mirror of
https://github.com/ezyang/htmlpurifier.git
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8f515b9cda
- Partially finished migrating to new Context object (done in r485). - Created HTMLPurifier_Harness to assist with testing, ChildDefTest migrated to that framework. git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@484 48356398-32a2-884e-a903-53898d9a118a
266 lines
10 KiB
PHP
266 lines
10 KiB
PHP
<?php
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require_once 'HTMLPurifier/Strategy.php';
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require_once 'HTMLPurifier/HTMLDefinition.php';
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/**
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* Takes a well formed list of tokens and fixes their nesting.
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*
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* HTML elements dictate which elements are allowed to be their children,
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* for example, you can't have a p tag in a span tag. Other elements have
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* much more rigorous definitions: tables, for instance, require a specific
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* order for their elements. There are also constraints not expressible by
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* document type definitions, such as the chameleon nature of ins/del
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* tags and global child exclusions.
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*
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* The first major objective of this strategy is to iterate through all the
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* nodes (not tokens) of the list of tokens and determine whether or not
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* their children conform to the element's definition. If they do not, the
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* child definition may optionally supply an amended list of elements that
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* is valid or require that the entire node be deleted (and the previous
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* node rescanned).
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*
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* The second objective is to ensure that explicitly excluded elements of
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* an element do not appear in its children. Code that accomplishes this
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* task is pervasive through the strategy, though the two are distinct tasks
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* and could, theoretically, be seperated (although it's not recommended).
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*
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* @note Whether or not unrecognized children are silently dropped or
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* translated into text depends on the child definitions.
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*
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* @todo Enable nodes to be bubbled out of the structure.
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*/
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class HTMLPurifier_Strategy_FixNesting extends HTMLPurifier_Strategy
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{
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function execute($tokens, $config, &$context) {
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//####################################################################//
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// Pre-processing
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// get a copy of the HTML definition
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$definition = $config->getHTMLDefinition();
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// insert implicit "parent" node, will be removed at end.
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// ! we might want to move this to configuration
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// DEFINITION CALL
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$parent_name = $definition->info_parent;
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array_unshift($tokens, new HTMLPurifier_Token_Start($parent_name));
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$tokens[] = new HTMLPurifier_Token_End($parent_name);
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// setup the context variables
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$parent_type = 'unknown'; // reference var that we alter
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$context->register('ParentType', $parent_type);
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//####################################################################//
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// Loop initialization
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// stack that contains the indexes of all parents,
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// $stack[count($stack)-1] being the current parent
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$stack = array();
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// stack that contains all elements that are excluded
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// same structure as $stack, but it is only populated when an element
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// with exclusions is processed, i.e. there won't be empty exclusions.
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$exclude_stack = array();
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//####################################################################//
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// Loop
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// iterate through all start nodes. Determining the start node
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// is complicated so it has been omitted from the loop construct
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for ($i = 0, $size = count($tokens) ; $i < $size; ) {
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//################################################################//
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// Gather information on children
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// child token accumulator
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$child_tokens = array();
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// scroll to the end of this node, report number, and collect
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// all children
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for ($j = $i, $depth = 0; ; $j++) {
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if ($tokens[$j]->type == 'start') {
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$depth++;
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// skip token assignment on first iteration, this is the
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// token we currently are on
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if ($depth == 1) continue;
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} elseif ($tokens[$j]->type == 'end') {
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$depth--;
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// skip token assignment on last iteration, this is the
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// end token of the token we're currently on
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if ($depth == 0) break;
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}
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$child_tokens[] = $tokens[$j];
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}
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// $i is index of start token
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// $j is index of end token
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//################################################################//
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// Gather information on parent
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// calculate parent information
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if ($count = count($stack)) {
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$parent_index = $stack[$count-1];
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$parent_name = $tokens[$parent_index]->name;
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$parent_def = $definition->info[$parent_name];
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} else {
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// unknown info, it won't be used anyway
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$parent_index = $parent_name = $parent_def = null;
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}
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// calculate context
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if (isset($parent_def)) {
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$parent_type = $parent_def->type;
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} else {
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// generally found in specialized elements like UL
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$parent_type = 'unknown';
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}
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//################################################################//
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// Determine whether element is explicitly excluded SGML-style
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// determine whether or not element is excluded by checking all
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// parent exclusions. The array should not be very large, two
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// elements at most.
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$excluded = false;
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if (!empty($exclude_stack)) {
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foreach ($exclude_stack as $lookup) {
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if (isset($lookup[$tokens[$i]->name])) {
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$excluded = true;
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// no need to continue processing
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break;
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}
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}
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}
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//################################################################//
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// Perform child validation
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if ($excluded) {
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// there is an exclusion, remove the entire node
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$result = false;
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} else {
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// DEFINITION CALL
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$def = $definition->info[$tokens[$i]->name];
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$child_def = $def->child;
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// have DTD child def validate children
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$result = $child_def->validateChildren(
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$child_tokens, $config, $context);
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// determine whether or not this element has any exclusions
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$excludes = $def->excludes;
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}
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// $result is now a bool or array
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//################################################################//
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// Process result by interpreting $result
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if ($result === true) {
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// leave the node as is
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// register start token as a parental node start
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$stack[] = $i;
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// register exclusions if there are any
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if (!empty($excludes)) $exclude_stack[] = $excludes;
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// move cursor to next possible start node
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$i++;
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} elseif($result === false) {
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// remove entire node
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// calculate length of inner tokens and current tokens
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$length = $j - $i + 1;
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// perform removal
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array_splice($tokens, $i, $length);
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// update size
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$size -= $length;
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// there is no start token to register,
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// current node is now the next possible start node
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// unless it turns out that we need to do a double-check
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if (!$parent_def->child->allow_empty) {
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// we need to do a double-check
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$i = $parent_index;
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array_pop($stack);
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}
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// PROJECTED OPTIMIZATION: Process all children elements before
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// reprocessing parent node.
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} else {
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// replace node with $result
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// calculate length of inner tokens
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$length = $j - $i - 1;
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// perform replacement
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array_splice($tokens, $i + 1, $length, $result);
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// update size
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$size -= $length;
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$size += count($result);
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// register start token as a parental node start
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$stack[] = $i;
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// register exclusions if there are any
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if (!empty($excludes)) $exclude_stack[] = $excludes;
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// move cursor to next possible start node
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$i++;
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}
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//################################################################//
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// Scroll to next start node
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// We assume, at this point, that $i is the index of the token
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// that is the first possible new start point for a node.
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// Test if the token indeed is a start tag, if not, move forward
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// and test again.
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while ($i < $size and $tokens[$i]->type != 'start') {
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if ($tokens[$i]->type == 'end') {
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// pop a token index off the stack if we ended a node
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array_pop($stack);
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// pop an exclusion lookup off exclusion stack if
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// we ended node and that node had exclusions
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if ($definition->info[$tokens[$i]->name]->excludes) {
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array_pop($exclude_stack);
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}
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}
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$i++;
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}
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}
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//####################################################################//
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// Post-processing
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// remove implicit parent tokens at the beginning and end
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array_shift($tokens);
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array_pop($tokens);
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// remove context variables
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$context->destroy('ParentType');
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//####################################################################//
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// Return
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return $tokens;
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}
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}
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?>
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