README

A comprehensive library for generating diff between two strings.

Introduction

Generated diff can be rendered in all of the standard formats including:

Text renderers:

• Context
• Json (plain text)
• Unified

HTML renderers:

• Combined
• Inline
• Json (HTML)
• Side by Side

Note that for HTML rendered results, you have to add CSS for a better visualization. You may modify one from example/diff-table.css or write your own from zero.

If you are okay with the default CSS, there is \Jfcherng\Diff\DiffHelper::getStyleSheet() which can be used to get the content of the example/diff-table.css.

Requirements

Installation

This package is available on Packagist by the name of jfcherng/php-diff.

composer require jfcherng/php-diff

Example

See files and readme in the example/ directory.

<?php

include __DIR__ . '/vendor/autoload.php';

use Jfcherng\Diff\Differ;
use Jfcherng\Diff\DiffHelper;
use Jfcherng\Diff\Factory\RendererFactory;
use Jfcherng\Diff\Renderer\RendererConstant;

$oldFile = __DIR__ . '/example/old_file.txt';
$newFile = __DIR__ . '/example/new_file.txt';

$old = 'This is the old string.';
$new = 'And this is the new one.';

// renderer class name:
//     Text renderers: Context, JsonText, Unified
//     HTML renderers: Combined, Inline, JsonHtml, SideBySide
$rendererName = 'Unified';

// the Diff class options
$differOptions = [
    // show how many neighbor lines
    // Differ::CONTEXT_ALL can be used to show the whole file
    'context' => 3,
    // ignore case difference
    'ignoreCase' => false,
    // ignore line ending difference
    'ignoreLineEnding' => false,
    // ignore whitespace difference
    'ignoreWhitespace' => false,
    // if the input sequence is too long, it will just gives up (especially for char-level diff)
    'lengthLimit' => 2000,
    // if truthy, when inputs are identical, the whole inputs will be rendered in the output
    'fullContextIfIdentical' => false,
];

// the renderer class options
$rendererOptions = [
    // how detailed the rendered HTML in-line diff is? (none, line, word, char)
    'detailLevel' => 'line',
    // renderer language: eng, cht, chs, jpn, ...
    // or an array which has the same keys with a language file
    // check the "Custom Language" section in the readme for more advanced usage
    'language' => 'eng',
    // show line numbers in HTML renderers
    'lineNumbers' => true,
    // show a separator between different diff hunks in HTML renderers
    'separateBlock' => true,
    // show the (table) header
    'showHeader' => true,
    // the frontend HTML could use CSS "white-space: pre;" to visualize consecutive whitespaces
    // but if you want to visualize them in the backend with "&nbsp;", you can set this to true
    'spacesToNbsp' => false,
    // HTML renderer tab width (negative = do not convert into spaces)
    'tabSize' => 4,
    // this option is currently only for the Combined renderer.
    // it determines whether a replace-type block should be merged or not
    // depending on the content changed ratio, which values between 0 and 1.
    'mergeThreshold' => 0.8,
    // this option is currently only for the Unified and the Context renderers.
    // RendererConstant::CLI_COLOR_AUTO = colorize the output if possible (default)
    // RendererConstant::CLI_COLOR_ENABLE = force to colorize the output
    // RendererConstant::CLI_COLOR_DISABLE = force not to colorize the output
    'cliColorization' => RendererConstant::CLI_COLOR_AUTO,
    // this option is currently only for the Json renderer.
    // internally, ops (tags) are all int type but this is not good for human reading.
    // set this to "true" to convert them into string form before outputting.
    'outputTagAsString' => false,
    // this option is currently only for the Json renderer.
    // it controls how the output JSON is formatted.
    // see available options on https://www.php.net/manual/en/function.json-encode.php
    'jsonEncodeFlags' => \JSON_UNESCAPED_SLASHES | \JSON_UNESCAPED_UNICODE,
    // this option is currently effective when the "detailLevel" is "word"
    // characters listed in this array can be used to make diff segments into a whole
    // for example, making "<del>good</del>-<del>looking</del>" into "<del>good-looking</del>"
    // this should bring better readability but set this to empty array if you do not want it
    'wordGlues' => [' ', '-'],
    // change this value to a string as the returned diff if the two input strings are identical
    'resultForIdenticals' => null,
    // extra HTML classes added to the DOM of the diff container
    'wrapperClasses' => ['diff-wrapper'],
];

