Simple query language parser

gistfile1.txt

{
  function makeNode(type, head, tail) {
    return tail.length > 0
      ? {
          type:  type,
          terms: [head].concat(tail.map(function(t) { return t[1]; }))
        }
      : head;
  }
}

OrExpression = head:AndExpression tail:(OR AndExpression)* {
  return makeNode("OR", head, tail);
}

AndExpression = head:Word tail:(AND? Word)* {
  return makeNode("AND", head, tail);
}

Word = !OR !AND chars:[a-zA-Z0-9]+ _ { return chars.join(""); }

OR  = "OR"  _
AND = "AND" _

_ = [ \r\n\t]*