NAME¶

read-lifo - (LIFO)

PURPOSE¶

Reads key/value pair from a LIFO list.

SYNTAX¶

read-lifo <list> \


    key <key> \


    value <value> \


    [ status <status> ]

DESCRIPTION¶

read-lifo retrieves an element from the LIFO <list> into <key> string (in "key" clause) and <value> string (in "value" clause).

Once an element has been retrieved, the next use of read-lifo will obtain the following one, in the reverse order they were put in. read-lifo starts with the last element put in, and moves backwards from there, unless rewind-lifo is called, which positions back to the last one. Note that write-lifo will cause the next read-lifo to start with the element just written, i.e. it implicitly calls rewind-lifo.

If the element is successfully retrieved, <status> number (in "status" clause) is GG_OKAY, otherwise it is GG_ERR_EXIST, which means there are no more elements to retrieve.

EXAMPLES¶

In this example, a LIFO list is created, and two key/value pairs added. They are then retrieved in a loop and printed out (twice with rewind), and then the list is purged:

%% /lifo public


    new-lifo mylist


    // Add data to the list


    write-lifo mylist key "key1" value "value1"


    write-lifo mylist key "some2" value "other2"


    start-loop


       // Get data from the list


       read-lifo mylist key k value v status st


       // Check if no more data


       if-true st not-equal GG_OKAY


           break-loop


       end-if


       @Obtained key <<print-out k>> with value <<print-out v>>


    end-loop


    // Go through the list again, use rewind-lifo for that


    rewind-lifo mylist


    start-loop


       read-lifo mylist key k value v status st


       if-true st not-equal GG_OKAY


           break-loop


       end-if


       @Again obtained key <<print-out k>> with value <<print-out v>>


    end-loop


    // Delete all in LIFO


    purge-lifo mylist


    // Verify nothing is left


    rewind-lifo mylist


    read-lifo mylist key k value v status st


    if-true st not-equal GG_OKAY


       @LIFO is empty


    end-if
%%

SEE ALSO¶

LIFO

delete-lifo get-lifo new-lifo purge-lifo read-lifo rewind-lifo write-lifo See all documentation