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processExtends.php
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processExtends.php
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<?php
/**
* @private
*/
class Less_Visitor_processExtends extends Less_Visitor {
public $allExtendsStack;
/**
* @param Less_Tree_Ruleset $root
*/
public function run( $root ) {
$extendFinder = new Less_Visitor_extendFinder();
$extendFinder->run( $root );
if ( !$extendFinder->foundExtends ) {
return $root;
}
$root->allExtends = $this->doExtendChaining( $root->allExtends, $root->allExtends );
$this->allExtendsStack = [];
$this->allExtendsStack[] = &$root->allExtends;
return $this->visitObj( $root );
}
private function doExtendChaining( $extendsList, $extendsListTarget, $iterationCount = 0 ) {
//
// chaining is different from normal extension.. if we extend an extend then we are not just copying, altering and pasting
// the selector we would do normally, but we are also adding an extend with the same target selector
// this means this new extend can then go and alter other extends
//
// this method deals with all the chaining work - without it, extend is flat and doesn't work on other extend selectors
// this is also the most expensive.. and a match on one selector can cause an extension of a selector we had already processed if
// we look at each selector at a time, as is done in visitRuleset
$extendsToAdd = [];
// loop through comparing every extend with every target extend.
// a target extend is the one on the ruleset we are looking at copy/edit/pasting in place
// e.g. .a:extend(.b) {} and .b:extend(.c) {} then the first extend extends the second one
// and the second is the target.
// the separation into two lists allows us to process a subset of chains with a bigger set, as is the
// case when processing media queries
for ( $extendIndex = 0, $extendsList_len = count( $extendsList ); $extendIndex < $extendsList_len; $extendIndex++ ) {
for ( $targetExtendIndex = 0; $targetExtendIndex < count( $extendsListTarget ); $targetExtendIndex++ ) {
$extend = $extendsList[$extendIndex];
$targetExtend = $extendsListTarget[$targetExtendIndex];
// Optimisation: Explicit reference, <https://github.com/wikimedia/less.php/pull/14>
if ( \array_key_exists( $targetExtend->object_id, $extend->parent_ids ) ) {
// ignore circular references
continue;
}
// find a match in the target extends self selector (the bit before :extend)
$selectorPath = [ $targetExtend->selfSelectors[0] ];
$matches = $this->findMatch( $extend, $selectorPath );
if ( $matches ) {
// we found a match, so for each self selector..
foreach ( $extend->selfSelectors as $selfSelector ) {
// process the extend as usual
$newSelector = $this->extendSelector( $matches, $selectorPath, $selfSelector );
// but now we create a new extend from it
$newExtend = new Less_Tree_Extend( $targetExtend->selector, $targetExtend->option, 0 );
$newExtend->selfSelectors = $newSelector;
// add the extend onto the list of extends for that selector
end( $newSelector )->extendList = [ $newExtend ];
// $newSelector[ count($newSelector)-1]->extendList = array($newExtend);
// record that we need to add it.
$extendsToAdd[] = $newExtend;
$newExtend->ruleset = $targetExtend->ruleset;
// remember its parents for circular references
$newExtend->parent_ids = array_merge( $newExtend->parent_ids, $targetExtend->parent_ids, $extend->parent_ids );
// only process the selector once.. if we have :extend(.a,.b) then multiple
// extends will look at the same selector path, so when extending
// we know that any others will be duplicates in terms of what is added to the css
if ( $targetExtend->firstExtendOnThisSelectorPath ) {
$newExtend->firstExtendOnThisSelectorPath = true;
$targetExtend->ruleset->paths[] = $newSelector;
}
}
}
}
}
if ( $extendsToAdd ) {
// try to detect circular references to stop a stack overflow.
// may no longer be needed. $this->extendChainCount++;
if ( $iterationCount > 100 ) {
try {
$selectorOne = $extendsToAdd[0]->selfSelectors[0]->toCSS();
$selectorTwo = $extendsToAdd[0]->selector->toCSS();
} catch ( Exception $e ) {
$selectorOne = "{unable to calculate}";
$selectorTwo = "{unable to calculate}";
}
throw new Less_Exception_Parser( "extend circular reference detected. One of the circular extends is currently:" . $selectorOne . ":extend(" . $selectorTwo . ")" );
}
// now process the new extends on the existing rules so that we can handle a extending b extending c ectending d extending e...
