org.apache.commons.io.input.CharSequenceReader Maven / Gradle / Ivy
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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.apache.commons.io.input;
import static org.apache.commons.io.IOUtils.EOF;
import java.io.Reader;
import java.io.Serializable;
/**
* {@link Reader} implementation that can read from String, StringBuffer,
* StringBuilder or CharBuffer.
*
* Note: Supports {@link #mark(int)} and {@link #reset()}.
*
* @since 1.4
*/
public class CharSequenceReader extends Reader implements Serializable {
private static final long serialVersionUID = 3724187752191401220L;
private final CharSequence charSequence;
private int idx;
private int mark;
/**
* 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 file 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;
}
return charSequence.charAt(idx++);
}
/**
* Read the specified 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();
}
}