feat: introduce attribute #[MapTo]

.gitignore

@@ -4,3 +4,6 @@ composer.lock
 .phpunit.result.cache
 tests/cache/
 tools/phpstan/cache/
+
+# dont commit this
+src/CustomTransformer/generated_transformers

docs/homepage.md

@@ -84,7 +84,7 @@ The mapping process could be extended in multiple ways.
 
 #### Map manually a single property
 
-You can override the mapping of a single property by leveraging `AutoMapper\Transformer\CustomTransformer\CustomPropertyTransformerInterface`.
+You can override the mapping of a single property by leveraging `AutoMapper\CustomTransformer\CustomPropertyTransformerInterface`.
 It can be useful if you need to map several properties from the source to a unique property in the target. 
 
 ```php
@@ -107,7 +107,7 @@ class BirthDateUserTransformer implements CustomPropertyTransformerInterface
 
 #### Map manually a whole object
 
-In order to customize the mapping of a whole object, you can leverage `AutoMapper\Transformer\CustomTransformer\CustomModelTransformerInterface`.
+In order to customize the mapping of a whole object, you can leverage `AutoMapper\CustomTransformer\CustomModelTransformerInterface`.
 You have then full control over the transformation between two types:
 
 ```php

src/Attribute/MapTo.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Attribute;
+
+#[\Attribute(\Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]
+final readonly class MapTo
+{
+    /**
+     * @param non-empty-string $propertyName
+     * @param 'array'|class-string|null $target
+     */
+    public function __construct(
+        public string $propertyName,
+        public string|null $target = null,
+    )
+    {
+    }
+}

src/AutoMapper.php

@@ -4,6 +4,8 @@
 
 namespace AutoMapper;
 
+use AutoMapper\CustomTransformer\CustomTransformerInterface;
+use AutoMapper\CustomTransformer\CustomTransformersRegistry;
 use AutoMapper\Exception\NoMappingFoundException;
 use AutoMapper\Extractor\ClassMethodToCallbackExtractor;
 use AutoMapper\Extractor\CustomTransformerExtractor;
@@ -17,8 +19,6 @@
 use AutoMapper\Transformer\ArrayTransformerFactory;
 use AutoMapper\Transformer\BuiltinTransformerFactory;
 use AutoMapper\Transformer\ChainTransformerFactory;
-use AutoMapper\Transformer\CustomTransformer\CustomTransformerInterface;
-use AutoMapper\Transformer\CustomTransformer\CustomTransformersRegistry;
 use AutoMapper\Transformer\DateTimeTransformerFactory;
 use AutoMapper\Transformer\EnumTransformerFactory;
 use AutoMapper\Transformer\MultipleTransformerFactory;

src/Transformer/CustomTransformer/CustomModelTransformerInterface.php → src/CustomTransformer/CustomModelTransformerInterface.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace AutoMapper\Transformer\CustomTransformer;
+namespace AutoMapper\CustomTransformer;
 
 use Symfony\Component\PropertyInfo\Type;
 

src/Transformer/CustomTransformer/CustomPropertyTransformerInterface.php → src/CustomTransformer/CustomPropertyTransformerInterface.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace AutoMapper\Transformer\CustomTransformer;
+namespace AutoMapper\CustomTransformer;
 
 /**
  * This interface should be implemented to handle custom transformations for specific property,

