[PHP 8.1] Add support for enums (nikic#758)

RFC: https://wiki.php.net/rfc/enumerations

Co-authored-by: Nikita Popov <nikita.ppv@gmail.com>

Author: TomasVotruba

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*.y]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 4

grammar/php7.y

@@ -28,7 +28,7 @@ reserved_non_modifiers:
     | T_FUNCTION | T_CONST | T_RETURN | T_PRINT | T_YIELD | T_LIST | T_SWITCH | T_ENDSWITCH | T_CASE | T_DEFAULT
     | T_BREAK | T_ARRAY | T_CALLABLE | T_EXTENDS | T_IMPLEMENTS | T_NAMESPACE | T_TRAIT | T_INTERFACE | T_CLASS
     | T_CLASS_C | T_TRAIT_C | T_FUNC_C | T_METHOD_C | T_LINE | T_FILE | T_DIR | T_NS_C | T_HALT_COMPILER | T_FN
-    | T_MATCH
+    | T_MATCH | T_ENUM
 ;
 
 semi_reserved:
@@ -356,6 +356,18 @@ class_declaration_statement:
             $this->checkInterface($$, #3); }
     | optional_attributes T_TRAIT identifier '{' class_statement_list '}'
           { $$ = Stmt\Trait_[$3, ['stmts' => $5, 'attrGroups' => $1]]; }
+    | optional_attributes T_ENUM identifier enum_scalar_type implements_list '{' class_statement_list '}'
+          { $$ = Stmt\Enum_[$3, ['scalarType' => $4, 'implements' => $5, 'stmts' => $7, 'attrGroups' => $1]];
+            $this->checkEnum($$, #3); }
+;
+
+enum_scalar_type:
+      /* empty */                                           { $$ = null; }
+    | ':' type                                              { $$ = $2; }
+
+enum_case_expr:
+      /* empty */                                           { $$ = null; }
+    | '=' expr                                              { $$ = $2; }
 ;
 
 class_entry_type:
@@ -637,6 +649,8 @@ class_statement:
           { $$ = Stmt\ClassMethod[$5, ['type' => $2, 'byRef' => $4, 'params' => $7, 'returnType' => $9, 'stmts' => $10, 'attrGroups' => $1]];
             $this->checkClassMethod($$, #2); }
     | T_USE class_name_list trait_adaptations               { $$ = Stmt\TraitUse[$2, $3]; }
+    | optional_attributes T_CASE identifier enum_case_expr semi
+         { $$ = Stmt\EnumCase[$3, $4, $1]; }
     | error                                                 { $$ = null; /* will be skipped */ }
 ;
 

grammar/tokens.y

@@ -83,6 +83,7 @@
 %token T_CLASS
 %token T_TRAIT
 %token T_INTERFACE
+%token T_ENUM
 %token T_EXTENDS
 %token T_IMPLEMENTS
 %token T_OBJECT_OPERATOR

lib/PhpParser/Node/Stmt/Class_.php

@@ -32,7 +32,7 @@ class Class_ extends ClassLike
      *                                'extends'     => null   : Name of extended class
      *                                'implements'  => array(): Names of implemented interfaces
      *                                'stmts'       => array(): Statements
-     *                                '$attrGroups' => array(): PHP attribute groups
+     *                                'attrGroups'  => array(): PHP attribute groups
      * @param array       $attributes Additional attributes
      */
     public function __construct($name, array $subNodes = [], array $attributes = []) {

lib/PhpParser/Node/Stmt/EnumCase.php

@@ -0,0 +1,37 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Node\Stmt;
+
+use PhpParser\Node;
+use PhpParser\Node\AttributeGroup;
+
+class EnumCase extends Node\Stmt
+{
+    /** @var Node\Identifier Enum case name */
+    public $name;
+    /** @var Node\Expr|null Enum case expression */
+    public $expr;
+    /** @var Node\AttributeGroup[] PHP attribute groups */
+    public $attrGroups;
+
+    /**
+     * @param string|Node\Identifier    $name       Enum case name
+     * @param Node\Expr|null            $expr       Enum case expression
+     * @param AttributeGroup[]          $attrGroups PHP attribute groups
+     * @param array                     $attributes Additional attributes
+     */
+    public function __construct($name, Node\Expr $expr = null, array $attrGroups = [], array $attributes = []) {
+        parent::__construct($attributes);
+        $this->name = \is_string($name) ? new Node\Identifier($name) : $name;
+        $this->expr = $expr;
+        $this->attrGroups = $attrGroups;
+    }
+
+    public function getSubNodeNames() : array {
+        return ['attrGroups', 'name', 'expr'];
+    }
+
+    public function getType() : string {
+        return 'Stmt_EnumCase';
+    }
+}

lib/PhpParser/Node/Stmt/Enum_.php

@@ -0,0 +1,40 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Node\Stmt;
+
+use PhpParser\Node;
+
+class Enum_ extends ClassLike
+{
+    /** @var null|Node\Identifier Scalar Type */
+    public $scalarType;
+    /** @var Node\Name[] Names of implemented interfaces */
+    public $implements;
+
+    /**
+     * @param string|Node\Identifier|null $name       Name
+     * @param array                       $subNodes   Array of the following optional subnodes:
+     *                                                'scalarType'  => null    : Scalar type
+     *                                                'implements'  => array() : Names of implemented interfaces
+     *                                                'stmts'       => array() : Statements
+     *                                                'attrGroups'  => array() : PHP attribute groups
+     * @param array                       $attributes Additional attributes
+     */
+    public function __construct($name, array $subNodes = [], array $attributes = []) {
+        $this->name = \is_string($name) ? new Node\Identifier($name) : $name;
+        $this->scalarType = $subNodes['scalarType'] ?? null;
+        $this->implements = $subNodes['implements'] ?? [];
+        $this->stmts = $subNodes['stmts'] ?? [];
+        $this->attrGroups = $subNodes['attrGroups'] ?? [];
+
+        parent::__construct($attributes);
+    }
+
+    public function getSubNodeNames() : array {
+        return ['attrGroups', 'name', 'scalarType', 'implements', 'stmts'];
+    }
+
+    public function getType() : string {
+        return 'Stmt_Enum';
+    }
+}

lib/PhpParser/Parser/Php5.php

@@ -193,9 +193,9 @@ class Php5 extends \PhpParser\ParserAbstract
         "'`'",
         "']'",
         "'\"'",
+        "T_ENUM",
         "T_NULLSAFE_OBJECT_OPERATOR",
-        "T_ATTRIBUTE",
-        "T_ENUM"
+        "T_ATTRIBUTE"
     );
 
     protected $tokenToSymbol = array(
@@ -235,10 +235,10 @@ class Php5 extends \PhpParser\ParserAbstract
            94,   95,   96,   97,   98,   99,  100,  101,  102,  103,
           104,  105,  106,  107,  108,  109,  110,  111,  112,  113,
           114,  115,  116,  117,  118,  119,  120,  121,  122,  123,
-          124,  125,  126,  127,  128,  129,  130,  131,  163,  132,
-          133,  134,  135,  136,  137,  138,  139,  140,  141,  142,
-          143,  144,  145,  146,  147,  148,  149,  150,  151,  152,
-          153,  164,  165
+          124,  125,  126,  127,  128,  163,  129,  130,  131,  164,
+          132,  133,  134,  135,  136,  137,  138,  139,  140,  141,
+          142,  143,  144,  145,  146,  147,  148,  149,  150,  151,
+          152,  153,  165
     );
 
     protected $action = array(