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authorGravatar Abseil Team <absl-team@google.com>2021-05-06 07:35:26 -0700
committerGravatar Andy Getz <durandal@google.com>2021-05-06 11:11:13 -0400
commit70b29fe5a5c1752158830eabc9aa273718b477af (patch)
tree1b610f6f1e53b8814f949b94c6f7ae8694af9419 /absl/strings/internal
parent037ade20d1132781aae3cda4d547a9e6a5f557bf (diff)
Export of internal Abseil changes
-- daf5a2b9ab3507ad5fb9aebe9165933f33098b83 by Abseil Team <absl-team@google.com>: Absl flat containers reserve enough space even in the presence of tombstones. PiperOrigin-RevId: 372339945 -- 9a61504867ba0eccc5046d7333090fbe3439cdd9 by Abseil Team <absl-team@google.com>: Add benchmark for BlockingCounter PiperOrigin-RevId: 372246068 -- 91ee87e6de09fc62970667ee52654c9dcf7c478d by Evan Brown <ezb@google.com>: In absl::StrSplit, support btree_multimap, and other non-std::multimap-multimaps by supporting any map type that returns iterator from insert(). Also: - Use emplace() instead of insert() when available, not just for std::(multi)map - we can potentially change some string copies to moves this way. - We no longer need the Insert class so remove it. PiperOrigin-RevId: 372209653 GitOrigin-RevId: daf5a2b9ab3507ad5fb9aebe9165933f33098b83 Change-Id: I83098fde4a722cd4b682f024d3bfa56c613f960c
Diffstat (limited to 'absl/strings/internal')
-rw-r--r--absl/strings/internal/str_split_internal.h68
1 files changed, 34 insertions, 34 deletions
diff --git a/absl/strings/internal/str_split_internal.h b/absl/strings/internal/str_split_internal.h
index a2f41c15..17c1bfe8 100644
--- a/absl/strings/internal/str_split_internal.h
+++ b/absl/strings/internal/str_split_internal.h
@@ -32,7 +32,7 @@
#include <array>
#include <initializer_list>
#include <iterator>
-#include <map>
+#include <tuple>
#include <type_traits>
#include <utility>
#include <vector>
@@ -182,6 +182,13 @@ template <typename T>
struct HasConstIterator<T, absl::void_t<typename T::const_iterator>>
: std::true_type {};
+// HasEmplace<T>::value is true iff there exists a method T::emplace().
+template <typename T, typename = void>
+struct HasEmplace : std::false_type {};
+template <typename T>
+struct HasEmplace<T, absl::void_t<decltype(std::declval<T>().emplace())>>
+ : std::true_type {};
+
// IsInitializerList<T>::value is true iff T is an std::initializer_list. More
// details below in Splitter<> where this is used.
std::false_type IsInitializerListDispatch(...); // default: No
@@ -372,50 +379,43 @@ class Splitter {
// value.
template <typename Container, typename First, typename Second>
struct ConvertToContainer<Container, std::pair<const First, Second>, true> {
+ using iterator = typename Container::iterator;
+
Container operator()(const Splitter& splitter) const {
Container m;
- typename Container::iterator it;
+ iterator it;
bool insert = true;
- for (const auto& sp : splitter) {
+ for (const absl::string_view sv : splitter) {
if (insert) {
- it = Inserter<Container>::Insert(&m, First(sp), Second());
+ it = InsertOrEmplace(&m, sv);
} else {
- it->second = Second(sp);
+ it->second = Second(sv);
}
insert = !insert;
}
return m;
}
- // Inserts the key and value into the given map, returning an iterator to
- // the inserted item. Specialized for std::map and std::multimap to use
- // emplace() and adapt emplace()'s return value.
- template <typename Map>
- struct Inserter {
- using M = Map;
- template <typename... Args>
- static typename M::iterator Insert(M* m, Args&&... args) {
- return m->insert(std::make_pair(std::forward<Args>(args)...)).first;
- }
- };
-
- template <typename... Ts>
- struct Inserter<std::map<Ts...>> {
- using M = std::map<Ts...>;
- template <typename... Args>
- static typename M::iterator Insert(M* m, Args&&... args) {
- return m->emplace(std::make_pair(std::forward<Args>(args)...)).first;
- }
- };
-
- template <typename... Ts>
- struct Inserter<std::multimap<Ts...>> {
- using M = std::multimap<Ts...>;
- template <typename... Args>
- static typename M::iterator Insert(M* m, Args&&... args) {
- return m->emplace(std::make_pair(std::forward<Args>(args)...));
- }
- };
+ // Inserts the key and an empty value into the map, returning an iterator to
+ // the inserted item. We use emplace() if available, otherwise insert().
+ template <typename M>
+ static absl::enable_if_t<HasEmplace<M>::value, iterator> InsertOrEmplace(
+ M* m, absl::string_view key) {
+ // Use piecewise_construct to support old versions of gcc in which pair
+ // constructor can't otherwise construct string from string_view.
+ return ToIter(m->emplace(std::piecewise_construct, std::make_tuple(key),
+ std::tuple<>()));
+ }
+ template <typename M>
+ static absl::enable_if_t<!HasEmplace<M>::value, iterator> InsertOrEmplace(
+ M* m, absl::string_view key) {
+ return ToIter(m->insert(std::make_pair(First(key), Second(""))));
+ }
+
+ static iterator ToIter(std::pair<iterator, bool> pair) {
+ return pair.first;
+ }
+ static iterator ToIter(iterator iter) { return iter; }
};
StringType text_;