$extendsToAdd = $this->doExtendChaining( $extendsToAdd, $extendsListTarget, $iterationCount + 1 );
}
return array_merge( $extendsList, $extendsToAdd );
}
protected function visitDeclaration( $declNode, &$visitDeeper ) {
$visitDeeper = false;
}
protected function visitMixinDefinition( $mixinDefinitionNode, &$visitDeeper ) {
$visitDeeper = false;
}
protected function visitSelector( $selectorNode, &$visitDeeper ) {
$visitDeeper = false;
}
protected function visitRuleset( $rulesetNode ) {
if ( $rulesetNode->root ) {
return;
}
$allExtends = end( $this->allExtendsStack );
$paths_len = count( $rulesetNode->paths );
// look at each selector path in the ruleset, find any extend matches and then copy, find and replace
foreach ( $allExtends as $allExtend ) {
for ( $pathIndex = 0; $pathIndex < $paths_len; $pathIndex++ ) {
// extending extends happens initially, before the main pass
if ( isset( $rulesetNode->extendOnEveryPath ) && $rulesetNode->extendOnEveryPath ) {
continue;
}
$selectorPath = $rulesetNode->paths[$pathIndex];
if ( end( $selectorPath )->extendList ) {
continue;
}
$this->ExtendMatch( $rulesetNode, $allExtend, $selectorPath );
}
}
}
private function ExtendMatch( $rulesetNode, $extend, $selectorPath ) {
$matches = $this->findMatch( $extend, $selectorPath );
if ( $matches ) {
foreach ( $extend->selfSelectors as $selfSelector ) {
$rulesetNode->paths[] = $this->extendSelector( $matches, $selectorPath, $selfSelector );
}
}
}
/**
* @param Less_Tree_Extend $extend
* @param Less_Tree_Selector[] $haystackSelectorPath
* @return false|array<array{index:int,initialCombinator:string}>
*/
private function findMatch( $extend, $haystackSelectorPath ) {
if ( !$this->HasMatches( $extend, $haystackSelectorPath ) ) {
return false;
}
//
// look through the haystack selector path to try and find the needle - extend.selector
// returns an array of selector matches that can then be replaced
//
$needleElements = $extend->selector->elements;
$potentialMatches = [];
$potentialMatches_len = 0;
$potentialMatch = null;
$matches = [];
// loop through the haystack elements
$haystack_path_len = count( $haystackSelectorPath );
for ( $haystackSelectorIndex = 0; $haystackSelectorIndex < $haystack_path_len; $haystackSelectorIndex++ ) {
$hackstackSelector = $haystackSelectorPath[$haystackSelectorIndex];
$haystack_elements_len = count( $hackstackSelector->elements );
for ( $hackstackElementIndex = 0; $hackstackElementIndex < $haystack_elements_len; $hackstackElementIndex++ ) {
$haystackElement = $hackstackSelector->elements[$hackstackElementIndex];
// if we allow elements before our match we can add a potential match every time. otherwise only at the first element.
