1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
// Copyright (c) 2011 AlphaSierraPapa for the SharpDevelop Team
//
// 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.Collections.Generic;
using System.Linq;
using ICSharpCode.NRefactory.CSharp;
using ICSharpCode.NRefactory.PatternMatching;
namespace ICSharpCode.Decompiler.Ast.Transforms
{
public class PushNegation: DepthFirstAstVisitor<object, object>, IAstTransform
{
sealed class LiftedOperator { }
/// <summary>
/// Annotation for lifted operators that cannot be transformed by PushNegation
/// </summary>
public static readonly object LiftedOperatorAnnotation = new LiftedOperator();
public override object VisitUnaryOperatorExpression(UnaryOperatorExpression unary, object data)
{
// lifted operators can't be transformed
if (unary.Annotation<LiftedOperator>() != null || unary.Expression.Annotation<LiftedOperator>() != null)
return base.VisitUnaryOperatorExpression(unary, data);
// Remove double negation
// !!a
if (unary.Operator == UnaryOperatorType.Not &&
unary.Expression is UnaryOperatorExpression &&
(unary.Expression as UnaryOperatorExpression).Operator == UnaryOperatorType.Not)
{
AstNode newNode = (unary.Expression as UnaryOperatorExpression).Expression;
unary.ReplaceWith(newNode);
return newNode.AcceptVisitor(this, data);
}
// Push through binary operation
// !((a) op (b))
BinaryOperatorExpression binaryOp = unary.Expression as BinaryOperatorExpression;
if (unary.Operator == UnaryOperatorType.Not && binaryOp != null) {
bool successful = true;
switch (binaryOp.Operator) {
case BinaryOperatorType.Equality:
binaryOp.Operator = BinaryOperatorType.InEquality;
break;
case BinaryOperatorType.InEquality:
binaryOp.Operator = BinaryOperatorType.Equality;
break;
case BinaryOperatorType.GreaterThan: // TODO: these are invalid for floats (stupid NaN)
binaryOp.Operator = BinaryOperatorType.LessThanOrEqual;
break;
case BinaryOperatorType.GreaterThanOrEqual:
binaryOp.Operator = BinaryOperatorType.LessThan;
break;
case BinaryOperatorType.LessThanOrEqual:
binaryOp.Operator = BinaryOperatorType.GreaterThan;
break;
case BinaryOperatorType.LessThan:
binaryOp.Operator = BinaryOperatorType.GreaterThanOrEqual;
break;
default:
successful = false;
break;
}
if (successful) {
unary.ReplaceWith(binaryOp);
return binaryOp.AcceptVisitor(this, data);
}
successful = true;
switch (binaryOp.Operator) {
case BinaryOperatorType.ConditionalAnd:
binaryOp.Operator = BinaryOperatorType.ConditionalOr;
break;
case BinaryOperatorType.ConditionalOr:
binaryOp.Operator = BinaryOperatorType.ConditionalAnd;
break;
default:
successful = false;
break;
}
if (successful) {
binaryOp.Left.ReplaceWith(e => new UnaryOperatorExpression(UnaryOperatorType.Not, e));
binaryOp.Right.ReplaceWith(e => new UnaryOperatorExpression(UnaryOperatorType.Not, e));
unary.ReplaceWith(binaryOp);
return binaryOp.AcceptVisitor(this, data);
}
}
return base.VisitUnaryOperatorExpression(unary, data);
}
readonly static AstNode asCastIsNullPattern = new BinaryOperatorExpression(
new AnyNode("expr").ToExpression().CastAs(new AnyNode("type")),
BinaryOperatorType.Equality,
new NullReferenceExpression()
);
readonly static AstNode asCastIsNotNullPattern = new BinaryOperatorExpression(
new AnyNode("expr").ToExpression().CastAs(new AnyNode("type")),
BinaryOperatorType.InEquality,
new NullReferenceExpression()
);
public override object VisitBinaryOperatorExpression(BinaryOperatorExpression binaryOperatorExpression, object data)
{
// lifted operators can't be transformed
if (binaryOperatorExpression.Annotation<LiftedOperator>() != null)
return base.VisitBinaryOperatorExpression(binaryOperatorExpression, data);
BinaryOperatorType op = binaryOperatorExpression.Operator;
bool? rightOperand = null;
if (binaryOperatorExpression.Right is PrimitiveExpression)
rightOperand = ((PrimitiveExpression)binaryOperatorExpression.Right).Value as bool?;
if (op == BinaryOperatorType.Equality && rightOperand == true || op == BinaryOperatorType.InEquality && rightOperand == false) {
// 'b == true' or 'b != false' is useless
binaryOperatorExpression.Left.AcceptVisitor(this, data);
binaryOperatorExpression.ReplaceWith(binaryOperatorExpression.Left);
return null;
} else if (op == BinaryOperatorType.Equality && rightOperand == false || op == BinaryOperatorType.InEquality && rightOperand == true) {
// 'b == false' or 'b != true' is a negation:
Expression left = binaryOperatorExpression.Left;
left.Remove();
UnaryOperatorExpression uoe = new UnaryOperatorExpression(UnaryOperatorType.Not, left);
binaryOperatorExpression.ReplaceWith(uoe);
return uoe.AcceptVisitor(this, data);
} else {
bool negate = false;
Match m = asCastIsNotNullPattern.Match(binaryOperatorExpression);
if (!m.Success) {
m = asCastIsNullPattern.Match(binaryOperatorExpression);
negate = true;
}
if (m.Success) {
Expression expr = m.Get<Expression>("expr").Single().Detach().IsType(m.Get<AstType>("type").Single().Detach());
if (negate)
expr = new UnaryOperatorExpression(UnaryOperatorType.Not, expr);
binaryOperatorExpression.ReplaceWith(expr);
return expr.AcceptVisitor(this, data);
} else {
return base.VisitBinaryOperatorExpression(binaryOperatorExpression, data);
}
}
}
void IAstTransform.Run(AstNode node)
{
node.AcceptVisitor(this, null);
}
}
}
|
