C++ Iter::prev方法代码示例

static void TestTInternalLList(skiatest::Reporter* reporter) {
    SkTInternalLList<ListElement> list;
    ListElement elements[4] = {
        ListElement(0),
        ListElement(1),
        ListElement(2),
        ListElement(3),
    };

    // list should be empty to start with
    check_list(list, reporter, true, 0, false, false, false, false, elements);

    list.addToHead(&elements[0]);

    check_list(list, reporter, false, 1, true, false, false, false, elements);

    list.addToHead(&elements[1]);
    list.addToHead(&elements[2]);
    list.addToHead(&elements[3]);

    check_list(list, reporter, false, 4, true, true, true, true, elements);

    // test out iterators
    typedef SkTInternalLList<ListElement>::Iter Iter;
    Iter iter;

    ListElement* cur = iter.init(list, Iter::kHead_IterStart);
    for (int i = 0; NULL != cur; ++i, cur = iter.next()) {
        REPORTER_ASSERT(reporter, cur->fID == 3-i);
    }

    cur = iter.init(list, Iter::kTail_IterStart);
    for (int i = 0; NULL != cur; ++i, cur = iter.prev()) {
        REPORTER_ASSERT(reporter, cur->fID == i);
    }

    // remove middle, frontmost then backmost
    list.remove(&elements[1]);
    list.remove(&elements[3]);
    list.remove(&elements[0]);

    check_list(list, reporter, false, 1, false, false, true, false, elements);

    // remove last element
    list.remove(&elements[2]);

    // list should be empty again
    check_list(list, reporter, true, 0, false, false, false, false, elements);

    // test out methods that add to the middle of the list.
    list.addAfter(&elements[1], NULL);
    check_list(list, reporter, false, 1, false, true, false, false, elements);

    list.remove(&elements[1]);

    list.addBefore(&elements[1], NULL);
    check_list(list, reporter, false, 1, false, true, false, false, elements);

    list.addBefore(&elements[0], &elements[1]);
    check_list(list, reporter, false, 2, true, true, false, false, elements);

    list.addAfter(&elements[3], &elements[1]);
    check_list(list, reporter, false, 3, true, true, false, true, elements);

    list.addBefore(&elements[2], &elements[3]);
    check_list(list, reporter, false, 4, true, true, true, true, elements);

    cur = iter.init(list, Iter::kHead_IterStart);
    for (int i = 0; NULL != cur; ++i, cur = iter.next()) {
        REPORTER_ASSERT(reporter, cur->fID == i);
    }
}

//.........这里部分代码省略.........
        REPORTER_ASSERT(reporter, !list1.isEmpty());

        list1.reset();
        list2.reset();
#if SK_ENABLE_INST_COUNT
        SkASSERT(0 == ListElement::InstanceCount());
#endif
        REPORTER_ASSERT(reporter, list1.isEmpty() && list2.isEmpty());

        // randomly perform insertions and deletions on a list and perform tests
        int count = 0;
        for (int j = 0; j < 100; ++j) {
            if (list1.isEmpty() || random.nextBiasedBool(3  * SK_Scalar1 / 4)) {
                int id = j;
                // Choose one of three ways to insert a new element: at the head, at the tail,
                // before a random element, after a random element
                int numValidMethods = 0 == count ? 2 : 4;
                int insertionMethod = random.nextULessThan(numValidMethods);
                switch (insertionMethod) {
                    case 0:
                        list1.addToHead(ListElement(id));
                        break;
                    case 1:
                        list1.addToTail(ListElement(id));
                        break;
                    case 2: // fallthru to share code that picks random element.
                    case 3: {
                        int n = random.nextULessThan(list1.count());
                        Iter iter = list1.headIter();
                        // remember the elements before/after the insertion point.
                        while (n--) {
                            iter.next();
                        }
                        Iter prev(iter);
                        Iter next(iter);
                        next.next();
                        prev.prev();

                        SkASSERT(NULL != iter.get());
                        // insert either before or after the iterator, then check that the
                        // surrounding sequence is correct.
                        if (2 == insertionMethod) {
                            SkNEW_INSERT_IN_LLIST_BEFORE(&list1, iter, ListElement, (id));
                            Iter newItem(iter);
                            newItem.prev();
                            REPORTER_ASSERT(reporter, newItem.get()->fID == id);

                            if (NULL != next.get()) {
                                REPORTER_ASSERT(reporter, next.prev()->fID == iter.get()->fID);
                            }
                            if (NULL != prev.get()) {
                                REPORTER_ASSERT(reporter, prev.next()->fID == id);
                            }
                        } else {
                            SkNEW_INSERT_IN_LLIST_AFTER(&list1, iter, ListElement, (id));
                            Iter newItem(iter);
                            newItem.next();
                            REPORTER_ASSERT(reporter, newItem.get()->fID == id);

                            if (NULL != next.get()) {
                                REPORTER_ASSERT(reporter, next.prev()->fID == id);
                            }
                            if (NULL != prev.get()) {
                                REPORTER_ASSERT(reporter, prev.next()->fID == iter.get()->fID);
                            }
                        }