    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.internal.util.CollectionFactory;
    021import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    022import org.apache.tapestry5.services.Request;
    023import org.apache.tapestry5.services.assets.AssetChecksumGenerator;
    024import org.apache.tapestry5.services.assets.StreamableResource;
    025import org.slf4j.Logger;
    026
    027import java.io.IOException;
    028import java.io.InputStream;
    029import java.util.Collections;
    030import java.util.List;
    031import java.util.logging.Level;
    032
    033/**
    034 * A wrapper around the Google Closure {@link Compiler} used to minimize
    035 * a JavaScript resource.
    036 */
    037public class GoogleClosureMinimizer extends AbstractMinimizer
    038{
    039
    040    private final static String OUTPUT_CHARSET = "utf-8";
    041
    042    private final List<SourceFile> EXTERNS = Collections.emptyList();
    043
    044    private final Request request;
    045
    046    static
    047    {
    048        Compiler.setLoggingLevel(Level.SEVERE);
    049    }
    050
    051    public GoogleClosureMinimizer(Logger logger, OperationTracker tracker, AssetChecksumGenerator checksumGenerator, Request request)
    052    {
    053        super(logger, tracker, checksumGenerator, "text/javascript");
    054        this.request = request;
    055    }
    056
    057    @Override
    058    protected boolean isEnabled(StreamableResource resource)
    059    {
    060        return request.getAttribute(TapestryConstants.DISABLE_JAVASCRIPT_MINIMIZATION) == null;
    061    }
    062
    063    @Override
    064    protected InputStream doMinimize(StreamableResource resource) throws IOException
    065    {
    066        // Don't bother to pool the Compiler
    067
    068        CompilerOptions options = new CompilerOptions();
    069        options.setCodingConvention(new ClosureCodingConvention());
    070        options.setOutputCharset(OUTPUT_CHARSET);
    071        options.setWarningLevel(DiagnosticGroups.CHECK_VARIABLES, CheckLevel.WARNING);
    072
    073        Compiler compiler = new Compiler();
    074
    075        compiler.disableThreads();
    076
    077        SourceFile input = SourceFile.fromInputStream(resource.toString(), resource.openStream());
    078
    079        List<SourceFile> inputs = Collections.singletonList(input);
    080
    081        Result result = compiler.compile(EXTERNS, inputs, options);
    082
    083        if (result.success)
    084        {
    085            return IOUtils.toInputStream(compiler.toSource(), OUTPUT_CHARSET);
    086        }
    087
    088        throw new RuntimeException(String.format("Compilation failed: %s.",
    089                InternalUtils.join(CollectionFactory.newList(result.errors), ";")));
    090    }
    091}