From 560ae69682b90e01656570f9deed34d65099adf9 Mon Sep 17 00:00:00 2001
From: Priyadi Iman Nurcahyo <1102197+priyadi@users.noreply.github.com>
Date: Sun, 14 Jan 2024 15:02:44 +0700
Subject: [PATCH] feat: If a transformer throws `RefuseToHandleException`, the
 `MainTransformer` will try the next suitable transformer.

---
 CHANGELOG.md                                  |  2 ++
 src/MainTransformer/MainTransformer.php       | 22 +++++++++-------
 src/Transformer/CopyTransformer.php           | 11 +++++++-
 .../Exception/RefuseToHandleException.php     | 25 +++++++++++++++++++
 4 files changed, 50 insertions(+), 10 deletions(-)
 create mode 100644 src/Transformer/Exception/RefuseToHandleException.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0a70d016..bb77d2e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@
   exceptions.
 * feat: Main transformer's exception now accepts `$context` variable.
 * feat: More useful `TransformerReturnsUnexpectedValueException` exception message.
+* feat: If a transformer throws `RefuseToHandleException`, the `MainTransformer`
+  will try the next suitable transformer.
 
 ## 0.5.8
 
diff --git a/src/MainTransformer/MainTransformer.php b/src/MainTransformer/MainTransformer.php
index 4d46096d..8edd153c 100644
--- a/src/MainTransformer/MainTransformer.php
+++ b/src/MainTransformer/MainTransformer.php
@@ -24,6 +24,7 @@
 use Rekalogika\Mapper\Transformer\Contracts\MainTransformerAwareInterface;
 use Rekalogika\Mapper\Transformer\Contracts\MixedType;
 use Rekalogika\Mapper\Transformer\Contracts\TransformerInterface;
+use Rekalogika\Mapper\Transformer\Exception\RefuseToHandleException;
 use Rekalogika\Mapper\TransformerRegistry\TransformerRegistryInterface;
 use Rekalogika\Mapper\TypeResolver\TypeResolverInterface;
 use Rekalogika\Mapper\Util\TypeCheck;
@@ -163,20 +164,23 @@ public function transform(
 
             // transform the source to the target
 
-            /** @var mixed */
-            $result = $transformer->transform(
-                source: $source,
-                target: $target,
-                sourceType: $sourceTypeForTransformer,
-                targetType: $targetTypeForTransformer,
-                context: $context
-            );
+            try {
+                /** @var mixed */
+                $result = $transformer->transform(
+                    source: $source,
+                    target: $target,
+                    sourceType: $sourceTypeForTransformer,
+                    targetType: $targetTypeForTransformer,
+                    context: $context
+                );
+            } catch (RefuseToHandleException) {
+                continue;
+            }
 
             // check the result type
 
             if (
                 !TypeCheck::isVariableInstanceOf($result, $targetType)
-                && $result !== null
             ) {
                 throw new TransformerReturnsUnexpectedValueException($source, $targetType, $result, $transformer, $context);
             }
diff --git a/src/Transformer/CopyTransformer.php b/src/Transformer/CopyTransformer.php
index aa0d5b4e..a4def39a 100644
--- a/src/Transformer/CopyTransformer.php
+++ b/src/Transformer/CopyTransformer.php
@@ -17,6 +17,8 @@
 use Rekalogika\Mapper\Transformer\Contracts\MixedType;
 use Rekalogika\Mapper\Transformer\Contracts\TransformerInterface;
 use Rekalogika\Mapper\Transformer\Contracts\TypeMapping;
+use Rekalogika\Mapper\Transformer\Exception\RefuseToHandleException;
+use Rekalogika\Mapper\Util\TypeCheck;
 use Symfony\Component\PropertyInfo\Type;
 
 final class CopyTransformer implements TransformerInterface
@@ -37,7 +39,14 @@ public function transform(
         if (!$clonable) {
             return $source;
         }
-        return clone $source;
+
+        $result = clone $source;
+
+        if ($targetType !== null && !TypeCheck::isVariableInstanceOf($result, $targetType)) {
+            throw new RefuseToHandleException();
+        }
+
+        return $result;
     }
 
     public function getSupportedTransformation(): iterable
diff --git a/src/Transformer/Exception/RefuseToHandleException.php b/src/Transformer/Exception/RefuseToHandleException.php
new file mode 100644
index 00000000..0d3e08b7
--- /dev/null
+++ b/src/Transformer/Exception/RefuseToHandleException.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Transformer\Exception;
+
+use Rekalogika\Mapper\Exception\RuntimeException;
+
+/**
+ * If a transformer throw this exception, it means that the transformer is not
+ * able to handle the given source type in an ad-hoc basis. The main transformer
+ * will try the next transformer for the task.
+ */
+class RefuseToHandleException extends RuntimeException
+{
+}