Name
dict_inc_or_put — Creates or increments an integer counter for a given key and a dictionary.
Synopsis
dict_inc_or_put ( |
inout dict dictionary , |
| in key any , | |
in value_increment integer
); |
Description
The function checks whether dict contains key . If it isn't so then the
function checks the datatype of the value associated with the key.
An error 42000 is signalled in case of non-integer value or a
negative integer value. If the value is positive then value_decrement is added to it and
the result become the new value associated with key in dict . If key is not in the
dictionary then a new item is added to the dict in order to associate the
key with value_increment .
Parameters
dict
Dictionary of counters. If the value is NULL then the function immediately returns zero.
key
Key of a dictionary item to process.
value decrement
A nonnegative integer (typically 1) that is added to the value
associated with key or used
as a starting value of a newly created counter.
Return Types
The function returns zero (for NULL dict ) or the changed (or the added)
value associated with the key .
Example
Example24.91.Simple Use
The function is convenient to deal with multisets, i.e., sets
with repeating elements. In this case the dictionary contains
distinct items as keys and counts of duplicates as associated
values. dict_inc_or_add is to add a
member, dict_dec_or_remove is to remove. The
following example gets an array of multisets and return the sum of
them.
create function DB.DBA.SUM_MULTISETS (inout msets any) returns any
{
declare sum_of_msets any;
sum_of_msets := dict_new (17);
foreach (any mset in msets) do
{
declare iter any;
declare memb any;
declare dup_count integer;
iter := mset; --- unlike dict_duplicate() this does not make copy of mset so it's fast.
dict_iter_rewind (iter);
while (dict_iter_next (iter, memb, dup_count))
dict_inc_or_put (sum_of_msets, memb, dup_count);
}
return sum_of_msets;
};