pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / util / StringHelper.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/StringHelper.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/StringHelper.java
new file mode 100644 (file)
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--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/StringHelper.java
@@ -0,0 +1,98 @@
+package org.apache.lucene.util;
+
+import java.util.Comparator;
+import java.util.StringTokenizer;
+
+/**
+ * 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.
+ */
+
+
+/**
+ * Methods for manipulating strings.
+ *
+ * @lucene.internal
+ */
+public abstract class StringHelper {
+  /**
+   * Expert:
+   * The StringInterner implementation used by Lucene.
+   * This shouldn't be changed to an incompatible implementation after other Lucene APIs have been used.
+   */
+  public static StringInterner interner = new SimpleStringInterner(1024,8);
+
+  /** Return the same string object for all equal strings */
+  public static String intern(String s) {
+    return interner.intern(s);
+  }
+
+  /**
+   * Compares two byte[] arrays, element by element, and returns the
+   * number of elements common to both arrays.
+   *
+   * @param bytes1 The first byte[] to compare
+   * @param bytes2 The second byte[] to compare
+   * @return The number of common elements.
+   */
+  public static final int bytesDifference(byte[] bytes1, int len1, byte[] bytes2, int len2) {
+    int len = len1 < len2 ? len1 : len2;
+    for (int i = 0; i < len; i++)
+      if (bytes1[i] != bytes2[i])
+        return i;
+    return len;
+  }
+  
+  private StringHelper() {
+  }
+  
+  /**
+   * @return a Comparator over versioned strings such as X.YY.Z
+   * @lucene.internal
+   */
+  public static Comparator<String> getVersionComparator() {
+    return versionComparator;
+  }
+  
+  private static Comparator<String> versionComparator = new Comparator<String>() {
+    public int compare(String a, String b) {
+      StringTokenizer aTokens = new StringTokenizer(a, ".");
+      StringTokenizer bTokens = new StringTokenizer(b, ".");
+      
+      while (aTokens.hasMoreTokens()) {
+        int aToken = Integer.parseInt(aTokens.nextToken());
+        if (bTokens.hasMoreTokens()) {
+          int bToken = Integer.parseInt(bTokens.nextToken());
+          if (aToken != bToken) {
+            return aToken < bToken ? -1 : 1;
+          }
+        } else {
+          // a has some extra trailing tokens. if these are all zeroes, thats ok.
+          if (aToken != 0) {
+            return 1; 
+          }
+        }
+      }
+      
+      // b has some extra trailing tokens. if these are all zeroes, thats ok.
+      while (bTokens.hasMoreTokens()) {
+        if (Integer.parseInt(bTokens.nextToken()) != 0)
+          return -1;
+      }
+      
+      return 0;
+    }
+  };
+}