// Copyright (C) 2008 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.parser.js;
import com.google.caja.lexer.CharProducer;
import com.google.caja.lexer.InputSource;
import com.google.caja.lexer.JsLexer;
import com.google.caja.lexer.JsTokenQueue;
import com.google.caja.lexer.ParseException;
import com.google.caja.render.Concatenator;
import com.google.caja.render.JsMinimalPrinter;
import com.google.caja.reporting.EchoingMessageQueue;
import com.google.caja.reporting.Message;
import com.google.caja.reporting.MessageContext;
import com.google.caja.reporting.MessageLevel;
import com.google.caja.reporting.MessagePart;
import com.google.caja.reporting.MessageQueue;
import com.google.caja.reporting.MessageType;
import com.google.caja.reporting.RenderContext;
import com.google.caja.util.Callback;
import com.google.caja.util.Charsets;
import com.google.caja.util.Pair;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Writer;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
/**
* An executable that compresses the input javascript.
* Usage
* <pre>
* java com.google.caja.parser.js.Minify file1.js file2.js ... > minified.js
* </pre>
*
* <p>This parses and renders JS so guarantees valid output, but does not
* otherwise change the structure. The output is semantically the same even
* in the presence of aliased eval.
*
* <p>It does strip comments and unnecessary whitespace.</p>
*
* <p>It does not rename local variables, inline constants or functions,
* eliminate dead code, or zip content.</p>
*
* @author mikesamuel@gmail.com
*/
public class Minify {
public static void main(String[] jsFilePaths) throws IOException {
List<Pair<InputSource, File>> inputs = checkInputs(jsFilePaths);
boolean passed = minify(inputs, new PrintWriter(System.out),
new PrintWriter(System.err));
System.exit(passed ? 0 : -1);
}
/** Called before opening files to checks that all input are readable. */
private static List<Pair<InputSource, File>> checkInputs(String... jsFiles)
throws IOException {
List<Pair<InputSource, File>> inputs
= new ArrayList<Pair<InputSource, File>>();
for (String jsFile : jsFiles) {
File f = new File(jsFile);
if (!f.canRead()) { throw new IOException("Cannot read " + jsFile); }
InputSource is = new InputSource(f.getAbsoluteFile().toURI());
inputs.add(Pair.pair(is, f));
}
return inputs;
}
public static boolean minify(Iterable<Pair<InputSource, File>> inputs,
Writer out, PrintWriter err)
throws IOException {
MessageContext mc = new MessageContext();
for (Pair<InputSource, File> input : inputs) {
mc.addInputSource(input.a);
}
final MessageQueue errs = new EchoingMessageQueue(
err, mc, false);
RenderContext rc = new RenderContext(
new JsMinimalPrinter(new Concatenator(out, new Callback<IOException>() {
public void handle(IOException ex) {
errs.addMessage(
MessageType.IO_ERROR,
MessagePart.Factory.valueOf(ex.getMessage()));
}
})));
for (Pair<InputSource, File> input : inputs) {
CharProducer cp = CharProducer.Factory.create(
new InputStreamReader(new FileInputStream(input.b),
Charsets.UTF_8.name()),
input.a);
JsLexer lexer = new JsLexer(cp);
JsTokenQueue tq = new JsTokenQueue(lexer, input.a);
Parser p = new Parser(tq, errs);
try {
while (!tq.isEmpty()) {
Block b = p.parse();
for (Statement topLevelStmt : b.children()) {
topLevelStmt.render(rc);
if (!topLevelStmt.isTerminal()) { rc.getOut().consume(";"); }
}
}
} catch (ParseException ex) {
ex.toMessageQueue(errs);
}
}
rc.getOut().noMoreTokens();
out.flush();
MessageLevel maxMessageLevel = MessageLevel.values()[0];
for (Message msg : errs.getMessages()) {
if (msg.getMessageLevel().compareTo(maxMessageLevel) >= 0) {
maxMessageLevel = msg.getMessageLevel();
}
}
return maxMessageLevel.compareTo(MessageLevel.ERROR) < 0;
}
}