SexpGrammar

A helper to manipulate sexp grammars.

Example

grammar = SexpGrammar.load(<<-YAML)

  # alternative rule
  bool_expr:
    - bool_and
    - bool_or
    - bool_not
    - var_ref
    - literal

  # non-terminal
  bool_and:
    - [ bool_expr, bool_expr ]
  bool_or:
    - [ bool_expr, bool_expr ]
  bool_not:
    - [ bool_expr ]
  literal:
    - [ truth_value ]
  var_ref:
    - [ var_name ]

  # terminals
  var_name:
    !ruby/regexp /^[a-z]+$/
  truth_value:
    - true
    - false

YAML

grammar === [:bool_and, [:bool_not, [:var_ref, "x"]], [:literal, true]]
# => true

grammar === [:bool_and, [:literal, "true"]]
# => false (second term is missing)

Links

https://github.com/blambeau/sexp_grammar