pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / store / RAMInputStream.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/RAMInputStream.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/RAMInputStream.java
new file mode 100644 (file)
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--- /dev/null
+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/store/RAMInputStream.java
@@ -0,0 +1,148 @@
+package org.apache.lucene.store;
+
+/**
+ * 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 java.io.EOFException;
+
+/** A memory-resident {@link IndexInput} implementation. 
+ *  
+ *  @lucene.internal */
+public class RAMInputStream extends IndexInput implements Cloneable {
+  static final int BUFFER_SIZE = RAMOutputStream.BUFFER_SIZE;
+
+  private RAMFile file;
+  private long length;
+
+  private byte[] currentBuffer;
+  private int currentBufferIndex;
+  
+  private int bufferPosition;
+  private long bufferStart;
+  private int bufferLength;
+
+  /** Please pass String name */
+  @Deprecated
+  public RAMInputStream(RAMFile f) throws IOException {
+    this("anonymous", f);
+  }
+
+  public RAMInputStream(String name, RAMFile f) throws IOException {
+    super("RAMInputStream(name=" + name + ")");
+    file = f;
+    length = file.length;
+    if (length/BUFFER_SIZE >= Integer.MAX_VALUE) {
+      throw new IOException("RAMInputStream too large length=" + length + ": " + name); 
+    }
+
+    // make sure that we switch to the
+    // first needed buffer lazily
+    currentBufferIndex = -1;
+    currentBuffer = null;
+  }
+
+  @Override
+  public void close() {
+    // nothing to do here
+  }
+
+  @Override
+  public long length() {
+    return length;
+  }
+
+  @Override
+  public byte readByte() throws IOException {
+    if (bufferPosition >= bufferLength) {
+      currentBufferIndex++;
+      switchCurrentBuffer(true);
+    }
+    return currentBuffer[bufferPosition++];
+  }
+
+  @Override
+  public void readBytes(byte[] b, int offset, int len) throws IOException {
+    while (len > 0) {
+      if (bufferPosition >= bufferLength) {
+        currentBufferIndex++;
+        switchCurrentBuffer(true);
+      }
+
+      int remainInBuffer = bufferLength - bufferPosition;
+      int bytesToCopy = len < remainInBuffer ? len : remainInBuffer;
+      System.arraycopy(currentBuffer, bufferPosition, b, offset, bytesToCopy);
+      offset += bytesToCopy;
+      len -= bytesToCopy;
+      bufferPosition += bytesToCopy;
+    }
+  }
+
+  private final void switchCurrentBuffer(boolean enforceEOF) throws IOException {
+    bufferStart = (long) BUFFER_SIZE * (long) currentBufferIndex;
+    if (currentBufferIndex >= file.numBuffers()) {
+      // end of file reached, no more buffers left
+      if (enforceEOF) {
+        throw new EOFException("Read past EOF (resource: " + this + ")");
+      } else {
+        // Force EOF if a read takes place at this position
+        currentBufferIndex--;
+        bufferPosition = BUFFER_SIZE;
+      }
+    } else {
+      currentBuffer = file.getBuffer(currentBufferIndex);
+      bufferPosition = 0;
+      long buflen = length - bufferStart;
+      bufferLength = buflen > BUFFER_SIZE ? BUFFER_SIZE : (int) buflen;
+    }
+  }
+
+  @Override
+  public void copyBytes(IndexOutput out, long numBytes) throws IOException {
+    assert numBytes >= 0: "numBytes=" + numBytes;
+    
+    long left = numBytes;
+    while (left > 0) {
+      if (bufferPosition == bufferLength) {
+        ++currentBufferIndex;
+        switchCurrentBuffer(true);
+      }
+      
+      final int bytesInBuffer = bufferLength - bufferPosition;
+      final int toCopy = (int) (bytesInBuffer < left ? bytesInBuffer : left);
+      out.writeBytes(currentBuffer, bufferPosition, toCopy);
+      bufferPosition += toCopy;
+      left -= toCopy;
+    }
+    
+    assert left == 0: "Insufficient bytes to copy: numBytes=" + numBytes + " copied=" + (numBytes - left);
+  }
+  
+  @Override
+  public long getFilePointer() {
+    return currentBufferIndex < 0 ? 0 : bufferStart + bufferPosition;
+  }
+
+  @Override
+  public void seek(long pos) throws IOException {
+    if (currentBuffer==null || pos < bufferStart || pos >= bufferStart + BUFFER_SIZE) {
+      currentBufferIndex = (int) (pos / BUFFER_SIZE);
+      switchCurrentBuffer(false);
+    }
+    bufferPosition = (int) (pos % BUFFER_SIZE);
+  }
+}