src/CustomTransformer/CustomTransformerGenerator.php

@@ -0,0 +1,144 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\CustomTransformer;
+
+use AutoMapper\Extractor\AstExtractor;
+use AutoMapper\Extractor\ReadAccessor;
+use PhpParser\Builder;
+use PhpParser\Node\Expr;
+use PhpParser\Node\Scalar\String_;
+use PhpParser\Node\Stmt;
+use PhpParser\PrettyPrinter\Standard;
+
+final readonly class CustomTransformerGenerator
+{
+    private AstExtractor $astExtractor;
+
+    public function __construct(
+        private CustomTransformersRegistry $customTransformerRegistry,
+        AstExtractor|null $astExtractor = null
+    ) {
+        $this->astExtractor = $astExtractor ?? new AstExtractor();
+    }
+
+    /**
+     * @return class-string<CustomTransformerInterface>
+     */
+    public function generateMapToCustomTransformer(
+        string $source,
+        string $target,
+        string $sourceProperty,
+        string $targetProperty,
+        ReadAccessor $readAccessor
+    ): string {
+        $transformerClass = strtr('MapTo_Transformer_{source}_{target}_{sourceProperty}_{targetProperty}', [
+            '{source}' => str_replace('\\', '_', $source),
+            '{target}' => str_replace('\\', '_', $target),
+            '{sourceProperty}' => $sourceProperty,
+            '{targetProperty}' => $targetProperty,
+        ]);
+
+        $file = __DIR__ . "/{$transformerClass}.php";
+
+        if (class_exists($transformerClass)) {
+            $this->customTransformerRegistry->addCustomTransformer(new $transformerClass());
+
+            return $transformerClass;
+        }
+
+        if (!file_exists($file)) {
+            $class = (new Builder\Class_($transformerClass))
+                ->makeFinal()
+                ->makeReadonly()
+                ->implement(CustomPropertyTransformerInterface::class)
+                ->addStmt($this->generateSupportsStatement($source, $target, $targetProperty))
+                ->addStmt($this->generateTransformStatement($readAccessor, $source))
+                ->getNode();
+
+            $code = "<?php\n" . (new Standard())->prettyPrint([$class]);
+            file_put_contents($file = __DIR__ . "/generated_transformers/{$transformerClass}.php", $code);
+        }
+
+        require_once $file;
+
+        $this->customTransformerRegistry->addCustomTransformer(new $transformerClass());
+
+        return $transformerClass;
+    }
+
+    /**
+     * public function supports(string $source, string $target, string $propertyName): bool
+     * {
+     *     return $source === [source type] && $target === [target type] && $propertyName === [target property];
+     * }
+     */
+    private function generateSupportsStatement(string $source, string $target, string $targetProperty): Stmt\ClassMethod
+    {
+        $supportsMethodInInterface = $this->astExtractor
+            ->extractClassLike(CustomPropertyTransformerInterface::class)
+            ->getMethod('supports') ?? throw new \LogicException(
+            'Cannot find "supports" method in interface ' . CustomPropertyTransformerInterface::class
+        );
+
+        return (new Builder\Method('supports'))
+            ->makePublic()
+            ->setReturnType($supportsMethodInInterface->getReturnType())
+            ->addParams($supportsMethodInInterface->getParams())
+            ->addStmt(
+                new Stmt\Return_(
+                    new Expr\BinaryOp\BooleanAnd(
+                        new Expr\BinaryOp\Identical(
+                            $supportsMethodInInterface->getParams()[0]->var,
+                            new String_($source)
+                        ),
+                        new Expr\BinaryOp\BooleanAnd(
+                            new Expr\BinaryOp\Identical(
+                                $supportsMethodInInterface->getParams()[1]->var,
+                                new String_($target)
+                            ),
+                            new Expr\BinaryOp\Identical(
+                                $supportsMethodInInterface->getParams()[2]->var,
+                                new String_($targetProperty)
+                            ),
+                        )
+                    )
+                )
+            )
+            ->getNode();
+    }
+
+    /**
+     * public function transform(object|array $source): mixed
+     * {
+     *     return $source->[sourceProperty accessor];
+     * }
+     */
+    private function generateTransformStatement(ReadAccessor $readAccessor, string $source): Stmt\ClassMethod
+    {
+        $transformMethodInInterface = $this->astExtractor
+            ->extractClassLike(CustomTransformerInterface::class)
+            ->getMethod('transform') ?? throw new \LogicException(
+            'Cannot find "transform" method in interface ' . CustomTransformerInterface::class
+        );
+
+        return (new Builder\Method('transform'))
+            ->makePublic()
+            ->setReturnType($transformMethodInInterface->getReturnType())
+            ->setDocComment(
+                <<<PHPDOC
+                /**
+                 * @param $source \$source 
+                 */
+                PHPDOC
+            )
+            ->addParams($transformMethodInInterface->getParams())
+            ->addStmt(
+                new Stmt\Return_(
+                    $readAccessor->getExpression($transformMethodInInterface->getParams()[0]->var)
+                )
+            )
+            ->getNode();
+    }
+}

src/Transformer/CustomTransformer/CustomTransformerInterface.php → src/CustomTransformer/CustomTransformerInterface.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace AutoMapper\Transformer\CustomTransformer;
+namespace AutoMapper\CustomTransformer;
 
