Parens free `until` statement, the opposite of `while`

until.macro.sjs

/*

`until cond {}` is equivalent to `while !(cond) {}`

Brackets are mandatory

The following syntaxes are also valid

`do {} until cond`
`until cond;`

*/

macro until {
  rule { $cond:expr { $body ... } } => {
    while (!$cond) { $body ... }
  }
  rule infix { do { $body ... } | $cond:expr } => {
    do { $body ... } while (!$cond)
  }
  rule { $cond:expr ; } => {
  	while (!$cond);
  }
}

export until;