`@Annotation` déclaration

annotation.macro.sjs

/*

Annotations can only occur immediately before a variable, a function declaration or an assignment

```
@Component('position')
module.exports = function (x, y) {
  return {x: x || 0, y: y || 0};
}

@Component('position)
function position(x, y) {
  return {x: x || 0, y: y || 0};
}
```

Parens are optionals if no argument is provided

```
@Component
function position(x, y) {
  return {x: x || 0, y: y || 0};
}
```

Multiples annotations per declarations are valid

```
@Entity('sprite')
@RequireComponents('position', 'texture')
module.exports = function (entity) {
  ...
};
````

Annotations must be constructor functions

The following is an expanded version of the first example

```
module.exports = function (x, y) {
  return {x: x || 0, y: y || 0};
};

module.exports.annotations = [new Component('position')];
```

*/

macro function_params {
  rule { ($args:ident (,) ...) }
}
 
macro annotation {
  rule { $name:ident ($args:expr (,) ...) }
  rule { $name:ident }
}
 
macro @ {
	rule {
		$annotation:annotation (@) ...
		function $name:ident $params:function_params { $body ... }
	} => {
		function $name $params { $body ... }
		$name.annotations = [$(new $annotation) (,) ...];
	}
	rule {
		$annotation:annotation (@) ...
		var $symbol:ident = $value:expr
	} => {
		var $symbol = $value
		$symbol.annotations = [$(new $annotation) (,) ...];
	}
	rule {
		$annotation:annotation (@) ...
		$symbol:ident = $value:expr
	} => {
		$symbol = $value
		$symbol.annotations = [$(new $annotation) (,) ...];
	}
	rule {
		$annotation:annotation (@) ...
		$path:ident (.) ... $symbol:ident = $value:expr
	} => {
		($path (.) ... . $symbol = $value).annotations = [
			$(new $annotation) (,) ...
		];
	}
}

export @;