forked from googleprojectzero/fuzzilli
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathExpression.swift
145 lines (124 loc) · 4.57 KB
/
Expression.swift
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
// Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
precedencegroup ExpressionBuilderPrecedence {
associativity: left
lowerThan: AdditionPrecedence
higherThan: AssignmentPrecedence
}
// We use the custom operator <> to build up expressions.
infix operator <> : ExpressionBuilderPrecedence
public enum Associativity: UInt8 {
case none
case left
case right
}
public enum Inlineability: UInt8 {
case never
case onlyFollowing
case singleUseOnly
case always
}
/// The type of an expression. Also serves as a constructor.
public struct ExpressionType: Equatable {
static private var nextId: UInt32 = 0
let id: UInt32
let precedence: UInt8
let associativity: Associativity
let inlineability: Inlineability
init(precedence: UInt8, associativity: Associativity = .none, inline inlineability: Inlineability = .never) {
self.id = ExpressionType.nextId
ExpressionType.nextId += 1
self.precedence = precedence
self.associativity = associativity
self.inlineability = inlineability
}
func new(_ initialText: String = "", inline inlineability: Inlineability) -> Expression {
return Expression(type: self, text: initialText, inlineability: inlineability, numSubexpressions: 0)
}
func new(_ initialText: String = "") -> Expression {
return Expression(type: self, text: initialText, inlineability: inlineability, numSubexpressions: 0)
}
public static func ==(lhs: ExpressionType, rhs: ExpressionType) -> Bool {
return lhs.id == rhs.id
}
}
/// An expression in the target language.
public struct Expression: CustomStringConvertible {
public let type: ExpressionType
public let text: String
public let inlineability: Inlineability
let numSubexpressions: UInt8
public var description: String {
return text
}
func canInline(_ instr: Instruction, _ uses: [Int]) -> Bool {
switch inlineability {
case .never:
return false
case .onlyFollowing:
return uses.count == 1 && uses[0] == instr.index + 1
case .singleUseOnly:
return uses.count == 1
case .always:
// Inlining should not cause instructions to not being emitted at all
return uses.count > 0
}
}
func needsBrackets(in other: Expression, isLhs: Bool = true) -> Bool {
if type.precedence == other.type.precedence {
if type.associativity != other.type.associativity {
return true
}
switch type.associativity {
case .none:
return true
case .left:
return !isLhs
case .right:
return isLhs
}
}
return type.precedence < other.type.precedence
}
func extended(by part: String) -> Expression {
return Expression(type: type,
text: text + part,
inlineability: inlineability,
numSubexpressions: numSubexpressions)
}
func extended(by part: Expression) -> Expression {
let newText: String
if part.needsBrackets(in: self, isLhs: numSubexpressions == 0) {
newText = text + "(" + part + ")"
} else {
newText = text + part
}
return Expression(type: type,
text: newText,
inlineability: Inlineability(rawValue: min(inlineability.rawValue, part.inlineability.rawValue))!,
numSubexpressions: numSubexpressions + 1)
}
static func <>(lhs: Expression, rhs: Expression) -> Expression {
return lhs.extended(by: rhs)
}
static func <>(lhs: Expression, rhs: String) -> Expression {
return lhs.extended(by: rhs)
}
static func <>(lhs: Expression, rhs: Int64) -> Expression {
return lhs.extended(by: String(rhs))
}
static func +(lhs: String, rhs: Expression) -> String {
return lhs + rhs.text
}
}