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1 // Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file | |
2 // for details. All rights reserved. Use of this source code is governed by a | |
3 // BSD-style license that can be found in the LICENSE file. | |
4 | |
5 package com.google.dart.compiler.backend.js.ast; | |
6 | |
7 /** | |
8 * Represents the operator in a JavaScript binary operation. | |
9 */ | |
10 public enum JsBinaryOperator implements JsOperator { | |
11 | |
12 /* | |
13 * Precedence indices from "JavaScript - The Definitive Guide" 4th Edition | |
14 * (page 57) | |
15 * | |
16 * | |
17 * Precedence 15 is for really important things that have their own AST | |
18 * classes. | |
19 * | |
20 * Precedence 14 is for unary operators. | |
21 */ | |
22 | |
23 MUL("*", 13, LEFT | INFIX), DIV("/", 13, LEFT | INFIX), MOD("%", 13, LEFT | |
24 | INFIX), | |
25 | |
26 ADD("+", 12, LEFT | INFIX), SUB("-", 12, LEFT | INFIX), | |
27 | |
28 SHL("<<", 11, LEFT | INFIX), SHR(">>", 11, LEFT | INFIX), SHRU(">>>", 11, | |
29 LEFT | INFIX), | |
30 | |
31 LT("<", 10, LEFT | INFIX), LTE("<=", 10, LEFT | INFIX), GT(">", 10, LEFT | |
32 | INFIX), GTE(">=", 10, LEFT | INFIX), INSTANCEOF("instanceof", 10, LEFT | |
33 | INFIX), INOP("in", 10, LEFT | INFIX), | |
34 | |
35 EQ("==", 9, LEFT | INFIX), NEQ("!=", 9, LEFT | INFIX), REF_EQ("===", 9, LEFT | |
36 | INFIX), REF_NEQ("!==", 9, LEFT | INFIX), | |
37 | |
38 BIT_AND("&", 8, LEFT | INFIX), | |
39 | |
40 BIT_XOR("^", 7, LEFT | INFIX), | |
41 | |
42 BIT_OR("|", 6, LEFT | INFIX), | |
43 | |
44 AND("&&", 5, LEFT | INFIX), | |
45 | |
46 OR("||", 4, LEFT | INFIX), | |
47 | |
48 // Precedence 3 is for the condition operator. | |
49 | |
50 // These assignment operators are right-associative. | |
51 ASG("=", 2, INFIX), ASG_ADD("+=", 2, INFIX), ASG_SUB("-=", 2, INFIX), ASG_MUL( | |
52 "*=", 2, INFIX), ASG_DIV("/=", 2, INFIX), ASG_MOD("%=", 2, INFIX), ASG_SHL
( | |
53 "<<=", 2, INFIX), ASG_SHR(">>=", 2, INFIX), ASG_SHRU(">>>=", 2, INFIX), AS
G_BIT_AND( | |
54 "&=", 2, INFIX), ASG_BIT_OR("|=", 2, INFIX), ASG_BIT_XOR("^=", 2, INFIX), | |
55 | |
56 COMMA(",", 1, LEFT | INFIX); | |
57 | |
58 private final int mask; | |
59 private final int precedence; | |
60 private final String symbol; | |
61 | |
62 private JsBinaryOperator(String symbol, int precedence, int mask) { | |
63 this.symbol = symbol; | |
64 this.precedence = precedence; | |
65 this.mask = mask; | |
66 } | |
67 | |
68 @Override | |
69 public int getPrecedence() { | |
70 return precedence; | |
71 } | |
72 | |
73 @Override | |
74 public String getSymbol() { | |
75 return symbol; | |
76 } | |
77 | |
78 public boolean isAssignment() { | |
79 /* | |
80 * Beware, flaky! Maybe I should have added Yet Another Field to | |
81 * BinaryOperator? | |
82 */ | |
83 return (getPrecedence() == ASG.getPrecedence()); | |
84 } | |
85 | |
86 @Override | |
87 public boolean isKeyword() { | |
88 return this == INSTANCEOF || this == INOP; | |
89 } | |
90 | |
91 @Override | |
92 public boolean isLeftAssociative() { | |
93 return (mask & LEFT) != 0; | |
94 } | |
95 | |
96 @Override | |
97 public boolean isPrecedenceLessThan(JsOperator other) { | |
98 return precedence < other.getPrecedence(); | |
99 } | |
100 | |
101 @Override | |
102 public boolean isValidInfix() { | |
103 return (mask & INFIX) != 0; | |
104 } | |
105 | |
106 @Override | |
107 public boolean isValidPostfix() { | |
108 return (mask & POSTFIX) != 0; | |
109 } | |
110 | |
111 @Override | |
112 public boolean isValidPrefix() { | |
113 return (mask & PREFIX) != 0; | |
114 } | |
115 | |
116 @Override | |
117 public String toString() { | |
118 return symbol; | |
119 } | |
120 } | |
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