Add support for union types

We definitely need to introduce a general "Type" abstraction in
the next major version.

grammar/php7.y

@@ -461,6 +461,7 @@ parameter:
 type_expr:
       type                                                  { $$ = $1; }
     | '?' type                                              { $$ = Node\NullableType[$2]; }
+    | union_type                                            { $$ = Node\UnionType[$1]; }
 ;
 
 type:
@@ -469,6 +470,11 @@ type:
     | T_CALLABLE                                            { $$ = Node\Identifier['callable']; }
 ;
 
+union_type:
+      type '|' type                                         { init($1, $3); }
+    | union_type '|' type                                   { push($1, $3); }
+;
+
 optional_type:
       /* empty */                                           { $$ = null; }
     | type_expr                                             { $$ = $1; }

lib/PhpParser/Node/Expr/ArrowFunction.php

@@ -17,7 +17,7 @@ class ArrowFunction extends Expr implements FunctionLike
     /** @var Node\Param[] */
     public $params = [];
 
-    /** @var null|Node\Identifier|Node\Name|Node\NullableType */
+    /** @var null|Node\Identifier|Node\Name|Node\NullableType|Node\UnionType */
     public $returnType;
 
     /** @var Expr */

lib/PhpParser/Node/Expr/Closure.php

@@ -16,7 +16,7 @@ class Closure extends Expr implements FunctionLike
     public $params;
     /** @var ClosureUse[] use()s */
     public $uses;
-    /** @var null|Node\Identifier|Node\Name|Node\NullableType Return type */
+    /** @var null|Node\Identifier|Node\Name|Node\NullableType|Node\UnionType Return type */
     public $returnType;
     /** @var Node\Stmt[] Statements */
     public $stmts;

lib/PhpParser/Node/FunctionLike.php

@@ -23,7 +23,7 @@ interface FunctionLike extends Node
     /**
      * Get the declared return type or null
      *
-     * @return null|Identifier|Node\Name|Node\NullableType
+     * @return null|Identifier|Node\Name|Node\NullableType|Node\UnionType
      */
     public function getReturnType();
 

lib/PhpParser/Node/Param.php

@@ -6,7 +6,7 @@ use PhpParser\NodeAbstract;
 
 class Param extends NodeAbstract
 {
-    /** @var null|Identifier|Name|NullableType Type declaration */
+    /** @var null|Identifier|Name|NullableType|UnionType Type declaration */
     public $type;
     /** @var bool Whether parameter is passed by reference */
     public $byRef;
@@ -20,12 +20,12 @@ class Param extends NodeAbstract
     /**
      * Constructs a parameter node.
      *
-     * @param Expr\Variable|Expr\Error                 $var        Parameter variable
+     * @param Expr\Variable|Expr\Error                           $var        Parameter variable
-     * @param null|Expr                                $default    Default value
+     * @param null|Expr                                          $default    Default value
-     * @param null|string|Identifier|Name|NullableType $type       Type declaration
+     * @param null|string|Identifier|Name|NullableType|UnionType $type       Type declaration
-     * @param bool                                     $byRef      Whether is passed by reference
+     * @param bool                                               $byRef      Whether is passed by reference
-     * @param bool                                     $variadic   Whether this is a variadic argument
+     * @param bool                                               $variadic   Whether this is a variadic argument
-     * @param array                                    $attributes Additional attributes
+     * @param array                                              $attributes Additional attributes
      */
     public function __construct(
         $var, Expr $default = null, $type = null,

lib/PhpParser/Node/Stmt/ClassMethod.php

@@ -15,7 +15,7 @@ class ClassMethod extends Node\Stmt implements FunctionLike
     public $name;
     /** @var Node\Param[] Parameters */
     public $params;
-    /** @var null|Node\Identifier|Node\Name|Node\NullableType Return type */
+    /** @var null|Node\Identifier|Node\Name|Node\NullableType|Node\UnionType Return type */
     public $returnType;
     /** @var Node\Stmt[]|null Statements */
     public $stmts;

lib/PhpParser/Node/Stmt/Function_.php

@@ -16,7 +16,7 @@ class Function_ extends Node\Stmt implements FunctionLike
     public $name;
     /** @var Node\Param[] Parameters */
     public $params;
-    /** @var null|Node\Identifier|Node\Name|Node\NullableType Return type */
+    /** @var null|Node\Identifier|Node\Name|Node\NullableType|Node\UnionType Return type */
     public $returnType;
     /** @var Node\Stmt[] Statements */
     public $stmts;

