org.directwebremoting.impl.YahooJSCompressor Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of dwr Show documentation
DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
The newest version!
/*
 * Copyright 2005 Joe Walker
 *
 * 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 org.directwebremoting.impl;

import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.directwebremoting.extend.Compressor;
import org.mozilla.javascript.ErrorReporter;
import org.mozilla.javascript.EvaluatorException;

import com.yahoo.platform.yui.compressor.JavaScriptCompressor;

/**
 * JavaScript Compression Implementation using the YUI Compressor.
 *
 * @author David Marginian [david at butterdev dot com]
 */
public class YahooJSCompressor implements Compressor
{
    /**
     * Constructor: YahooJSCompressor using default property values.
     */
    public YahooJSCompressor() throws InstantiationException
    {
        this(null);
    }

    /**
     * Constructor: YahooJSCompressor using the property map passed in.
     *
     * @param specifiedCompressorParameters
     */
    public YahooJSCompressor(Map specifiedCompressorParameters) throws InstantiationException
    {
        try
        {
            new JavaScriptCompressor(new StringReader(""), new YahooJSErrorReporter());
        }
        catch (NoClassDefFoundError ncdf)
        {
            throw new InstantiationException("com.yahoo.platform.yui.compressor.JavaScriptCompressor is not available, assuming Yahoo Compressor is not here from yuicompressor.jar ");
        }
        catch (Exception e)
        {
            // We don't care about this!  The instansiation above is just to ensure that the Yahoo compressor is
            // on the classpath.  If the actual test compression fails we don't need to do anything.
        }
        setCompressorParameters(specifiedCompressorParameters);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.Compressor#compressJavaScript(java.lang.String)
     */
    public String compressJavaScript(String script) throws IOException
    {
        StringReader stringReader = new StringReader(script);
        JavaScriptCompressor yuiJavaScriptCompressor = new JavaScriptCompressor(stringReader, new YahooJSErrorReporter());
        StringWriter stringWriter = new StringWriter();
        yuiJavaScriptCompressor.compress(stringWriter, (Integer) compressorParameters.get(PARAMETER_LINEBREAK), (Boolean) compressorParameters.get(PARAMETER_MUNGE),
                (Boolean) compressorParameters.get(PARAMETER_VERBOSE), (Boolean) compressorParameters.get(PARAMETER_PRESERVE_ALL_SEMICOLONS),
                (Boolean) compressorParameters.get(PARAMETER_DISABLE_OPTIMIZATIONS));
        String compressedScript = stringWriter.toString();
        return compressedScript;
    }

    /**
     * Builds the compressor parameter map using the parameters specified or
     * the default parameters.
     *
     * @param configuredCompressorParameters -
     *   Parameters specified by the applications configuration. We still need
     *   to validate these parameters and use defaults if all of the parameters
     *   were not specified.
     */
    private void setCompressorParameters(Map configuredCompressorParameters)
    {
        String mungeString = null;
        String disableOptString = null;
        String preserveSemiString = null;
        String verboseString = null;
        String linebreakString = null;
        if (null != configuredCompressorParameters)
        {
            mungeString = (String) configuredCompressorParameters.get(PARAMETER_MUNGE);
            disableOptString = (String) configuredCompressorParameters.get(PARAMETER_DISABLE_OPTIMIZATIONS);
            preserveSemiString = (String) configuredCompressorParameters.get(PARAMETER_PRESERVE_ALL_SEMICOLONS);
            verboseString = (String) configuredCompressorParameters.get(PARAMETER_VERBOSE);
            linebreakString = (String) configuredCompressorParameters.get(PARAMETER_LINEBREAK);
        }
        // Place either the configured parameters or the default parameters into the compressorParameters Map
        compressorParameters.put(PARAMETER_MUNGE, (null != mungeString) ? Boolean.valueOf(mungeString) : DEFAULT_MUNGE);
        compressorParameters.put(PARAMETER_DISABLE_OPTIMIZATIONS, (null != disableOptString) ? Boolean.valueOf(disableOptString) : DEFAULT_DISABLE_OPTIMIZATIONS);
        compressorParameters.put(PARAMETER_PRESERVE_ALL_SEMICOLONS, (null != preserveSemiString) ? Boolean.valueOf(preserveSemiString) : DEFAULT_PRESERVE_ALL_SEMICOLONS);
        compressorParameters.put(PARAMETER_VERBOSE, (null != verboseString) ? Boolean.valueOf(verboseString) : DEFAULT_VERBOSE);
        compressorParameters.put(PARAMETER_LINEBREAK, (null != linebreakString) ? Integer.valueOf(linebreakString) : DEFAULT_LINEBREAK);
    }

    /**
     * ErrorReporter implementation required by the YUI Compressor compress.
     */
    protected static class YahooJSErrorReporter implements ErrorReporter
    {
        public void warning(String message, String sourceName, int line, String lineSource, int lineOffset)
        {
            if (line < 0)
            {
                log.warn(message);
            }
            else
            {
                log.error("\n" + line + ':' + lineOffset + ':' + message);
            }
        }

        public void error(String message, String sourceName, int line, String lineSource, int lineOffset)
        {
            if (line < 0)
            {
                log.error(message);
            }
            else
            {
                log.error(line + ':' + lineOffset + ':' + message);
            }
        }

        public EvaluatorException runtimeError(String message, String sourceName, int line, String lineSource, int lineOffset)
        {
            error(message, sourceName, line, lineSource, lineOffset);
            return new EvaluatorException(message);
        }
    }

    private static final Log log = LogFactory.getLog(YahooJSCompressor.class);

    private final Map compressorParameters = new HashMap();

    // Fields representing the parameters that can be configured for this Compressor.
    // Obfuscates the script
    private static final String PARAMETER_MUNGE = "munge";

    // Display informational messages and warnings.
    private static final String PARAMETER_VERBOSE = "verbose";

    // Some source control tools don't like it when files containing lines longer
    // than, say 8000 characters, are checked in. The linebreak option is used in
    // that case to split long lines after a specific column.
    private static final String PARAMETER_LINEBREAK = "linebreak";

    // Append a semi-colon at the end, even if unnecessary semi-colons are
    // supposed to be removed. This is especially useful when concatenating
    // several minified files (the absence of an ending semi-colon at the
    // end of one file may very likely cause a syntax error)
    private static final String PARAMETER_PRESERVE_ALL_SEMICOLONS = "preserveAllSemiColons";

    // Disable all the built-in micro optimizations.
    private static final String PARAMETER_DISABLE_OPTIMIZATIONS = "disableOptimizations";

    // Default values for the parameters that can be configured for this Compressor in case they
    // are not specified.
    private static final Boolean DEFAULT_MUNGE = Boolean.FALSE;

    private static final Boolean DEFAULT_VERBOSE = Boolean.FALSE;

    private static final Integer DEFAULT_LINEBREAK = 20000;

    private static final Boolean DEFAULT_PRESERVE_ALL_SEMICOLONS = Boolean.FALSE;

    private static final Boolean DEFAULT_DISABLE_OPTIMIZATIONS = Boolean.FALSE;
}