if ( $extend->allowBefore || ( $haystackSelectorIndex === 0 && $hackstackElementIndex === 0 ) ) {
$potentialMatches[] = [ 'pathIndex' => $haystackSelectorIndex, 'index' => $hackstackElementIndex, 'matched' => 0, 'initialCombinator' => $haystackElement->combinator ];
$potentialMatches_len++;
}
for ( $i = 0; $i < $potentialMatches_len; $i++ ) {
$potentialMatch = &$potentialMatches[$i];
$potentialMatch = $this->PotentialMatch( $potentialMatch, $needleElements, $haystackElement, $hackstackElementIndex );
// if we are still valid and have finished, test whether we have elements after and whether these are allowed
if ( $potentialMatch && $potentialMatch['matched'] === $extend->selector->elements_len ) {
$potentialMatch['finished'] = true;
if ( !$extend->allowAfter && ( $hackstackElementIndex + 1 < $haystack_elements_len || $haystackSelectorIndex + 1 < $haystack_path_len ) ) {
$potentialMatch = null;
}
}
// if null we remove, if not, we are still valid, so either push as a valid match or continue
if ( $potentialMatch ) {
if ( $potentialMatch['finished'] ) {
$potentialMatch['length'] = $extend->selector->elements_len;
$potentialMatch['endPathIndex'] = $haystackSelectorIndex;
$potentialMatch['endPathElementIndex'] = $hackstackElementIndex + 1; // index after end of match
$potentialMatches = []; // we don't allow matches to overlap, so start matching again
$potentialMatches_len = 0;
$matches[] = $potentialMatch;
}
continue;
}
array_splice( $potentialMatches, $i, 1 );
$potentialMatches_len--;
$i--;
}
}
}
return $matches;
}
// Before going through all the nested loops, lets check to see if a match is possible
// Reduces Bootstrap 3.1 compile time from ~6.5s to ~5.6s
private function HasMatches( $extend, $haystackSelectorPath ) {
if ( !$extend->selector->cacheable ) {
return true;
}
$first_el = $extend->selector->_oelements[0];
foreach ( $haystackSelectorPath as $hackstackSelector ) {
if ( !$hackstackSelector->cacheable ) {
return true;
}
// Optimisation: Explicit reference, <https://github.com/wikimedia/less.php/pull/14>
if ( \array_key_exists( $first_el, $hackstackSelector->_oelements_assoc ) ) {
return true;
}
}
return false;
}
/**
* @param array $potentialMatch
* @param Less_Tree_Element[] $needleElements
* @param Less_Tree_Element $haystackElement
* @param int $hackstackElementIndex
*/
private function PotentialMatch( $potentialMatch, $needleElements, $haystackElement, $hackstackElementIndex ) {
if ( $potentialMatch['matched'] > 0 ) {
// selectors add " " onto the first element. When we use & it joins the selectors together, but if we don't
// then each selector in haystackSelectorPath has a space before it added in the toCSS phase. so we need to work out
// what the resulting combinator will be
$targetCombinator = $haystackElement->combinator;
if ( $targetCombinator === '' && $hackstackElementIndex === 0 ) {
$targetCombinator = ' ';
}
if ( $needleElements[ $potentialMatch['matched'] ]->combinator !== $targetCombinator ) {
return null;
}
}
// if we don't match, null our match to indicate failure
if ( !$this->isElementValuesEqual( $needleElements[$potentialMatch['matched'] ]->value, $haystackElement->value ) ) {
return null;
}
$potentialMatch['finished'] = false;
$potentialMatch['matched']++;
return $potentialMatch;
}
/**
* @param string|Less_Tree_Attribute|Less_Tree_Dimension|Less_Tree_Keyword $elementValue1
* @param string|Less_Tree_Attribute|Less_Tree_Dimension|Less_Tree_Keyword $elementValue2
* @return bool
*/
private function isElementValuesEqual( $elementValue1, $elementValue2 ) {
if ( $elementValue1 === $elementValue2 ) {
return true;
}
if ( is_string( $elementValue1 ) || is_string( $elementValue2 ) ) {
return false;
}
if ( $elementValue1 instanceof Less_Tree_Attribute ) {
return $this->isAttributeValuesEqual( $elementValue1, $elementValue2 );
}
$elementValue1 = $elementValue1->value;
if ( $elementValue1 instanceof Less_Tree_Selector ) {
return $this->isSelectorValuesEqual( $elementValue1, $elementValue2 );
}
return false;
}
/**
* @param Less_Tree_Selector $elementValue1
*/
private function isSelectorValuesEqual( $elementValue1, $elementValue2 ) {
$elementValue2 = $elementValue2->value;
if ( !( $elementValue2 instanceof Less_Tree_Selector ) || $elementValue1->elements_len !== $elementValue2->elements_len ) {
return false;
}
