| /* |
| * Copyright 2007 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; |
| |
| import com.google.gwt.dev.js.ast.JsArrayAccess; |
| import com.google.gwt.dev.js.ast.JsArrayLiteral; |
| import com.google.gwt.dev.js.ast.JsBinaryOperation; |
| import com.google.gwt.dev.js.ast.JsBlock; |
| import com.google.gwt.dev.js.ast.JsBooleanLiteral; |
| import com.google.gwt.dev.js.ast.JsBreak; |
| import com.google.gwt.dev.js.ast.JsCase; |
| import com.google.gwt.dev.js.ast.JsCatch; |
| import com.google.gwt.dev.js.ast.JsConditional; |
| import com.google.gwt.dev.js.ast.JsContext; |
| import com.google.gwt.dev.js.ast.JsContinue; |
| import com.google.gwt.dev.js.ast.JsDebugger; |
| import com.google.gwt.dev.js.ast.JsDefault; |
| import com.google.gwt.dev.js.ast.JsDoWhile; |
| import com.google.gwt.dev.js.ast.JsEmpty; |
| import com.google.gwt.dev.js.ast.JsExprStmt; |
| import com.google.gwt.dev.js.ast.JsExpression; |
| import com.google.gwt.dev.js.ast.JsFor; |
| import com.google.gwt.dev.js.ast.JsForIn; |
| import com.google.gwt.dev.js.ast.JsFunction; |
| import com.google.gwt.dev.js.ast.JsIf; |
| import com.google.gwt.dev.js.ast.JsInvocation; |
| import com.google.gwt.dev.js.ast.JsLabel; |
| import com.google.gwt.dev.js.ast.JsNameOf; |
| import com.google.gwt.dev.js.ast.JsNameRef; |
| import com.google.gwt.dev.js.ast.JsNew; |
| import com.google.gwt.dev.js.ast.JsNullLiteral; |
| import com.google.gwt.dev.js.ast.JsNumberLiteral; |
| import com.google.gwt.dev.js.ast.JsNumericEntry; |
| import com.google.gwt.dev.js.ast.JsObjectLiteral; |
| import com.google.gwt.dev.js.ast.JsParameter; |
| import com.google.gwt.dev.js.ast.JsPostfixOperation; |
| import com.google.gwt.dev.js.ast.JsPrefixOperation; |
| import com.google.gwt.dev.js.ast.JsProgram; |
| import com.google.gwt.dev.js.ast.JsPropertyInitializer; |
| import com.google.gwt.dev.js.ast.JsRegExp; |
| import com.google.gwt.dev.js.ast.JsReturn; |
| import com.google.gwt.dev.js.ast.JsStringLiteral; |
| import com.google.gwt.dev.js.ast.JsSwitch; |
| import com.google.gwt.dev.js.ast.JsThisRef; |
| import com.google.gwt.dev.js.ast.JsThrow; |
| import com.google.gwt.dev.js.ast.JsTry; |
| import com.google.gwt.dev.js.ast.JsVars; |
| import com.google.gwt.dev.js.ast.JsVars.JsVar; |
| import com.google.gwt.dev.js.ast.JsVisitor; |
| import com.google.gwt.dev.js.ast.JsWhile; |
| |
| /** |
| * Precedence indices from "JavaScript - The Definitive Guide" 4th Edition (page |
| * 57) |
| * |
| * Precedence 17 is for indivisible primaries that either don't have children, |
| * or provide their own delimiters. |
| * |
| * Precedence 16 is for really important things that have their own AST classes. |
| * |
| * Precedence 15 is for the new construct. |
| * |
| * Precedence 14 is for unary operators. |
| * |
| * Precedences 12 through 4 are for non-assigning binary operators. |
| * |
| * Precedence 3 is for the tertiary conditional. |
| * |
| * Precedence 2 is for assignments. |
| * |
| * Precedence 1 is for comma operations. |
| */ |
| class JsPrecedenceVisitor extends JsVisitor { |
| |
| static final int PRECEDENCE_NEW = 15; |
| |
| public static int exec(JsExpression expression) { |
| JsPrecedenceVisitor visitor = new JsPrecedenceVisitor(); |
| visitor.accept(expression); |
| if (visitor.answer < 0) { |
| throw new RuntimeException("Precedence must be >= 0!"); |
| } |
| return visitor.answer; |
| } |
| |
| private int answer = -1; |
| |
| private JsPrecedenceVisitor() { |
| } |
| |
| @Override |
| public boolean visit(JsArrayAccess x, JsContext ctx) { |
| answer = 16; |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsArrayLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsBinaryOperation x, JsContext ctx) { |
| answer = x.getOperator().getPrecedence(); |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsBlock x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsBooleanLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsBreak x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsCase x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsCatch x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsConditional x, JsContext ctx) { |
| answer = 3; |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsContinue x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsDebugger x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsDefault x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsDoWhile x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsEmpty x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsExprStmt x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsFor x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsForIn x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsFunction x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsIf x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsInvocation x, JsContext ctx) { |
| answer = 16; |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsLabel x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsNameOf x, JsContext ctx) { |
| answer = 17; // Similar to string literal |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsNameRef x, JsContext ctx) { |
| if (x.getQualifier() == null) { |
| answer = 17; // primary |
| } else { |
| answer = 16; // property access |
| } |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsNew x, JsContext ctx) { |
| answer = PRECEDENCE_NEW; |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsNullLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsNumberLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsNumericEntry x, JsContext ctx) { |
| answer = 17; // same as number literal |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsObjectLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsParameter x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsPostfixOperation x, JsContext ctx) { |
| answer = x.getOperator().getPrecedence(); |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsPrefixOperation x, JsContext ctx) { |
| answer = x.getOperator().getPrecedence(); |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsProgram x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsPropertyInitializer x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsRegExp x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsReturn x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsStringLiteral x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsSwitch x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsThisRef x, JsContext ctx) { |
| answer = 17; // primary |
| return false; |
| } |
| |
| @Override |
| public boolean visit(JsThrow x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsTry x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsVar x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsVars x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| @Override |
| public boolean visit(JsWhile x, JsContext ctx) { |
| throw new RuntimeException("Only expressions have precedence."); |
| } |
| |
| } |