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/*
 * 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.
 *
 */
package org.codehaus.groovy.util;

import java.io.Reader;
import java.io.Serializable;

/**
 * {@link Reader} implementation that can read from String, StringBuffer,
 * StringBuilder, CharBuffer or GString.
 * 

* Note: Supports {@link #mark(int)} and {@link #reset()}. *

* Note: This class is mostly a copy from Commons IO and * is intended for internal Groovy usage only. It may be deprecated and * removed from Groovy at a faster pace than other classes. If you need this * functionality in your Groovy programs, we recommend using the Commons IO * equivalent directly. */ public class CharSequenceReader extends Reader implements Serializable { private static final long serialVersionUID = -6661279371843310693L; private final CharSequence charSequence; private int idx; private int mark; private static final int EOF = -1; /** * Construct a new instance with the specified character sequence. * * @param charSequence The character sequence, may be {@code null} */ public CharSequenceReader(final CharSequence charSequence) { this.charSequence = charSequence != null ? charSequence : ""; } /** * Close resets the reader back to the start and removes any marked position. */ @Override public void close() { idx = 0; mark = 0; } /** * Mark the current position. * * @param readAheadLimit ignored */ @Override public void mark(final int readAheadLimit) { mark = idx; } /** * Mark is supported (returns true). * * @return {@code true} */ @Override public boolean markSupported() { return true; } /** * Read a single character. * * @return the next character from the character sequence * or -1 if the end has been reached. */ @Override public int read() { if (idx >= charSequence.length()) { return EOF; } else { return charSequence.charAt(idx++); } } /** * Read the sepcified number of characters into the array. * * @param array The array to store the characters in * @param offset The starting position in the array to store * @param length The maximum number of characters to read * @return The number of characters read or -1 if there are * no more */ @Override public int read(final char[] array, final int offset, final int length) { if (idx >= charSequence.length()) { return EOF; } if (array == null) { throw new NullPointerException("Character array is missing"); } if (length < 0 || offset < 0 || offset + length > array.length) { throw new IndexOutOfBoundsException("Array Size=" + array.length + ", offset=" + offset + ", length=" + length); } int count = 0; for (int i = 0; i < length; i++) { final int c = read(); if (c == EOF) { return count; } array[offset + i] = (char)c; count++; } return count; } /** * Reset the reader to the last marked position (or the beginning if * mark has not been called). */ @Override public void reset() { idx = mark; } /** * Skip the specified number of characters. * * @param n The number of characters to skip * @return The actual number of characters skipped */ @Override public long skip(final long n) { if (n < 0) { throw new IllegalArgumentException( "Number of characters to skip is less than zero: " + n); } if (idx >= charSequence.length()) { return EOF; } final int dest = (int)Math.min(charSequence.length(), idx + n); final int count = dest - idx; idx = dest; return count; } /** * Return a String representation of the underlying * character sequence. * * @return The contents of the character sequence */ @Override public String toString() { return charSequence.toString(); } }





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