Allow applying the Param attribute at parameter level

Author: carlos-granados

doc/Param.md

@@ -16,6 +16,8 @@ If the function or method has more than one parameter, the types for the differe
 
 If any of the parameters is variadic, the `...` operator needs to be listed with the type, not the argument name.
 
+You can also directly apply the attribute to any of the method/function parameters. In that case, the name of the argument is optional and, if added, should match the name of the parameter to which it is applied.
+
 ## Example usage
 
 ```php
@@ -58,5 +60,12 @@ class ParamExample
     public function variadicMethodParam(...$params)
     {
     }    
+
+    // Attribute applied at parameter level
+    public function paramOnParam(
+        #[Param('string[]')]
+        array $param
+    ) {
+    }
 }
 ```

src/Param.php

@@ -9,6 +9,7 @@
 #[Attribute(
     Attribute::TARGET_METHOD |
     Attribute::TARGET_FUNCTION |
+    Attribute::TARGET_PARAMETER |
     Attribute::IS_REPEATABLE
 )]
 final class Param

tests/ParamTest.php

@@ -54,6 +54,11 @@ public function testVariadicMethodParam(): void
         $this->assertEquals(['params' => 'string ...'], $this->variadicMethodParam('Test'));
     }
 
+    public function testParamOnParam(): void
+    {
+        $this->assertEquals(['param' => 'string'], $this->paramOnParam('Test'));
+    }
+
     #[Param(param: 'string')]
     private function methodParam(string $param): array
     {
@@ -94,6 +99,13 @@ private function variadicMethodParam(string ...$params): array
         return $this->getParams(__FUNCTION__);
     }
 
+    private function paramOnParam(
+        #[Param('string')]
+        string $param
+    ): array {
+        return $this->getParams(__FUNCTION__);
+    }
+
     private function getParams(string $functionName): array
     {
         $reflection = new ReflectionMethod($this, $functionName);
@@ -112,6 +124,20 @@ public static function getParamsFromReflection(
             }
         }
 
+        $parameters = $reflection->getParameters();
+        foreach ($parameters as $parameter) {
+            $attributes = $parameter->getAttributes();
+            foreach ($attributes as $attribute) {
+                if ($attribute->getName() === Param::class) {
+                    $attribute->newInstance();
+                    $arguments = $attribute->getArguments();
+                    $argument = $arguments[array_key_first($arguments)];
+                    $params[$parameter->name] = $argument;
+                    ;
+                }
+            }
+        }
+
         return $params;
     }
 }