views/template_loader.php

   1 <?php
   2 // Hoplite
   3 // Copyright (c) 2011 Blue Static
   4 //
   5 // This program is free software: you can redistribute it and/or modify it
   6 // under the terms of the GNU General Public License as published by the Free
   7 // Software Foundation, either version 3 of the License, or any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful, but WITHOUT
  10 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 // more details.
  13 //
  14 // You should have received a copy of the GNU General Public License along with
  15 // this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 namespace hoplite\views;
  18
  19 /*!
  20   This class knows how to load and cache templates to the file system.
  21 */
  22 class TemplateLoader
  23 {
  24   /*! @var TemplateLoader Singleton instance */
  25   static private $instance = NULL;
  26
  27   /*! @var string Base path for loading the template file. Use %s to indicate
  28                   where the name (passed to the constructor) should be
  29                   substituted.
  30   */
  31   protected $template_path = '%s.tpl';
  32
  33   /*! @var string The cache path for templates. Unlike |$template_path|, this
  34                   should only be a path, to which the cached template name will
  35                   be appended. This should not end with a trailing slash.
  36   */
  37   protected $cache_path = '/tmp/phalanx_views';
  38
  39   /*! @var string A header to put at the beginning of each cached template file,
  40                   common for setting include paths or cache debug information.
  41   */
  42   protected $cache_prefix = '';
  43
  44   /*! @var array An array of Template objects, keyed by the template name. */
  45   protected $cache = array();
  46
  47   /*! Gets the singleton instance. */
  48   static public function GetInstance()
  49   {
  50     if (!self::$instance) {
  51       $class = get_called_class();
  52       self::$instance = new $class();
  53     }
  54     return self::$instance;
  55   }
  56   /*! Sets the singleton instance. */
  57   static public function SetInstance($instance) { self::$instance = $instance; }
  58
  59   /*! Accessors */
  60   public function set_template_path($path) { $this->template_path = $path; }
  61   function template_path() { return $this->template_path; }
  62
  63   public function set_cache_path($path) { $this->cache_path = $path; }
  64   public function cache_path() { return $this->cache_path; }
  65
  66   /*!
  67     Loads a template from a file, creates a Template object, and returns a copy
  68     of that object.
  69
  70     @param string Template name, with wich the template plath is formatted.
  71
  72     @return Template Clone of the cached template.
  73   */
  74   public function Load($name)
  75   {
  76     // First check the memory cache.
  77     if (isset($this->cache[$name]))
  78       return clone $this->cache[$name];
  79
  80     // Then check the filesystem cache.
  81     $template = $this->_LoadIfCached($name);
  82     if ($template) {
  83       $this->cache[$name] = $template;
  84       return clone $template;
  85     }
  86
  87     // Finally, parse and cache the template.
  88     $template = $this->_Cache($name);
  89     $this->cache[$name] = $template;
  90     return clone $template;
  91   }
  92
  93   /*! Convenience function for loading templates. */
  94   static public function Fetch($name)
  95   {
  96     return self::GetInstance()->Load($name);
  97   }
  98
  99   /*!
 100     Loads a cached filesystem template if it is up-to-date.
 101
 102     @param string Template name
 103
 104     @return Template|NULL
 105   */
 106   protected function _LoadIfCached($name)
 107   {
 108     $cache_path = $this->_CachePath($name);
 109     $tpl_path   = $this->_TemplatePath($name);
 110
 111     // Make sure the cached file exists and hasn't gotten out-of-date.
 112     if (!file_exists($cache_path) || filemtime($cache_path) < filemtime($tpl_path))
 113       return NULL;
 114
 115     // Load the contents of the cache.
 116     $data = @file_get_contents($cache_path);
 117     if ($data === FALSE)
 118       return NULL;
 119
 120     return Template::NewWithCompiledData($data);
 121   }
 122
 123   /*!
 124     Loads a raw template from the file system, stores the compiled template in
 125     the file system, and returns a new template object with that data.
 126
 127     @param string Template name.
 128
 129     @return Template
 130   */
 131   protected function _Cache($name)
 132   {
 133     $cache_path = $this->_CachePath($name);
 134     $tpl_path   = $this->_TemplatePath($name);
 135
 136     $data = @file_get_contents($tpl_path);
 137     if ($data === FALSE)
 138       throw new TemplateLoaderException('Could not load template ' . $name);
 139
 140     $template = Template::NewWithData($data);
 141
 142     // Cache the file.
 143     if (file_put_contents($cache_path, $this->cache_prefix . $template->template()) === FALSE)
 144       throw new TemplateLoaderException('Could not cache ' . $name . ' to ' . $cache_path);
 145
 146     return $template;
 147   }
 148
 149   /*! Returns the template path for a given template name. */
 150   protected function _TemplatePath($name)
 151   {
 152     return sprintf($this->template_path, $name);
 153   }
 154
 155   /*! Returns the cache path for a given template name. */
 156   protected function _CachePath($name)
 157   {
 158     return $this->cache_path . $name . '.phpi';
 159   }
 160 }
 161
 162 class TemplateLoaderException extends \Exception {}