pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/ReqExclScorer.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/ReqExclScorer.java
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+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/ReqExclScorer.java
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+package org.apache.lucene.search;
+
+/**
+ * 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;
+
+
+/** A Scorer for queries with a required subscorer
+ * and an excluding (prohibited) sub DocIdSetIterator.
+ * <br>
+ * This <code>Scorer</code> implements {@link Scorer#skipTo(int)},
+ * and it uses the skipTo() on the given scorers.
+ */
+class ReqExclScorer extends Scorer {
+  private Scorer reqScorer;
+  private DocIdSetIterator exclDisi;
+  private int doc = -1;
+
+  /** Construct a <code>ReqExclScorer</code>.
+   * @param reqScorer The scorer that must match, except where
+   * @param exclDisi indicates exclusion.
+   */
+  public ReqExclScorer(Scorer reqScorer, DocIdSetIterator exclDisi) {
+    super(reqScorer.weight);
+    this.reqScorer = reqScorer;
+    this.exclDisi = exclDisi;
+  }
+
+  @Override
+  public int nextDoc() throws IOException {
+    if (reqScorer == null) {
+      return doc;
+    }
+    doc = reqScorer.nextDoc();
+    if (doc == NO_MORE_DOCS) {
+      reqScorer = null; // exhausted, nothing left
+      return doc;
+    }
+    if (exclDisi == null) {
+      return doc;
+    }
+    return doc = toNonExcluded();
+  }
+  
+  /** Advance to non excluded doc.
+   * <br>On entry:
+   * <ul>
+   * <li>reqScorer != null,
+   * <li>exclScorer != null,
+   * <li>reqScorer was advanced once via next() or skipTo()
+   *      and reqScorer.doc() may still be excluded.
+   * </ul>
+   * Advances reqScorer a non excluded required doc, if any.
+   * @return true iff there is a non excluded required doc.
+   */
+  private int toNonExcluded() throws IOException {
+    int exclDoc = exclDisi.docID();
+    int reqDoc = reqScorer.docID(); // may be excluded
+    do {  
+      if (reqDoc < exclDoc) {
+        return reqDoc; // reqScorer advanced to before exclScorer, ie. not excluded
+      } else if (reqDoc > exclDoc) {
+        exclDoc = exclDisi.advance(reqDoc);
+        if (exclDoc == NO_MORE_DOCS) {
+          exclDisi = null; // exhausted, no more exclusions
+          return reqDoc;
+        }
+        if (exclDoc > reqDoc) {
+          return reqDoc; // not excluded
+        }
+      }
+    } while ((reqDoc = reqScorer.nextDoc()) != NO_MORE_DOCS);
+    reqScorer = null; // exhausted, nothing left
+    return NO_MORE_DOCS;
+  }
+
+  @Override
+  public int docID() {
+    return doc;
+  }
+
+  /** Returns the score of the current document matching the query.
+   * Initially invalid, until {@link #nextDoc()} is called the first time.
+   * @return The score of the required scorer.
+   */
+  @Override
+  public float score() throws IOException {
+    return reqScorer.score(); // reqScorer may be null when next() or skipTo() already return false
+  }
+  
+  @Override
+  public int advance(int target) throws IOException {
+    if (reqScorer == null) {
+      return doc = NO_MORE_DOCS;
+    }
+    if (exclDisi == null) {
+      return doc = reqScorer.advance(target);
+    }
+    if (reqScorer.advance(target) == NO_MORE_DOCS) {
+      reqScorer = null;
+      return doc = NO_MORE_DOCS;
+    }
+    return doc = toNonExcluded();
+  }
+}