org.apache.shindig.gadgets.parse.caja.CajaCssParser.java Source code

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Here is the source code for org.apache.shindig.gadgets.parse.caja.CajaCssParser.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.apache.shindig.gadgets.parse.caja;

import org.apache.shindig.gadgets.GadgetException;
import org.apache.shindig.gadgets.parse.GadgetCssParser;
import org.apache.shindig.gadgets.parse.ParsedCssDeclaration;
import org.apache.shindig.gadgets.parse.ParsedCssRule;

import com.google.caja.lexer.CharProducer;
import com.google.caja.lexer.CssLexer;
import com.google.caja.lexer.CssTokenType;
import com.google.caja.lexer.InputSource;
import com.google.caja.lexer.ParseException;
import com.google.caja.lexer.Token;
import com.google.caja.lexer.TokenConsumer;
import com.google.caja.lexer.TokenQueue;
import com.google.caja.parser.css.CssParser;
import com.google.caja.parser.css.CssTree;
import com.google.caja.reporting.MessageContext;
import com.google.caja.reporting.RenderContext;
import com.google.caja.util.Criterion;

import com.google.common.collect.Lists;
import com.google.inject.Singleton;

import java.io.StringReader;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;

@Singleton
public class CajaCssParser implements GadgetCssParser {

    public List<ParsedCssRule> parse(String css) throws GadgetException {
        if (css.matches("\\s*")) {
            return Lists.newArrayList();
        }

        CssParser parser = getParser(css);
        CssTree.StyleSheet stylesheet = null;

        try {
            stylesheet = parser.parseStyleSheet();
        } catch (ParseException e) {
            throw new GadgetException(GadgetException.Code.CSS_PARSE_ERROR, e);
        }

        ArrayList<ParsedCssRule> rules = Lists.newArrayListWithExpectedSize(stylesheet.children().size());
        for (CssTree node : stylesheet.children()) {
            if (node instanceof CssTree.RuleSet) {
                rules.add(new CajaParsedCssRule((CssTree.RuleSet) node));
            }
        }

        return rules;
    }

    public List<ParsedCssDeclaration> parseInline(String style) throws GadgetException {
        if (style.matches("\\s*")) {
            return Lists.newArrayList();
        }

        CssParser parser = getParser(style);
        CssTree.DeclarationGroup declGroup = null;

        try {
            declGroup = parser.parseDeclarationGroup();
        } catch (ParseException e) {
            throw new GadgetException(GadgetException.Code.CSS_PARSE_ERROR, e);
        }

        List<ParsedCssDeclaration> attributes = Lists.newArrayListWithExpectedSize(declGroup.children().size());
        for (CssTree node : declGroup.children()) {
            if (node instanceof CssTree.Declaration) {
                CssTree.Declaration decl = (CssTree.Declaration) node;
                if (decl.getProperty() != null) {
                    attributes.add(new CajaParsedCssDeclaration(decl));
                }
            }
        }

        return attributes;
    }

    private CssParser getParser(String content) {
        InputSource source = null;
        try {
            source = new InputSource(new URI("http://dummy.com/"));
        } catch (URISyntaxException e) {
            // Never happens. Dummy URI needed to satisfy API.
            // We may want to pass in the gadget URI for auditing
            // purposes at some point.
        }
        CharProducer producer = CharProducer.Factory.create(new StringReader(content), source);
        CssLexer lexer = new CssLexer(producer);
        return new CssParser(new TokenQueue<CssTokenType>(lexer, source, new Criterion<Token<CssTokenType>>() {
            public boolean accept(Token<CssTokenType> tok) {
                return tok.type != CssTokenType.COMMENT && tok.type != CssTokenType.SPACE;
            }
        }));
    }

    private static String renderCssTreeElement(CssTree elem) {
        StringBuffer selBuffer = new StringBuffer();
        TokenConsumer tc = elem.makeRenderer(selBuffer, null);
        elem.render(new RenderContext(new MessageContext(), tc));
        return selBuffer.toString();
    }

    private static class CajaParsedCssRule implements ParsedCssRule {
        private final List<ParsedCssDeclaration> attributes;
        private final List<String> selectors;

        private CajaParsedCssRule(CssTree.RuleSet ruleSet) {
            attributes = Lists.newArrayList();
            selectors = Lists.newArrayList();

            for (CssTree child : ruleSet.children()) {
                if (child instanceof CssTree.Selector) {
                    selectors.add(renderCssTreeElement(child));
                } else if (child instanceof CssTree.Declaration) {
                    CssTree.Declaration decl = (CssTree.Declaration) child;
                    if (decl.getProperty() != null) {
                        attributes.add(new CajaParsedCssDeclaration(decl));
                    }
                }
            }
        }

        public List<ParsedCssDeclaration> getDeclarations() {
            return attributes;
        }

        public List<String> getSelectors() {
            return selectors;
        }
    }

    private static class CajaParsedCssDeclaration implements ParsedCssDeclaration {
        private final String key;
        private final String value;

        private CajaParsedCssDeclaration(CssTree.Declaration declaration) {
            key = declaration.getProperty().getPropertyName().getCanonicalForm();
            value = renderCssTreeElement(declaration.getExpr());
        }

        public String getName() {
            return key;
        }

        public String getValue() {
            return value;
        }
    }
}