fix: handle scalar value casting in union types only in flexible mode

src/Library/Container.php

@@ -56,8 +56,6 @@
 use CuyZ\Valinor\Type\Parser\Template\BasicTemplateParser;
 use CuyZ\Valinor\Type\Parser\Template\TemplateParser;
 use CuyZ\Valinor\Type\Parser\TypeParser;
-use CuyZ\Valinor\Type\Resolver\Union\UnionNullNarrower;
-use CuyZ\Valinor\Type\Resolver\Union\UnionScalarNarrower;
 use CuyZ\Valinor\Type\ScalarType;
 use CuyZ\Valinor\Type\Types\ArrayType;
 use CuyZ\Valinor\Type\Types\IterableType;
@@ -102,7 +100,7 @@ public function __construct(Settings $settings)
                     ScalarType::class => new ScalarNodeBuilder($settings->flexible),
                 ]);
 
-                $builder = new UnionNodeBuilder($builder, new UnionNullNarrower(new UnionScalarNarrower()));
+                $builder = new UnionNodeBuilder($builder, $settings->flexible);
 
                 $builder = new ClassNodeBuilder(
                     $builder,

src/Mapper/Tree/Builder/ObjectImplementations.php

@@ -6,6 +6,7 @@
 
 use CuyZ\Valinor\Definition\FunctionDefinition;
 use CuyZ\Valinor\Definition\FunctionsContainer;
+use CuyZ\Valinor\Mapper\Tree\Exception\CannotResolveObjectType;
 use CuyZ\Valinor\Mapper\Tree\Exception\InvalidAbstractObjectName;
 use CuyZ\Valinor\Mapper\Tree\Exception\InvalidResolvedImplementationValue;
 use CuyZ\Valinor\Mapper\Tree\Exception\MissingObjectImplementationRegistration;
@@ -14,7 +15,6 @@
 use CuyZ\Valinor\Mapper\Tree\Exception\ResolvedImplementationIsNotAccepted;
 use CuyZ\Valinor\Type\Parser\Exception\InvalidType;
 use CuyZ\Valinor\Type\Parser\TypeParser;
-use CuyZ\Valinor\Type\Resolver\Exception\CannotResolveObjectType;
 use CuyZ\Valinor\Type\Type;
 use CuyZ\Valinor\Type\Types\ClassStringType;
 use CuyZ\Valinor\Type\Types\ClassType;

src/Mapper/Tree/Builder/UnionNodeBuilder.php

@@ -4,21 +4,27 @@
 
 namespace CuyZ\Valinor\Mapper\Tree\Builder;
 
+use CuyZ\Valinor\Mapper\Tree\Exception\CannotResolveTypeFromUnion;
 use CuyZ\Valinor\Mapper\Tree\Shell;
-use CuyZ\Valinor\Type\Resolver\Union\UnionNarrower;
+use CuyZ\Valinor\Type\EnumType;
+use CuyZ\Valinor\Type\ScalarType;
+use CuyZ\Valinor\Type\Type;
+use CuyZ\Valinor\Type\Types\NullType;
 use CuyZ\Valinor\Type\Types\UnionType;
 
+use function count;
+
 /** @internal */
 final class UnionNodeBuilder implements NodeBuilder
 {
     private NodeBuilder $delegate;
 
-    private UnionNarrower $unionNarrower;
+    private bool $flexible;
 
-    public function __construct(NodeBuilder $delegate, UnionNarrower $unionNarrower)
+    public function __construct(NodeBuilder $delegate, bool $flexible)
     {
         $this->delegate = $delegate;
-        $this->unionNarrower = $unionNarrower;
+        $this->flexible = $flexible;
     }
 
     public function build(Shell $shell, RootNodeBuilder $rootBuilder): TreeNode
@@ -29,8 +35,40 @@ public function build(Shell $shell, RootNodeBuilder $rootBuilder): TreeNode
             return $this->delegate->build($shell, $rootBuilder);
         }
 
-        $narrowedType = $this->unionNarrower->narrow($type, $shell->value());
+        $narrowedType = $this->narrow($type, $shell->value());
 
         return $rootBuilder->build($shell->withType($narrowedType));
     }
+
+    /**
+     * @param mixed $source
+     */
+    private function narrow(UnionType $type, $source): Type
+    {
+        $subTypes = $type->types();
+
+        if ($source !== null && count($subTypes) === 2) {
+            if ($subTypes[0] instanceof NullType) {
+                return $subTypes[1];
+            } elseif ($subTypes[1] instanceof NullType) {
+                return $subTypes[0];
+            }
+        }
+
+        foreach ($subTypes as $subType) {
+            if (! $subType instanceof ScalarType) {
+                continue;
+            }
+
+            if (! $this->flexible && ! $subType instanceof EnumType) {
+                continue;
+            }
+
+            if ($subType->canCast($source)) {
+                return $subType;
+            }
+        }
+
+        throw new CannotResolveTypeFromUnion($source, $type);
+    }
 }

