pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/CodecUtil.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/CodecUtil.java
new file mode 100644 (file)
index 0000000..d5b5452
--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/CodecUtil.java
@@ -0,0 +1,79 @@
+package org.apache.lucene.util;
+
+/**
+ * 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.CorruptIndexException;
+import org.apache.lucene.index.IndexFormatTooNewException;
+import org.apache.lucene.index.IndexFormatTooOldException;
+import org.apache.lucene.store.DataInput;
+import org.apache.lucene.store.DataOutput;
+
+/**
+ * @lucene.experimental
+ */
+
+public final class CodecUtil {
+  private CodecUtil() {} // no instance
+
+  private final static int CODEC_MAGIC = 0x3fd76c17;
+
+  public static DataOutput writeHeader(DataOutput out, String codec, int version)
+    throws IOException {
+    BytesRef bytes = new BytesRef(codec);
+    if (bytes.length != codec.length() || bytes.length >= 128) {
+      throw new IllegalArgumentException("codec must be simple ASCII, less than 128 characters in length [got " + codec + "]");
+    }
+    out.writeInt(CODEC_MAGIC);
+    out.writeString(codec);
+    out.writeInt(version);
+
+    return out;
+  }
+
+  public static int headerLength(String codec) {
+    return 9+codec.length();
+  }
+
+  public static int checkHeader(DataInput in, String codec, int minVersion, int maxVersion)
+    throws IOException {
+
+    // Safety to guard against reading a bogus string:
+    final int actualHeader = in.readInt();
+    if (actualHeader != CODEC_MAGIC) {
+      throw new CorruptIndexException("codec header mismatch: actual header=" + actualHeader + " vs expected header=" + CODEC_MAGIC + " (resource: " + in + ")");
+    }
+
+    final String actualCodec = in.readString();
+    if (!actualCodec.equals(codec)) {
+      throw new CorruptIndexException("codec mismatch: actual codec=" + actualCodec + " vs expected codec=" + codec + " (resource: " + in + ")");
+    }
+
+    final int actualVersion = in.readInt();
+    if (actualVersion < minVersion) {
+      throw new IndexFormatTooOldException(in, actualVersion, minVersion, maxVersion);
+    }
+    if (actualVersion > maxVersion) {
+      throw new IndexFormatTooNewException(in, actualVersion, minVersion, maxVersion);
+    }
+
+    return actualVersion;
+  }
+}