Diagrams with Reflector and the Graph Plug-in (Part 2)

//
// Equality.cs:
//
// Author:
//	Cesar Lopez Nataren (cesar@ciencias.unam.mx)
//
// (C) 2003, 2004 Cesar Lopez Nataren
// (C) 2005, Novell Inc, (http://novell.com)
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Text;
using System.Diagnostics;
using System.Reflection.Emit;

namespace Microsoft.JScript {

	public class Equality : BinaryOp {

		internal Equality (AST parent, AST left, AST right, JSToken op, Location location)
			: base (parent, left, right, op, location)
		{
		}

		public Equality (int i)
			: base (null, null, null, (JSToken) i, null)
		{
		}

		[DebuggerStepThroughAttribute]
		[DebuggerHiddenAttribute]
		public bool EvaluateEquality (object v1, object v2)
		{
			IConvertible ic1 = v1 as IConvertible;
			IConvertible ic2 = v2 as IConvertible;

			TypeCode tc1 = Convert.GetTypeCode (v1, ic1);
			TypeCode tc2 = Convert.GetTypeCode (v2, ic2);

			bool both_numbers = Convert.IsNumberTypeCode (tc1) && Convert.IsNumberTypeCode (tc2);
			if ((tc1 == tc2) || both_numbers) {
				switch (tc1) {
				case TypeCode.DBNull:
				case TypeCode.Empty:
					return true;

				case TypeCode.Boolean:
					return ic1.ToBoolean (null) == ic2.ToBoolean (null);

				case TypeCode.String:
					return ic1.ToString (null) == ic2.ToString (null);

				case TypeCode.Object:
					if (v1 is ScriptFunction && v2 is ScriptFunction)
						return v1 == v2 || v1.Equals (v2);
					else
						return v1 == v2;

				default:
					if (both_numbers) {
						double num1;
						if (Convert.IsFloatTypeCode (tc1))
							num1 = ic1.ToDouble (null);
						else
							num1 = (double) ic1.ToInt64 (null);

						double num2;
						if (Convert.IsFloatTypeCode (tc2))
							num2 = ic2.ToDouble (null);
						else
							num2 = (double) ic2.ToInt64 (null);

						return num1 == num2;
					} else
						return false;
				}
			} else {
				bool swapped = false;

			redo:
				switch (tc1) {
				case TypeCode.DBNull:
					if (tc2 == TypeCode.Empty)
						return true;
					break;

				case TypeCode.String:
					if (Convert.IsNumberTypeCode (tc2))
						return EvaluateEquality (Convert.ToNumber (v1), v2);
					break;

				case TypeCode.Boolean:
					return EvaluateEquality (Convert.ToNumber (v1), v2);

				case TypeCode.Object:
					if (tc2 == TypeCode.String || Convert.IsNumberTypeCode (tc2))
						return EvaluateEquality (Convert.ToPrimitive (v1, null), v2);
					break;
				}

				if (!swapped) {
					swapped = true;

					object vt = v1;
					v1 = v2;
					v2 = vt;

					ic1 = v1 as IConvertible;
					ic2 = v2 as IConvertible;

					tc1 = Convert.GetTypeCode (v1, ic1);
					tc2 = Convert.GetTypeCode (v2, ic2);

					goto redo;
				} else
					return false;
			}
		}

		public static bool JScriptEquals (object v1, object v2)
		{
			throw new NotImplementedException ();
		}

		internal override bool Resolve (Environment env)
		{
			bool r = true;
			if (left != null)
				r &= left.Resolve (env);
			if (right != null)
				r &= right.Resolve (env);
			return r;
		}

		internal override bool Resolve (Environment env, bool no_effect)
		{
			this.no_effect = no_effect;
			return Resolve (env);
		}

		internal override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			LocalBuilder local_builder;

			if (op != JSToken.None) {
				Type t = typeof (Equality);
				local_builder = ig.DeclareLocal (t);
				if (op == JSToken.Equal)
					ig.Emit (OpCodes.Ldc_I4_S, (byte) 53);
				else if (op == JSToken.NotEqual)
					ig.Emit (OpCodes.Ldc_I4_S, (byte) 54);
				ig.Emit (OpCodes.Newobj, t.GetConstructor (new Type [] { typeof (int) }));
				ig.Emit (OpCodes.Stloc, local_builder);
				ig.Emit (OpCodes.Ldloc, local_builder);
			}

			if (left != null) {
				left.Emit (ec);
				CodeGenerator.EmitBox (ig, left);
			}
			if (right != null) {
				right.Emit (ec);
				CodeGenerator.EmitBox (ig, right);
			}

			if (op == JSToken.Equal || op == JSToken.NotEqual) {
				ig.Emit (OpCodes.Call, typeof (Equality).GetMethod ("EvaluateEquality"));

				if (no_effect) {
					Label t_lbl = ig.DefineLabel ();
					Label f_lbl = ig.DefineLabel ();

					if (op == JSToken.Equal)
						ig.Emit (OpCodes.Brtrue_S, t_lbl);
					else if (op == JSToken.NotEqual)
						ig.Emit (OpCodes.Brfalse_S, t_lbl);

					ig.Emit (OpCodes.Ldc_I4_0);
					ig.Emit (OpCodes.Br_S, f_lbl);
					ig.MarkLabel (t_lbl);
					ig.Emit (OpCodes.Ldc_I4_1);
					ig.MarkLabel (f_lbl);
					ig.Emit (OpCodes.Pop);
				}
			}
		}
	}
}