pylucene 3.5.0-3

[pylucene.git] / lucene-java-3.5.0 / lucene / src / java / org / apache / lucene / queryParser / FastCharStream.java

diff --git a/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/queryParser/FastCharStream.java b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/queryParser/FastCharStream.java
new file mode 100644 (file)
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+++ b/lucene-java-3.5.0/lucene/src/java/org/apache/lucene/queryParser/FastCharStream.java
@@ -0,0 +1,124 @@
+// FastCharStream.java
+package org.apache.lucene.queryParser;
+
+/**
+ * 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.*;
+
+/** An efficient implementation of JavaCC's CharStream interface.  <p>Note that
+ * this does not do line-number counting, but instead keeps track of the
+ * character position of the token in the input, as required by Lucene's {@link
+ * org.apache.lucene.analysis.Token} API. 
+ * */
+public final class FastCharStream implements CharStream {
+  char[] buffer = null;
+
+  int bufferLength = 0;                                  // end of valid chars
+  int bufferPosition = 0;                        // next char to read
+
+  int tokenStart = 0;                            // offset in buffer
+  int bufferStart = 0;                           // position in file of buffer
+
+  Reader input;                                          // source of chars
+
+  /** Constructs from a Reader. */
+  public FastCharStream(Reader r) {
+    input = r;
+  }
+
+  public final char readChar() throws IOException {
+    if (bufferPosition >= bufferLength)
+      refill();
+    return buffer[bufferPosition++];
+  }
+
+  private final void refill() throws IOException {
+    int newPosition = bufferLength - tokenStart;
+
+    if (tokenStart == 0) {                       // token won't fit in buffer
+      if (buffer == null) {                      // first time: alloc buffer
+       buffer = new char[2048];
+      } else if (bufferLength == buffer.length) { // grow buffer
+       char[] newBuffer = new char[buffer.length*2];
+       System.arraycopy(buffer, 0, newBuffer, 0, bufferLength);
+       buffer = newBuffer;
+      }
+    } else {                                     // shift token to front
+      System.arraycopy(buffer, tokenStart, buffer, 0, newPosition);
+    }
+
+    bufferLength = newPosition;                          // update state
+    bufferPosition = newPosition;
+    bufferStart += tokenStart;
+    tokenStart = 0;
+
+    int charsRead =                              // fill space in buffer
+      input.read(buffer, newPosition, buffer.length-newPosition);
+    if (charsRead == -1)
+      throw new IOException("read past eof");
+    else
+      bufferLength += charsRead;
+  }
+
+  public final char BeginToken() throws IOException {
+    tokenStart = bufferPosition;
+    return readChar();
+  }
+
+  public final void backup(int amount) {
+    bufferPosition -= amount;
+  }
+
+  public final String GetImage() {
+    return new String(buffer, tokenStart, bufferPosition - tokenStart);
+  }
+
+  public final char[] GetSuffix(int len) {
+    char[] value = new char[len];
+    System.arraycopy(buffer, bufferPosition - len, value, 0, len);
+    return value;
+  }
+
+  public final void Done() {
+    try {
+      input.close();
+    } catch (IOException e) {
+      System.err.println("Caught: " + e + "; ignoring.");
+    }
+  }
+
+  public final int getColumn() {
+    return bufferStart + bufferPosition;
+  }
+  public final int getLine() {
+    return 1;
+  }
+  public final int getEndColumn() {
+    return bufferStart + bufferPosition;
+  }
+  public final int getEndLine() {
+    return 1;
+  }
+  public final int getBeginColumn() {
+    return bufferStart + tokenStart;
+  }
+  public final int getBeginLine() {
+    return 1;
+  }
+}