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/*
* Copyright 2008 Google Inc.
*
* 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
*
* http://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.
*/
package com.google.gwt.dev.js.ast;
/**
* Represents the operator in a JavaScript binary operation.
*/
public enum JsBinaryOperator implements JsOperator {
/*
* Precedence indices from "JavaScript - The Definitive Guide" 4th Edition
* (page 57)
*
*
* Precedence 15 is for really important things that have their own AST
* classes.
*
* Precedence 14 is for unary operators.
*/
MUL("*", 13, LEFT | INFIX), DIV("/", 13, LEFT | INFIX), MOD("%", 13, LEFT
| INFIX),
ADD("+", 12, LEFT | INFIX), SUB("-", 12, LEFT | INFIX),
SHL("<<", 11, LEFT | INFIX), SHR(">>", 11, LEFT | INFIX), SHRU(">>>", 11,
LEFT | INFIX),
LT("<", 10, LEFT | INFIX), LTE("<=", 10, LEFT | INFIX), GT(">", 10, LEFT
| INFIX), GTE(">=", 10, LEFT | INFIX), INSTANCEOF("instanceof", 10, LEFT
| INFIX), INOP("in", 10, LEFT | INFIX),
EQ("==", 9, LEFT | INFIX), NEQ("!=", 9, LEFT | INFIX), REF_EQ("===", 9, LEFT
| INFIX), REF_NEQ("!==", 9, LEFT | INFIX),
BIT_AND("&", 8, LEFT | INFIX),
BIT_XOR("^", 7, LEFT | INFIX),
BIT_OR("|", 6, LEFT | INFIX),
AND("&&", 5, LEFT | INFIX),
OR("||", 4, LEFT | INFIX),
// Precedence 3 is for the condition operator.
// These assignment operators are right-associative.
ASG("=", 2, INFIX), ASG_ADD("+=", 2, INFIX), ASG_SUB("-=", 2, INFIX), ASG_MUL(
"*=", 2, INFIX), ASG_DIV("/=", 2, INFIX), ASG_MOD("%=", 2, INFIX), ASG_SHL(
"<<=", 2, INFIX), ASG_SHR(">>=", 2, INFIX), ASG_SHRU(">>>=", 2, INFIX), ASG_BIT_AND(
"&=", 2, INFIX), ASG_BIT_OR("|=", 2, INFIX), ASG_BIT_XOR("^=", 2, INFIX),
COMMA(",", 1, LEFT | INFIX);
private final int mask;
private final int precedence;
private final String symbol;
private JsBinaryOperator(String symbol, int precedence, int mask) {
this.symbol = symbol;
this.precedence = precedence;
this.mask = mask;
}
public int getPrecedence() {
return precedence;
}
public String getSymbol() {
return symbol;
}
public boolean isAssignment() {
/*
* Beware, flaky! Maybe I should have added Yet Another Field to
* BinaryOperator?
*/
return (getPrecedence() == ASG.getPrecedence());
}
public boolean isKeyword() {
return this == INSTANCEOF || this == INOP;
}
public boolean isLeftAssociative() {
return (mask & LEFT) != 0;
}
public boolean isPrecedenceLessThan(JsOperator other) {
return precedence < other.getPrecedence();
}
public boolean isValidInfix() {
return (mask & INFIX) != 0;
}
public boolean isValidPostfix() {
return (mask & POSTFIX) != 0;
}
public boolean isValidPrefix() {
return (mask & PREFIX) != 0;
}
@Override
public String toString() {
return symbol;
}
}
