Parens free `for`, `for in` and `for own` statements

for.macro.sjs

/*

```
for var i = 0; i < length; i += 1 {
  ...
}

for var key in object {
  ...
}

for own var key in object {
  ...
}
```

Brackets are mandatory

A `for own` loop iterates only over own properties

*/

macro assignment {
	rule { $symbol:ident = $value:expr }
	rule { $symbol:ident }
}
 
macro statement {
	rule { ($expression:expr (,) ...) }
	rule { $expression:expr (,) ... }
}
 
macro for_assignment {
	rule { var $assignment:assignment (,) ... }
	rule { $statement:statement }
}

macro for_statements {
	rule { $assignments:for_assignment ; $cond:statement ; $final:statement }
}
 
macro for_in_assignment {
	rule { var $assignment:assignment }
	rule { $symbol:ident }
}
 
let for = macro {
  rule { ($statements:for_statements) } => {
    for ($statements)
  }
  rule { $statements:for_statements ; } => {
  	for ($statements);
  }
  rule { $statements:for_statements { $body ... } } => {
    for ($statements) { $body ... }
  }
  rule { ($assignment:for_in_assignment in $object:expr) } => {
    for ($assignment in $object)
  }
  rule { $assignment:for_in_assignment in $object:expr ; } => {
    for ($assignment in $object);
  }
  rule { $assignment:for_in_assignment in $object:expr { $body ... } } => {
    for ($assignment in $object) { $body ... }
  }
  rule { own $assignment:for_in_assignment in $object:expr ; } => {
	var ref = $object, proto = ref.__proto__;
	ref.__proto__ = null;
	for ($assignment in ref);
	ref.__proto__ = proto;
  }
  rule { own $assignment:for_in_assignment in $object:expr { $body ... } } => {
  	var ref = $object, proto = ref.__proto__;
	ref.__proto__ = null;
	for ($assignment in ref) { $body ... }
	ref.__proto__ = proto;
  }
}

export for;