Add cache file to enable faster generation of output.

Caching of the results of the tags includes a md5 of the file.  This
allows different git branches to continue to make use of the cache file
4 when switching.  Caching of fields is not included.  You will currently
get unexpected behaviour if using a cachefile with different fields included.

Performance seen from changes;
    - When updating Moodle 2.4 using a cache file, updates are approximately 3 seconds with no changes.

Author: mr-russ

PHPCtags.class.php

@@ -23,6 +23,7 @@ class PHPCtags
     private $mLines;
     private $mOptions;
     private $tagdata;
+    private $cachefile;
     private $filecount;
 
     public function __construct($options)
@@ -60,6 +61,10 @@ public function addFile($file)
         $this->mFiles[realpath($file)] = 1;
     }
 
+    public function setCacheFile($file) {
+        $this->cachefile = $file;
+    }
+
     public function addFiles($files)
     {
         foreach ($files as $file) {
@@ -377,6 +382,13 @@ private function full_render() {
             $str = self::stringSortByLine($str, $this->mOptions['sort'] == 'foldcase');
         }
 
+        // Save all tag information to a file for faster updates if a cache file was specified.
+        if (isset($this->cachefile)) {
+            file_put_contents($this->cachefile, serialize($this->tagdata));
+            if ($this->mOptions['v']) {
+                echo "Saved cache file.".PHP_EOL;
+            }
+        }
         return $str;
     }
 
@@ -395,6 +407,14 @@ public function export()
 
     private function process($file)
     {
+        // Load the tag md5 data to skip unchanged files.
+        if (!isset($this->tagdata) && isset($this->cachefile) && file_exists($this->cachefile)) {
+            if ($this->mOptions['v']) {
+                echo "Loaded cache file.".PHP_EOL;
+            }
+            $this->tagdata = unserialize(file_get_contents($this->cachefile));
+        }
+
         if (is_dir($file) && isset($this->mOptions['R'])) {
             $iterator = new RecursiveIteratorIterator(
                 new RecursiveDirectoryIterator(

bootstrap.php

@@ -41,6 +41,8 @@
   -f <name>
        Write tags to specified file. Value of "-" writes tags to stdout
        ["tags"].
+  -C <name>
+       Use a cache file to store tags for faster updates.
   -n   Equivalent to --excmd=number.
   -N   Equivalent to --excmd=pattern.
   -o   Alternative for -f.
@@ -203,6 +205,7 @@
 try {
     $ctags = new PHPCtags($options);
     $ctags->addFiles($argv);
+    $ctags->setCacheFile(isset($options['C']) ? $options['C'] : null);
     $result = $ctags->export();
 } catch (Exception $e) {
     die("phpctags: {$e->getMessage()}".PHP_EOL);