mirror of
https://github.com/ezyang/htmlpurifier.git
synced 2024-11-13 00:38:42 +00:00
458 lines
18 KiB
PHP
458 lines
18 KiB
PHP
<?php
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/**
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* Takes tokens makes them well-formed (balance end tags, etc.)
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*/
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class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
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{
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/**
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* Array stream of tokens being processed.
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*/
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protected $tokens;
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/**
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* Current index in $tokens.
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*/
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protected $t;
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/**
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* Current nesting of elements.
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*/
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protected $stack;
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/**
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* Injectors active in this stream processing.
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*/
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protected $injectors;
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/**
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* Current instance of HTMLPurifier_Config.
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*/
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protected $config;
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/**
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* Current instance of HTMLPurifier_Context.
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*/
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protected $context;
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public function execute($tokens, $config, $context) {
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$definition = $config->getHTMLDefinition();
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// local variables
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$generator = new HTMLPurifier_Generator($config, $context);
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$escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
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$e = $context->get('ErrorCollector', true);
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$t = false; // token index
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$i = false; // injector index
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$token = false; // the current token
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$reprocess = false; // whether or not to reprocess the same token
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$stack = array();
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// member variables
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$this->stack =& $stack;
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$this->t =& $t;
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$this->tokens =& $tokens;
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$this->config = $config;
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$this->context = $context;
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// context variables
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$context->register('CurrentNesting', $stack);
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$context->register('InputIndex', $t);
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$context->register('InputTokens', $tokens);
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$context->register('CurrentToken', $token);
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// -- begin INJECTOR --
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$this->injectors = array();
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$injectors = $config->getBatch('AutoFormat');
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$def_injectors = $definition->info_injector;
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$custom_injectors = $injectors['Custom'];
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unset($injectors['Custom']); // special case
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foreach ($injectors as $injector => $b) {
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// XXX: Fix with a legitimate lookup table of enabled filters
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if (strpos($injector, '.') !== false) continue;
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$injector = "HTMLPurifier_Injector_$injector";
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if (!$b) continue;
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$this->injectors[] = new $injector;
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}
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foreach ($def_injectors as $injector) {
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// assumed to be objects
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$this->injectors[] = $injector;
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}
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foreach ($custom_injectors as $injector) {
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if (is_string($injector)) {
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$injector = "HTMLPurifier_Injector_$injector";
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$injector = new $injector;
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}
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$this->injectors[] = $injector;
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}
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// give the injectors references to the definition and context
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// variables for performance reasons
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foreach ($this->injectors as $ix => $injector) {
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$error = $injector->prepare($config, $context);
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if (!$error) continue;
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array_splice($this->injectors, $ix, 1); // rm the injector
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trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
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}
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// -- end INJECTOR --
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// a note on punting:
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// In order to reduce code duplication, whenever some code needs
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// to make HTML changes in order to make things "correct", the
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// new HTML gets sent through the purifier, regardless of its
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// status. This means that if we add a start token, because it
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// was totally necessary, we don't have to update nesting; we just
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// punt ($reprocess = true; continue;) and it does that for us.
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// isset is in loop because $tokens size changes during loop exec
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for (
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$t = 0;
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$t == 0 || isset($tokens[$t - 1]);
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// only increment if we don't need to reprocess
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$reprocess ? $reprocess = false : $t++
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) {
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// check for a rewind
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if (is_int($i) && $i >= 0) {
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// possibility: disable rewinding if the current token has a
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// rewind set on it already. This would offer protection from
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// infinite loop, but might hinder some advanced rewinding.
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$rewind_to = $this->injectors[$i]->getRewind();
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if (is_int($rewind_to) && $rewind_to < $t) {
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if ($rewind_to < 0) $rewind_to = 0;
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while ($t > $rewind_to) {
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$t--;
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$prev = $tokens[$t];
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// indicate that other injectors should not process this token,
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// but we need to reprocess it
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unset($prev->skip[$i]);
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$prev->rewind = $i;
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if ($prev instanceof HTMLPurifier_Token_Start) array_pop($this->stack);
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elseif ($prev instanceof HTMLPurifier_Token_End) $this->stack[] = $prev->start;
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}
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}
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$i = false;
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}
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// handle case of document end
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if (!isset($tokens[$t])) {
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// kill processing if stack is empty
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if (empty($this->stack)) break;
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// peek
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$top_nesting = array_pop($this->stack);
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$this->stack[] = $top_nesting;
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// send error
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if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
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}
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// append, don't splice, since this is the end
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$tokens[] = new HTMLPurifier_Token_End($top_nesting->name);
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// punt!
