JSONPath

gistfile1.txt

start = fieldName;

fieldName = selector ('.' selector)*

selector = word '[' (numOfexpr/ ('"' qword '"') / ('\'' qword '\'')) ']' / word / '@'

word = chars:([a-zA-Z$:][a-zA-Z_0-9:]*)  {
  var ret = chars[0];
  for(i = 1; i < chars.length; i++) {
    ret = ret + chars[i].join('');
  }
  return ret;
}

numOfexpr = number / expr

expr = ope
number = digits

digits = [0-9]+ 

qword = chars:([\x20-\x21]/[\x23-\x26]/[\x28-\x7E]/[a-zA-Z]/[a-zA-Z_0-9])*