PHP 8.0 | Tokenizer/PHP: efficiency tweaks

This PR contains two separate, small efficiency tweaks for the `match` expression retokenization.

1. The tokenizer was walking backwards in the `match` backfill, while it could have just used `$finalTokens[$lastNotEmptyToken]` to get the last non-empty token.
2. There was some redundancy in the tokens which were being checked for the token "before".
    For tokens like, `T_CLASS` and `T_CONST`, the next token after the `match` keyword could never be an open parenthesis, so they would already be marked as "not match".

Includes additional tests.
Additionally, when I initially started the work on backfilling `match` expressions, the nullsafe object operator had not yet been backfilled, so there was not test covering that case. Added now just to be on the safe side.

Note: all extra tests would already pass prior to this change. These are just extra safeguards.

src/Tokenizers/PHP.php

@@ -1288,33 +1288,22 @@ protected function tokenize($string)
                         break;
                     }
 
-                    // Next was an open parenthesis, now check what is before the match keyword.
-                    for ($y = ($stackPtr - 1); $y >= 0; $y--) {
-                        if (is_array($tokens[$y]) === true
-                            && isset(Util\Tokens::$emptyTokens[$tokens[$y][0]]) === true
-                        ) {
-                            continue;
-                        }
+                    $notMatchContext = [
+                        T_PAAMAYIM_NEKUDOTAYIM     => true,
+                        T_OBJECT_OPERATOR          => true,
+                        T_NULLSAFE_OBJECT_OPERATOR => true,
+                        T_NS_SEPARATOR             => true,
+                        T_NEW                      => true,
+                        T_FUNCTION                 => true,
+                    ];
 
-                        if (is_array($tokens[$y]) === true
-                            && ($tokens[$y][0] === T_PAAMAYIM_NEKUDOTAYIM
-                            || $tokens[$y][0] === T_OBJECT_OPERATOR
-                            || $tokens[$y][0] === T_NS_SEPARATOR
-                            || $tokens[$y][0] === T_NEW
-                            || $tokens[$y][0] === T_FUNCTION
-                            || $tokens[$y][0] === T_CLASS
-                            || $tokens[$y][0] === T_INTERFACE
-                            || $tokens[$y][0] === T_TRAIT
-                            || $tokens[$y][0] === T_NAMESPACE
-                            || $tokens[$y][0] === T_CONST)
-                        ) {
-                            // This is not a match expression.
-                            break 2;
-                        }
+                    if (isset($notMatchContext[$finalTokens[$lastNotEmptyToken]['code']]) === true) {
+                        // Also not a match expression.
+                        break;
+                    }
 
-                        $isMatch = true;
-                        break 2;
-                    }//end for
+                    $isMatch = true;
+                    break;
                 }//end for
 
                 if ($isMatch === true && $token[0] === T_STRING) {

tests/Core/Tokenizer/BackfillMatchTokenTest.inc

@@ -220,7 +220,7 @@ $a = MyClass::Match[$a];
 $a = $obj->match($param);
 
 /* testNoMatchMethodCallUpper */
-$a = $obj->MATCH()->chain($param);
+$a = $obj??->MATCH()->chain($param);
 
 /* testNoMatchPropertyAccess */
 $a = $obj->match;
@@ -282,6 +282,18 @@ function match() {}
 // Intentional fatal error. Match is now a reserved keyword.
 namespace Match {}
 
+/* testNoMatchExtendedClassDeclaration */
+// Intentional fatal error. Match is now a reserved keyword.
+class Foo extends Match {}
+
+/* testNoMatchImplementedClassDeclaration */
+// Intentional fatal error. Match is now a reserved keyword.
+class Bar implements Match {}
+
+/* testNoMatchInUseStatement */
+// Intentional fatal error in PHP < 8. Match is now a reserved keyword.
+use Match\me;
+
 function brokenMatchNoCurlies($x) {
     /* testNoMatchMissingCurlies */
     // Intentional fatal error. New control structure is not supported without curly braces.

tests/Core/Tokenizer/BackfillMatchTokenTest.php

@@ -296,6 +296,18 @@ public function dataNotAMatchStructure()
                 '/* testNoMatchNamespaceDeclaration */',
                 'Match',
             ],
+            'class_extends_declaration'            => [
+                '/* testNoMatchExtendedClassDeclaration */',
+                'Match',
+            ],
+            'class_implements_declaration'         => [
+                '/* testNoMatchImplementedClassDeclaration */',
+                'Match',
+            ],
+            'use_statement'                        => [
+                '/* testNoMatchInUseStatement */',
+                'Match',
+            ],
             'unsupported_inline_control_structure' => ['/* testNoMatchMissingCurlies */'],
             'unsupported_alternative_syntax'       => ['/* testNoMatchAlternativeSyntax */'],
             'live_coding'                          => ['/* testLiveCoding */'],