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package org.apache.lucene.queryParser;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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/** An efficient implementation of JavaCC's CharStream interface. <p>Note that
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* this does not do line-number counting, but instead keeps track of the
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* character position of the token in the input, as required by Lucene's {@link
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* org.apache.lucene.analysis.Token} API.
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public final class FastCharStream implements CharStream {
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int bufferLength = 0; // end of valid chars
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int bufferPosition = 0; // next char to read
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int tokenStart = 0; // offset in buffer
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int bufferStart = 0; // position in file of buffer
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Reader input; // source of chars
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/** Constructs from a Reader. */
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public FastCharStream(Reader r) {
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public final char readChar() throws IOException {
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if (bufferPosition >= bufferLength)
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return buffer[bufferPosition++];
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private final void refill() throws IOException {
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int newPosition = bufferLength - tokenStart;
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if (tokenStart == 0) { // token won't fit in buffer
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if (buffer == null) { // first time: alloc buffer
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buffer = new char[2048];
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} else if (bufferLength == buffer.length) { // grow buffer
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char[] newBuffer = new char[buffer.length*2];
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System.arraycopy(buffer, 0, newBuffer, 0, bufferLength);
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} else { // shift token to front
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System.arraycopy(buffer, tokenStart, buffer, 0, newPosition);
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bufferLength = newPosition; // update state
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bufferPosition = newPosition;
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bufferStart += tokenStart;
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int charsRead = // fill space in buffer
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input.read(buffer, newPosition, buffer.length-newPosition);
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throw new IOException("read past eof");
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bufferLength += charsRead;
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public final char BeginToken() throws IOException {
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tokenStart = bufferPosition;
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public final void backup(int amount) {
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bufferPosition -= amount;
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public final String GetImage() {
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return new String(buffer, tokenStart, bufferPosition - tokenStart);
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public final char[] GetSuffix(int len) {
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char[] value = new char[len];
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System.arraycopy(buffer, bufferPosition - len, value, 0, len);
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public final void Done() {
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} catch (IOException e) {
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System.err.println("Caught: " + e + "; ignoring.");
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public final int getColumn() {
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return bufferStart + bufferPosition;
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public final int getLine() {
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public final int getEndColumn() {
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return bufferStart + bufferPosition;
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public final int getEndLine() {
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public final int getBeginColumn() {
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return bufferStart + tokenStart;
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public final int getBeginLine() {