Documentation

NativeEngine
in package
implements DiffEngineInterface

Class used internally by Horde_Text_Diff to actually compute the diffs.

This class is implemented using native PHP code.

The algorithm used here is mostly lifted from the perl module Algorithm::Diff (version 1.06) by Ned Konz, which is available at: http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip

More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html

Some ideas (and a bit of code) are taken from analyze.c, of GNU diffutils-2.7, which can be found at: ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz

Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from Geoffrey T. Dairiki dairiki@dairiki.org. The original PHP version of this code was written by him, and is used/adapted with his permission.

Copyright 2004-2017 Horde LLC (http://www.horde.org/)

See the enclosed file LICENSE for license information (LGPL). If you did not receive this file, see http://www.horde.org/licenses/lgpl21.

Tags
author

Geoffrey T. Dairiki dairiki@dairiki.org

Interfaces, Classes, Traits and Enums

DiffEngineInterface
Interface for Diff Engines

Table of Contents

$in_seq  : array<string|int, mixed>|null
$lcs  : int|null
$seq  : array<string|int, mixed>|null
$xchanged  : array<string|int, mixed>
$xind  : array<string|int, mixed>
$xv  : array<string|int, mixed>
$ychanged  : array<string|int, mixed>
$yind  : array<string|int, mixed>
$yv  : array<string|int, mixed>
$fromLines  : array<string|int, mixed>
$toLines  : array<string|int, mixed>
__construct()  : mixed
Constructor.
diff()  : OperationList
Returns the array of differences.
_compareseq()  : mixed
Finds LCS of two sequences.
_diag()  : mixed
Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments.
_lcsPos()  : mixed
_shiftBoundaries()  : mixed
Adjusts inserts/deletes of identical lines to join changes as much as possible.

Properties

$xchanged

protected array<string|int, mixed> $xchanged = []

$ychanged

protected array<string|int, mixed> $ychanged = []

Methods

__construct()

Constructor.

public __construct(array<string|int, string> $fromLines, array<string|int, string> $toLines) : mixed
Parameters
$fromLines : array<string|int, string>

lines of text from old file

$toLines : array<string|int, string>

lines of text from new file

Return values
mixed —

_compareseq()

Finds LCS of two sequences.

protected _compareseq(mixed $xoff, mixed $xlim, mixed $yoff, mixed $ylim) : mixed

The results are recorded in the vectors $this->{x,y}changed[], by storing a 1 in the element for each line that is an insertion or deletion (ie. is not in the LCS).

The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.

Note that XLIM, YLIM are exclusive bounds. All line numbers are origin-0 and discarded lines are not counted.

Parameters
$xoff : mixed
$xlim : mixed
$yoff : mixed
$ylim : mixed
Return values
mixed —

_diag()

Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments.

protected _diag(mixed $xoff, mixed $xlim, mixed $yoff, mixed $ylim, mixed $nchunks) : mixed

Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of NCHUNKS+1 (X, Y) indexes giving the diving points between sub sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1), the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) == (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).

This public function assumes that the first lines of the specified portions of the two files do not match, and likewise that the last lines do not match. The caller must trim matching lines from the beginning and end of the portions it is going to specify.

Parameters
$xoff : mixed
$xlim : mixed
$yoff : mixed
$ylim : mixed
$nchunks : mixed
Return values
mixed —

_lcsPos()

protected _lcsPos(mixed $ypos) : mixed
Parameters
$ypos : mixed
Return values
mixed —

_shiftBoundaries()

Adjusts inserts/deletes of identical lines to join changes as much as possible.

protected _shiftBoundaries(mixed $lines, mixed &$changed, mixed $other_changed) : mixed

We do something when a run of changed lines include a line at one end and has an excluded, identical line at the other. We are free to choose which identical line is included. `compareseq' usually chooses the one at the beginning, but usually it is cleaner to consider the following identical line to be the "change".

This is extracted verbatim from analyze.c (GNU diffutils-2.7).

Parameters
$lines : mixed
$changed : mixed
$other_changed : mixed
Return values
mixed —

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