Arithmetic Grammar for Ohm

Arithmetic.json

[
  {
    "text": "2 * (42 - 1) / 9",
    "startRule": "Exp",
    "shouldMatch": true
  },
  {
    "text": "1+2*3",
    "startRule": "Exp",
    "shouldMatch": true
  },
  {
    "text": "I CAN HAS CHEEZBURGER?",
    "startRule": "Exp",
    "shouldMatch": false
  },
  {
    "text": " (  \t123   ) ",
    "startRule": "Exp",
    "shouldMatch": true
  },
  {
    "text": "(2+4)*7",
    "startRule": "Exp",
    "shouldMatch": true
  }
]

Arithmetic.ohm

Arithmetic {
Exp
  = AddExp

AddExp
  = AddExp "+" MulExp  -- plus
  | AddExp "-" MulExp  -- minus
  | MulExp

MulExp
  = MulExp "*" ExpExp  -- times
  | MulExp "/" ExpExp  -- divide
  | ExpExp

ExpExp
  = PriExp "^" ExpExp  -- power
  | PriExp

PriExp
  = "(" Exp ")"  -- paren
  | "+" PriExp   -- pos
  | "-" PriExp   -- neg
  | ident
  | number

ident  (an identifier)
  = letter alnum*

number  (a number)
  = digit* "." digit+  -- fract
  | digit+             -- whole
}