Function json_subscript_impl

libbuild2/variable.cxx:1969–2101

Return the value as well as the indication of whether the index/name is in range.

  // in range.
  //
  static pair<value, bool>
  json_subscript_impl (const value& val, value* val_data,
                       uint64_t i, const string& n, bool index)
  {
    const json_value& jv (val.as<json_value> ());

    json_value jr;

    if (index)
    {
      if (i >= (jv.type == json_type::array  ? jv.array.size ()  :
                jv.type == json_type::object ? jv.object.size () :
                jv.type == json_type::null   ? 0 : 1))
        return make_pair (value (), false);

      switch (jv.type)
      {
      case json_type::boolean:
      case json_type::signed_number:
      case json_type::hexadecimal_signed_number:
      case json_type::unsigned_number:
      case json_type::hexadecimal_unsigned_number:
      case json_type::string:
        {
          // Steal the value if possible.
          //
          jr = (&val == val_data
                ? json_value (move (const_cast<json_value&> (jv)))
                : json_value (jv));
          break;
        }
      case json_type::array:
        {
          // Steal the value if possible.
          //
          const json_value& r (jv.array[i]);
          jr = (&val == val_data
                ? json_value (move (const_cast<json_value&> (r)))
                : json_value (r));
          break;
        }
      case json_type::object:
        {
          // Represent as an object with one member.
          //
          new (&jr.object) json_value::object_type ();
          jr.type = json_type::object;

          // Steal the member if possible.
          //
          const json_member& m (jv.object[i]);
          jr.object.push_back (&val == val_data
                               ? json_member (move (const_cast<json_member&> (m)))
                               : json_member (m));
          break;
        }
      case json_type::null:
        assert (false);