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/*
* Copyright (C) 2009, Google Inc.
* Copyright (C) 2008-2009, Johannes E. Schindelin <johannes.schindelin@gmx.de>
* and other copyright owners as documented in the project's IP log.
*
* This program and the accompanying materials are made available
* under the terms of the Eclipse Distribution License v1.0 which
* accompanies this distribution, is reproduced below, and is
* available at http://www.eclipse.org/org/documents/edl-v10.php
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* - Neither the name of the Eclipse Foundation, Inc. nor the
* names of its contributors may be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.eclipse.jgit.diff;
import java.io.IOException;
import java.io.OutputStream;
import org.eclipse.jgit.util.IntList;
import org.eclipse.jgit.util.RawParseUtils;
/**
* A Sequence supporting UNIX formatted text in byte[] format.
* <p>
* Elements of the sequence are the lines of the file, as delimited by the UNIX
* newline character ('\n'). The file content is treated as 8 bit binary text,
* with no assumptions or requirements on character encoding.
* <p>
* Note that the first line of the file is element 0, as defined by the Sequence
* interface API. Traditionally in a text editor a patch file the first line is
* line number 1. Callers may need to subtract 1 prior to invoking methods if
* they are converting from "line number" to "element index".
*/
public class RawText implements Sequence {
/** The file content for this sequence. */
protected final byte[] content;
/** Map of line number to starting position within {@link #content}. */
protected final IntList lines;
/** Hash code for each line, for fast equality elimination. */
protected final IntList hashes;
/**
* Create a new sequence from an existing content byte array.
* <p>
* The entire array (indexes 0 through length-1) is used as the content.
*
* @param input
* the content array. The array is never modified, so passing
* through cached arrays is safe.
*/
public RawText(final byte[] input) {
content = input;
lines = RawParseUtils.lineMap(content, 0, content.length);
hashes = computeHashes();
}
public int size() {
// The line map is always 2 entries larger than the number of lines in
// the file. Index 0 is padded out/unused. The last index is the total
// length of the buffer, and acts as a sentinel.
//
return lines.size() - 2;
}
public boolean equals(final int i, final Sequence other, final int j) {
return equals(this, i + 1, (RawText) other, j + 1);
}
private static boolean equals(final RawText a, final int ai,
final RawText b, final int bi) {
if (a.hashes.get(ai) != b.hashes.get(bi))
return false;
int as = a.lines.get(ai);
int bs = b.lines.get(bi);
final int ae = a.lines.get(ai + 1);
final int be = b.lines.get(bi + 1);
if (ae - as != be - bs)
return false;
while (as < ae) {
if (a.content[as++] != b.content[bs++])
return false;
}
return true;
}
/**
* Write a specific line to the output stream, without its trailing LF.
* <p>
* The specified line is copied as-is, with no character encoding
* translation performed.
* <p>
* If the specified line ends with an LF ('\n'), the LF is <b>not</b>
* copied. It is up to the caller to write the LF, if desired, between
* output lines.
*
* @param out
* stream to copy the line data onto.
* @param i
* index of the line to extract. Note this is 0-based, so line
* number 1 is actually index 0.
* @throws IOException
* the stream write operation failed.
*/
public void writeLine(final OutputStream out, final int i)
throws IOException {
final int start = lines.get(i + 1);
int end = lines.get(i + 2);
if (content[end - 1] == '\n')
end--;
out.write(content, start, end - start);
}
/**
* Determine if the file ends with a LF ('\n').
*
* @return true if the last line has an LF; false otherwise.
*/
public boolean isMissingNewlineAtEnd() {
final int end = lines.get(lines.size() - 1);
if (end == 0)
return true;
return content[end - 1] != '\n';
}
private IntList computeHashes() {
final IntList r = new IntList(lines.size());
r.add(0);
for (int lno = 1; lno < lines.size() - 1; lno++) {
final int ptr = lines.get(lno);
final int end = lines.get(lno + 1);
r.add(hashLine(content, ptr, end));
}
r.add(0);
return r;
}
/**
* Compute a hash code for a single line.
*
* @param raw
* the raw file content.
* @param ptr
* first byte of the content line to hash.
* @param end
* 1 past the last byte of the content line.
* @return hash code for the region <code>[ptr, end)</code> of raw.
*/
protected int hashLine(final byte[] raw, int ptr, final int end) {
int hash = 5381;
for (; ptr < end; ptr++)
hash = (hash << 5) ^ (raw[ptr] & 0xff);
return hash;
}
}
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