/*
* 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.jjs.impl;
import com.google.gwt.core.ext.linker.StatementRanges;
import com.google.gwt.core.ext.soyc.Range;
import com.google.gwt.dev.jjs.SourceInfo;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* Limits top-level blocks to MAX_BLOCK_SIZE statements.
*/
public class JsIEBlockTextTransformer extends JsAbstractTextTransformer {
// uncomment to test
// private static final int MAX_BLOCK_SIZE = 10;
private static final int MAX_BLOCK_SIZE = 1 << 15 - 1;
private int currentStatementCount;
private boolean doSplits;
private Set<Integer> statementsAddedBlockClose = new HashSet<Integer>();
private Set<Integer> statementsAddedBlockOpen = new HashSet<Integer>();
public JsIEBlockTextTransformer(JsAbstractTextTransformer xformer) {
super(xformer);
}
public JsIEBlockTextTransformer(String js, StatementRanges statementRanges,
Map<Range, SourceInfo> sourceInfoMap) {
super(js, statementRanges, sourceInfoMap);
}
/**
* Do not perform clustering, only fix up IE7 block issue.
*/
@Override
public void exec() {
doSplits = statementRanges.numStatements() > MAX_BLOCK_SIZE;
if (doSplits) {
int statementIndices[] = new int[statementRanges.numStatements()];
for (int i = 0; i < statementRanges.numStatements(); i++) {
statementIndices[i] = i;
}
recomputeJsAndStatementRanges(statementIndices);
}
}
public Set<Integer> getStatementsAddedBlockClose() {
return statementsAddedBlockClose;
}
public Set<Integer> getStatementsAddedBlockOpen() {
return statementsAddedBlockOpen;
}
/**
* Record start of statement, and optionally inject new open block.
*/
@Override
protected void beginStatement(int index, StringBuilder newJs, ArrayList<Integer> starts) {
if (doSplits && currentStatementCount == 0) {
super.beginStatement(index, newJs, starts);
newJs.append('{');
statementsAddedBlockOpen.add(Integer.valueOf(index));
} else if (!doSplits) {
super.beginStatement(index, newJs, starts);
}
}
@Override
protected void beginStatements(StringBuilder newJs, ArrayList<Integer> starts,
ArrayList<Integer> ends) {
super.beginStatements(newJs, starts, ends);
currentStatementCount = 0;
}
/**
* Record end of statement, and optionally inject close block, if block is
* full.
*/
@Override
protected void endStatement(int index, StringBuilder newJs, ArrayList<Integer> ends) {
currentStatementCount++;
if (doSplits && currentStatementCount == MAX_BLOCK_SIZE) {
newJs.append('}');
super.endStatement(index, newJs, ends);
currentStatementCount = 0;
statementsAddedBlockClose.add(Integer.valueOf(index));
} else if (!doSplits) {
super.endStatement(index, newJs, ends);
}
}
/**
* Used to close a trailing block which never filled.
*/
@Override
protected void endStatements(StringBuilder newJs, ArrayList<Integer> starts,
ArrayList<Integer> ends) {
optionallyCloseLastBlock(newJs, ends);
super.endStatements(newJs, starts, ends);
}
/**
* Fixes the index ranges of individual expressions in the generated
* JS after chunking statements into blocks that satisfy the IE block
* size problem. Loops over each expression, determines whether the
* statement in which it falls has a brace inserted before/after, and
* shifts forward according to where it falls in the block.
*/
@Override
protected void updateSourceInfoMap() {
if (sourceInfoMap != null) {
Range[] oldExpressionRanges = sourceInfoMap.keySet().toArray(new Range[0]);
Arrays.sort(oldExpressionRanges, Range.SOURCE_ORDER_COMPARATOR);
// iterate over expression ranges and shift
Map<Range, SourceInfo> updatedInfoMap = new HashMap<Range, SourceInfo>();
Range entireProgram =
new Range(0, originalStatementRanges.end(originalStatementRanges.numStatements() - 1));
int shift = 0;
// set to keep track of which statements have already shifted.
// need to account for when a shift has already been added for the extra
// open brace in a statement--sometimes there are multiple expressions
// that all start at the same place a the beginning of a statement in
// the expression list
// ex: _.gC=function x()... yields the expressions _, _.gC, _.gC = ...
Set<Integer> shiftAdded = new HashSet<Integer>();
for (int i = 0, j = 0; j < oldExpressionRanges.length; j++) {
Range oldExpression = oldExpressionRanges[j];
if (oldExpression.equals(entireProgram)) {
continue;
}
if (originalStatementRanges.start(i) > oldExpression.getStart()
|| oldExpression.getEnd() > originalStatementRanges.end(i)) {
// expression should fall in the next statement
i++;
assert originalStatementRanges.start(i) <= oldExpression.getStart()
&& oldExpression.getEnd() <= originalStatementRanges.end(i);
if (statementsAddedBlockClose.contains(Integer.valueOf(i - 1))) {
// there's an extra statement index in the addedBlockClose list,
// which corresponds to the extra closing brace at the end of the
// program. but this index doesn't match up to the indices in the
// old statement ranges--it's equal to the # of statements in the
// original code divided by the IE block size
if (i != statementRanges.numStatements()) {
shift++;
}
}
}
if (statementsAddedBlockOpen.contains(Integer.valueOf(i))
&& oldExpression.getStart() == originalStatementRanges.start(i)
&& !shiftAdded.contains(i)) {
shift++;
shiftAdded.add(Integer.valueOf(i));
}
int newStart = oldExpression.getStart() + shift;
int newEnd = oldExpression.getEnd() + shift;
Range newExpression = new Range(newStart, newEnd);
updatedInfoMap.put(newExpression, sourceInfoMap.get(oldExpression));
}
updatedInfoMap.put(new Range(0, entireProgram.getEnd() + shift),
sourceInfoMap.get(entireProgram));
sourceInfoMap = updatedInfoMap;
}
}
/**
* Close last block if it never filled.
*/
private void optionallyCloseLastBlock(StringBuilder newJs, ArrayList<Integer> ends) {
if (doSplits && currentStatementCount > 0 && currentStatementCount < MAX_BLOCK_SIZE) {
newJs.append("}");
ends.add(newJs.length());
statementsAddedBlockClose.add(Integer.valueOf(ends.size() - 1));
}
}
}