lib/PhpParser/Node/Stmt/Property.php

@@ -6,6 +6,7 @@ use PhpParser\Node;
 use PhpParser\Node\Identifier;
 use PhpParser\Node\Name;
 use PhpParser\Node\NullableType;
+use PhpParser\Node\UnionType;
 
 class Property extends Node\Stmt
 {
@@ -13,16 +14,16 @@ class Property extends Node\Stmt
     public $flags;
     /** @var PropertyProperty[] Properties */
     public $props;
-    /** @var null|Identifier|Name|NullableType Type declaration */
+    /** @var null|Identifier|Name|NullableType|UnionType Type declaration */
     public $type;
 
     /**
      * Constructs a class property list node.
      *
-     * @param int                                      $flags      Modifiers
+     * @param int                                                $flags      Modifiers
-     * @param PropertyProperty[]                       $props      Properties
+     * @param PropertyProperty[]                                 $props      Properties
-     * @param array                                    $attributes Additional attributes
+     * @param array                                              $attributes Additional attributes
-     * @param null|string|Identifier|Name|NullableType $type       Type declaration
+     * @param null|string|Identifier|Name|NullableType|UnionType $type       Type declaration
      */
     public function __construct(int $flags, array $props, array $attributes = [], $type = null) {
         $this->attributes = $attributes;

lib/PhpParser/Node/UnionType.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types=1);
+
+namespace PhpParser\Node;
+
+use PhpParser\NodeAbstract;
+
+class UnionType extends NodeAbstract
+{
+    /** @var (Identifier|Name)[] Types */
+    public $types;
+
+    /**
+     * Constructs a union type.
+     *
+     * @param (Identifier|Name)[] $types      Types
+     * @param array               $attributes Additional attributes
+     */
+    public function __construct(array $types, array $attributes = []) {
+        $this->attributes = $attributes;
+        $this->types = $types;
+    }
+
+    public function getSubNodeNames() : array {
+        return ['types'];
+    }
+    
+    public function getType() : string {
+        return 'UnionType';
+    }
+}

lib/PhpParser/NodeVisitor/NameResolver.php

@@ -162,12 +162,18 @@ class NameResolver extends NodeVisitorAbstract
     }
 
     private function resolveType($node) {
+        if ($node instanceof Name) {
+            return $this->resolveClassName($node);
+        }
         if ($node instanceof Node\NullableType) {
             $node->type = $this->resolveType($node->type);
             return $node;
         }
-        if ($node instanceof Name) {
+        if ($node instanceof Node\UnionType) {
-            return $this->resolveClassName($node);
+            foreach ($node->types as &$type) {
+                $type = $this->resolveType($type);
+            }
+            return $node;
         }
         return $node;
     }

lib/PhpParser/ParserAbstract.php

@@ -656,6 +656,8 @@ abstract class ParserAbstract implements Parser
             'iterable' => true,
             'void'     => true,
             'object'   => true,
+            'null'     => true,
+            'false'    => true,
         ];
 
         if (!$name->isUnqualified()) {

lib/PhpParser/PrettyPrinter/Standard.php

@@ -37,6 +37,10 @@ class Standard extends PrettyPrinterAbstract
         return '?' . $this->p($node->type);
     }
 
+    protected function pUnionType(Node\UnionType $node) {
+        return $this->pImplode($node->types, '|');
+    }
+
     protected function pIdentifier(Node\Identifier $node) {
         return $node->name;
     }

lib/PhpParser/PrettyPrinterAbstract.php

@@ -1295,6 +1295,7 @@ abstract class PrettyPrinterAbstract
             //'Expr_ShellExec->parts' => '', // TODO These need to be treated more carefully
             //'Scalar_Encapsed->parts' => '',
             'Stmt_Catch->types' => '|',
+            'UnionType->types' => '|',
             'Stmt_If->elseifs' => ' ',
             'Stmt_TryCatch->catches' => ' ',
 
@@ -1396,6 +1397,7 @@ abstract class PrettyPrinterAbstract
              * Stmt_TraitUseAdaptation_Precedence->insteadof
              * Stmt_Unset->vars
              * Stmt_Use->uses
+             * UnionType->types
              */
 
