pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FilteredTermEnum.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FilteredTermEnum.java
new file mode 100644 (file)
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--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/search/FilteredTermEnum.java
@@ -0,0 +1,104 @@
+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 org.apache.lucene.index.Term;
+import org.apache.lucene.index.TermEnum;
+
+/** Abstract class for enumerating a subset of all terms. 
+
+  <p>Term enumerations are always ordered by Term.compareTo().  Each term in
+  the enumeration is greater than all that precede it.  */
+public abstract class FilteredTermEnum extends TermEnum {
+    /** the current term */
+    protected Term currentTerm = null;
+    
+    /** the delegate enum - to set this member use {@link #setEnum} */
+    protected TermEnum actualEnum = null;
+    
+    public FilteredTermEnum() {}
+
+    /** Equality compare on the term */
+    protected abstract boolean termCompare(Term term);
+    
+    /** Equality measure on the term */
+    public abstract float difference();
+
+    /** Indicates the end of the enumeration has been reached */
+    protected abstract boolean endEnum();
+    
+    /**
+     * use this method to set the actual TermEnum (e.g. in ctor),
+     * it will be automatically positioned on the first matching term.
+     */
+    protected void setEnum(TermEnum actualEnum) throws IOException {
+        this.actualEnum = actualEnum;
+        // Find the first term that matches
+        Term term = actualEnum.term();
+        if (term != null && termCompare(term)) 
+            currentTerm = term;
+        else next();
+    }
+    
+    /** 
+     * Returns the docFreq of the current Term in the enumeration.
+     * Returns -1 if no Term matches or all terms have been enumerated.
+     */
+    @Override
+    public int docFreq() {
+        if (currentTerm == null) return -1;
+        assert actualEnum != null;
+        return actualEnum.docFreq();
+    }
+    
+    /** Increments the enumeration to the next element.  True if one exists. */
+    @Override
+    public boolean next() throws IOException {
+        if (actualEnum == null) return false; // the actual enumerator is not initialized!
+        currentTerm = null;
+        while (currentTerm == null) {
+            if (endEnum()) return false;
+            if (actualEnum.next()) {
+                Term term = actualEnum.term();
+                if (termCompare(term)) {
+                    currentTerm = term;
+                    return true;
+                }
+            }
+            else return false;
+        }
+        currentTerm = null;
+        return false;
+    }
+    
+    /** Returns the current Term in the enumeration.
+     * Returns null if no Term matches or all terms have been enumerated. */
+    @Override
+    public Term term() {
+        return currentTerm;
+    }
+    
+    /** Closes the enumeration to further activity, freeing resources.  */
+    @Override
+    public void close() throws IOException {
+        if (actualEnum != null) actualEnum.close();
+        currentTerm = null;
+        actualEnum = null;
+    }
+}