pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/regex/JakartaRegexpCapabilities.java b/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/regex/JakartaRegexpCapabilities.java
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+++ b/lucene-java-3.5.0/lucene/contrib/queries/src/java/org/apache/lucene/search/regex/JakartaRegexpCapabilities.java
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+package org.apache.lucene.search.regex;
+
+/**
+ * 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 org.apache.regexp.RE;
+import org.apache.regexp.REProgram;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+/**
+ * Implementation tying <a href="http://jakarta.apache.org/regexp">Jakarta
+ * Regexp</a> to RegexQuery. Jakarta Regepx internally supports a
+ * {@link #prefix} implementation which can offer performance gains under
+ * certain circumstances. Yet, the implementation appears to be rather shaky as
+ * it doesn't always provide a prefix even if one would exist.
+ */
+public class JakartaRegexpCapabilities implements RegexCapabilities {
+  private RE regexp;
+
+  private static Field prefixField;
+  private static Method getPrefixMethod;
+  static {
+    try {
+      getPrefixMethod = REProgram.class.getMethod("getPrefix");
+    } catch (Exception e) {
+      getPrefixMethod = null;
+    }
+    try {
+      prefixField = REProgram.class.getDeclaredField("prefix");
+      prefixField.setAccessible(true);
+    } catch (Exception e) {
+      prefixField = null;
+    }
+  }
+  
+  // Define the flags that are possible. Redefine them here
+  // to avoid exposing the RE class to the caller.
+  
+  private int flags = RE.MATCH_NORMAL;
+
+  /**
+   * Flag to specify normal, case-sensitive matching behaviour. This is the default.
+   */
+  public static final int FLAG_MATCH_NORMAL = RE.MATCH_NORMAL;
+  
+  /**
+   * Flag to specify that matching should be case-independent (folded)
+   */
+  public static final int FLAG_MATCH_CASEINDEPENDENT = RE.MATCH_CASEINDEPENDENT;
+ 
+  /**
+   * Constructs a RegexCapabilities with the default MATCH_NORMAL match style.
+   */
+  public JakartaRegexpCapabilities() {}
+  
+  /**
+   * Constructs a RegexCapabilities with the provided match flags.
+   * Multiple flags should be ORed together.
+   * 
+   * @param flags The matching style
+   */
+  public JakartaRegexpCapabilities(int flags)
+  {
+    this.flags = flags;
+  }
+  
+  public void compile(String pattern) {
+    regexp = new RE(pattern, this.flags);
+  }
+
+  public boolean match(String string) {
+    return regexp.match(string);
+  }
+
+  public String prefix() {
+    try {
+      final char[] prefix;
+      if (getPrefixMethod != null) {
+        prefix = (char[]) getPrefixMethod.invoke(regexp.getProgram());
+      } else if (prefixField != null) {
+        prefix = (char[]) prefixField.get(regexp.getProgram());
+      } else {
+        return null;
+      }
+      return prefix == null ? null : new String(prefix);
+    } catch (Exception e) {
+      // if we cannot get the prefix, return none
+      return null;
+    }
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+
+    final JakartaRegexpCapabilities that = (JakartaRegexpCapabilities) o;
+
+    if (regexp != null ? !regexp.equals(that.regexp) : that.regexp != null) return false;
+
+    return true;
+  }
+
+  @Override
+  public int hashCode() {
+    return (regexp != null ? regexp.hashCode() : 0);
+  }
+}