com.osbcp.csssquasher.Squasher.java Source code

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Here is the source code for com.osbcp.csssquasher.Squasher.java

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/*
 * 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.
 * 
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 */

package com.osbcp.csssquasher;

import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.List;

import org.apache.commons.io.FileUtils;

import com.osbcp.cssparser.CSSParser;
import com.osbcp.cssparser.Rule;
import com.yahoo.platform.yui.compressor.CssCompressor;

/**
 * Main class for OSBCP CSS Squasher.
 * 
 * @author <a href="mailto:christoffer@christoffer.me">Christoffer Pettersson</a>
 */

public final class Squasher {

    /**
     * Main entry point for using the minifer as a stand alone application.
     * 
     * @param arguments First argument [0] should be the path of the CSS file that should be minified.
     * @throws Exception If any errors occur.
     */

    public static void main(final String[] arguments) throws Exception {

        if (arguments.length != 1) {

            System.out.println("Usage: java -jar osbcp-css-squasher-x.y.z.jar [input file]");

        } else {

            File file = new File(arguments[0]);

            String contents = FileUtils.readFileToString(file);

            ResultObject results = Squasher.squash(contents);

            String compressedCSS = results.getCompressedCSS();

            System.out.println(compressedCSS);

        }

    }

    /**
     * Squashes CSS.
     * 
     * @param originalCSS String representation of CSS.
     * @return Squashed, refacotored and compressed CSS.
     * @throws Exception If any error occurs.
     */

    public static ResultObject squash(final String originalCSS) throws Exception {

        List<Rule> rules = CSSParser.parse(originalCSS);
        StringBuilder log = new StringBuilder();

        while (true) {

            LogicMerger merger = new LogicMerger(log);
            rules = merger.merge(rules);
            int merged = merger.getNumberOfMerges();
            log.append("Managed to merge '" + merged + "' rules.\n");
            //   System.out.println(toString(rules));

            LogicSquashDuplicates squasher = new LogicSquashDuplicates(log);
            rules = squasher.squash(rules);
            int squashed = squasher.getNbrOfSquashedRules();
            log.append("Managed to squash '" + squashed + "' rules.\n");
            //         System.out.println(toString(rules));

            LogicRefactor refactorizer = new LogicRefactor(log);
            rules = refactorizer.refactor(rules);
            int refactored = refactorizer.getNumberOfRefactored();
            log.append("Managed to refactor '" + refactored + "' rules.\n");
            //         System.out.println(toString(rules));

            // Job done if no more to squash or refactor 
            if (merged == 0 && squashed == 0 && refactored == 0) {
                log.append("Could not merge, squash or refactor anymore.\n");
                break;
            }

        }

        String refactoredCSS = toString(rules);

        String compressedCSS = compress(log, refactoredCSS);

        log.append("Squasher is happy. Exiting.\n");

        return new ResultObject(originalCSS, refactoredCSS, compressedCSS, log.toString(), rules);

    }

    /**
     * Performs the YUI Compressor on a String.
     * 
     * @param log Log object.
     * @param css The CSS that should be compressed.
     * @return Compressed CSS.
     * @throws IOException If any error occurs.
     */

    private static String compress(final StringBuilder log, final String css) throws IOException {

        StringReader reader = new StringReader(css);

        StringWriter writer = new StringWriter();

        CssCompressor compressor = new CssCompressor(reader);

        compressor.compress(writer, -1);

        String compressedCSS = writer.toString();

        log.append("Compressed the CSS from '" + css.length() + "' characters to '" + compressedCSS.length()
                + "' characters.\n");

        return compressedCSS;

    }

    /**
     * Compiles the whole list of rules into a String.
     * 
     * @param rules The list of rules.
     * @return A pretty String.
     */

    private static String toString(final List<Rule> rules) {

        StringBuilder out = new StringBuilder();

        for (Rule rule : rules) {
            out.append(rule.toString());
        }

        return out.toString();

    }

}