// Copyright (C) 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.caja.ancillary.opt;
import com.google.caja.lexer.CharProducer;
import com.google.caja.lexer.FilePosition;
import com.google.caja.lexer.JsLexer;
import com.google.caja.lexer.JsTokenQueue;
import com.google.caja.lexer.ParseException;
import com.google.caja.parser.js.Block;
import com.google.caja.parser.js.Expression;
import com.google.caja.parser.js.Literal;
import com.google.caja.parser.js.ObjProperty;
import com.google.caja.parser.js.ObjectConstructor;
import com.google.caja.parser.js.Parser;
import com.google.caja.parser.js.Statement;
import com.google.caja.parser.js.StringLiteral;
import com.google.caja.parser.js.ValueProperty;
import com.google.caja.render.Concatenator;
import com.google.caja.render.JsMinimalPrinter;
import com.google.caja.reporting.DevNullMessageQueue;
import com.google.caja.reporting.Message;
import com.google.caja.reporting.MessageContext;
import com.google.caja.reporting.MessageQueue;
import com.google.caja.reporting.PropertyNameQuotingMode;
import com.google.caja.reporting.RenderContext;
import com.google.caja.reporting.SimpleMessageQueue;
import com.google.common.collect.Lists;
import java.io.File;
import java.io.IOException;
import java.util.List;
/**
* Optimizes JavaScript code.
*
* @author mikesamuel@gmail.com
*/
public class JsOptimizer {
private final List<Statement> compUnits = Lists.newArrayList();
private ParseTreeKB optimizer;
private boolean rename;
private final MessageQueue mq;
public JsOptimizer(MessageQueue mq) { this.mq = mq; }
/**
* Register an input for optimization.
*/
public JsOptimizer addInput(Statement stmt) {
compUnits.add(stmt);
return this;
}
/**
* Sets the environment file to use during optimization.
* The environment file contains facts about the environment in which the
* optimized output is expected to run, so allows for interpreter-specific
* optimization.
*/
public JsOptimizer setEnvJson(ObjectConstructor envJson) {
if (optimizer == null) { optimizer = new ParseTreeKB(); }
List<? extends ObjProperty> props = envJson.children();
for (ObjProperty prop : props) {
// JSON had better not have getters
ValueProperty vprop = (ValueProperty) prop;
Expression value = vprop.getValueExpr().fold(false); // fold negative nums
if (!(value instanceof Literal)) {
// True for "*useragent*" property inserted by JSKB.
continue;
}
StringLiteral sl = vprop.getPropertyNameNode();
String rawExpr = sl.getValue();
rawExpr = " " + rawExpr.substring(1, rawExpr.length() - 1) + " ";
CharProducer valueCp = CharProducer.Factory.fromJsString(
CharProducer.Factory.fromString(rawExpr, sl.getFilePosition()));
try {
Expression expr = jsExpr(valueCp, DevNullMessageQueue.singleton());
optimizer.addFact(expr, Fact.is((Literal) value));
} catch (ParseException ex) {
continue; // Triggered for browser specific extensions such as for each
}
}
return this;
}
/**
* Sets a flag telling the optimizer whether to rename local variables where
* doing so would not change semantics on an interpreter that does not allow
* aliasing of {@code eval}.
*/
public JsOptimizer setRename(boolean rename) {
this.rename = rename;
return this;
}
/**
* Returns an optimized version of the concatenation of the programs
* registered via {@link #addInput}.
*/
public Statement optimize() {
Block block = new Block(FilePosition.UNKNOWN, compUnits);
// Do first since this improves the performance of the ConstVarInliner.
VarCollector.optimize(block);
if (optimizer != null) {
block = optimizer.optimize(block, mq);
}
if (rename) {
// We pool after the ConstLocalOptimizer invoked by optimizer has run.
block = ConstantPooler.optimize(block);
// Now we shorten any long names introduced by the constant pooler.
block = new LocalVarRenamer(mq).optimize(block);
}
// Finally we rearrange statements and convert conditionals to expressions
// where it will make things shorter.
return (Statement) StatementSimplifier.optimize(block, mq);
}
public static void main(String... args) throws IOException {
MessageQueue mq = new SimpleMessageQueue();
MessageContext mc = new MessageContext();
JsOptimizer opt = new JsOptimizer(mq);
opt.setRename(true);
opt.setEnvJson(new ObjectConstructor(FilePosition.UNKNOWN));
try {
for (int i = 0, n = args.length; i < n; ++i) {
String arg = args[i];
if ("--norename".equals(arg)) {
opt.setRename(false);
} else if (arg.startsWith("--envjson=")) {
String jsonfile = arg.substring(arg.indexOf('=') + 1);
CharProducer json = CharProducer.Factory.fromFile(
new File(jsonfile), "UTF-8");
opt.setEnvJson((ObjectConstructor) jsExpr(json, mq));
} else {
if ("--".equals(arg)) { ++i; }
for (;i < n; ++i) {
CharProducer cp = CharProducer.Factory.fromFile(
new File(args[i]), "UTF-8");
mc.addInputSource(cp.getCurrentPosition().source());
opt.addInput(js(cp, mq));
}
}
}
} catch (ParseException ex) {
ex.toMessageQueue(mq);
}
Statement out = opt.optimize();
for (Message msg : mq.getMessages()) {
msg.format(mc, System.err);
System.err.println();
}
JsMinimalPrinter printer = new JsMinimalPrinter(
new Concatenator(System.out, null));
RenderContext rc = new RenderContext(printer)
.withPropertyNameQuotingMode(PropertyNameQuotingMode.NO_QUOTES);
if (out instanceof Block) {
((Block) out).renderBody(rc);
} else {
out.render(rc);
}
printer.noMoreTokens();
}
private static Block js(CharProducer cp, MessageQueue mq)
throws ParseException {
return jsParser(cp, mq).parse();
}
private static Expression jsExpr(CharProducer cp, MessageQueue mq)
throws ParseException {
Parser p = jsParser(cp, mq);
Expression e = p.parseExpression(true);
p.getTokenQueue().expectEmpty();
return e;
}
private static Parser jsParser(CharProducer cp, MessageQueue mq) {
JsLexer lexer = new JsLexer(cp, false);
JsTokenQueue tq = new JsTokenQueue(lexer, cp.getCurrentPosition().source());
tq.setInputRange(cp.filePositionForOffsets(cp.getOffset(), cp.getLimit()));
return new Parser(tq, mq);
}
}