pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/fst/ByteSequenceOutputs.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/fst/ByteSequenceOutputs.java
new file mode 100644 (file)
index 0000000..8969090
--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/fst/ByteSequenceOutputs.java
@@ -0,0 +1,138 @@
+package org.apache.lucene.util.fst;
+
+/**
+ * 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.store.DataInput;
+import org.apache.lucene.store.DataOutput;
+import org.apache.lucene.util.BytesRef;
+
+/**
+ * Output is a sequence of bytes, for each input term.
+ *
+ * @lucene.experimental
+ */
+
+public final class ByteSequenceOutputs extends Outputs<BytesRef> {
+
+  private final static BytesRef NO_OUTPUT = new BytesRef();
+
+  private ByteSequenceOutputs() {
+  }
+
+  public static ByteSequenceOutputs getSingleton() {
+    return new ByteSequenceOutputs();
+  }
+
+  @Override
+  public BytesRef common(BytesRef output1, BytesRef output2) {
+    assert output1 != null;
+    assert output2 != null;
+
+    int pos1 = output1.offset;
+    int pos2 = output2.offset;
+    int stopAt1 = pos1 + Math.min(output1.length, output2.length);
+    while(pos1 < stopAt1) {
+      if (output1.bytes[pos1] != output2.bytes[pos2]) {
+        break;
+      }
+      pos1++;
+      pos2++;
+    }
+
+    if (pos1 == output1.offset) {
+      // no common prefix
+      return NO_OUTPUT;
+    } else if (pos1 == output1.offset + output1.length) {
+      // output1 is a prefix of output2
+      return output1;
+    } else if (pos2 == output2.offset + output2.length) {
+      // output2 is a prefix of output1
+      return output2;
+    } else {
+      return new BytesRef(output1.bytes, output1.offset, pos1-output1.offset);
+    }
+  }
+
+  @Override
+  public BytesRef subtract(BytesRef output, BytesRef inc) {
+    assert output != null;
+    assert inc != null;
+    if (inc == NO_OUTPUT) {
+      // no prefix removed
+      return output;
+    } else if (inc.length == output.length) {
+      // entire output removed
+      return NO_OUTPUT;
+    } else {
+      assert inc.length < output.length: "inc.length=" + inc.length + " vs output.length=" + output.length;
+      assert inc.length > 0;
+      return new BytesRef(output.bytes, output.offset + inc.length, output.length-inc.length);
+    }
+  }
+
+  @Override
+  public BytesRef add(BytesRef prefix, BytesRef output) {
+    assert prefix != null;
+    assert output != null;
+    if (prefix == NO_OUTPUT) {
+      return output;
+    } else if (output == NO_OUTPUT) {
+      return prefix;
+    } else {
+      assert prefix.length > 0;
+      assert output.length > 0;
+      BytesRef result = new BytesRef(prefix.length + output.length);
+      System.arraycopy(prefix.bytes, prefix.offset, result.bytes, 0, prefix.length);
+      System.arraycopy(output.bytes, output.offset, result.bytes, prefix.length, output.length);
+      result.length = prefix.length + output.length;
+      return result;
+    }
+  }
+
+  @Override
+  public void write(BytesRef prefix, DataOutput out) throws IOException {
+    assert prefix != null;
+    out.writeVInt(prefix.length);
+    out.writeBytes(prefix.bytes, prefix.offset, prefix.length);
+  }
+
+  @Override
+  public BytesRef read(DataInput in) throws IOException {
+    final int len = in.readVInt();
+    if (len == 0) {
+      return NO_OUTPUT;
+    } else {
+      final BytesRef output = new BytesRef(len);
+      in.readBytes(output.bytes, 0, len);
+      output.length = len;
+      return output;
+    }
+  }
+
+  @Override
+  public BytesRef getNoOutput() {
+    return NO_OUTPUT;
+  }
+
+  @Override
+  public String outputToString(BytesRef output) {
+    return output.utf8ToString();
+  }
+}