optimized context access on PHP 7.4

Author: fabpot

CHANGELOG

@@ -1,6 +1,6 @@
 * 1.40.2 (2019-XX-XX)
 
- * n/a
+ * optimized context access on PHP 7.4
 
 * 1.40.1 (2019-04-29)
 

src/Node/Expression/NameExpression.php

@@ -36,13 +36,20 @@ public function compile(Compiler $compiler)
         if ($this->getAttribute('is_defined_test')) {
             if ($this->isSpecial()) {
                 $compiler->repr(true);
+            } elseif (\PHP_VERSION_ID >= 700400) {
+                $compiler
+                    ->raw('array_key_exists(')
+                    ->string($name)
+                    ->raw(', $context)')
+                ;
             } else {
                 $compiler
                     ->raw('(isset($context[')
                     ->string($name)
                     ->raw(']) || array_key_exists(')
                     ->string($name)
-                    ->raw(', $context))');
+                    ->raw(', $context))')
+                ;
             }
         } elseif ($this->isSpecial()) {
             $compiler->raw($this->specialVars[$name]);