// FastCharStream.javapackage 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;  }}