ClosureCompressorPlugin.java

/*
 * Copyright (C) 2011 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.exoplatform.portal.resource.compressor.impl;

import java.io.Reader;
import java.io.Writer;

import org.exoplatform.container.xml.InitParams;
import org.exoplatform.container.xml.ValueParam;
import org.exoplatform.management.annotations.Managed;
import org.exoplatform.management.annotations.ManagedDescription;
import org.exoplatform.portal.resource.compressor.BaseResourceCompressorPlugin;
import org.exoplatform.portal.resource.compressor.ResourceCompressorException;
import org.exoplatform.portal.resource.compressor.ResourceType;

import com.google.javascript.jscomp.CompilationLevel;
import com.google.javascript.jscomp.Compiler;
import com.google.javascript.jscomp.CompilerOptions;
import com.google.javascript.jscomp.JSSourceFile;
import com.google.javascript.jscomp.WarningLevel;

/**
 * A compressor based on the Google <a href="http://code.google.com/closure/>Closure Tools</a> javascript compiler. This plugin
 * compresses javascript resources and provides three levels of compression, configured via the <code>level</code> init param:
 * <ul>
 * <li><code>basic</code> encodes with the <code>WHITESPACE_ONLY</code> Closure level</li>
 * <li><code>simple</code> encodes with the <code>SIMPLE_OPTIMIZATIONS</code> Closure level</li>
 * <li><code>advanced</code> encodes with the <code>ADVANCED_OPTIMIZATIONS</code> Closure level</li>
 * </ul>
 * The precise meaning of the Closure levels are described on <a
 * href="http://code.google.com/closure/compiler/docs/compilation_levels.html>this page</a>.
 */
public class ClosureCompressorPlugin extends BaseResourceCompressorPlugin {

    /** . */
    private volatile CompilationLevel compilationLevel;

    public ClosureCompressorPlugin(InitParams params) {
        super(params);

        //
        ValueParam vp = params.getValueParam("level");
        CompilationLevel level = null;
        if (vp != null) {
            String value = vp.getValue().trim().toLowerCase();
            log.debug("found compressor level configuration " + value);
            setLevel(value);
        }

        //
        if (level == null) {
            log.debug("no compressor level found, will use simple level instead");
            level = CompilationLevel.SIMPLE_OPTIMIZATIONS;
        }

        //
        this.compilationLevel = level;
    }

    @Managed
    @ManagedDescription("The compression level value among {basic,simple,advanced}")
    public String getLevel() {
        if (compilationLevel == CompilationLevel.WHITESPACE_ONLY) {
            return "basic";
        } else if (compilationLevel == CompilationLevel.ADVANCED_OPTIMIZATIONS) {
            return "advanced";
        } else {
            return "simple";
        }
    }

    @Managed
    public void setLevel(String level) {
        if (level != null) {
            level = level.trim().toLowerCase();
            if ("basic".equals(level)) {
                log.debug("configuring to basic level configuration");
                compilationLevel = CompilationLevel.WHITESPACE_ONLY;
            } else if ("simple".equals(level)) {
                log.debug("configuring to simple level configuration");
                compilationLevel = CompilationLevel.SIMPLE_OPTIMIZATIONS;
            } else if ("advanced".equals(level)) {
                log.debug("configuring to advanced level configuration");
                compilationLevel = CompilationLevel.ADVANCED_OPTIMIZATIONS;
            }
        }
    }

    public ResourceType getResourceType() {
        return ResourceType.JAVASCRIPT;
    }

    public void compress(Reader input, Writer output) throws ResourceCompressorException {
        CompilationLevel level = compilationLevel;
        if (level == null) {
            level = CompilationLevel.SIMPLE_OPTIMIZATIONS;
        }

        //
        Compiler compiler = new Compiler();
        CompilerOptions options = new CompilerOptions();
        level.setOptionsForCompilationLevel(options);
        WarningLevel.QUIET.setOptionsForWarningLevel(options);
        JSSourceFile extern = JSSourceFile.fromCode("extern", "");

        //
        JSSourceFile jsInput;
        try {
            String code = JSSourceFile.fromReader("code", input).getCode();
            jsInput = JSSourceFile.fromCode("jsInput", code);
            compiler.compile(extern, jsInput, options);
            output.write(compiler.toSource());
        } catch (Exception ex) {
            throw new ResourceCompressorException(ex);
        }
    }
}