PEG Sexprs

sexprs.peg

 {
  function getType(def, head) {
    switch (head) {
    	case "and":
        case "or":
        case "not":
        	return "booleanOperator";
        case "eq":
        case "ne":
        case "lt":
        case "lte":
        case "gt":
        case "gte":
        case "exists":
        	return "filterOperator";
        case "interval":
        case "groupBy":
        case "granularity":
        case "filter":
        	return "field";
        default:
        	return def;
    }
  }
}

List
  = "(" head:Atom _ tail:(_ (Integer / String / Pair / List) _)+ ")" { 
	var ret = { type: getType('List', head) };
    tail = tail.map(function(i) { 
    	return i.filter(function(j) { return !Array.isArray(j); });
    });
    ret.head = head;
    ret.tail = tail.map(function(i) { return i[0]; });
    return ret;
  }
  
Pair
  = "(" head:Atom _ tail:String ")" {
  	var ret = { type: getType('Pair', head) };
    ret.head = head;
    ret.tail = tail;
    return ret;
  }

String "string"
  = '"' atom:Atom '"' { return atom; }

Integer "integer"
  = [0-9]+ { return parseInt(text(), 10); }

Atom "atom"
  = [a-zA-Z0-9]* { return text(); }

_ "whitespace"
  = [ \t\n\r]*

For us with PEG.js