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/**
* Copyright (C) 2009 Jesse Wilson
*
* 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.publicobject.io;

import java.io.RandomAccessFile;
import java.io.File;
import java.io.IOException;

/**
* Adapts a text file as a character sequence so that it can be directly manipulated by regular
* expressions and other character utilities. The file may be at most 2 GB in size and encoded with
* {@code ISO-8859-1}; otherwise behaviour is undefined.
*
* @author jessewilson@google.com (Jesse Wilson)
*/
public final class FileCharSequence implements CharSequence {

private final RandomAccessFile randomAccess;
private final long start;
private final long end;

public FileCharSequence(File file) throws IOException {
randomAccess = new RandomAccessFile(file, "r");
start = 0;
end = randomAccess.length();
}

private FileCharSequence(FileCharSequence prototype, long start, long end) {
this.randomAccess = prototype.randomAccess;
this.start = start;
this.end = end;
}

public int length() {
return (int) (end - start);
}

public char charAt(int index) {
try {
randomAccess.seek(start + index);
return (char) randomAccess.read();
} catch (IOException e) {
throw new RuntimeException(e);
}
}

public CharSequence subSequence(int start, int end) {
return new FileCharSequence(this, this.start + start, this.start + end);
}

public void close() throws IOException {
randomAccess.close();
}

@Override
public String toString() {
try {
byte[] bytes = new byte[length()];
randomAccess.seek(start);
randomAccess.readFully(bytes);
return new String(bytes, "ISO-8859-1");
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}

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Change log

r6 by limpbizkit on Apr 21, 2009   Diff
Whoops, a bug in the subsequence of a
subsequence.
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Older revisions

r3 by limpbizkit on Apr 21, 2009   Diff
Adapt a file to a string-like-thing.
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File info

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