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$reprocess = true;
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continue;
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}
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$token = $tokens[$t];
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//echo '<br>'; printTokens($tokens, $t); printTokens($this->stack);
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// quick-check: if it's not a tag, no need to process
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if (empty($token->is_tag)) {
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if ($token instanceof HTMLPurifier_Token_Text) {
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) continue;
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if ($token->rewind !== null && $token->rewind !== $i) continue;
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$injector->handleText($token);
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$this->processToken($token, $i);
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$reprocess = true;
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break;
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}
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}
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// another possibility is a comment
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continue;
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}
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if (isset($definition->info[$token->name])) {
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$type = $definition->info[$token->name]->child->type;
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} else {
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$type = false; // Type is unknown, treat accordingly
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}
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// quick tag checks: anything that's *not* an end tag
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$ok = false;
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if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
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// claims to be a start tag but is empty
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$token = new HTMLPurifier_Token_Empty($token->name, $token->attr);
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$ok = true;
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} elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
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// claims to be empty but really is a start tag
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$this->swap(new HTMLPurifier_Token_End($token->name));
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$this->insertBefore(new HTMLPurifier_Token_Start($token->name, $token->attr));
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// punt (since we had to modify the input stream in a non-trivial way)
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$reprocess = true;
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continue;
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} elseif ($token instanceof HTMLPurifier_Token_Empty) {
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// real empty token
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$ok = true;
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} elseif ($token instanceof HTMLPurifier_Token_Start) {
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// start tag
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// ...unless they also have to close their parent
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if (!empty($this->stack)) {
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$parent = array_pop($this->stack);
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$this->stack[] = $parent;
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if (isset($definition->info[$parent->name])) {
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$elements = $definition->info[$parent->name]->child->getAllowedElements($config);
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$autoclose = !isset($elements[$token->name]);
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} else {
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$autoclose = false;
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}
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$carryover = false;
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if ($autoclose && $definition->info[$parent->name]->formatting) {
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$carryover = true;
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}
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if ($autoclose) {
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// errors need to be updated
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$new_token = new HTMLPurifier_Token_End($parent->name);
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$new_token->start = $parent;
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if ($carryover) {
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$element = clone $parent;
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$element->armor['MakeWellFormed_TagClosedError'] = true;
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$element->carryover = true;
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$this->processToken(array($new_token, $token, $element));
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} else {
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$this->insertBefore($new_token);
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}
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if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
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if (!$carryover) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
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} else {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
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}
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}
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$reprocess = true;
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continue;
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}
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}
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$ok = true;
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}
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if ($ok) {
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) continue;
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if ($token->rewind !== null && $token->rewind !== $i) continue;
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$injector->handleElement($token);
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$this->processToken($token, $i);
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$reprocess = true;
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break;
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}
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if (!$reprocess) {
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// ah, nothing interesting happened; do normal processing
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$this->swap($token);
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if ($token instanceof HTMLPurifier_Token_Start) {
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$this->stack[] = $token;
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} elseif ($token instanceof HTMLPurifier_Token_End) {
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throw new HTMLPurifier_Exception('Improper handling of end tag in start code; possible error in MakeWellFormed');
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}
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}
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continue;
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}
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// sanity check: we should be dealing with a closing tag
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if (!$token instanceof HTMLPurifier_Token_End) {
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throw new HTMLPurifier_Exception('Unaccounted for tag token in input stream, bug in HTML Purifier');
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}
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// make sure that we have something open
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if (empty($this->stack)) {
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if ($escape_invalid_tags) {
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if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
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$this->swap(new HTMLPurifier_Token_Text(
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$generator->generateFromToken($token)
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));
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} else {
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$this->remove();
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if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
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}
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$reprocess = true;
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continue;
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}
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// first, check for the simplest case: everything closes neatly.
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// Eventually, everything passes through here; if there are problems
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// we modify the input stream accordingly and then punt, so that
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// the tokens get processed again.
