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   1  <?php
   2  
   3  /**
   4   * Injects tokens into the document while parsing for well-formedness.
   5   * This enables "formatter-like" functionality such as auto-paragraphing,
   6   * smiley-ification and linkification to take place.
   7   *
   8   * A note on how handlers create changes; this is done by assigning a new
   9   * value to the $token reference. These values can take a variety of forms and
  10   * are best described HTMLPurifier_Strategy_MakeWellFormed->processToken()
  11   * documentation.
  12   *
  13   * @todo Allow injectors to request a re-run on their output. This
  14   *       would help if an operation is recursive.
  15   */
  16  abstract class HTMLPurifier_Injector
  17  {
  18  
  19      /**
  20       * Advisory name of injector, this is for friendly error messages.
  21       * @type string
  22       */
  23      public $name;
  24  
  25      /**
  26       * @type HTMLPurifier_HTMLDefinition
  27       */
  28      protected $htmlDefinition;
  29  
  30      /**
  31       * Reference to CurrentNesting variable in Context. This is an array
  32       * list of tokens that we are currently "inside"
  33       * @type array
  34       */
  35      protected $currentNesting;
  36  
  37      /**
  38       * Reference to current token.
  39       * @type HTMLPurifier_Token
  40       */
  41      protected $currentToken;
  42  
  43      /**
  44       * Reference to InputZipper variable in Context.
  45       * @type HTMLPurifier_Zipper
  46       */
  47      protected $inputZipper;
  48  
  49      /**
  50       * Array of elements and attributes this injector creates and therefore
  51       * need to be allowed by the definition. Takes form of
  52       * array('element' => array('attr', 'attr2'), 'element2')
  53       * @type array
  54       */
  55      public $needed = array();
  56  
  57      /**
  58       * Number of elements to rewind backwards (relative).
  59       * @type bool|int
  60       */
  61      protected $rewindOffset = false;
  62  
  63      /**
  64       * Rewind to a spot to re-perform processing. This is useful if you
  65       * deleted a node, and now need to see if this change affected any
  66       * earlier nodes. Rewinding does not affect other injectors, and can
  67       * result in infinite loops if not used carefully.
  68       * @param bool|int $offset
  69       * @warning HTML Purifier will prevent you from fast-forwarding with this
  70       *          function.
  71       */
  72      public function rewindOffset($offset)
  73      {
  74          $this->rewindOffset = $offset;
  75      }
  76  
  77      /**
  78       * Retrieves rewind offset, and then unsets it.
  79       * @return bool|int
  80       */
  81      public function getRewindOffset()
  82      {
  83          $r = $this->rewindOffset;
  84          $this->rewindOffset = false;
  85          return $r;
  86      }
  87  
  88      /**
  89       * Prepares the injector by giving it the config and context objects:
  90       * this allows references to important variables to be made within
  91       * the injector. This function also checks if the HTML environment
  92       * will work with the Injector (see checkNeeded()).
  93       * @param HTMLPurifier_Config $config
  94       * @param HTMLPurifier_Context $context
  95       * @return bool|string Boolean false if success, string of missing needed element/attribute if failure
  96       */
  97      public function prepare($config, $context)
  98      {
  99          $this->htmlDefinition = $config->getHTMLDefinition();
 100          // Even though this might fail, some unit tests ignore this and
 101          // still test checkNeeded, so be careful. Maybe get rid of that
 102          // dependency.
 103          $result = $this->checkNeeded($config);
 104          if ($result !== false) {
 105              return $result;
 106          }
 107          $this->currentNesting =& $context->get('CurrentNesting');
 108          $this->currentToken   =& $context->get('CurrentToken');
 109          $this->inputZipper    =& $context->get('InputZipper');
 110          return false;
 111      }
 112  
 113      /**
 114       * This function checks if the HTML environment
 115       * will work with the Injector: if p tags are not allowed, the
 116       * Auto-Paragraphing injector should not be enabled.
