24.7.1.3 Defining the Grammar of a Language

The usual way to define the SMIE grammar of a language is by defining a new global variable that holds the precedence table by giving a set of BNF rules. For example, the grammar definition for a small Pascal-like language could look like:

(require 'smie)
(defvar sample-smie-grammar
  (smie-prec2->grammar
   (smie-bnf->prec2
    '((id)
      (inst ("begin" insts "end")
            ("if" exp "then" inst "else" inst)
            (id ":=" exp)
            (exp))
      (insts (insts ";" insts) (inst))
      (exp (exp "+" exp)
           (exp "*" exp)
           ("(" exps ")"))
      (exps (exps "," exps) (exp)))
    '((assoc ";"))
    '((assoc ","))
    '((assoc "+") (assoc "*")))))

A few things to note: