/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed 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 com.sun.org.apache.regexp.internal;
import java.io.Reader;
import java.io.IOException;
/**
* Encapsulates java.io.Reader as CharacterIterator
*
* @author <a href="mailto:ales.novak@netbeans.com">Ales Novak</a>
*/
public final class ReaderCharacterIterator implements CharacterIterator
{
/** Underlying reader */
private final Reader reader;
/** Buffer of read chars */
private final StringBuffer buff;
/** read end? */
private boolean closed;
/** @param reader a Reader, which is parsed */
public ReaderCharacterIterator(Reader reader)
{
this.reader = reader;
this.buff = new StringBuffer(512);
this.closed = false;
}
/** @return a substring */
public String substring(int beginIndex, int endIndex)
{
try
{
ensure(endIndex);
return buff.toString().substring(beginIndex, endIndex);
}
catch (IOException e)
{
throw new StringIndexOutOfBoundsException(e.getMessage());
}
}
/** @return a substring */
public String substring(int beginIndex)
{
try
{
readAll();
return buff.toString().substring(beginIndex);
}
catch (IOException e)
{
throw new StringIndexOutOfBoundsException(e.getMessage());
}
}
/** @return a character at the specified position. */
public char charAt(int pos)
{
try
{
ensure(pos);
return buff.charAt(pos);
}
catch (IOException e)
{
throw new StringIndexOutOfBoundsException(e.getMessage());
}
}
/** @return <tt>true</tt> iff if the specified index is after the end of the character stream */
public boolean isEnd(int pos)
{
if (buff.length() > pos)
{
return false;
}
else
{
try
{
ensure(pos);
return (buff.length() <= pos);
}
catch (IOException e)
{
throw new StringIndexOutOfBoundsException(e.getMessage());
}
}
}
/** Reads n characters from the stream and appends them to the buffer */
private int read(int n) throws IOException
{
if (closed)
{
return 0;
}
char[] c = new char[n];
int count = 0;
int read = 0;
do
{
read = reader.read(c);
if (read < 0) // EOF
{
closed = true;
break;
}
count += read;
buff.append(c, 0, read);
}
while (count < n);
return count;
}
/** Reads rest of the stream. */
private void readAll() throws IOException
{
while(! closed)
{
read(1000);
}
}
/** Reads chars up to the idx */
private void ensure(int idx) throws IOException
{
if (closed)
{
return;
}
if (idx < buff.length())
{
return;
}
read(idx + 1 - buff.length());
}
}