DiffEngine Class Reference

This diff implementation is mainly lifted from the LCS algorithm of the Eclipse project which in turn is based on Myers' "An O(ND) difference algorithm and its variations" (http://citeseer.ist.psu.edu/myers86ond.html) with range compression (see Wu et al. More...

Public Member Functions
	__construct ( $tooLong=2000000, $powLimit=1.45)
	diff ( $from_lines, $to_lines)
	Performs diff. More...
	diff_range ( $from_lines, $to_lines)
	getLcsLength ()
	setBailoutComplexity ( $value)
	Sets the complexity (in comparison operations) that can't be exceeded. More...

Public Attributes
	$added
	$heuristicUsed
	$length
	$removed

Protected Member Functions
	diffInternal (array $from, array $to)

Protected Attributes
	$bailoutComplexity = 0

Private Member Functions
	find_middle_snake ( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake)
	lcs_rec ( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake)
	shiftBoundaries (array $lines, array &$changed, array $other_changed)
	Adjust inserts/deletes of identical lines to join changes as much as possible. More...

Static Private Member Functions
static	findMostProgress ( $M, $N, $limit, $V)

Private Attributes
string[]	$from
	$lcsLengthCorrectedForHeuristic = false
	$m
	$maxDifferences
	$n
	$powLimit
string[]	$to
	$tooLong

Detailed Description

This diff implementation is mainly lifted from the LCS algorithm of the Eclipse project which in turn is based on Myers' "An O(ND) difference algorithm and its variations" (http://citeseer.ist.psu.edu/myers86ond.html) with range compression (see Wu et al.

's "An O(NP) Sequence Comparison Algorithm").

This implementation supports an upper bound on the execution time.

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

Complexity: O((M + N)D) worst case time, O(M + N + D^2) expected time, O(M + N) space

Author

Guy Van den Broeck, Geoffrey T. Dairiki, Tim Starling

Definition at line 47 of file DiffEngine.php.

Constructor & Destructor Documentation

__construct()

DiffEngine::__construct	(		$tooLong = 2000000,
			$powLimit = 1.45
	)

Definition at line 72 of file DiffEngine.php.

References $powLimit, and $tooLong.

Member Function Documentation

diff()

DiffEngine::diff	(		$from_lines,
			$to_lines
	)

Performs diff.

Parameters

string[]	$from_lines
string[]	$to_lines

Exceptions

ComplexityException

Returns

DiffOp[]

Definition at line 86 of file DiffEngine.php.

References diffInternal(), and shiftBoundaries().

Referenced by diff_range().

diff_range()

DiffEngine::diff_range	(		$from_lines,
			$to_lines
	)

Definition at line 415 of file DiffEngine.php.

References $ranges, diff(), and n.

diffInternal()

DiffEngine::diffInternal ( array  $from, array  $to  )

protected

Parameters

string[]	$from
string[]	$to

Exceptions

ComplexityException

Definition at line 286 of file DiffEngine.php.

References $added, $from, $m, $n, $removed, $to, lcs_rec(), n, and wfDebug().

Referenced by diff().

find_middle_snake()

DiffEngine::find_middle_snake (   $bottoml1,   $topl1,   $bottoml2,   $topl2, &  $V, &  $snake  )

private

Definition at line 492 of file DiffEngine.php.

References $from, $to, findMostProgress(), and wfDebug().

Referenced by lcs_rec().

findMostProgress()

static DiffEngine::findMostProgress (   $M,   $N,   $limit,   $V  )

staticprivate

Definition at line 716 of file DiffEngine.php.

Referenced by find_middle_snake().

getLcsLength()

DiffEngine::getLcsLength

(

)

Returns

mixed

Definition at line 798 of file DiffEngine.php.

References $length.

lcs_rec()

DiffEngine::lcs_rec (   $bottoml1,   $topl1,   $bottoml2,   $topl2, &  $V, &  $snake  )

private

Definition at line 450 of file DiffEngine.php.

References find_middle_snake().

Referenced by diffInternal().

setBailoutComplexity()

DiffEngine::setBailoutComplexity

(

$value

)

Sets the complexity (in comparison operations) that can't be exceeded.

Parameters

int

$value

Definition at line 143 of file DiffEngine.php.

Referenced by Diff\__construct().

shiftBoundaries()

DiffEngine::shiftBoundaries ( array  $lines, array &  $changed, array  $other_changed  )

private

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

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

string[]	$lines
string[]	$changed
string[]	$other_changed

Definition at line 164 of file DiffEngine.php.

References $lines.

Referenced by diff().

Member Data Documentation

$added

DiffEngine::$added

Definition at line 69 of file DiffEngine.php.

Referenced by diffInternal().

$bailoutComplexity

DiffEngine::$bailoutComplexity = 0

protected

Definition at line 60 of file DiffEngine.php.

$from

string [] DiffEngine::$from

private

Definition at line 51 of file DiffEngine.php.

Referenced by diffInternal(), and find_middle_snake().

$heuristicUsed

DiffEngine::$heuristicUsed

Definition at line 70 of file DiffEngine.php.

$lcsLengthCorrectedForHeuristic

DiffEngine::$lcsLengthCorrectedForHeuristic = false

private

Definition at line 64 of file DiffEngine.php.

$length

DiffEngine::$length

Definition at line 67 of file DiffEngine.php.

Referenced by getLcsLength().

$m

DiffEngine::$m

private

Definition at line 54 of file DiffEngine.php.

Referenced by diffInternal().

$maxDifferences

DiffEngine::$maxDifferences

private

Definition at line 63 of file DiffEngine.php.

$n

DiffEngine::$n

private

Definition at line 55 of file DiffEngine.php.

Referenced by diffInternal().

$powLimit

DiffEngine::$powLimit

private

Definition at line 58 of file DiffEngine.php.

Referenced by __construct().

$removed

DiffEngine::$removed

Definition at line 68 of file DiffEngine.php.

Referenced by diffInternal().

$to

string [] DiffEngine::$to

private

Definition at line 53 of file DiffEngine.php.

Referenced by diffInternal(), and find_middle_snake().

$tooLong

DiffEngine::$tooLong

private

Definition at line 57 of file DiffEngine.php.

Referenced by __construct().

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The documentation for this class was generated from the following file:

• includes/diff/DiffEngine.php