ExpressionType.Not:
                    Out(node.Type == typeof(bool) ? "!" : "~");
                    break;

                case ExpressionType.OnesComplement:
                    Out("~");
                    break;

                case ExpressionType.Negate:
                    Out("-");
                    break;

                case ExpressionType.NegateChecked:
                    Out("#-");
                    break;

                case ExpressionType.UnaryPlus:
                    Out("+");
                    break;

                case ExpressionType.ArrayLength:
                    break;

                case ExpressionType.Quote:
                    Out("'");
                    break;

                case ExpressionType.Throw:
                    if (node.Operand == null)
                    {
                        Out(".Rethrow");
                    }
                    else
                    {
                        Out(".Throw", Flow.Space);
                    }
                    break;

                case ExpressionType.IsFalse:
                    Out(".IsFalse");
                    break;

                case ExpressionType.IsTrue:
                    Out(".IsTrue");
                    break;

                case ExpressionType.Decrement:
                    Out(".Decrement");
                    break;

                case ExpressionType.Increment:
                    Out(".Increment");
                    break;

                case ExpressionType.PreDecrementAssign:
                    Out("--");
                    break;

                case ExpressionType.PreIncrementAssign:
                    Out("++");
                    break;

                case ExpressionType.Unbox:
                    Out(".Unbox");
                    break;
            }

            ParenthesizedVisit(node, node.Operand);

            switch (node.NodeType)
            {
                case ExpressionType.TypeAs:
                    Out(Flow.Space, ".As", Flow.Space | Flow.Break);
                    Out(node.Type.ToString());
                    break;

                case ExpressionType.ArrayLength:
                    Out(".Length");
                    break;

                case ExpressionType.PostDecrementAssign:
                    Out("--");
                    break;

                case ExpressionType.PostIncrementAssign:
                    Out("++");
                    break;
            }
            return node;
        }

        protected internal override Expression VisitBlock(BlockExpression node)
        {
            Out(".Block");

            // Display <type> if the type of the BlockExpression is different from the
            // last expression's type in the block.
            if (node.Type != node.GetExpression(node.ExpressionCount - 1).Type)
            {
                Out(string.Format(CultureInfo.CurrentCulture, "<{0}>", node.Type.ToString()));
            }

            VisitDeclarations(node.Variables);
            Out(" ");
            // Use ; to separate expressions in the block
            VisitExpressions('{', ';', node.Expressions);

            return node;
        }

        protected internal override Expression VisitDefault(DefaultExpression node)
        {
            Out(".Default(" + node.Type + ")");
            return node;
        }

        protected internal override Expression VisitLabel(LabelExpression node)
        {
            Out(".Label", Flow.NewLine);
            Indent();
            Visit(node.DefaultValue);
            Dedent();
            NewLine();
            DumpLabel(node.Target);
            return node;
        }

        protected internal override Expression VisitGoto(GotoExpression node)
        {
            Out("." + node.Kind.ToString(), Flow.Space);
            Out(GetLabelTargetName(node.Target), Flow.Space);
            Out("{", Flow.Space);
            Visit(node.Value);
            Out(Flow.Space, "}");
            return node;
        }

        protected internal override Expression VisitLoop(LoopExpression node)
        {
            Out(".Loop", Flow.Space);
            if (node.ContinueLabel != null)
            {
                DumpLabel(node.ContinueLabel);
            }
            Out(" {", Flow.NewLine);
            Indent();
            Visit(node.Body);
            Dedent();
            Out(Flow.NewLine, "}");
            if (node.BreakLabel != null)
            {
                Out("", Flow.NewLine);
                DumpLabel(node.BreakLabel);
            }
            return node;
        }

        protected override SwitchCase VisitSwitchCase(SwitchCase node)
        {
            foreach (var test in node.TestValues)
            {
                Out(".Case (");
                Visit(test);
                Out("):", Flow.NewLine);
            }
            Indent();
            Indent();
            Visit(node.Body);
            Dedent();
            Dedent();
            NewLine();
            return node;
        }

        protected internal override Expression VisitSwitch(SwitchExpression node)
        {
            Out(".Switch ");
            Out("(");
            Visit(node.SwitchValue);
            Out(") {", Flow.NewLine);
            Visit(node.Cases, VisitSwitchCase);
            if (node.DefaultBody != null)
            {
                Out(".Default:", Flow.NewLine);
                Indent();
                Indent();
                Visit(node.DefaultBody);
                Dedent();
                Dedent();
                NewLine();
            }
            Out("}");
            return node;
        }