for ( $i = 0; $i < $elementValue1->elements_len; $i++ ) {
if ( $elementValue1->elements[$i]->combinator !== $elementValue2->elements[$i]->combinator ) {
if ( $i !== 0 || ( $elementValue1->elements[$i]->combinator || ' ' ) !== ( $elementValue2->elements[$i]->combinator || ' ' ) ) {
return false;
}
}
if ( !$this->isElementValuesEqual( $elementValue1->elements[$i]->value, $elementValue2->elements[$i]->value ) ) {
return false;
}
}
return true;
}
/**
* @param Less_Tree_Attribute $elementValue1
*/
private function isAttributeValuesEqual( $elementValue1, $elementValue2 ) {
if ( $elementValue1->op !== $elementValue2->op || $elementValue1->key !== $elementValue2->key ) {
return false;
}
if ( !$elementValue1->value || !$elementValue2->value ) {
if ( $elementValue1->value || $elementValue2->value ) {
return false;
}
return true;
}
$elementValue1 = $elementValue1->value;
if ( $elementValue1 instanceof Less_Tree_Quoted ) {
$elementValue1 = $elementValue1->value;
}
$elementValue2 = $elementValue2->value;
if ( $elementValue2 instanceof Less_Tree_Quoted ) {
$elementValue2 = $elementValue2->value;
}
return $elementValue1 === $elementValue2;
}
private function extendSelector( $matches, $selectorPath, $replacementSelector ) {
// for a set of matches, replace each match with the replacement selector
$currentSelectorPathIndex = 0;
$currentSelectorPathElementIndex = 0;
$path = [];
$selectorPath_len = count( $selectorPath );
for ( $matchIndex = 0, $matches_len = count( $matches ); $matchIndex < $matches_len; $matchIndex++ ) {
$match = $matches[$matchIndex];
$selector = $selectorPath[ $match['pathIndex'] ];
$firstElement = new Less_Tree_Element(
$match['initialCombinator'],
$replacementSelector->elements[0]->value,
$replacementSelector->elements[0]->index,
$replacementSelector->elements[0]->currentFileInfo
);
if ( $match['pathIndex'] > $currentSelectorPathIndex && $currentSelectorPathElementIndex > 0 ) {
$last_path = end( $path );
$last_path->elements = array_merge( $last_path->elements, array_slice( $selectorPath[$currentSelectorPathIndex]->elements, $currentSelectorPathElementIndex ) );
$currentSelectorPathElementIndex = 0;
$currentSelectorPathIndex++;
}
$newElements = array_merge(
array_slice(
$selector->elements,
$currentSelectorPathElementIndex,
// last parameter of array_slice is different than the last parameter of javascript's slice
$match['index'] - $currentSelectorPathElementIndex
),
[ $firstElement ],
array_slice( $replacementSelector->elements, 1 )
);
if ( $currentSelectorPathIndex === $match['pathIndex'] && $matchIndex > 0 ) {
$last_key = count( $path ) - 1;
$path[$last_key]->elements = array_merge( $path[$last_key]->elements, $newElements );
} else {
$path = array_merge( $path, array_slice( $selectorPath, $currentSelectorPathIndex, $match['pathIndex'] ) );
$path[] = new Less_Tree_Selector( $newElements );
}
$currentSelectorPathIndex = $match['endPathIndex'];
$currentSelectorPathElementIndex = $match['endPathElementIndex'];
if ( $currentSelectorPathElementIndex >= count( $selectorPath[$currentSelectorPathIndex]->elements ) ) {
$currentSelectorPathElementIndex = 0;
$currentSelectorPathIndex++;
}
}
if ( $currentSelectorPathIndex < $selectorPath_len && $currentSelectorPathElementIndex > 0 ) {
$last_path = end( $path );
$last_path->elements = array_merge( $last_path->elements, array_slice( $selectorPath[$currentSelectorPathIndex]->elements, $currentSelectorPathElementIndex ) );
$currentSelectorPathIndex++;
}
$slice_len = $selectorPath_len - $currentSelectorPathIndex;
$path = array_merge( $path, array_slice( $selectorPath, $currentSelectorPathIndex, $slice_len ) );
return $path;
}
protected function visitMedia( $mediaNode ) {
$newAllExtends = array_merge( $mediaNode->allExtends, end( $this->allExtendsStack ) );
$this->allExtendsStack[] = $this->doExtendChaining( $newAllExtends, $mediaNode->allExtends );
}
protected function visitMediaOut() {
array_pop( $this->allExtendsStack );
}
protected function visitAtRule( $atRuleNode ) {
$newAllExtends = array_merge( $atRuleNode->allExtends, end( $this->allExtendsStack ) );
$this->allExtendsStack[] = $this->doExtendChaining( $newAllExtends, $atRuleNode->allExtends );
}
protected function visitAtRuleOut() {
array_pop( $this->allExtendsStack );
}
}

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