bircher/php-merge

A PHP merge utility using the Diff php library or the command line git.

2.0.0 2017-07-11 06:51 UTC

README

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Introduction

When working with revisions of text one sometimes faces the problem that there are several revisions based off the same original text. Rather than choosing one and discarding the other we want to merge the two revisions.

Git does that already wonderfully. In a php application we want a simple tool that does the same. There is the xdiff PECL extension which has the xdiff_string_merge3 function. But xdiff_string_merge3 does not behave the same way as git and xdiff may not be available on your system.

PhpMerge is a small library that solves this problem. There are two classes: \PhpMerge\PhpMerge and \PhpMerge\GitMerge that implement the \PhpMerge\PhpMergeInterface which has just a merge method.

PhpMerge uses SebastianBergmann\Diff\Differ to get the differences between the different versions and calculates the merged text from it. GitMerge uses GitWrapper\GitWrapper, writes the text to a temporary file and uses the command line git to merge the text.

Usage

Simple example:

use PhpMerge\PhpMerge;

// Create a merger instance.
$merger = new PhpMerge();

// Get the texts to merge.
$original = <<<'EOD'
unchanged
replaced
unchanged
normal
unchanged
unchanged
removed
EOD;
$version1= <<<'EOD'
added
unchanged
replacement
unchanged
normal
unchanged
unchanged
EOD;
$version2 = <<<'EOD'
unchanged
replaced
unchanged
normal??
unchanged
unchanged
EOD;
$expected = <<<'EOD'
added
unchanged
replacement
unchanged
normal??
unchanged
unchanged
EOD;

$result = $merger->merge($original, $version1, $version2);
// $result == $expected;

With merge conflicts:

// Continuing from before with:
use Phpmerge\MergeException;
use PhpMerge\MergeConflict;


$conflicting = <<<'EOD'
unchanged
replaced
unchanged
normal!!
unchanged
unchanged
EOD;

try {
    $merger->merge($original, $version2, $conflicting);
} catch (MergeException $exception) {
    /** @var MergeConflict[] $conflicts */
    $conflicts = $exception->getConflicts();

    $original_lines = $conflicts[0]->getBase();
    // $original_lines == ['normal'];
    
    $version2_lines = $conflicts[0]->getRemote();
    // $version2_lines == ['normal??'];
    
    $conflicting_lines = $conflicts[0]->getLocal();
    // $conflicting_lines == ['normal!!'];
    
    $line_numer_of_conflict = $conflicts[0]->getBaseLine();
    // $line_numer_of_conflict == 3; // Count starts with 0.
    
    // It is also possible to get the merged version using the first version
    // to resolve conflicts.
    $merged = $exception->getMerged();
    // $merged == $version2;
    // In this case, but in general there could be non-conflicting changes.
    
    $line_in_merged = $conflicts[0]->getMergedLine();
    // $line_in_merged == 3; // Count starts with 0.
}

Using the command line git to perform the merge:

use PhpMerge\GitMerge;

$merger = new GitMerge();

// Use as the previous example.

Installation

PhpMerge can be installed with Composer by adding the library as a dependency to your composer.json file.

{
    "require": {
        "bircher/php-merge": "~2.0"
    }
}

To use the command line git with GitMerge:

{
    "require": {
        "bircher/php-merge": "~2.0",
        "cpliakas/git-wrapper": "~1.0"
    }
}

Please refer to Composer's documentation for installation and usage instructions.

Difference to ~1.0

In the ~2.0 version we dropped support for php 5 and use php 7 constructs instead. This means that the PhpMergeInterface type-hints the arguments and return type as strings. In addition to that all classes are now final and it is clearer what the API is. We can consider making the classes inheritable if needed without breaking the api but not the other way around.

If you have just been using the ~1.0 version as described in this document the version ~2.0 will continue to work.