@external propSource highlighting from "./highlight.js"
@top Program { line* }

line { 
  CommandCall semi |
  expr semi
}

@skip { space }

@tokens {
  @precedence { Number "-"}
  space { @whitespace+ }
  Number { "-"? $[0-9]+ ('.' $[0-9]+)? }
  Boolean { "true" | "false" }
  String { '\'' !["]* '\'' }
  NamedArgPrefix { $[a-z]+ $[a-z0-9\-]* "=" }  // matches "lines=", "follow=", etc.

  fn[@name=keyword] { "fn" }
  equals[@name=operator] { "=" }
  ":"[@name=colon]
  "+"[@name=operator]
  "-"[@name=operator]
  "*"[@name=operator]
  "/"[@name=operator]
  leftParen[@name=paren] { "(" }
  rightParen[@name=paren] { ")" }
}

@external tokens tokenizer from "./tokenizers" { 
  Identifier,
  Command,
  CommandPartial
}

@external tokens argTokenizer from "./tokenizers" {
  UnquotedArg
}

@external tokens insertSemicolon from "./tokenizers" { insertedSemi }

@precedence {
  multiplicative @left,
  additive @left,
  namedComplete @left,
  function @right
  assignment @right
}

expr {
  Assignment |
  Function |
  BinOp |
  atom
}

semi { insertedSemi | ";" }

argValue { atom | UnquotedArg }

CommandCall { (Command | CommandPartial) (NamedArg | PartialNamedArg | Arg)* }
Arg { !namedComplete argValue }
NamedArg { NamedArgPrefix !namedComplete argValue }  // Required atom, higher precedence
PartialNamedArg { NamedArgPrefix }  // Just the prefix

Assignment { Identifier !assignment equals expr }

Function { !function fn Params ":" expr }
Params { Identifier* }

BinOp { 
  expr !multiplicative "*" expr |
  expr !multiplicative "/" expr |
  expr !additive "+" expr |
  expr !additive "-" expr
}

ParenExpr { leftParen expr rightParen }
atom { Identifier ~command | Number | String | Boolean | ParenExpr }