/*
* 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.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.isLeaf()) {
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(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.");
}
}