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