From 93a2fdec953e596640eda3821c99c97027b59052 Mon Sep 17 00:00:00 2001
From: Andrey Legayev <andrey@ven.com>
Date: Fri, 20 Mar 2020 01:07:26 +0200
Subject: [PATCH] ProcessExtends: Use map instead of list for selectors and
 parents

* Convert Less\Tree\Extend#parent_ids from a list to a map.

* Maintain a copy of Less\Tree\Selector#_oelements list in map form.
  Keep the list as well for now because there is a logical order to this
  information, which callers outside ProcessExtends depend on.

These change bring an performance improvement.
About 4% speedup for Magento2.

Co-authored-by: Timo Tijhof <krinklemail@gmail.com>
---
 lib/Less/Tree/Extend.php            | 11 ++++++++---
 lib/Less/Tree/Selector.php          |  5 +++++
 lib/Less/Visitor/processExtends.php | 10 ++++++----
 test/index.php                      |  2 +-
 4 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/lib/Less/Tree/Extend.php b/lib/Less/Tree/Extend.php
index 8f21e939..c08a2a96 100644
--- a/lib/Less/Tree/Extend.php
+++ b/lib/Less/Tree/Extend.php
@@ -42,8 +42,13 @@ public function __construct($selector, $option, $index){
 			break;
 		}
 
-		$this->object_id = $i++;
-		$this->parent_ids = array($this->object_id);
+		// This must use a string (instead of int) so that array_merge()
+		// preserves keys on arrays that use IDs in their keys.
+		$this->object_id = 'id_' . $i++;
+
+		$this->parent_ids = array(
+			$this->object_id => true
+		);
 	}
 
     public function accept( $visitor ){
@@ -74,4 +79,4 @@ public function findSelfSelectors( $selectors ){
 		$this->selfSelectors = array(new Less_Tree_Selector($selfElements));
 	}
 
-}
\ No newline at end of file
+}
diff --git a/lib/Less/Tree/Selector.php b/lib/Less/Tree/Selector.php
index 6b9dae61..6625fb8a 100644
--- a/lib/Less/Tree/Selector.php
+++ b/lib/Less/Tree/Selector.php
@@ -22,6 +22,7 @@ class Less_Tree_Selector extends Less_Tree{
 	public $elements_len = 0;
 
 	public $_oelements;
+	public $_oelements_assoc;
 	public $_oelements_len;
 	public $cacheable = true;
 
@@ -83,6 +84,8 @@ public function match( $other ){
 	public function CacheElements(){
 
 		$this->_oelements = array();
+		$this->_oelements_assoc = array();
+
 		$css = '';
 
 		foreach($this->elements as $v){
@@ -108,6 +111,8 @@ public function CacheElements(){
 				array_shift($this->_oelements);
 				$this->_oelements_len--;
 			}
+
+			$this->_oelements_assoc = array_fill_keys($this->_oelements, true);
 		}
 	}
 
diff --git a/lib/Less/Visitor/processExtends.php b/lib/Less/Visitor/processExtends.php
index bb5f0824..3f779af5 100644
--- a/lib/Less/Visitor/processExtends.php
+++ b/lib/Less/Visitor/processExtends.php
@@ -53,8 +53,9 @@ private function doExtendChaining( $extendsList, $extendsListTarget, $iterationC
 				$extend = $extendsList[$extendIndex];
 				$targetExtend = $extendsListTarget[$targetExtendIndex];
 
-				// look for circular references
-				if( in_array($targetExtend->object_id, $extend->parent_ids,true) ){
+				// Optimisation: Explicit reference, <https://github.com/wikimedia/less.php/pull/14>
+				if( \array_key_exists($targetExtend->object_id, $extend->parent_ids) ){
+					// ignore circular references
 					continue;
 				}
 
@@ -269,7 +270,8 @@ private function HasMatches($extend, $haystackSelectorPath){
 				return true;
 			}
 
-			if( in_array($first_el, $hackstackSelector->_oelements) ){
+			// Optimisation: Explicit reference, <https://github.com/wikimedia/less.php/pull/14>
+			if( \array_key_exists($first_el, $hackstackSelector->_oelements_assoc) ){
 				return true;
 			}
 		}
@@ -466,4 +468,4 @@ protected function visitDirectiveOut(){
 		array_pop($this->allExtendsStack);
 	}
 
-}
\ No newline at end of file
+}
diff --git a/test/index.php b/test/index.php
index 2545f18c..fd76c640 100644
--- a/test/index.php
+++ b/test/index.php
@@ -690,7 +690,7 @@ function obj($mixed, $objects = array() ) {
 
 
 	$exclude_keys = array('originalRuleset','currentFileInfo','lookups','index','ruleset_id','type','_rulesets','_variables','allowImports','_css','cache_string','elements_len',
-					'_oelements','first_oelements','_oelements_len','cacheable', ); //'variable','combinator'
+					'_oelements','_oelements_assoc','first_oelements','_oelements_len','cacheable', ); //'variable','combinator'
 	//$exclude_keys = array();
 
 	$type = gettype($mixed);