program: decl*

?decl: iface
  | node
  | func

sep_trail{item, punc}: item (punc item)? punc?

func: "fn" ident "(" ")" ("->" ty) "{" "}"

iface: "iface" ident "{" sep_trail{iface_field, ","} "}"
iface_field: ident ":" ident

iface_ref: ident
iface_refs: iface_ref*
node: "node" ident ":" iface_refs "{" variants "}"
variants: variant*
variant: prod "=>" "{" equations "}"
prod: sym*
?sym: sym_rename
  | sym_lit
sym_lit: ESCAPED_STRING
sym_rename: "<" ident ":" node_ref ">"
?node_ref: node_ref_name
  | node_regex
node_ref_name: ident
node_regex: ESCAPED_STRING
equations: equation_semi*
equation_semi: equation ";"
// TODO: the left side should really be a separate type
// called lvalue, and should NOT include literals
equation: expr "=" expr

// Expressions
?expr: expr2
  | expr_add
expr_add: expr "+" expr2

?expr2: expr3
  | expr_mul
  | expr_call
expr_mul: expr2 "*" expr3
expr_call: expr2 "(" args ")"

?expr3: "(" expr ")"
  | expr_dot
  | expr_name
expr_dot: expr3 "." ident
expr_name: ident

args: sep_trail{expr, ","}

ty: ident

ident: IDENT
COMMENT: /\/\/[^\n]*/
IDENT: /([a-zA-Z][a-zA-Z0-9_]*)|(_[a-zA-Z0-9_]+)/

%import python.STRING
%import common.WS
%import common.ESCAPED_STRING

%ignore WS
%ignore COMMENT