 117       * @param HTMLPurifier_Config $config
 118       * @return bool|string Boolean false if success, string of missing needed element/attribute if failure
 119       */
 120      public function checkNeeded($config)
 121      {
 122          $def = $config->getHTMLDefinition();
 123          foreach ($this->needed as $element => $attributes) {
 124              if (is_int($element)) {
 125                  $element = $attributes;
 126              }
 127              if (!isset($def->info[$element])) {
 128                  return $element;
 129              }
 130              if (!is_array($attributes)) {
 131                  continue;
 132              }
 133              foreach ($attributes as $name) {
 134                  if (!isset($def->info[$element]->attr[$name])) {
 135                      return "$element.$name";
 136                  }
 137              }
 138          }
 139          return false;
 140      }
 141  
 142      /**
 143       * Tests if the context node allows a certain element
 144       * @param string $name Name of element to test for
 145       * @return bool True if element is allowed, false if it is not
 146       */
 147      public function allowsElement($name)
 148      {
 149          if (!empty($this->currentNesting)) {
 150              $parent_token = array_pop($this->currentNesting);
 151              $this->currentNesting[] = $parent_token;
 152              $parent = $this->htmlDefinition->info[$parent_token->name];
 153          } else {
 154              $parent = $this->htmlDefinition->info_parent_def;
 155          }
 156          if (!isset($parent->child->elements[$name]) || isset($parent->excludes[$name])) {
 157              return false;
 158          }
 159          // check for exclusion
 160          for ($i = count($this->currentNesting) - 2; $i >= 0; $i--) {
 161              $node = $this->currentNesting[$i];
 162              $def  = $this->htmlDefinition->info[$node->name];
 163              if (isset($def->excludes[$name])) {
 164                  return false;
 165              }
 166          }
 167          return true;
 168      }
 169  
 170      /**
 171       * Iterator function, which starts with the next token and continues until
 172       * you reach the end of the input tokens.
 173       * @warning Please prevent previous references from interfering with this
 174       *          functions by setting $i = null beforehand!
 175       * @param int $i Current integer index variable for inputTokens
 176       * @param HTMLPurifier_Token $current Current token variable.
 177       *          Do NOT use $token, as that variable is also a reference
 178       * @return bool
 179       */
 180      protected function forward(&$i, &$current)
 181      {
 182          if ($i === null) {
 183              $i = count($this->inputZipper->back) - 1;
 184          } else {
 185              $i--;
 186          }
 187          if ($i < 0) {
 188              return false;
 189          }
 190          $current = $this->inputZipper->back[$i];
 191          return true;
 192      }
 193  
 194      /**
 195       * Similar to _forward, but accepts a third parameter $nesting (which
 196       * should be initialized at 0) and stops when we hit the end tag
 197       * for the node $this->inputIndex starts in.
 198       * @param int $i Current integer index variable for inputTokens
 199       * @param HTMLPurifier_Token $current Current token variable.
 200       *          Do NOT use $token, as that variable is also a reference
 201       * @param int $nesting
 202       * @return bool
 203       */
 204      protected function forwardUntilEndToken(&$i, &$current, &$nesting)
 205      {
 206          $result = $this->forward($i, $current);
 207          if (!$result) {
 208              return false;
 209          }
 210          if ($nesting === null) {
 211              $nesting = 0;
 212          }
 213          if ($current instanceof HTMLPurifier_Token_Start) {
 214              $nesting++;
 215          } elseif ($current instanceof HTMLPurifier_Token_End) {
 216              if ($nesting <= 0) {
 217                  return false;
 218              }
 219              $nesting--;
 220          }
 221          return true;
 222      }
 223  
 224      /**
 225       * Iterator function, starts with the previous token and continues until
 226       * you reach the beginning of input tokens.
 227       * @warning Please prevent previous references from interfering with this
 228       *          functions by setting $i = null beforehand!
 229       * @param int $i Current integer index variable for inputTokens
 230       * @param HTMLPurifier_Token $current Current token variable.
 231       *          Do NOT use $token, as that variable is also a reference
 232       * @return bool
 233       */
 234      protected function backward(&$i, &$current)
 235      {
 236          if ($i === null) {
 237              $i = count($this->inputZipper->front) - 1;
 238          } else {
 239              $i--;
 240          }
 241          if ($i < 0) {
 242              return false;
 243          }
 244          $current = $this->inputZipper->front[$i];
 245          return true;
 246      }
 247  
 248      /**
 249       * Handler that is called when a text token is processed
 250       */
 251      public function handleText(&$token)
 252      {
 253      }
 254  
 255      /**
 256       * Handler that is called when a start or empty token is processed
 257       */
 258      public function handleElement(&$token)
 259      {
 260      }
 261  
 262      /**
 263       * Handler that is called when an end token is processed
 264       */
 265      public function handleEnd(&$token)
 266      {
 267          $this->notifyEnd($token);
 268      }
 269  
 270      /**
 271       * Notifier that is called when an end token is processed
 272       * @param HTMLPurifier_Token $token Current token variable.
 273       * @note This differs from handlers in that the token is read-only
 274       * @deprecated
 275       */
 276      public function notifyEnd($token)
 277      {
 278      }
 279  }
 280  
 281  // vim: et sw=4 sts=4