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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (NUTCH-2248) CSS parser plugin
Date Mon, 11 Apr 2016 17:12:25 GMT

    [ https://issues.apache.org/jira/browse/NUTCH-2248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15235504#comment-15235504
] 

ASF GitHub Bot commented on NUTCH-2248:
---------------------------------------

Github user lewismc commented on a diff in the pull request:

    https://github.com/apache/nutch/pull/102#discussion_r59242509
  
    --- Diff: src/plugin/parse-css/src/java/org/apache/nutch/parse/css/CssParser.java ---
    @@ -0,0 +1,225 @@
    +/**
    + * 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.nutch.parse.css;
    +
    +import java.io.*;
    +import java.net.MalformedURLException;
    +import java.net.URL;
    +import java.nio.charset.StandardCharsets;
    +import java.util.ArrayList;
    +import java.util.List;
    +
    +import com.steadystate.css.parser.CSSOMParser;
    +import com.steadystate.css.parser.SACParserCSS3;
    +import org.apache.hadoop.conf.Configuration;
    +import org.apache.nutch.metadata.Metadata;
    +import org.apache.nutch.protocol.Content;
    +import org.apache.nutch.parse.*;
    +import org.apache.nutch.util.*;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +import org.w3c.css.sac.CSSParseException;
    +import org.w3c.css.sac.InputSource;
    +import org.w3c.dom.css.*;
    +
    +
    +public class CssParser implements org.apache.nutch.parse.Parser {
    +  public static final Logger LOG = LoggerFactory.getLogger(CssParser.class);
    +
    +  /**
    +   * Suppresses warnings, logs all errors, and throws fatal errors
    +   */
    +  private class ErrorHandler implements org.w3c.css.sac.ErrorHandler {
    +    @Override
    +    public void warning(CSSParseException exception) { }
    +
    +    @Override
    +    public void error(CSSParseException exception) {
    +      LOG.debug("CSS parser error: " + exception.getMessage());
    +    }
    +
    +    @Override
    +    public void fatalError(CSSParseException exception) {
    +      error(exception);
    +      throw exception;
    +    }
    +  }
    +
    +  private Configuration config;
    +
    +  /** Parses CSS stylesheets for outlinks.
    +   *
    +   * Extracts :
    +   *
    +   *   - \\@import url(...) ...;
    +   *   - \\@import '...';
    +   *   - \\@font-face src: <uri>
    +   *   - and all non-custom style property values matching url(...)
    +   *
    +   * Ignores:
    +   *
    +   *   - \\@namespace <uri>
    +   *   - \\@document <url>
    +   *
    +   * @param content CSS resource content to be parsed
    +   * @return result of parse
    +   */
    +  @Override
    +  public ParseResult getParse(Content content) {
    +    CSSOMParser parser;
    +    parser = new CSSOMParser(new SACParserCSS3());
    +    parser.setErrorHandler(new ErrorHandler());
    +
    +    URL base;
    +    try {
    +      base = new URL(content.getBaseUrl());
    +    } catch (MalformedURLException e) {
    +      return new ParseStatus(e)
    +        .getEmptyParseResult(content.getUrl(), getConf());
    +    }
    +
    +    ByteArrayInputStream bis = new ByteArrayInputStream(content.getContent());
    +    Reader reader = new InputStreamReader(bis, StandardCharsets.UTF_8);
    +    InputSource source = new InputSource(reader);
    +    CSSStyleSheet sheet;
    +    try {
    +      sheet = parser.parseStyleSheet(source, null, content.getBaseUrl());
    +    } catch (IOException e) {
    +      return new ParseStatus(e)
    +        .getEmptyParseResult(content.getUrl(), getConf());
    +    } finally {
    +      try {
    +        reader.close();
    +      } catch (IOException e) {
    +        LOG.warn("failed to close reader");
    +      }
    +    }
    +
    +    CSSRuleList rules = sheet.getCssRules();
    +    List<String> urls = new ArrayList<String>();
    +    for (int i = 0; i < rules.getLength(); i++) {
    +      CSSRule rule = rules.item(i);
    +      switch (rule.getType()) {
    +        // @import
    +        case CSSRule.IMPORT_RULE:
    +          urls.add(((CSSImportRule) rule).getHref());
    +          break;
    +
    +        // @font-face
    +        case CSSRule.FONT_FACE_RULE:
    +          collectStyleDeclarationOutlinks(((CSSFontFaceRule)rule).getStyle(), urls);
    +          break;
    +
    +        // normal CSS style rule
    +        case CSSRule.STYLE_RULE:
    +          collectStyleDeclarationOutlinks(((CSSStyleRule)rule).getStyle(), urls);
    +          break;
    +
    +        // ignore @charset, @media, @page and unknown at-rules
    +        default:
    +          break;
    +      }
    +    }
    +
    +    // resolve each relative URL to create a list of Outlinks
    +    List<Outlink> outlinks = new ArrayList<Outlink>();
    +    for (int i = 0; i < urls.size(); i++) {
    +      String rawUrl = urls.get(i);
    +      try {
    +        URL url = URLUtil.resolveURL(base, rawUrl);
    +        outlinks.add(new Outlink(url.toString(), ""));
    +      } catch (MalformedURLException e) {
    +        LOG.debug("failed to resolve url (base: " + base + ", path: " + rawUrl + ")");
    --- End diff --
    
    Can you use ```LOG.debug("failed to resolve url (base: {}, path: {})", base, rawUrl);
```


> CSS parser plugin
> -----------------
>
>                 Key: NUTCH-2248
>                 URL: https://issues.apache.org/jira/browse/NUTCH-2248
>             Project: Nutch
>          Issue Type: New Feature
>          Components: parser, plugin
>    Affects Versions: 1.12
>            Reporter: Joseph Naegele
>
> This plugin allows for collecting {{uri}} links from CSS (stylesheets). This is useful
for collecting parent stylesheets, fonts, and images needed to display web pages as intended.
> Parsed Outlinks do not have associated anchors, and no additional text/content is parsed
from the stylesheet.



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