/*
* Copyright 2009 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.ConfigurationProperty;
import com.google.gwt.core.ext.PropertyOracle;
import com.google.gwt.dev.jjs.InternalCompilerException;
import com.google.gwt.dev.js.ast.JsContext;
import com.google.gwt.dev.js.ast.JsModVisitor;
import com.google.gwt.dev.js.ast.JsProgram;
import com.google.gwt.dev.js.ast.JsStatement;
import com.google.gwt.dev.js.ast.JsVars;
import com.google.gwt.dev.js.ast.JsVars.JsVar;
import java.util.ArrayList;
import java.util.List;
/**
* Divides large var statements into smaller ones. Very long var statements have
* trouble on some browsers, including the initial Safari 4 beta. See Issue
* 3455.
*/
public class JsBreakUpLargeVarStatements extends JsModVisitor {
private static final String CONFIG_PROP_MAX_VARS = "compiler.max.vars.per.var";
public static void exec(JsProgram program, PropertyOracle[] propertyOracles) {
(new JsBreakUpLargeVarStatements(propertyOracles)).accept(program);
}
private static JsVars last(List<JsVars> list) {
return list.get(list.size() - 1);
}
private final int maxVarsPerStatement;
private JsBreakUpLargeVarStatements(PropertyOracle[] propertyOracles) {
maxVarsPerStatement = getMaxVarsPerStatement(propertyOracles[0]);
}
@Override
public void endVisit(JsVars x, JsContext<JsStatement> context) {
if (maxVarsPerStatement < 0) {
return;
}
if (x.getNumVars() > maxVarsPerStatement) {
// compute a list of smaller JsVars statements
List<JsVars> smallerVars = new ArrayList<JsVars>();
smallerVars.add(makeNewChildVars(x));
for (JsVar var : x) {
if (last(smallerVars).getNumVars() >= maxVarsPerStatement) {
// Previous statement is full; start a new one
smallerVars.add(makeNewChildVars(x));
}
last(smallerVars).add(var);
}
// replace x by the sequence smallerVars
for (JsVars sv : smallerVars) {
context.insertBefore(sv);
}
context.removeMe();
}
}
/**
* Look up in the specified property oracle the maximum number of variables to
* allow per var statement.
*/
private int getMaxVarsPerStatement(PropertyOracle propertyOracle)
throws InternalCompilerException, NumberFormatException {
ConfigurationProperty prop;
try {
prop = propertyOracle.getConfigurationProperty(CONFIG_PROP_MAX_VARS);
} catch (BadPropertyValueException e) {
throw new InternalCompilerException("Could not find property "
+ CONFIG_PROP_MAX_VARS, e);
}
int t = Integer.parseInt(prop.getValues().get(0));
return t;
}
/**
* Make a new, empty {@link JsVars} that is a child of x.
*/
private JsVars makeNewChildVars(JsVars x) {
return new JsVars(x.getSourceInfo().makeChild(
JsBreakUpLargeVarStatements.class,
"breaking up a large vars statement into smaller ones"));
}
}