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}