pylucene 3.5.0-3

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

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/packed/PackedWriter.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/packed/PackedWriter.java
new file mode 100644 (file)
index 0000000..92e3615
--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/util/packed/PackedWriter.java
@@ -0,0 +1,114 @@
+package org.apache.lucene.util.packed;
+
+/**
+ * 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.lucene.store.DataOutput;
+
+import java.io.IOException;
+
+// Packs high order byte first, to match
+// IndexOutput.writeInt/Long/Short byte order
+
+/**
+ * Generic writer for space-optimal packed values. The resulting bits can be
+ * used directly by Packed32, Packed64 and PackedDirect* and will always be
+ * long-aligned.
+ */
+
+class PackedWriter extends PackedInts.Writer {
+  private long pending;
+  private int pendingBitPos;
+
+  // masks[n-1] masks for bottom n bits
+  private final long[] masks;
+  private int written = 0;
+
+  public PackedWriter(DataOutput out, int valueCount, int bitsPerValue)
+                                                            throws IOException {
+    super(out, valueCount, bitsPerValue);
+
+    pendingBitPos = 64;
+    masks = new long[bitsPerValue - 1];
+
+    long v = 1;
+    for (int i = 0; i < bitsPerValue - 1; i++) {
+      v *= 2;
+      masks[i] = v - 1;
+    }
+  }
+
+  /**
+   * Do not call this after finish
+   */
+  @Override
+  public void add(long v) throws IOException {
+    assert v <= PackedInts.maxValue(bitsPerValue) : "v=" + v
+            + " maxValue=" + PackedInts.maxValue(bitsPerValue);
+    assert v >= 0;
+    //System.out.println("    packedw add v=" + v + " pendingBitPos=" + pendingBitPos);
+
+    // TODO
+    if (pendingBitPos >= bitsPerValue) {
+      // not split
+
+      // write-once, so we can |= w/o first masking to 0s
+      pending |= v << (pendingBitPos - bitsPerValue);
+      if (pendingBitPos == bitsPerValue) {
+        // flush
+        out.writeLong(pending);
+        pending = 0;
+        pendingBitPos = 64;
+      } else {
+        pendingBitPos -= bitsPerValue;
+      }
+
+    } else {
+      // split
+
+      // write top pendingBitPos bits of value into bottom bits of pending
+      pending |= (v >> (bitsPerValue - pendingBitPos)) & masks[pendingBitPos - 1];
+      //System.out.println("      part1 (v >> " + (bitsPerValue - pendingBitPos) + ") & " + masks[pendingBitPos-1]);
+
+      // flush
+      out.writeLong(pending);
+
+      // write bottom (bitsPerValue - pendingBitPos) bits of value into top bits of pending
+      pendingBitPos = 64 - bitsPerValue + pendingBitPos;
+      //System.out.println("      part2 v << " + pendingBitPos);
+      pending = (v << pendingBitPos);
+    }
+    written++;
+  }
+
+  @Override
+  public void finish() throws IOException {
+    while (written < valueCount) {
+      add(0L); // Auto flush
+    }
+
+    if (pendingBitPos != 64) {
+      out.writeLong(pending);
+    }
+  }
+
+  @Override
+  public String toString() {
+    return "PackedWriter(written " + written + "/" + valueCount + " with "
+            + bitsPerValue + " bits/value)";
+  }
+}