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ListPopFront

ListPopFront

Description

Remove the first element of the list and optionally store its value.

Parameters

Name Direction Description
l in,out List handle.
val out Optional destination for the popped element.

Success

Returns to the caller. The head node is unlinked, its allocator-owned storage freed; list length shrinks by one, the next node becomes the new head. When val is non-NULL the removed value is memcopied into *val.

Failure

Function cannot fail. Calling on an empty list is a caller bug and aborts via LOG_FATAL.

Usage example (Cross-references)

Usage examples (Cross-references) 
                if (ListLen(list) > 0) {
                    i32 popped;
                    ListPopFront(list, &popped);
                }
                break;
        result      = result && list_matches(GENERIC_LIST(&list), (const int[]) {10, 30, 40}, 3);
    
        ListPopFront(&list, &removed);
        result = result && (removed == 10);
        result = result && list_matches(GENERIC_LIST(&list), (const int[]) {30, 40}, 2);
    
    static bool test_list_pop_front_empty_fails(void) {
        WriteFmt("Testing ListPopFront on empty list\n");
    
        List(int) list = ListInit(get_test_alloc());
    
        List(int) list = ListInit(get_test_alloc());
        ListPopFront(&list, NULL);
    
        return false;
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ListPopBackListPtrAt