Diff implementation

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6.0.1 2024-03-02 07:30 UTC

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sebastian/diff

Diff implementation for PHP, factored out of PHPUnit into a stand-alone component.

Installation

You can add this library as a local, per-project dependency to your project using Composer:

composer require sebastian/diff

If you only need this library during development, for instance to run your project's test suite, then you should add it as a development-time dependency:

composer require --dev sebastian/diff

Usage

Generating diff

The Differ class can be used to generate a textual representation of the difference between two strings:

<?php
use SebastianBergmann\Diff\Differ;

$differ = new Differ;
print $differ->diff('foo', 'bar');

The code above yields the output below:

--- Original
+++ New
@@ @@
-foo
+bar

There are three output builders available in this package:

UnifiedDiffOutputBuilder

This is default builder, which generates the output close to udiff and is used by PHPUnit.

<?php

use SebastianBergmann\Diff\Differ;
use SebastianBergmann\Diff\Output\UnifiedDiffOutputBuilder;

$builder = new UnifiedDiffOutputBuilder(
    "--- Original\n+++ New\n", // custom header
    false                      // do not add line numbers to the diff 
);

$differ = new Differ($builder);
print $differ->diff('foo', 'bar');

StrictUnifiedDiffOutputBuilder

Generates (strict) Unified diff's (unidiffs) with hunks, similar to diff -u and compatible with patch and git apply.

<?php

use SebastianBergmann\Diff\Differ;
use SebastianBergmann\Diff\Output\StrictUnifiedDiffOutputBuilder;

$builder = new StrictUnifiedDiffOutputBuilder([
    'collapseRanges'      => true, // ranges of length one are rendered with the trailing `,1`
    'commonLineThreshold' => 6,    // number of same lines before ending a new hunk and creating a new one (if needed)
    'contextLines'        => 3,    // like `diff:  -u, -U NUM, --unified[=NUM]`, for patch/git apply compatibility best to keep at least @ 3
    'fromFile'            => '',
    'fromFileDate'        => null,
    'toFile'              => '',
    'toFileDate'          => null,
]);

$differ = new Differ($builder);
print $differ->diff('foo', 'bar');

DiffOnlyOutputBuilder

Output only the lines that differ.

<?php

use SebastianBergmann\Diff\Differ;
use SebastianBergmann\Diff\Output\DiffOnlyOutputBuilder;

$builder = new DiffOnlyOutputBuilder(
    "--- Original\n+++ New\n"
);

$differ = new Differ($builder);
print $differ->diff('foo', 'bar');

DiffOutputBuilderInterface

You can pass any output builder to the Differ class as longs as it implements the DiffOutputBuilderInterface.

Parsing diff

The Parser class can be used to parse a unified diff into an object graph:

use SebastianBergmann\Diff\Parser;
use SebastianBergmann\Git;

$git = new Git('/usr/local/src/money');

$diff = $git->getDiff(
  '948a1a07768d8edd10dcefa8315c1cbeffb31833',
  'c07a373d2399f3e686234c4f7f088d635eb9641b'
);

$parser = new Parser;

print_r($parser->parse($diff));

The code above yields the output below:

Array
(
    [0] => SebastianBergmann\Diff\Diff Object
        (
            [from:SebastianBergmann\Diff\Diff:private] => a/tests/MoneyTest.php
            [to:SebastianBergmann\Diff\Diff:private] => b/tests/MoneyTest.php
            [chunks:SebastianBergmann\Diff\Diff:private] => Array
                (
                    [0] => SebastianBergmann\Diff\Chunk Object
                        (
                            [start:SebastianBergmann\Diff\Chunk:private] => 87
                            [startRange:SebastianBergmann\Diff\Chunk:private] => 7
                            [end:SebastianBergmann\Diff\Chunk:private] => 87
                            [endRange:SebastianBergmann\Diff\Chunk:private] => 7
                            [lines:SebastianBergmann\Diff\Chunk:private] => Array
                                (
                                    [0] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>      * @covers SebastianBergmann\Money\Money::add
                                        )

                                    [1] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>      * @covers SebastianBergmann\Money\Money::newMoney
                                        )

                                    [2] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>      */
                                        )

                                    [3] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 2
                                            [content:SebastianBergmann\Diff\Line:private] =>     public function testAnotherMoneyWithSameCurrencyObjectCanBeAdded()
                                        )

                                    [4] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 1
                                            [content:SebastianBergmann\Diff\Line:private] =>     public function testAnotherMoneyObjectWithSameCurrencyCanBeAdded()
                                        )

                                    [5] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>     {
                                        )

                                    [6] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>         $a = new Money(1, new Currency('EUR'));
                                        )

                                    [7] => SebastianBergmann\Diff\Line Object
                                        (
                                            [type:SebastianBergmann\Diff\Line:private] => 3
                                            [content:SebastianBergmann\Diff\Line:private] =>         $b = new Money(2, new Currency('EUR'));
                                        )
                                )
                        )
                )
        )
)

Note: If the chunk size is 0 lines, i.e., getStartRange() or getEndRange() return 0, the number of line returned by getStart() or getEnd() is one lower than one would expect. It is the line number after which the chunk should be inserted or deleted; in all other cases, it gives the first line number of the replaced range of lines.