// one-line simply compare two files
$result = DiffHelper::calculateFiles($oldFile, $newFile, $rendererName, $differOptions, $rendererOptions);
// one-line simply compare two strings
$result = DiffHelper::calculate($old, $new, $rendererName, $differOptions, $rendererOptions);
// or even shorter if you are happy with default options
$result = DiffHelper::calculate($old, $new, $rendererName);

// custom usage
$differ = new Differ(explode("\n", $old), explode("\n", $new), $differOptions);
$renderer = RendererFactory::make($rendererName, $rendererOptions); // or your own renderer object
$result = $renderer->render($differ);

// use the JSON result to render in HTML
$jsonResult = DiffHelper::calculate($old, $new, 'Json'); // may store the JSON result in your database
$htmlRenderer = RendererFactory::make('Inline', $rendererOptions);
$result = $htmlRenderer->renderArray(json_decode($jsonResult, true));

Rendered Results

HTML Diff In-line Detailed Rendering

None-level	Line-level (Default)
Word-level	Char-level

Renderer: Inline

<?php $rendererOptions = ['detailLevel' => 'line'];

Renderer: Side By Side

<?php $rendererOptions = ['detailLevel' => 'line'];

Renderer: Combined

<?php $rendererOptions = ['detailLevel' => 'word'];

This renderer is suitable for articles and always has no line number information.