        protected override CatchBlock VisitCatchBlock(CatchBlock node)
        {
            Out(Flow.NewLine, "} .Catch (" + node.Test);
            if (node.Variable != null)
            {
                Out(Flow.Space, "");
                VisitParameter(node.Variable);
            }
            if (node.Filter != null)
            {
                Out(") .If (", Flow.Break);
                Visit(node.Filter);
            }
            Out(") {", Flow.NewLine);
            Indent();
            Visit(node.Body);
            Dedent();
            return node;
        }

        protected internal override Expression VisitTry(TryExpression node)
        {
            Out(".Try {", Flow.NewLine);
            Indent();
            Visit(node.Body);
            Dedent();
            Visit(node.Handlers, VisitCatchBlock);
            if (node.Finally != null)
            {
                Out(Flow.NewLine, "} .Finally {", Flow.NewLine);
                Indent();
                Visit(node.Finally);
                Dedent();
            }
            else if (node.Fault != null)
            {
                Out(Flow.NewLine, "} .Fault {", Flow.NewLine);
                Indent();
                Visit(node.Fault);
                Dedent();
            }

            Out(Flow.NewLine, "}");
            return node;
        }

        protected internal override Expression VisitIndex(IndexExpression node)
        {
            if (node.Indexer != null)
            {
                OutMember(node, node.Object, node.Indexer);
            }
            else
            {
                ParenthesizedVisit(node, node.Object);
            }

            VisitExpressions('[', node.Arguments);
            return node;
        }

        protected internal override Expression VisitExtension(Expression node)
        {
            Out(string.Format(CultureInfo.CurrentCulture, ".Extension<{0}>", node.GetType().ToString()));

            if (node.CanReduce)
            {
                Out(Flow.Space, "{", Flow.NewLine);
                Indent();
                Visit(node.Reduce());
                Dedent();
                Out(Flow.NewLine, "}");
            }

            return node;
        }

        protected internal override Expression VisitDebugInfo(DebugInfoExpression node)
        {
            Out(string.Format(
                CultureInfo.CurrentCulture,
                ".DebugInfo({0}: {1}, {2} - {3}, {4})",
                node.Document.FileName,
                node.StartLine,
                node.StartColumn,
                node.EndLine,
                node.EndColumn)
            );
            return node;
        }

        private void DumpLabel(LabelTarget target)
        {
            Out(string.Format(CultureInfo.CurrentCulture, ".LabelTarget {0}:", GetLabelTargetName(target)));
        }

        private string GetLabelTargetName(LabelTarget target)
        {
            if (string.IsNullOrEmpty(target.Name))
            {
                // Create the label target name as #Label1, #Label2, etc.
                return string.Format(CultureInfo.CurrentCulture, "#Label{0}", GetLabelTargetId(target));
            }
            else
            {
                return GetDisplayName(target.Name);
            }
        }

        private void WriteLambda(LambdaExpression lambda)
        {
            Out(
                string.Format(
                    CultureInfo.CurrentCulture,
                    ".Lambda {0}<{1}>",
                    GetLambdaName(lambda),
                    lambda.Type.ToString())
            );

            VisitDeclarations(lambda.Parameters);

            Out(Flow.Space, "{", Flow.NewLine);
            Indent();
            Visit(lambda.Body);
            Dedent();
            Out(Flow.NewLine, "}");
            Debug.Assert(_stack.Count == 0);
        }

        private string GetLambdaName(LambdaExpression lambda)
        {
            if (string.IsNullOrEmpty(lambda.Name))
            {
                return "#Lambda" + GetLambdaId(lambda);
            }
            return GetDisplayName(lambda.Name);
        }

        private static bool ContainsWhiteSpace(string name)
        {
            foreach (var c in name)
            {
                if (char.IsWhiteSpace(c))
                {
                    return true;
                }
            }
            return false;
        }

        private static string QuoteName(string name)
        {
            return string.Format(CultureInfo.CurrentCulture, "'{0}'", name);
        }

        private static string GetDisplayName(string name)
        {
            if (ContainsWhiteSpace(name))
            {
                // if name has whitespaces in it, quote it
                return QuoteName(name);
            }
            else
            {
                return name;
            }
        }

        #endregion The AST Output
    }
}

#endif