pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / highlighter / src / java / org / apache / lucene / search / vectorhighlight / SimpleFragListBuilder.java

diff --git a/lucene-java-3.5.0/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/SimpleFragListBuilder.java b/lucene-java-3.5.0/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/SimpleFragListBuilder.java
new file mode 100644 (file)
index 0000000..8a9447b
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+++ b/lucene-java-3.5.0/lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/SimpleFragListBuilder.java
@@ -0,0 +1,99 @@
+package org.apache.lucene.search.vectorhighlight;
+
+/**
+ * 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.
+ */
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.lucene.search.vectorhighlight.FieldPhraseList.WeightedPhraseInfo;
+
+/**
+ * A simple implementation of {@link FragListBuilder}.
+ */
+public class SimpleFragListBuilder implements FragListBuilder {
+  
+  public static final int MARGIN_DEFAULT = 6;
+  public static final int MIN_FRAG_CHAR_SIZE_FACTOR = 3;
+
+  final int margin;
+  final int minFragCharSize;
+
+  public SimpleFragListBuilder( int margin ){
+    if( margin < 0 )
+      throw new IllegalArgumentException( "margin(" + margin + ") is too small. It must be 0 or higher." );
+
+    this.margin = margin;
+    this.minFragCharSize = Math.max( 1, margin * MIN_FRAG_CHAR_SIZE_FACTOR );
+  }
+
+  public SimpleFragListBuilder(){
+    this( MARGIN_DEFAULT );
+  }
+
+  public FieldFragList createFieldFragList(FieldPhraseList fieldPhraseList, int fragCharSize) {
+    if( fragCharSize < minFragCharSize )
+      throw new IllegalArgumentException( "fragCharSize(" + fragCharSize + ") is too small. It must be " +
+          minFragCharSize + " or higher." );
+
+    FieldFragList ffl = new FieldFragList( fragCharSize );
+
+    List<WeightedPhraseInfo> wpil = new ArrayList<WeightedPhraseInfo>();
+    Iterator<WeightedPhraseInfo> ite = fieldPhraseList.phraseList.iterator();
+    WeightedPhraseInfo phraseInfo = null;
+    int startOffset = 0;
+    boolean taken = false;
+    while( true ){
+      if( !taken ){
+        if( !ite.hasNext() ) break;
+        phraseInfo = ite.next();
+      }
+      taken = false;
+      if( phraseInfo == null ) break;
+
+      // if the phrase violates the border of previous fragment, discard it and try next phrase
+      if( phraseInfo.getStartOffset() < startOffset ) continue;
+
+      wpil.clear();
+      wpil.add( phraseInfo );
+      int st = phraseInfo.getStartOffset() - margin < startOffset ?
+          startOffset : phraseInfo.getStartOffset() - margin;
+      int en = st + fragCharSize;
+      if( phraseInfo.getEndOffset() > en )
+        en = phraseInfo.getEndOffset();
+      startOffset = en;
+
+      while( true ){
+        if( ite.hasNext() ){
+          phraseInfo = ite.next();
+          taken = true;
+          if( phraseInfo == null ) break;
+        }
+        else
+          break;
+        if( phraseInfo.getEndOffset() <= en )
+          wpil.add( phraseInfo );
+        else
+          break;
+      }
+      ffl.add( st, en, wpil );
+    }
+    return ffl;
+  }
+
+}