misc: narrow union types during node build

src/Library/Container.php

@@ -32,14 +32,14 @@
 use CuyZ\Valinor\Mapper\Tree\Builder\ScalarNodeBuilder;
 use CuyZ\Valinor\Mapper\Tree\Builder\ShapedArrayNodeBuilder;
 use CuyZ\Valinor\Mapper\Tree\Builder\ShellVisitorNodeBuilder;
+use CuyZ\Valinor\Mapper\Tree\Builder\UnionNodeBuilder;
 use CuyZ\Valinor\Mapper\Tree\Builder\ValueAlteringNodeBuilder;
 use CuyZ\Valinor\Mapper\Tree\Builder\VisitorNodeBuilder;
 use CuyZ\Valinor\Mapper\Tree\Visitor\AggregateShellVisitor;
 use CuyZ\Valinor\Mapper\Tree\Visitor\AttributeShellVisitor;
 use CuyZ\Valinor\Mapper\Tree\Visitor\InterfaceShellVisitor;
 use CuyZ\Valinor\Mapper\Tree\Visitor\ObjectBindingShellVisitor;
 use CuyZ\Valinor\Mapper\Tree\Visitor\ShellVisitor;
-use CuyZ\Valinor\Mapper\Tree\Visitor\UnionShellVisitor;
 use CuyZ\Valinor\Mapper\TreeMapper;
 use CuyZ\Valinor\Mapper\TreeMapperContainer;
 use CuyZ\Valinor\Type\Parser\CachedParser;
@@ -92,15 +92,6 @@ public function __construct(Settings $settings)
 
             ShellVisitor::class => function () use ($settings): ShellVisitor {
                 return new AggregateShellVisitor(
-                    new UnionShellVisitor(
-                        new UnionNullNarrower(
-                            new UnionObjectNarrower(
-                                new UnionScalarNarrower(),
-                                $this->get(ClassDefinitionRepository::class),
-                                $this->get(ObjectBuilderFactory::class),
-                            )
-                        )
-                    ),
                     new InterfaceShellVisitor(
                         $settings->interfaceMapping,
                         $this->get(TypeParser::class),
@@ -129,6 +120,14 @@ public function __construct(Settings $settings)
                     ScalarType::class => new ScalarNodeBuilder(),
                 ]);
 
+                $builder = new UnionNodeBuilder($builder, new UnionNullNarrower(
+                    new UnionObjectNarrower(
+                        new UnionScalarNarrower(),
+                        $this->get(ClassDefinitionRepository::class),
+                        $this->get(ObjectBuilderFactory::class),
+                    )
+                ));
+
                 $builder = new VisitorNodeBuilder($builder, $settings->nodeVisitors);
                 $builder = new ValueAlteringNodeBuilder($builder, $settings->valueModifier);
                 $builder = new ShellVisitorNodeBuilder($builder, $this->get(ShellVisitor::class));

src/Mapper/Tree/Builder/UnionNodeBuilder.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace CuyZ\Valinor\Mapper\Tree\Builder;
+
+use CuyZ\Valinor\Mapper\Tree\Node;
+use CuyZ\Valinor\Mapper\Tree\Shell;
+use CuyZ\Valinor\Type\Resolver\Union\UnionNarrower;
+use CuyZ\Valinor\Type\Types\UnionType;
+
+/** @internal */
+final class UnionNodeBuilder implements NodeBuilder
+{
+    private NodeBuilder $delegate;
+
+    private UnionNarrower $unionNarrower;
+
+    public function __construct(NodeBuilder $delegate, UnionNarrower $unionNarrower)
+    {
+        $this->delegate = $delegate;
+        $this->unionNarrower = $unionNarrower;
+    }
+
+    public function build(Shell $shell, RootNodeBuilder $rootBuilder): Node
+    {
+        $type = $shell->type();
+        $value = $shell->value();
+
+        if (! $type instanceof UnionType) {
+            return $this->delegate->build($shell, $rootBuilder);
+        }
+
+        $narrowedType = $this->unionNarrower->narrow($type, $value);
+
+        return $rootBuilder->build($shell->withType($narrowedType));
+    }
+}