/*
* Copyright 2010 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.core.ext.BadPropertyValueException;
import com.google.gwt.core.ext.PropertyOracle;
import com.google.gwt.core.ext.SelectionProperty;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.dev.jjs.SourceInfo;
import com.google.gwt.dev.js.ast.JsBinaryOperation;
import com.google.gwt.dev.js.ast.JsBinaryOperator;
import com.google.gwt.dev.js.ast.JsContext;
import com.google.gwt.dev.js.ast.JsExpression;
import com.google.gwt.dev.js.ast.JsModVisitor;
import com.google.gwt.dev.js.ast.JsPrefixOperation;
import com.google.gwt.dev.js.ast.JsProgram;
import com.google.gwt.dev.js.ast.JsUnaryOperator;
/**
* Coerces lhs of right shift operations to int. Necessary for Safari 5 bug
* https://bugs.webkit.org/show_bug.cgi?id=40367 fixed in
* http://trac.webkit.org/changeset/60990 -- this should be removed once that
* fix has been pushed.
*/
public class JsCoerceIntShift {
// TODO(jat): remove this once Safari 5 has the update
/**
* Rewrite a >> b as (~~a) >> b.
*/
private static class MyVisitor extends JsModVisitor {
@Override
public void endVisit(JsBinaryOperation x, JsContext ctx) {
JsBinaryOperator op = x.getOperator();
if (op != JsBinaryOperator.SHR && op != JsBinaryOperator.SHRU) {
return;
}
SourceInfo sourceInfo = x.getSourceInfo();
JsExpression lhs = x.getArg1();
JsExpression rhs = x.getArg2();
JsExpression newNode = new JsBinaryOperation(sourceInfo, op,
new JsPrefixOperation(sourceInfo, JsUnaryOperator.BIT_NOT,
new JsPrefixOperation(sourceInfo, JsUnaryOperator.BIT_NOT, lhs)),
rhs);
ctx.replaceMe(newNode);
}
}
/**
* If this permutation may be executed on WebKit, rewrite a >> b as ~~a >> b.
*
* @param program
* @param logger
* @param propertyOracles
* @return true if any changes were made
*/
public static boolean exec(JsProgram program, TreeLogger logger,
PropertyOracle[] propertyOracles) {
boolean seenWebKit = false;
for (PropertyOracle oracle : propertyOracles) {
try {
SelectionProperty prop = oracle.getSelectionProperty(logger,
"user.agent");
// TODO(jat): more checks if we split up the safari permutation
if ("safari".equals(prop.getCurrentValue())) {
seenWebKit = true;
break;
}
} catch (BadPropertyValueException e) {
// if we couldn't get the property, assume this might be used on WebKit.
seenWebKit = true;
break;
}
}
if (!seenWebKit) {
return false;
}
MyVisitor v = new MyVisitor();
v.accept(program);
return v.didChange();
}
}