Allow caching of the calculated diffs using a doctrine cache provider

composer.json

@@ -22,15 +22,19 @@
         "php": ">=5.3.3",
         "ezyang/htmlpurifier": "^4.7"
     },
+    "require-dev": {
+        "phpunit/phpunit": "~4.8",
+        "doctrine/cache": "~1.0"
+    },
+    "suggest": {
+        "doctrine/cache": "Used for caching the calculated diffs using a Doctrine Cache Provider"
+    },
     "autoload": {
         "psr-0": { "Caxy\\HtmlDiff": "lib/" }
     },
     "autoload-dev": {
         "psr-4": { "Caxy\\Tests\\": "tests/Caxy/Tests" }
     },
-    "require-dev": {
-        "phpunit/phpunit": "^4.8"
-    },
     "extra": {
         "branch-alias": {
             "dev-master": "0.1.x-dev"

lib/Caxy/HtmlDiff/AbstractDiff.php

@@ -53,6 +53,11 @@ abstract class AbstractDiff
      */
     protected $newWords = array();
 
+    /**
+     * @var DiffCache[]
+     */
+    private $diffCaches = array();
+
     /**
      * AbstractDiff constructor.
      *
@@ -81,6 +86,37 @@ public function __construct($oldText, $newText, $encoding = 'UTF-8', $specialCas
         $this->content = '';
     }
 
+    /**
+     * @return bool|string
+     */
+    abstract public function build();
+
+    /**
+     * @return DiffCache|null
+     */
+    protected function getDiffCache()
+    {
+        if (!$this->hasDiffCache()) {
+            return null;
+        }
+
+        $hash = spl_object_hash($this->getConfig()->getCacheProvider());
+
+        if (!array_key_exists($hash, $this->diffCaches)) {
+            $this->diffCaches[$hash] = new DiffCache($this->getConfig()->getCacheProvider());
+        }
+
+        return $this->diffCaches[$hash];
+    }
+
+    /**
+     * @return bool
+     */
+    protected function hasDiffCache()
+    {
+        return null !== $this->getConfig()->getCacheProvider();
+    }
+
     /**
      * @return HtmlDiffConfig
      */

lib/Caxy/HtmlDiff/DiffCache.php

@@ -0,0 +1,112 @@
+<?php
+
+namespace Caxy\HtmlDiff;
+
+use Doctrine\Common\Cache\Cache;
+
+/**
+ * Class DiffCache
+ * @package Caxy\HtmlDiff
+ */
+class DiffCache
+{
+    /**
+     * @var Cache
+     */
+    protected $cacheProvider;
+
+    /**
+     * DiffCache constructor.
+     *
+     * @param Cache $cacheProvider
+     */
+    public function __construct(Cache $cacheProvider)
+    {
+        $this->cacheProvider = $cacheProvider;
+    }
+
+    /**
+     * @return Cache
+     */
+    public function getCacheProvider()
+    {
+        return $this->cacheProvider;
+    }
+
+    /**
+     * @param Cache $cacheProvider
+     *
+     * @return DiffCache
+     */
+    public function setCacheProvider($cacheProvider)
+    {
+        $this->cacheProvider = $cacheProvider;
+
+        return $this;
+    }
+
+    /**
+     * @param string $oldText
+     * @param string $newText
+     *
+     * @return bool
+     */
+    public function contains($oldText, $newText)
+    {
+        return $this->cacheProvider->contains($this->getHashKey($oldText, $newText));
+    }
+
+    /**
+     * @param string $oldText
+     * @param string $newText
+     *
+     * @return string
+     */
+    public function fetch($oldText, $newText)
+    {
+        return $this->cacheProvider->fetch($this->getHashKey($oldText, $newText));
+    }
+
+    /**
+     * @param string $oldText
+     * @param string $newText
+     * @param string $data
+     * @param int    $lifeTime
+     *
+     * @return bool
+     */
+    public function save($oldText, $newText, $data, $lifeTime = 0)
+    {
+        return $this->cacheProvider->save($this->getHashKey($oldText, $newText), $data, $lifeTime);
+    }
+
+    /**
+     * @param string $oldText
+     * @param string $newText
+     *
+     * @return bool
+     */
+    public function delete($oldText, $newText)
+    {
+        return $this->cacheProvider->delete($this->getHashKey($oldText, $newText));
+    }
+
+    /**
+     * @return array|null
+     */
+    public function getStats()
+    {
+        return $this->cacheProvider->getStats();
+    }
+
+    /**
+     * @param string $oldText
+     * @param string $newText
+     *
+     * @return string
+     */
+    protected function getHashKey($oldText, $newText)
+    {
+        return sprintf('%s_%s', md5($oldText), md5($newText));
+    }
+}

