Add support to create type with multiple string values

This is to help create phpstan types of string constants

Author: sunkan

src/ValueObject/Type.php

@@ -19,6 +19,7 @@ final class Type
 	private string $namespace = '';
 	/** @var Type[] */
 	private array $types = [];
+	private bool $noneValidTypeHint = false;
 
 	/**
 	 * @param list<string> $types
@@ -38,6 +39,16 @@ public static function fromIdentifier(Identifier $identifier): self
 		return self::fromString($identifier->toString());
 	}
 
+	public static function enumString(string ...$values): self
+	{
+		$self = new self('');
+		$self->noneValidTypeHint = true;
+		foreach ($values as $value) {
+			$self->types[] = new self("'$value'");
+		}
+		return $self;
+	}
+
 	public static function fromString(string $type): self
 	{
 		if (!trim($type, '? ')) {
@@ -158,6 +169,10 @@ public function addUnion(Type|string $type): void
 
 	public function getTypeHint(bool $renderUnion = false): ?string
 	{
+		if ($this->noneValidTypeHint) {
+			return null;
+		}
+
 		if (count($this->types) > 1) {
 			if ($renderUnion) {
 				$typeHint = [];

tests/ValueObject/TypeTest.php

@@ -326,4 +326,31 @@ public function testMixedWithNullable(): void
 		$this->assertSame('mixed|object', $type->getDocBlockTypeHint());
 		$this->assertSame('mixed|object', $type->getTypeHint(true));
 	}
+
+	public function testEnumStringValues(): void
+	{
+		$type = Type::enumString('value1', 'value2', 'value3');
+		$this->assertSame("'value1'|'value2'|'value3'", $type->getDocBlockTypeHint());
+		$this->assertNull($type->getTypeHint());
+		$this->assertNull($type->getTypeHint(true));
+	}
+
+	public function testEnumStringValueNullable(): void
+	{
+		$type = Type::enumString('value1', 'value2', 'value3');
+		$type->addUnion('null');
+		$this->assertSame("'value1'|'value2'|'value3'|null", $type->getDocBlockTypeHint());
+		$this->assertNull($type->getTypeHint());
+		$this->assertNull($type->getTypeHint(true));
+	}
+
+	public function testEnumStringValueNullableAndClass(): void
+	{
+		$type = Type::enumString('value1', 'value2', 'value3');
+		$type->addUnion('null');
+		$type->addUnion(\BackedEnum::class);
+		$this->assertSame("'value1'|'value2'|'value3'|BackedEnum|null", $type->getDocBlockTypeHint());
+		$this->assertNull($type->getTypeHint());
+		$this->assertNull($type->getTypeHint(true));
+	}
 }