Name

dict_iter_next — Fetches a pair of key and value from a dictionary iterator and moves the iterator to the next pair.

Synopsis

dict_iter_next ( inout dict dictionary ,
out ret_key any ,
out ret_value any );

Description

The function gets the dictionary iterator initialized earlier by dict_iter_rewind and checks whether the iterator is still valid and not in conflict with any changes made by dict_put or the like. After that, if the iterator is in the position past the last item of the dictionary then zero is returned. If the iterator points to some item then ret_key and ret_value parameters are set to the key and value of the current item, the iterator is advanced to the next position (next item if present, otherwise past the end of the dictionary) and a nonzero integer is returned. If ret_value is a constant or an expression but not a plain variable then it is left unchanged but no error is signalled, so if the caller procedure needs only values of keys from dictionary then any constant like zero can be passed as a third parameter. Similarly, ret_key is not necessarily a variable.

Note that the values of ret_key and ret_value are left unchanged if the iterator points past the end of the dictionary. They are not filled in with NULLs or something like that.

Parameters

dict

Dictionary iterator

ret_key

The variable to be filled in with the key of the item. The parameter is ignored if it is not a plain variable.

ret_value

The variable to be filled in with the value (dependant part) of the item. The parameter is ignored if it is not a plain variable.

Return Types

The function returns a nonzero integer if the item is successfully fetched, zero otherwise

Errors

This function can generate the following errors:

Table24.25.

Error Code Description
22023 SR630 Function dict_iter_next() tries to iterate a volatile dictionary changed after last dict_iter_rewind (). Not every change in the dictionary results in this error. If the dict_iter_next() and dict_put () (or similar function) are both called with same variable passed as dict parameter then the function might adjust the iterator to match the changed state of the dictionary so it remains valid. In addition, if dict_put () changes only the value associated with some key but does not extend the dictionary with a new item then it does not invalidate any iterators.

Example

Example24.92.Simplest read throughout the dictionary.

The procedure creates a dictionary, puts couple of items into it and then print them to the server's console

create function dict_iterator_test ()
{
  declare dict, dkey, dvalue any;
  dict := dict_new (10);
  dict_put (dict, 'a', 1); dict_put (dict, 'b', 2);
  dict_iter_rewind (dict);
  while (dict_iter_next (dict, dkey, dvalue))
    dbg_obj_princ (' key is ' dkey, ', corresponding value is ', dvalue);
}