src/Type/Resolver/Exception/CannotResolveObjectType.php → src/Mapper/Tree/Exception/CannotResolveObjectType.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace CuyZ\Valinor\Type\Resolver\Exception;
+namespace CuyZ\Valinor\Mapper\Tree\Exception;
 
 use RuntimeException;
 

src/Type/Resolver/Exception/CannotResolveTypeFromUnion.php → src/Mapper/Tree/Exception/CannotResolveTypeFromUnion.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace CuyZ\Valinor\Type\Resolver\Exception;
+namespace CuyZ\Valinor\Mapper\Tree\Exception;
 
 use CuyZ\Valinor\Mapper\Tree\Message\ErrorMessage;
 use CuyZ\Valinor\Mapper\Tree\Message\HasParameters;
@@ -22,7 +22,10 @@ final class CannotResolveTypeFromUnion extends RuntimeException implements Error
     /** @var array<string, string> */
     private array $parameters;
 
-    public function __construct(UnionType $unionType)
+    /**
+     * @param mixed $source
+     */
+    public function __construct($source, UnionType $unionType)
     {
         $this->parameters = [
             'allowed_types' => implode(
@@ -32,9 +35,15 @@ public function __construct(UnionType $unionType)
             ),
         ];
 
-        $this->body = TypeHelper::containsObject($unionType)
-            ? 'Invalid value {source_value}.'
-            : 'Value {source_value} does not match any of {allowed_types}.';
+        if ($source === null) {
+            $this->body = TypeHelper::containsObject($unionType)
+                ? 'Cannot be empty.'
+                : 'Cannot be empty and must be filled with a value matching any of {allowed_types}.';
+        } else {
+            $this->body = TypeHelper::containsObject($unionType)
+                ? 'Invalid value {source_value}.'
+                : 'Value {source_value} does not match any of {allowed_types}.';
+        }
 
         parent::__construct(StringFormatter::for($this), 1607027306);
     }

src/Mapper/Tree/Message/DefaultMessage.php

@@ -14,6 +14,9 @@ interface DefaultMessage
         'Value {source_value} does not match any of {allowed_types}.' => [
             'en' => 'Value {source_value} does not match any of {allowed_types}.',
         ],
+        'Cannot be empty and must be filled with a value matching any of {allowed_types}.' => [
+            'en' => 'Cannot be empty and must be filled with a value matching any of {allowed_types}.',
+        ],
         'Value {source_value} does not match type {expected_type}.' => [
             'en' => 'Value {source_value} does not match type {expected_type}.',
         ],

tests/Integration/Mapping/Fixture/NativeUnionValues.php

@@ -6,6 +6,7 @@
 
 // @PHP8.0 move inside \CuyZ\Valinor\Tests\Integration\Mapping\UnionValuesMappingTest
 use CuyZ\Valinor\Tests\Fixture\Object\ObjectWithConstants;
+use DateTimeInterface;
 
 class NativeUnionValues
 {
@@ -27,6 +28,10 @@ class NativeUnionValues
     /** @var int|false */
     public int|bool $intOrLiteralFalse = 42;
 
+    public DateTimeInterface|null $dateTimeOrNull = null;
+
+    public null|DateTimeInterface $nullOrDateTime = null;
+
     /** @var ObjectWithConstants::CONST_WITH_STRING_VALUE_A|ObjectWithConstants::CONST_WITH_INTEGER_VALUE_A */
     public string|int $constantWithStringValue = 1653398288;
 
@@ -51,6 +56,8 @@ public function __construct(
         string|null $nullableWithNull = 'Schwifty!',
         int|bool $intOrLiteralTrue = 42,
         int|bool $intOrLiteralFalse = 42,
+        DateTimeInterface|null $dateTimeOrNull = null,
+        null|DateTimeInterface $nullOrDateTime = null,
         string|int $constantWithStringValue = 1653398288,
         string|int $constantWithIntegerValue = 'some string value'
     ) {
@@ -62,6 +69,8 @@ public function __construct(
         $this->nullableWithNull = $nullableWithNull;
         $this->intOrLiteralTrue = $intOrLiteralTrue;
         $this->intOrLiteralFalse = $intOrLiteralFalse;
+        $this->dateTimeOrNull = $dateTimeOrNull;
+        $this->nullOrDateTime = $nullOrDateTime;
         $this->constantWithStringValue = $constantWithStringValue;
         $this->constantWithIntegerValue = $constantWithIntegerValue;
     }