summaryrefslogtreecommitdiffstats
path: root/src/corelib/tools/qhash.h
diff options
context:
space:
mode:
authorGiuseppe D'Angelo <giuseppe.dangelo@kdab.com>2022-03-01 04:24:38 +0100
committerGiuseppe D'Angelo <giuseppe.dangelo@kdab.com>2022-03-04 00:21:44 +0100
commit0deff80eabd577f3514d255e32f74502c914dfe1 (patch)
tree353014233bbb87123679ac985de18daee3834341 /src/corelib/tools/qhash.h
parentdd5fc20e902187356538d1c993d9ece729f6f505 (diff)
Associative containers: add a way to obtain a key/value range
Our associative containers' iterator's value_type isn't a destructurable type (yielding key/value). This means that something like for (auto [k, v] : map) doesn't even compile -- one can only "directly" iterate on the values. For quite some time we've had QKeyValueIterator to allow key/value iteration, but then one had to resort to a "traditional" for loop: for (auto i = map.keyValueBegin(), e = keyValueEnd(); i!=e; ++i) This can be easily packaged in an adaptor class, which is what this commmit does, thereby offering a C++17-compatible way to obtain key/value iteration over associative containers. Something possibly peculiar is the fact that the range so obtained is a range of pairs of references -- not a range of references to pairs. But that's easily explained by the fact that we have no pairs to build references to; hence, for (auto &[k, v] : map.asKeyValueRange()) doesn't compile (lvalue reference doesn't bind to prvalue pair). Instead, both of these compile: for (auto [k, v] : map.asKeyValueRange()) for (auto &&[k, v] : map.asKeyValueRange()) and in *both* cases one gets references to the keys/values in the map. If the map is non-const, the reference to the value is mutable. Last but not least, implement pinning for rvalue containers. [ChangeLog][QtCore][QMap] Added asKeyValueRange(). [ChangeLog][QtCore][QMultiMap] Added asKeyValueRange(). [ChangeLog][QtCore][QHash] Added asKeyValueRange(). [ChangeLog][QtCore][QMultiHash] Added asKeyValueRange(). Task-number: QTBUG-4615 Change-Id: Ic8506bff38b2f753494b21ab76f52e05c06ffc8b Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Diffstat (limited to 'src/corelib/tools/qhash.h')
-rw-r--r--src/corelib/tools/qhash.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index 0eb91e7604..73a0225106 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -1228,6 +1228,10 @@ public:
inline const_key_value_iterator constKeyValueBegin() const noexcept { return const_key_value_iterator(begin()); }
inline const_key_value_iterator keyValueEnd() const noexcept { return const_key_value_iterator(end()); }
inline const_key_value_iterator constKeyValueEnd() const noexcept { return const_key_value_iterator(end()); }
+ auto asKeyValueRange() & { return QtPrivate::QKeyValueRange(*this); }
+ auto asKeyValueRange() const & { return QtPrivate::QKeyValueRange(*this); }
+ auto asKeyValueRange() && { return QtPrivate::QKeyValueRange(std::move(*this)); }
+ auto asKeyValueRange() const && { return QtPrivate::QKeyValueRange(std::move(*this)); }
iterator erase(const_iterator it)
{
@@ -1843,6 +1847,10 @@ public:
inline const_key_value_iterator constKeyValueBegin() const noexcept { return const_key_value_iterator(begin()); }
inline const_key_value_iterator keyValueEnd() const noexcept { return const_key_value_iterator(end()); }
inline const_key_value_iterator constKeyValueEnd() const noexcept { return const_key_value_iterator(end()); }
+ auto asKeyValueRange() & { return QtPrivate::QKeyValueRange(*this); }
+ auto asKeyValueRange() const & { return QtPrivate::QKeyValueRange(*this); }
+ auto asKeyValueRange() && { return QtPrivate::QKeyValueRange(std::move(*this)); }
+ auto asKeyValueRange() const && { return QtPrivate::QKeyValueRange(std::move(*this)); }
iterator detach(const_iterator it)
{