views/template.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 require_once HOPLITE_ROOT . '/base/filter.php';
  20
  21 /*!
  22  A Template is initialized with a text file (typically HTML) and can render it
  23  with data from some model. It has a short macro expansion system, equivalent
  24  to PHP short open tags, but usable on all installations. Template caching of
  25  the parsed state is available.
  26 */
  27 class Template
  28 {
  29   /*! @var string The name of the template. */
  30   protected $template_name = '';
  31
  32   /*! @var string The compiled template. */
  33   protected $data = NULL;
  34
  35   /*! @var array Variables to provide to the template. */
  36   protected $vars = array();
  37
  38   /*!
  39     Creates a new Template with a given name.
  40     @param string
  41   */
  42   private function __construct($name)
  43   {
  44     $this->template_name = $name;
  45   }
  46
  47   static public function NewWithData($data)
  48   {
  49     $template = new Template('');
  50     $template->data = $template->_ProcessTemplate($data);
  51     return $template;
  52   }
  53
  54   static public function NewFromCompiledData($data)
  55   {
  56     $template = new Template('');
  57     $template->data = $data;
  58     return $template;
  59   }
  60
  61   /*! Gets the name of the template. */
  62   public function template_name() { return $this->template_name; }
  63
  64   /*! Gets the parsed data of the template. */
  65   public function template() { return $this->data; }
  66
  67   /*! Overload property accessors to set view variables. */
  68   public function __get($key)
  69   {
  70     return $this->vars[$key];
  71   }
  72   public function __set($key, $value)
  73   {
  74     $this->vars[$key] = $value;
  75   }
  76
  77   /*! This includes the template and renders it out. */
  78   public function Render()
  79   {
  80     $_template = $this->data;
  81     $_vars = $this->vars;
  82     $render = function () use ($_template, $_vars) {
  83       extract($_vars);
  84       eval('?>' . $_template . '<' . '?');
  85     };
  86     $render();
  87   }
  88
  89   /*! @brief Does any pre-processing on the template.
  90     This performs the macro expansion. The language is very simple and is merely
  91     shorthand for the PHP tags.
  92
  93     The most common thing needed in templates is string escaped output from an
  94     expression. HTML entities are automatically escaped in this format:
  95       <p>Hello, {% $user->name %}!</p>
  96
  97     To specify the type to format, you use the pipe symbol and then one of the
  98     following types: str (default; above), int, float, raw.
  99       <p>Hello, {% %user->name | str %}</p>
 100       <p>Hello, user #{% $user->user_id | int %}</p>
 101
 102     To evaluate a non-printing expression, simply add a '!' before the first '%':
 103       {!% if (!$user->user_id): %}<p>Hello, Guest!</p>{!% endif %}
 104
 105     @param string Raw template data
 106     @return string Executable PHP
 107   */
 108   protected function _ProcessTemplate($data)
 109   {
 110     // The parsed output as compiled PHP.
 111     $processed = '';
 112
 113     // If processing a macro, this contains the contents of the macro while
 114     // it is being extracted from the template.
 115     $macro = '';
 116     $in_macro = FALSE;
 117
 118     $length = strlen($data);
 119     $i = 0;  // The current position of the iterator.
 120     $looking_for_end = FALSE;  // Whehter or not an end tag is expected.
 121     $line_number = 1;  // The current line number.
 122     $column_number = 0;  // The current column number.
 123
 124     while ($i < $length) {
 125       // See how far the current position is from the end of the string.
 126       $delta = $length - $i;
 127
 128       // When a new line is reached, update the counters.
 129       if ($data[$i] == "\n") {
 130         ++$line_number;
 131         $column_number = 0;
 132       }
 133
 134       // Check for simple PHP short-tag expansion.
 135       if ($delta >= 3 && substr($data, $i, 3) == '{!%') {
 136         // If an expansion has already been opened, then it's an error to nest.
 137         if ($looking_for_end)
 138           throw new TemplateException("Unexpected start of expansion at line $line_number:$column_number");
 139
 140         $looking_for_end = TRUE;
 141         $processed .= '<' . '?php';
 142         $i += 3;
 143         continue;
 144       }
 145       // Check for either the end tag or the start of a macro expansion.
 146       else if ($delta >= 2) {
 147         $substr = substr($data, $i, 2);
 148         // Check for an end tag.
 149         if ($substr == '%}') {
 150           // If an end tag was encountered without an open tag, that's an error.
 151           if (!$looking_for_end)
 152             throw new TemplateException("Unexpected end of expansion at line $line_number:$column_number");
 153
 154           // If this is a macro, it's time to process it.
 155           if ($in_macro)
 156             $processed .= $this->_ProcessMacro($macro);
 157
 158           $looking_for_end = FALSE;
 159           $in_macro = FALSE;
 160           $processed .= ' ?>';
 161           $i += 2;
 162           continue;
 163         }
 164         // Check for the beginning of a macro.
 165         else if ($substr == '{%') {
 166           $processed .= '<' . '?php echo ';
 167           $macro = '';
 168           $in_macro = TRUE;
 169           $looking_for_end = TRUE;
 170           $i += 2;
 171           continue;
 172         }
 173       }
 174
 175       // All other characters go into a storage bin. If currently in a macro,
 176       // save off the data separately for parsing.
 177       if ($in_macro)
 178         $macro .= $data[$i];
 179       else
 180         $processed .= $data[$i];
 181       ++$i;
 182     }
 183
 184     return $processed;
 185   }
 186
 187   /*!
 188     Takes the contents of a macro |{% $some_var | int %}|, which is the part in
 189     between the open and close brackets (excluding '%') and transforms it into a
 190     PHP statement.
 191   */
 192   protected function _ProcessMacro($macro)
 193   {
 194     // The pipe operator specifies how to sanitize the output.
 195     $formatter_pos = strrpos($macro, '|');
 196
 197     // No specifier defaults to escaped string.
 198     if ($formatter_pos === FALSE)
 199       return 'hoplite\\base\\filter\\String(' . $macro . ')';
 200
 201     // Otherwise, apply the right filter.
 202     $formatter = trim(substr($macro, $formatter_pos + 1));
 203     $function = '';
 204     switch (strtolower($formatter)) {
 205       case 'int':   $function = 'Int'; break;
 206       case 'float': $function = 'Float'; break;
 207       case 'str':   $function = 'String'; break;
 208       case 'raw':   $function = 'RawString'; break;
 209       default:
 210         throw new TemplateException('Invalid macro formatter "' . $formatter . '"');
 211     }
 212
 213     // Now get the expression and return a PHP statement.
 214     $expression = trim(substr($macro, 0, $formatter_pos));
 215     return 'hoplite\\base\\filter\\' . $function . '(' . $expression . ')';
 216   }
 217 }
 218
 219 class TemplateException extends \Exception {}