    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.internal.webresources;
    014
    015import com.google.javascript.jscomp.*;
    016import com.google.javascript.jscomp.Compiler;
    017import org.apache.commons.io.IOUtils;
    018import org.apache.tapestry5.TapestryConstants;
    019import org.apache.tapestry5.ioc.OperationTracker;
    020import org.apache.tapestry5.ioc.annotations.Symbol;
    021import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
    022import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    023import org.apache.tapestry5.services.Request;
    024import org.apache.tapestry5.services.assets.AssetChecksumGenerator;
    025import org.apache.tapestry5.services.assets.StreamableResource;
    026import org.apache.tapestry5.webresources.WebResourcesSymbols;
    027import org.slf4j.Logger;
    028
    029import java.io.IOException;
    030import java.io.InputStream;
    031import java.util.Collections;
    032import java.util.List;
    033import java.util.logging.Level;
    034
    035/**
    036 * A wrapper around the Google Closure {@link Compiler} used to minimize
    037 * a JavaScript resource.
    038 */
    039public class GoogleClosureMinimizer extends AbstractMinimizer
    040{
    041
    042    private final static String OUTPUT_CHARSET = "utf-8";
    043
    044    private final List<SourceFile> EXTERNS = Collections.emptyList();
    045
    046    private final Request request;
    047    private final CompilationLevel compilationLevel;
    048
    049    static
    050    {
    051        Compiler.setLoggingLevel(Level.SEVERE);
    052    }
    053
    054    public GoogleClosureMinimizer(Logger logger, OperationTracker tracker, AssetChecksumGenerator checksumGenerator, Request request,
    055                                  @Symbol(WebResourcesSymbols.COMPILATION_LEVEL)
    056                                  CompilationLevel compilationLevel)
    057    {
    058        super(logger, tracker, checksumGenerator, "text/javascript");
    059        this.request = request;
    060        this.compilationLevel = compilationLevel;
    061    }
    062
    063    @Override
    064    protected boolean isEnabled(StreamableResource resource)
    065    {
    066        return request.getAttribute(TapestryConstants.DISABLE_JAVASCRIPT_MINIMIZATION) == null;
    067    }
    068
    069    @Override
    070    protected InputStream doMinimize(StreamableResource resource) throws IOException
    071    {
    072        // Don't bother to pool the Compiler
    073
    074        CompilerOptions options = new CompilerOptions();
    075
    076        compilationLevel.setOptionsForCompilationLevel(options);
    077
    078        options.setCodingConvention(new ClosureCodingConvention());
    079        options.setOutputCharset(OUTPUT_CHARSET);
    080        options.setWarningLevel(DiagnosticGroups.CHECK_VARIABLES, CheckLevel.WARNING);
    081
    082        Compiler compiler = new Compiler();
    083
    084        compiler.disableThreads();
    085
    086        SourceFile input = SourceFile.fromInputStream(resource.toString(), resource.openStream());
    087
    088        List<SourceFile> inputs = Collections.singletonList(input);
    089
    090        Result result = compiler.compile(EXTERNS, inputs, options);
    091
    092        if (result.success)
    093        {
    094            return IOUtils.toInputStream(compiler.toSource(), OUTPUT_CHARSET);
    095        }
    096
    097        throw new RuntimeException(String.format("Compilation failed: %s.",
    098                InternalUtils.join(CollectionFactory.newList(result.errors), ";")));
    099    }
    100}