Renderer: Unified

About the Unified diff format: https://en.wikipedia.org/wiki/Diff#Unified_format

@@ -1,3 +1,4 @@
-<p>Hello World!</p>
+<div>Hello World!</div>
 ~~~~~~~~~~~~~~~~~~~
+Let's add a new line here.
 X
@@ -7,6 +8,5 @@
 N
-Do you know in Chinese, "金槍魚罐頭" means tuna can.
+Do you know in Japanese, "魚の缶詰" means fish can.
 This is just a useless line.
 G
-// remember to delete this line
 Say hello to my neighbors.

Renderer: Context

About the Context diff format: https://en.wikipedia.org/wiki/Diff#Context_format

***************
*** 1,3 ****
! <p>Hello World!</p>
  ~~~~~~~~~~~~~~~~~~~
  X
--- 1,4 ----
! <div>Hello World!</div>
  ~~~~~~~~~~~~~~~~~~~
+ Let's add a new line here.
  X
***************
*** 7,12 ****
  N
! Do you know in Chinese, "金槍魚罐頭" means tuna can.
  This is just a useless line.
  G
- // remember to delete this line
  Say hello to my neighbors.
--- 8,12 ----
  N
! Do you know in Japanese, "魚の缶詰" means fish can.
  This is just a useless line.
  G
  Say hello to my neighbors.

Renderer: Text JSON

This renderer has no detailed diff.

[
  [
    {
      "tag": "rep",
      "old": {
        "offset": 0,
        "lines": ["<p>Hello World! Good-looking.</p>"]
      },
      "new": {
        "offset": 0,
        "lines": ["<div>Hello World! Bad-tempered.</div>"]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 1,
        "lines": ["~~~~~~~~~~~~~~~~~~~"]
      },
      "new": {
        "offset": 1,
        "lines": ["~~~~~~~~~~~~~~~~~~~"]
      }
    },
    {
      "tag": "ins",
      "old": {
        "offset": 2,
        "lines": []
      },
      "new": {
        "offset": 2,
        "lines": ["Let's add a new line here."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 2,
        "lines": ["X"]
      },
      "new": {
        "offset": 3,
        "lines": ["X"]
      }
    }
  ],
  [
    {
      "tag": "eq",
      "old": {
        "offset": 6,
        "lines": ["N"]
      },
      "new": {
        "offset": 7,
        "lines": ["N"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 7,
        "lines": ["Do you know in Chinese, \"金槍魚罐頭\" means tuna can."]
      },
      "new": {
        "offset": 8,
        "lines": ["Do you know in Japanese, \"魚の缶詰\" means fish can."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 8,
        "lines": ["\t  \tTab visualization test.", "G"]
      },
      "new": {
        "offset": 9,
        "lines": ["\t  \tTab visualization test.", "G"]
      }
    },
    {
      "tag": "del",
      "old": {
        "offset": 10,
        "lines": ["// remember to delete this line"]
      },
      "new": {
        "offset": 11,
        "lines": []
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 11,
        "lines": ["Say hello to my neighbors."]
      },
      "new": {
        "offset": 11,
        "lines": ["Say hello to my neighbors."]
      }
    }
  ],
  [
    {
      "tag": "eq",
      "old": {
        "offset": 14,
        "lines": ["B"]
      },
      "new": {
        "offset": 14,
        "lines": ["B"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 15,
        "lines": ["Donec rutrum."]
      },
      "new": {
        "offset": 15,
        "lines": ["Donec rutrum test.", "There is a new inserted line."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 16,
        "lines": ["C"]
      },
      "new": {
        "offset": 17,
        "lines": ["C"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 17,
        "lines": ["Sed dictum lorem ipsum."]
      },
      "new": {
        "offset": 18,
        "lines": ["Sed dolor lorem ipsum hendrerit."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 18,
        "lines": [""]
      },
      "new": {
        "offset": 19,
        "lines": [""]
      }
    }
  ]
]

Renderer: HTML JSON

For a "tag": "rep" (8) block, this renderer has HTML-style detailed diff. If you don't need those detailed diff, consider using the JsonText renderer.

[
  [
    {
      "tag": "rep",
      "old": {
        "offset": 0,
        "lines": ["&lt;<del>p&gt;Hello World! Good-looking.&lt;/p</del>&gt;"]
      },
      "new": {
        "offset": 0,
        "lines": ["&lt;<ins>div&gt;Hello World! Bad-tempered.&lt;/div</ins>&gt;"]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 1,
        "lines": ["~~~~~~~~~~~~~~~~~~~"]
      },
      "new": {
        "offset": 1,
        "lines": ["~~~~~~~~~~~~~~~~~~~"]
      }
    },
    {
      "tag": "ins",
      "old": {
        "offset": 2,
        "lines": [""]
      },
      "new": {
        "offset": 2,
        "lines": ["Let's add a new line here."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 2,
        "lines": ["X"]
      },
      "new": {
        "offset": 3,
        "lines": ["X"]
      }
    }
  ],
  [
    {
      "tag": "eq",
      "old": {
        "offset": 6,
        "lines": ["N"]
      },
      "new": {
        "offset": 7,
        "lines": ["N"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 7,
        "lines": ["Do you know in <del>Chinese, \"金槍魚罐頭\" means tuna</del> can."]
      },
      "new": {
        "offset": 8,
        "lines": ["Do you know in <ins>Japanese, \"魚の缶詰\" means fish</ins> can."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 8,
        "lines": ["\t  \tTab visualization test.", "G"]
      },
      "new": {
        "offset": 9,
        "lines": ["\t  \tTab visualization test.", "G"]
      }
    },
    {
      "tag": "del",
      "old": {
        "offset": 10,
        "lines": ["// remember to delete this line"]
      },
      "new": {
        "offset": 11,
        "lines": [""]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 11,
        "lines": ["Say hello to my neighbors."]
      },
      "new": {
        "offset": 11,
        "lines": ["Say hello to my neighbors."]
      }
    }
  ],
  [
    {
      "tag": "eq",
      "old": {
        "offset": 14,
        "lines": ["B"]
      },
      "new": {
        "offset": 14,
        "lines": ["B"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 15,
        "lines": ["Donec rutrum."]
      },
      "new": {
        "offset": 15,
        "lines": ["Donec rutrum test.", "There is a new inserted line."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 16,
        "lines": ["C"]
      },
      "new": {
        "offset": 17,
        "lines": ["C"]
      }
    },
    {
      "tag": "rep",
      "old": {
        "offset": 17,
        "lines": ["Sed d<del>ictum lorem ipsum</del>."]
      },
      "new": {
        "offset": 18,
        "lines": ["Sed d<ins>olor lorem ipsum hendrerit</ins>."]
      }
    },
    {
      "tag": "eq",
      "old": {
        "offset": 18,
        "lines": [""]
      },
      "new": {
        "offset": 19,
        "lines": [""]
      }
    }
  ]
]

Custom Language

Override an Existing Language

If you just want to override some translations of an existing language...

$rendererOptions = [
  'language' => [
    // use English as the base language
    'eng',
    // your custom overrides
    [
      // use "Diff" as the new value of the "differences" key
      'differences' => 'Diff',
    ],
    // maybe more overrides if you somehow need them...
  ],
]

Acknowledgment

This package is built on the top of chrisboulton/php-diff initially. But the original repository looks like no longer maintained. Here have been quite lots of rewrites and new features since then, hence I re-started this as a new package for better visibility.