Cache.java :  » HTML-Parser » jericho-html » au » id » jericho » lib » html » Java Open Source

// Jericho HTML Parser - Java based library for analysing and manipulating HTML
// Version 2.5
// Copyright (C) 2007 Martin Jericho
// http://jerichohtml.sourceforge.net/
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of either one of the following licences:
//
// 1. The Eclipse Public License (EPL) version 1.0,
// included in this distribution in the file licence-epl-1.0.html
// or available at http://www.eclipse.org/legal/epl-v10.html
//
// 2. The GNU Lesser General Public License (LGPL) version 2.1 or later,
// included in this distribution in the file licence-lgpl-2.1.txt
// or available at http://www.gnu.org/licenses/lgpl.txt
//
// This library is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the individual licence texts for more details.

package au.id.jericho.lib.html;

import java.util.*;

/**
 * Represents a cached map of character positions to tags.
 * The allTagTypesSubCache object is used to cache all tags.
 * Additional subcaches are used to cache single tag types, which increases the performance when searching for those tag types.
 * A list of tag types to be cached separately is specified in the SeparatelyCachedTagTypes property.
 * The standard implementation caches only COMMENT tag types separately, as these tag types are searched extensively
 * in the process of ensuring that every non-server tag is not located inside a comment.
 */
final class Cache {
  public final Source source;
  private final SubCache allTagTypesSubCache;
  private final SubCache[] subCaches; // contains allTagTypesSubCache plus a SubCache object for each separately cached tag type

  public Cache(final Source source) {
    this.source=source;
    allTagTypesSubCache=new SubCache(this,null);
    TagType[] separatelyCachedTagTypes=getSeparatelyCachedTagTypes();
    subCaches=new SubCache[separatelyCachedTagTypes.length+1];
    subCaches[0]=allTagTypesSubCache;
    for (int i=0; i<separatelyCachedTagTypes.length; i++)
      subCaches[i+1]=new SubCache(this,separatelyCachedTagTypes[i]);
  }

  public void clear() {
    for (int i=0; i<subCaches.length; i++) subCaches[i].clear();
  }

  public Tag getTagAt(final int pos) {
    return source.useAllTypesCache
      ?  allTagTypesSubCache.getTagAt(pos)
      : Tag.getTagAtUncached(source,pos);
  }

  public Tag findPreviousOrNextTag(final int pos, final boolean previous) {
    // returns null if pos is out of range.
    return allTagTypesSubCache.findPreviousOrNextTag(pos,previous);
  }

  public Tag findPreviousOrNextTag(final int pos, final TagType tagType, final boolean previous) {
    // returns null if pos is out of range.
    for (int i=source.useAllTypesCache ? 0 : 1; i<subCaches.length; i++)
      if (tagType==subCaches[i].tagType) return subCaches[i].findPreviousOrNextTag(pos,previous);
    return Tag.findPreviousOrNextTagUncached(source,pos,tagType,previous,ParseText.NO_BREAK);
  }

  public Tag addTagAt(final int pos) {
    final Tag tag=Tag.getTagAtUncached(source,pos);
    allTagTypesSubCache.addTagAt(pos,tag);
    if (tag==null) return tag;
    final TagType tagType=tag.getTagType();
    for (int i=1; i<subCaches.length; i++) {
      if (tagType==subCaches[i].tagType) {
        subCaches[i].addTagAt(pos,tag);
        return tag;
      }
    }
    return tag;
  }

  public int getTagCount() {
    return allTagTypesSubCache.size()-2;
  }

  public Iterator getTagIterator() {
    return allTagTypesSubCache.getTagIterator();
  }

  public void loadAllTags(final List tags, final Tag[] allRegisteredTags, final StartTag[] allRegisteredStartTags) {
    // assumes the tags list implements RandomAccess
    final int tagCount=tags.size();
    allTagTypesSubCache.bulkLoad_Init(tagCount);
    int registeredTagIndex=0;
    int registeredStartTagIndex=0;
    for (int i=0; i<tagCount; i++) {
      Tag tag=(Tag)tags.get(i);
      if (!tag.isUnregistered()) {
        allRegisteredTags[registeredTagIndex++]=tag;
        if (tag instanceof StartTag) allRegisteredStartTags[registeredStartTagIndex++]=(StartTag)tag;
      }
      allTagTypesSubCache.bulkLoad_Set(i,tag);
      for (int x=1; x<subCaches.length; x++) {
        if (tag.getTagType()==subCaches[x].tagType) {
          subCaches[x].bulkLoad_AddToTypeSpecificCache(tag);
          break;
        }
      }
    }
    for (int x=1; x<subCaches.length; x++)
      subCaches[x].bulkLoad_FinaliseTypeSpecificCache();
  }

  public String toString() {
    StringBuffer sb=new StringBuffer();
    for (int i=0; i<subCaches.length; i++) subCaches[i].appendTo(sb);
    return sb.toString();
  }

  protected int getSourceLength() {
    return source.end;
  }
  
  private static TagType[] getSeparatelyCachedTagTypes() {
    return TagType.getTagTypesIgnoringEnclosedMarkup();
  }
}