 /**
  * @experimental

src/Transformer/CustomTransformer/CustomTransformersRegistry.php → src/CustomTransformer/CustomTransformersRegistry.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace AutoMapper\Transformer\CustomTransformer;
+namespace AutoMapper\CustomTransformer;
 
 use AutoMapper\MapperMetadataInterface;
 use Symfony\Component\PropertyInfo\Type;
@@ -22,6 +22,7 @@ public function addCustomTransformer(CustomTransformerInterface $customTransform
     {
         if (!\in_array($customTransformer, $this->customTransformers, true)) {
             $this->customTransformers[] = $customTransformer;
+            $this->prioritizedCustomTransformers = null; // reset priority computation
         }
     }
 
@@ -46,7 +47,7 @@ public function getCustomTransformerClass(MapperMetadataInterface $mapperMetadat
     }
 
     /**
-     * @return list<CustomTransformerInterface>
+     * @return CustomTransformerInterface
      */
     private function prioritizedCustomTransformers(): array
     {

src/Transformer/CustomTransformer/PrioritizedCustomTransformerInterface.php → src/CustomTransformer/PrioritizedCustomTransformerInterface.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace AutoMapper\Transformer\CustomTransformer;
+namespace AutoMapper\CustomTransformer;
 
 /**
  * @experimental

src/Extractor/AstExtractor.php

@@ -0,0 +1,93 @@
+<?php
+
+declare(strict_types=1);
+
+namespace AutoMapper\Extractor;
+
+use AutoMapper\Exception\InvalidArgumentException;
+use AutoMapper\Exception\RuntimeException;
+use PhpParser\Node;
+use PhpParser\NodeTraverser;
+use PhpParser\NodeVisitor\NameResolver;
+use PhpParser\Parser;
+use PhpParser\ParserFactory;
+
+final readonly class AstExtractor
+{
+    private Parser $parser;
+
+    public function __construct(?Parser $parser = null)
+    {
+        $this->parser = $parser ?? (new ParserFactory())->create(ParserFactory::PREFER_PHP7);
+    }
+
+    public function extractClassLike(string $class, bool $resolveImports = false): Node\Stmt\ClassLike
+    {
+        $fileName = (new \ReflectionClass($class))->getFileName();
+        if (false === $fileName) {
+            throw new RuntimeException("You cannot extract code from \"{$class}\" class.");
+        }
+        $fileContents = file_get_contents($fileName);
+        if (false === $fileContents) {
+            throw new RuntimeException("File \"{$fileName}\" for \"{$class}\" couldn't be read.");
+        }
+
+        $statements = $this->parser->parse($fileContents);
+
+        if (null === $statements) {
+            throw new RuntimeException("Couldn't parse file \"{$fileName}\" for class \"{$class}\".");
+        }
+
+        if ($resolveImports) {
+            $statements = $this->resolveFullyQualifiedClassNames($statements);
+        }
+
+        try {
+            $namespaceStatement = self::findUnique(Node\Stmt\Namespace_::class, $statements, $fileName);
+        } catch (\Exception) {
+            // if no namespace, directly search for a class
+            return self::findUnique(Node\Stmt\ClassLike::class, $statements, $fileName);
+        }
+
+        return self::findUnique(Node\Stmt\ClassLike::class, $namespaceStatement->stmts, $fileName);
+    }
+
+    /**
+     * @template T of Node
+     *
+     * @param class-string<T> $searchedStatementClass
+     * @param Node[] $statements
+     *
+     * @return T
+     */
+    private static function findUnique(string $searchedStatementClass, array $statements, string $fileName): Node
+    {
+        $foundStatements = array_filter(
+            $statements,
+            static fn(Node $statement): bool => $statement instanceof $searchedStatementClass,
+        );
+
+        if (\count($foundStatements) > 1) {
+            throw new InvalidArgumentException("Multiple \"{$searchedStatementClass}\" found in file \"{$fileName}\".");
+        }
+
+        return array_values($foundStatements)[0] ?? throw new InvalidArgumentException(
+            "No \"{$searchedStatementClass}\" found in file \"{$fileName}\"."
+        );
+    }
+
+    /**
+     * Transform all statements with imported class names, into FQCNs.
+     *
+     * @param Node[] $statements
+     *
+     * @return Node[]
+     */
+    private function resolveFullyQualifiedClassNames(array $statements): array
+    {
+        $nodeTraverser = new NodeTraverser();
+        $nodeTraverser->addVisitor(new NameResolver());
+
+        return $nodeTraverser->traverse($statements);
+    }
+}