pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / search / spans / SpanScorer.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/spans/SpanScorer.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/spans/SpanScorer.java
new file mode 100644 (file)
index 0000000..1d2d9f5
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+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/spans/SpanScorer.java
@@ -0,0 +1,118 @@
+package org.apache.lucene.search.spans;
+
+/**
+ * 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.io.IOException;
+
+import org.apache.lucene.search.Explanation;
+import org.apache.lucene.search.Weight;
+import org.apache.lucene.search.Scorer;
+import org.apache.lucene.search.Similarity;
+
+/**
+ * Public for extension only.
+ */
+public class SpanScorer extends Scorer {
+  protected Spans spans;
+  protected byte[] norms;
+  protected float value;
+
+  protected boolean more = true;
+
+  protected int doc;
+  protected float freq;
+
+  protected SpanScorer(Spans spans, Weight weight, Similarity similarity, byte[] norms)
+  throws IOException {
+    super(similarity, weight);
+    this.spans = spans;
+    this.norms = norms;
+    this.value = weight.getValue();
+    if (this.spans.next()) {
+      doc = -1;
+    } else {
+      doc = NO_MORE_DOCS;
+      more = false;
+    }
+  }
+
+  @Override
+  public int nextDoc() throws IOException {
+    if (!setFreqCurrentDoc()) {
+      doc = NO_MORE_DOCS;
+    }
+    return doc;
+  }
+
+  @Override
+  public int advance(int target) throws IOException {
+    if (!more) {
+      return doc = NO_MORE_DOCS;
+    }
+    if (spans.doc() < target) { // setFreqCurrentDoc() leaves spans.doc() ahead
+      more = spans.skipTo(target);
+    }
+    if (!setFreqCurrentDoc()) {
+      doc = NO_MORE_DOCS;
+    }
+    return doc;
+  }
+  
+  protected boolean setFreqCurrentDoc() throws IOException {
+    if (!more) {
+      return false;
+    }
+    doc = spans.doc();
+    freq = 0.0f;
+    do {
+      int matchLength = spans.end() - spans.start();
+      freq += getSimilarity().sloppyFreq(matchLength);
+      more = spans.next();
+    } while (more && (doc == spans.doc()));
+    return true;
+  }
+
+  @Override
+  public int docID() { return doc; }
+
+  @Override
+  public float score() throws IOException {
+    float raw = getSimilarity().tf(freq) * value; // raw score
+    return norms == null? raw : raw * getSimilarity().decodeNormValue(norms[doc]); // normalize
+  }
+  
+  @Override
+  public float freq() throws IOException {
+    return freq;
+  }
+
+  /** This method is no longer an official member of {@link Scorer},
+   * but it is needed by SpanWeight to build an explanation. */
+  protected Explanation explain(final int doc) throws IOException {
+    Explanation tfExplanation = new Explanation();
+
+    int expDoc = advance(doc);
+
+    float phraseFreq = (expDoc == doc) ? freq : 0.0f;
+    tfExplanation.setValue(getSimilarity().tf(phraseFreq));
+    tfExplanation.setDescription("tf(phraseFreq=" + phraseFreq + ")");
+
+    return tfExplanation;
+  }
+
+}