pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / contrib / queries / src / java / org / apache / lucene / search / BooleanFilter.java

diff --git a/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java b/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/BooleanFilter.java
@@ -0,0 +1,157 @@
+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;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Iterator;
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.search.BooleanClause.Occur;
+import org.apache.lucene.util.FixedBitSet;
+
+/**
+ * A container Filter that allows Boolean composition of Filters.
+ * Filters are allocated into one of three logical constructs;
+ * SHOULD, MUST NOT, MUST
+ * The results Filter BitSet is constructed as follows:
+ * SHOULD Filters are OR'd together
+ * The resulting Filter is NOT'd with the NOT Filters
+ * The resulting Filter is AND'd with the MUST Filters
+ */
+public class BooleanFilter extends Filter implements Iterable<FilterClause> {
+
+  private final List<FilterClause> clauses = new ArrayList<FilterClause>();
+
+  /**
+   * Returns the a DocIdSetIterator representing the Boolean composition
+   * of the filters that have been added.
+   */
+  @Override
+  public DocIdSet getDocIdSet(IndexReader reader) throws IOException {
+    FixedBitSet res = null;
+    
+    for (final FilterClause fc : clauses) {
+      if (fc.getOccur() == Occur.SHOULD) {
+        final DocIdSetIterator disi = getDISI(fc.getFilter(), reader);
+        if (disi == null) continue;
+        if (res == null) {
+          res = new FixedBitSet(reader.maxDoc());
+        }
+        res.or(disi);
+      }
+    }
+    
+    for (final FilterClause fc : clauses) {
+      if (fc.getOccur() == Occur.MUST_NOT) {
+        if (res == null) {
+          res = new FixedBitSet(reader.maxDoc());
+          res.set(0, reader.maxDoc()); // NOTE: may set bits on deleted docs
+        }
+        final DocIdSetIterator disi = getDISI(fc.getFilter(), reader);
+        if (disi != null) {
+          res.andNot(disi);
+        }
+      }
+    }
+    
+    for (final FilterClause fc : clauses) {
+      if (fc.getOccur() == Occur.MUST) {
+        final DocIdSetIterator disi = getDISI(fc.getFilter(), reader);
+        if (disi == null) {
+          return DocIdSet.EMPTY_DOCIDSET; // no documents can match
+        }
+        if (res == null) {
+          res = new FixedBitSet(reader.maxDoc());
+          res.or(disi);
+        } else {
+          res.and(disi);
+        }
+      }
+    }
+
+    return res != null ? res : DocIdSet.EMPTY_DOCIDSET;
+  }
+
+  private static DocIdSetIterator getDISI(Filter filter, IndexReader reader)
+      throws IOException {
+    final DocIdSet set = filter.getDocIdSet(reader);
+    return (set == null || set == DocIdSet.EMPTY_DOCIDSET) ? null : set.iterator();
+  }
+
+  /**
+  * Adds a new FilterClause to the Boolean Filter container
+  * @param filterClause A FilterClause object containing a Filter and an Occur parameter
+  */
+  public void add(FilterClause filterClause) {
+    clauses.add(filterClause);
+  }
+  
+  public final void add(Filter filter, Occur occur) {
+    add(new FilterClause(filter, occur));
+  }
+  
+  /**
+  * Returns the list of clauses
+  */
+  public List<FilterClause> clauses() {
+    return clauses;
+  }
+  
+  /** Returns an iterator on the clauses in this query. It implements the {@link Iterable} interface to
+   * make it possible to do:
+   * <pre>for (FilterClause clause : booleanFilter) {}</pre>
+   */
+  public final Iterator<FilterClause> iterator() {
+    return clauses().iterator();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+
+    if ((obj == null) || (obj.getClass() != this.getClass())) {
+      return false;
+    }
+
+    final BooleanFilter other = (BooleanFilter)obj;
+    return clauses.equals(other.clauses);
+  }
+
+  @Override
+  public int hashCode() {
+    return 657153718 ^ clauses.hashCode();
+  }
+  
+  /** Prints a user-readable version of this Filter. */
+  @Override
+  public String toString() {
+    final StringBuilder buffer = new StringBuilder("BooleanFilter(");
+    final int minLen = buffer.length();
+    for (final FilterClause c : clauses) {
+      if (buffer.length() > minLen) {
+        buffer.append(' ');
+      }
+      buffer.append(c);
+    }
+    return buffer.append(')').toString();
+  }
+}