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map_difference: Parametrize value comparison

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If map value type is lw_shared_ptr<T>, for example, we need to be able
to pass our own value comparison function to the difference() function.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
This commit is contained in:
Pekka Enberg
2015-05-26 14:02:31 +03:00
parent 5ab968137f
commit a388b088c6
3 changed files with 33 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
db/legacy_schema_tables.cc
View File

@@ -559,7 +559,9 @@ std::vector<const char*> ALL { KEYSPACES, COLUMNFAMILIES, COLUMNS, TRIGGERS, USE
* that means that a keyspace had been recreated and dropped, and the recreated keyspace had never found a way
* to this node
*/
auto diff = difference(before, after);
auto diff = difference(before, after, [](const lw_shared_ptr<query::result_set>& x, const lw_shared_ptr<query::result_set>& y) -> bool {
return *x == *y;
});
for (auto&& entry : diff.entries_only_on_right) {
if (!entry.second->empty()) {

23
map_difference.hh
View File

@@ -39,12 +39,19 @@ struct map_difference {
{ }
};
template<typename Key, typename Tp, typename Compare, typename Alloc>
template<typename Key,
typename Tp,
typename Compare = std::less<Key>,
typename Eq = std::equal_to<Tp>,
typename Alloc>
inline
map_difference<Key, Tp, Compare, Alloc>
difference(const std::map<Key, Tp, Compare, Alloc>& left,
const std::map<Key, Tp, Compare, Alloc>& right,
const Compare& key_comp, const Alloc& alloc) {
Compare key_comp,
Eq equals = Eq(),
Alloc alloc = Alloc())
{
map_difference<Key, Tp, Compare, Alloc> diff{key_comp, alloc};
diff.entries_only_on_right = right;
for (auto&& kv : left) {
@@ -52,9 +59,9 @@ difference(const std::map<Key, Tp, Compare, Alloc>& left,
auto&& it = right.find(left_key);
if (it != right.end()) {
diff.entries_only_on_right.erase(left_key);
auto&& left_value = kv.second;
auto&& right_value = it->second;
if (left_value == right_value) {
const Tp& left_value = kv.second;
const Tp& right_value = it->second;
if (equals(left_value, right_value)) {
diff.entries_in_common.emplace(kv);
} else {
value_difference<Tp> value_diff{left_value, right_value};
@@ -67,9 +74,9 @@ difference(const std::map<Key, Tp, Compare, Alloc>& left,
return diff;
}
template<typename Key, typename Tp, typename Compare, typename Alloc>
template<typename Key, typename Tp, typename Compare, typename Eq, typename Alloc>
inline
map_difference<Key, Tp, Compare, Alloc>
difference(const std::map<Key, Tp, Compare, Alloc>& left, const std::map<Key, Tp, Compare, Alloc>& right) {
return difference(left, right, left.key_comp(), left.get_allocator());
difference(const std::map<Key, Tp, Compare, Alloc>& left, const std::map<Key, Tp, Compare, Alloc>& right, Eq equals) {
return difference(left, right, left.key_comp(), equals);
}

20
tests/urchin/map_difference_test.cc
View File

@@ -17,7 +17,9 @@ BOOST_AUTO_TEST_CASE(both_empty) {
map<int, int> left;
map<int, int> right;
auto diff = difference(left, right);
auto diff = difference(left, right, [](int x, int y) -> bool {
return x == y;
});
BOOST_REQUIRE(diff.entries_only_on_left.empty());
BOOST_REQUIRE(diff.entries_only_on_right.empty());
@@ -32,7 +34,9 @@ BOOST_AUTO_TEST_CASE(left_empty) {
right.emplace(1, 100);
right.emplace(2, 200);
auto diff = difference(left, right);
auto diff = difference(left, right, [](int x, int y) -> bool {
return x == y;
});
BOOST_REQUIRE(diff.entries_only_on_left.empty());
BOOST_REQUIRE(diff.entries_only_on_right == right);
@@ -47,7 +51,9 @@ BOOST_AUTO_TEST_CASE(right_empty) {
left.emplace(1, 100);
left.emplace(2, 200);
auto diff = difference(left, right);
auto diff = difference(left, right, [](int x, int y) -> bool {
return x == y;
});
BOOST_REQUIRE(diff.entries_only_on_left == left);
BOOST_REQUIRE(diff.entries_only_on_right.empty());
@@ -65,7 +71,9 @@ BOOST_AUTO_TEST_CASE(both_same) {
right.emplace(1, 100);
right.emplace(2, 200);
auto diff = difference(left, right);
auto diff = difference(left, right, [](int x, int y) -> bool {
return x == y;
});
BOOST_REQUIRE(diff.entries_only_on_left.empty());
BOOST_REQUIRE(diff.entries_only_on_right.empty());
@@ -83,7 +91,9 @@ BOOST_AUTO_TEST_CASE(differing_values) {
right.emplace(1, 1000);
right.emplace(2, 2000);
auto diff = difference(left, right);
auto diff = difference(left, right, [](int x, int y) -> bool {
return x == y;
});
BOOST_REQUIRE(diff.entries_only_on_left.empty());
BOOST_REQUIRE(diff.entries_only_on_right.empty());