lib/Caxy/HtmlDiff/HtmlDiff.php

@@ -91,6 +91,12 @@ public function getInsertSpaceInReplace()
      */
     public function build()
     {
+        if ($this->hasDiffCache() && $this->getDiffCache()->contains($this->oldText, $this->newText)) {
+            $this->content = $this->getDiffCache()->fetch($this->oldText, $this->newText);
+
+            return $this->content;
+        }
+
         $this->splitInputsToWords();
         $this->replaceIsolatedDiffTags();
         $this->indexNewWords();
@@ -100,6 +106,10 @@ public function build()
             $this->performOperation( $item );
         }
 
+        if ($this->hasDiffCache()) {
+            $this->getDiffCache()->save($this->oldText, $this->newText, $this->content);
+        }
+
         return $this->content;
     }
 

lib/Caxy/HtmlDiff/HtmlDiffConfig.php

@@ -68,6 +68,11 @@ class HtmlDiffConfig
      */
     protected $useTableDiffing = true;
 
+    /**
+     * @var null|\Doctrine\Common\Cache\Cache
+     */
+    protected $cacheProvider;
+
     /**
      * @return HtmlDiffConfig
      */
@@ -416,6 +421,26 @@ public function setUseTableDiffing($useTableDiffing)
         return $this;
     }
 
+    /**
+     * @param null|\Doctrine\Common\Cache\Cache $cacheProvider
+     *
+     * @return $this
+     */
+    public function setCacheProvider(\Doctrine\Common\Cache\Cache $cacheProvider = null)
+    {
+        $this->cacheProvider = $cacheProvider;
+
+        return $this;
+    }
+
+    /**
+     * @return null|\Doctrine\Common\Cache\Cache
+     */
+    public function getCacheProvider()
+    {
+        return $this->cacheProvider;
+    }
+
     /**
      * @param string $tag
      *

lib/Caxy/HtmlDiff/ListDiffNew.php

@@ -29,12 +29,24 @@ public static function create($oldText, $newText, HtmlDiffConfig $config = null)
 
     public function build()
     {
+        if ($this->hasDiffCache() && $this->getDiffCache()->contains($this->oldText, $this->newText)) {
+            $this->content = $this->getDiffCache()->fetch($this->oldText, $this->newText);
+
+            return $this->content;
+        }
+
         $this->splitInputsToWords();
 
-        return $this->diffLists(
+        $this->content = $this->diffLists(
             $this->buildDiffList($this->oldWords),
             $this->buildDiffList($this->newWords)
         );
+
+        if ($this->hasDiffCache()) {
+            $this->getDiffCache()->save($this->oldText, $this->newText, $this->content);
+        }
+
+        return $this->content;
     }
 
     protected function diffLists(DiffList $oldList, DiffList $newList)

lib/Caxy/HtmlDiff/Table/TableDiff.php

@@ -92,6 +92,12 @@ public function __construct($oldText, $newText, $encoding = 'UTF-8', $specialCas
      */
     public function build()
     {
+        if ($this->hasDiffCache() && $this->getDiffCache()->contains($this->oldText, $this->newText)) {
+            $this->content = $this->getDiffCache()->fetch($this->oldText, $this->newText);
+
+            return $this->content;
+        }
+
         $this->buildTableDoms();
 
         $this->diffDom = new \DOMDocument();
@@ -100,6 +106,10 @@ public function build()
 
         $this->diffTableContent();
 
+        if ($this->hasDiffCache()) {
+            $this->getDiffCache()->save($this->oldText, $this->newText, $this->content);
+        }
+
         return $this->content;
     }