             /* TODO

test/PhpParser/NodeVisitor/NameResolverTest.php

@@ -94,13 +94,6 @@ namespace Baz {
     C;
     E;
     K;
-
-    class ClassWithTypeProperties
-    {
-        public float $php = 7.4;
-        public ?Foo $person;
-        protected static ?bool $probability;
-    }
 }
 EOC;
         $expectedCode = <<<'EOC'
@@ -169,12 +162,6 @@ namespace Baz {
     \Y\T\B\C;
     \Y\T\D\E;
     \Z\T\K;
-    class ClassWithTypeProperties
-    {
-        public float $php = 7.4;
-        public ?\Baz\Foo $person;
-        protected static ?bool $probability;
-    }
 }
 EOC;
 
@@ -210,6 +197,14 @@ class A extends B implements C, D {
 
 interface A extends C, D {
     public function a(A $a) : A;
+    public function b(A|B|int $a): A|B|int;
+}
+
+class ClassWithTypeProperties {
+    public float $php = 7.4;
+    public ?Foo $person;
+    protected static ?bool $probability;
+    public A|B|int $prop;
 }
 
 function f(A $a) : A {}
@@ -252,6 +247,14 @@ class A extends \NS\B implements \NS\C, \NS\D
 interface A extends \NS\C, \NS\D
 {
     public function a(\NS\A $a) : \NS\A;
+    public function b(\NS\A|\NS\B|int $a) : \NS\A|\NS\B|int;
+}
+class ClassWithTypeProperties
+{
+    public float $php = 7.4;
+    public ?\NS\Foo $person;
+    protected static ?bool $probability;
+    public \NS\A|\NS\B|int $prop;
 }
 function f(\NS\A $a) : \NS\A
 {

test/code/formatPreservation/listInsertion.test

@@ -306,4 +306,14 @@ $stmts[0]->expr->expr->items[] = new Expr\ArrayItem(new Scalar\LNumber(24));
 $array = [
     1, 2,
     3, 24,
-];
+];
+-----
+<?php
+function test(): A
+|B {}
+-----
+$stmts[0]->returnType->types[] = new Node\Name('C');
+-----
+<?php
+function test(): A
+|B|C {}

test/code/formatPreservation/listRemoval.test

@@ -38,4 +38,15 @@ function foo(
     $b,
     $x,
     $y
-) {}
+) {}
+-----
+<?php
+function test(): A
+|B
+|C {}
+-----
+array_pop($stmts[0]->returnType->types);
+-----
+<?php
+function test(): A
+|B {}

test/code/parser/stmt/function/unionTypes.test

@@ -0,0 +1,92 @@
+Union types
+-----
+<?php
+
+class Test {
+    public A|iterable|null $prop;
+}
+
+function test(A|B $a): int|false {}
+-----
+!!php7
+array(
+    0: Stmt_Class(
+        flags: 0
+        name: Identifier(
+            name: Test
+        )
+        extends: null
+        implements: array(
+        )
+        stmts: array(
+            0: Stmt_Property(
+                flags: MODIFIER_PUBLIC (1)
+                type: UnionType(
+                    types: array(
+                        0: Name(
+                            parts: array(
+                                0: A
+                            )
+                        )
+                        1: Identifier(
+                            name: iterable
+                        )
+                        2: Identifier(
+                            name: null
+                        )
+                    )
+                )
+                props: array(
+                    0: Stmt_PropertyProperty(
+                        name: VarLikeIdentifier(
+                            name: prop
+                        )
+                        default: null
+                    )
+                )
+            )
+        )
+    )
+    1: Stmt_Function(
+        byRef: false
+        name: Identifier(
+            name: test
+        )
+        params: array(
+            0: Param(
+                type: UnionType(
+                    types: array(
+                        0: Name(
+                            parts: array(
+                                0: A
+                            )
+                        )
+                        1: Name(
+                            parts: array(
+                                0: B
+                            )
+                        )
+                    )
+                )
+                byRef: false
+                variadic: false
+                var: Expr_Variable(
+                    name: a
+                )
+                default: null
+            )
+        )
+        returnType: UnionType(
+            types: array(
+                0: Identifier(
+                    name: int
+                )
+                1: Identifier(
+                    name: false
+                )
+            )
+        )
+        stmts: array(
+        )
+    )
+)

test/code/prettyPrinter/stmt/union_types.test

@@ -0,0 +1,18 @@
+Union types
+-----
+<?php
+
+class Test {
+    public A|iterable|null $prop;
+}
+
+function test(A|B $a): int|false {}
+-----
+!!php7
+class Test
+{
+    public A|iterable|null $prop;
+}
+function test(A|B $a) : int|false
+{
+}