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$current_parent = array_pop($this->stack);
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if ($current_parent->name == $token->name) {
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$token->start = $current_parent;
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foreach ($this->injectors as $i => $injector) {
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if (isset($token->skip[$i])) continue;
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if ($token->rewind !== null && $token->rewind !== $i) continue;
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$injector->handleEnd($token);
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$this->processToken($token, $i);
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$this->stack[] = $current_parent;
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$reprocess = true;
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break;
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}
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continue;
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}
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// okay, so we're trying to close the wrong tag
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// undo the pop previous pop
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$this->stack[] = $current_parent;
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// scroll back the entire nest, trying to find our tag.
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// (feature could be to specify how far you'd like to go)
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$size = count($this->stack);
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// -2 because -1 is the last element, but we already checked that
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$skipped_tags = false;
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for ($j = $size - 2; $j >= 0; $j--) {
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if ($this->stack[$j]->name == $token->name) {
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$skipped_tags = array_slice($this->stack, $j);
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break;
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}
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}
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// we didn't find the tag, so remove
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if ($skipped_tags === false) {
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if ($escape_invalid_tags) {
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$this->swap(new HTMLPurifier_Token_Text(
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$generator->generateFromToken($token)
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));
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if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
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} else {
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$this->remove();
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if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
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}
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$reprocess = true;
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continue;
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}
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// do errors, in REVERSE $j order: a,b,c with </a></b></c>
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$c = count($skipped_tags);
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if ($e) {
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for ($j = $c - 1; $j > 0; $j--) {
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// notice we exclude $j == 0, i.e. the current ending tag, from
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// the errors...
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if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
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$e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
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}
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}
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}
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// insert tags, in FORWARD $j order: c,b,a with </a></b></c>
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$replace = array($token);
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for ($j = 1; $j < $c; $j++) {
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// ...as well as from the insertions
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$new_token = new HTMLPurifier_Token_End($skipped_tags[$j]->name);
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$new_token->start = $skipped_tags[$j];
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array_unshift($replace, $new_token);
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if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
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$element = clone $skipped_tags[$j];
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$element->carryover = true;
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$element->armor['MakeWellFormed_TagClosedError'] = true;
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$replace[] = $element;
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}
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}
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$this->processToken($replace);
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$reprocess = true;
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continue;
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}
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$context->destroy('CurrentNesting');
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$context->destroy('InputTokens');
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$context->destroy('InputIndex');
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$context->destroy('CurrentToken');
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unset($this->injectors, $this->stack, $this->tokens, $this->t);
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return $tokens;
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}
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/**
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* Processes arbitrary token values for complicated substitution patterns.
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* In general:
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*
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* If $token is an array, it is a list of tokens to substitute for the
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* current token. These tokens then get individually processed. If there
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* is a leading integer in the list, that integer determines how many
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* tokens from the stream should be removed.
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*
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* If $token is a regular token, it is swapped with the current token.
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*
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* If $token is false, the current token is deleted.
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*
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* If $token is an integer, that number of tokens (with the first token
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* being the current one) will be deleted.
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*
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* @param $token Token substitution value
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* @param $injector Injector that performed the substitution; default is if
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* this is not an injector related operation.
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*/
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protected function processToken($token, $injector = -1) {
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// normalize forms of token
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if (is_object($token)) $token = array(1, $token);
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if (is_int($token)) $token = array($token);
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if ($token === false) $token = array(1);
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if (!is_array($token)) throw new HTMLPurifier_Exception('Invalid token type from injector');
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if (!is_int($token[0])) array_unshift($token, 1);
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if ($token[0] === 0) throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
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// $token is now an array with the following form:
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// array(number nodes to delete, new node 1, new node 2, ...)
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$delete = array_shift($token);
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$old = array_splice($this->tokens, $this->t, $delete, $token);
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if ($injector > -1) {
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// determine appropriate skips
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$oldskip = isset($old[0]) ? $old[0]->skip : array();
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foreach ($token as $object) {
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$object->skip = $oldskip;
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$object->skip[$injector] = true;
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}
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}
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}
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/**
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* Inserts a token before the current token. Cursor now points to this token
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*/
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private function insertBefore($token) {
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array_splice($this->tokens, $this->t, 0, array($token));
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}
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/**
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* Removes current token. Cursor now points to new token occupying previously
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* occupied space.
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*/
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private function remove() {
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array_splice($this->tokens, $this->t, 1);
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}
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/**
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* Swap current token with new token. Cursor points to new token (no change).
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*/
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private function swap($token) {
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$this->tokens[$this->t] = $token;
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}
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}
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// vim: et sw=4 sts=4
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