RetroZilla/gc/boehm/leaksoup/FileTable.java

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2015-10-21 05:03:22 +02:00
/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* The contents of this file are subject to the Netscape Public
* License Version 1.1 (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.mozilla.org/NPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is Mozilla Communicator client code, released
* March 31, 1998.
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Patrick C. Beard <beard@netscape.com>
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU Public License (the "GPL"), in which case the
* provisions of the GPL are applicable instead of those above.
* If you wish to allow use of your version of this file only
* under the terms of the GPL and not to allow others to use your
* version of this file under the NPL, indicate your decision by
* deleting the provisions above and replace them with the notice
* and other provisions required by the GPL. If you do not delete
* the provisions above, a recipient may use your version of this
* file under either the NPL or the GPL.
*/
import java.io.*;
import java.util.*;
/**
* Provides a way to map from byte offsets into a file to line numbers.
*/
public class FileTable {
private static class Line {
int mOffset;
int mLength;
Line(int offset, int length) {
mOffset = offset;
mLength = length;
}
}
private Line[] mLines;
public FileTable(String path) throws IOException {
Vector lines = new Vector();
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(path)));
int offset = 0;
for (String line = reader.readLine(); line != null; line = reader.readLine()) {
// always add 1 for the line feed.
int length = 1 + line.length();
lines.addElement(new Line(offset, length));
offset += length;
}
reader.close();
int size = lines.size();
mLines = new Line[size];
lines.copyInto(mLines);
}
public int getLine(int offset) {
// use binary search to find the line which spans this offset.
int length = mLines.length;
int minIndex = 0, maxIndex = length - 1;
int index = maxIndex / 2;
while (minIndex <= maxIndex) {
Line line = mLines[index];
if (offset < line.mOffset) {
maxIndex = (index - 1);
index = (minIndex + maxIndex) / 2;
} else {
if (offset < (line.mOffset + line.mLength)) {
return index;
}
minIndex = (index + 1);
index = (minIndex + maxIndex) / 2;
}
}
// this case shouldn't happen, but provides a helpful value to detect errors.
return -1;
}
}