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authorpechatnov <pechatnov@yandex-team.ru>2022-02-10 16:48:57 +0300
committerDaniil Cherednik <dcherednik@yandex-team.ru>2022-02-10 16:48:57 +0300
commit132a3640fac343164b858d0a914e020a848a2848 (patch)
tree5d5cb817648f650d76cf1076100726fd9b8448e8 /library/cpp/iterator/concatenate.h
parent8e9b2f8bbf4a2320f539eef5b85555f42c065425 (diff)
downloadydb-132a3640fac343164b858d0a914e020a848a2848.tar.gz
Restoring authorship annotation for <pechatnov@yandex-team.ru>. Commit 2 of 2.
Diffstat (limited to 'library/cpp/iterator/concatenate.h')
-rw-r--r--library/cpp/iterator/concatenate.h262
1 files changed, 131 insertions, 131 deletions
diff --git a/library/cpp/iterator/concatenate.h b/library/cpp/iterator/concatenate.h
index fe7e802aa0..64d2cd451a 100644
--- a/library/cpp/iterator/concatenate.h
+++ b/library/cpp/iterator/concatenate.h
@@ -1,136 +1,136 @@
-#pragma once
-
-#include <util/generic/store_policy.h>
-
-#include <iterator>
-#include <tuple>
-
-
-namespace NPrivate {
-
- template <typename TValue_, typename... TContainers>
- struct TConcatenator {
- template <std::size_t... I>
- struct TConcatenatorWithIndex {
- private:
- using THolders = std::tuple<TAutoEmbedOrPtrPolicy<TContainers>...>;
- using TValue = TValue_;
- using TIteratorState = std::tuple<decltype(std::begin(std::declval<TContainers&>()))...>;
- using TSentinelState = std::tuple<decltype(std::end(std::declval<TContainers&>()))...>;
-
- struct TIterator;
- struct TSentinelCandidate {
- TSentinelState Iterators_;
- std::size_t Position_;
- THolders* HoldersPtr_;
- };
- using TSentinel = std::conditional_t<std::is_same_v<TIteratorState, TSentinelState>,
- TIterator, TSentinelCandidate>;
-
- struct TIterator {
- private:
- friend struct TConcatenatorWithIndex<I...>;
-
- // important, that it is a static function, compiler better optimizes such code
- template <std::size_t index = 0, typename TMaybeConstIteratorState>
- static TValue GetCurrentValue(std::size_t position, TMaybeConstIteratorState& iterators) {
- if constexpr (index >= sizeof...(TContainers)) {
- // never happened when use of iterator is correct
- return *std::get<0>(iterators);
- } else {
- if (position == index) {
- return *std::get<index>(iterators);
- } else {
- return GetCurrentValue<index + 1>(position, iterators);
- }
- }
- }
-
- template <bool needIncrement, std::size_t index = 0>
- void MaybeIncrementIteratorAndSkipExhaustedContainers() {
- if constexpr (index >= sizeof...(TContainers)) {
- return;
- } else {
- if (Position_ == index) {
- if constexpr (needIncrement) {
- ++std::get<index>(Iterators_);
- }
- if (!(std::get<index>(Iterators_) != std::end(*std::get<index>(*HoldersPtr_).Ptr()))) {
- ++Position_;
- MaybeIncrementIteratorAndSkipExhaustedContainers<false, index + 1>();
- }
- } else {
- MaybeIncrementIteratorAndSkipExhaustedContainers<needIncrement, index + 1>();
- }
- }
- }
- public:
- using difference_type = std::ptrdiff_t;
- using value_type = TValue;
- using pointer = std::remove_reference_t<TValue>*;
- using reference = std::remove_reference_t<TValue>&;
- using iterator_category = std::input_iterator_tag;
-
- TValue operator*() {
- return GetCurrentValue(Position_, Iterators_);
- }
- TValue operator*() const {
- return GetCurrentValue(Position_, Iterators_);
- }
+#pragma once
+
+#include <util/generic/store_policy.h>
+
+#include <iterator>
+#include <tuple>
+
+
+namespace NPrivate {
+
+ template <typename TValue_, typename... TContainers>
+ struct TConcatenator {
+ template <std::size_t... I>
+ struct TConcatenatorWithIndex {
+ private:
+ using THolders = std::tuple<TAutoEmbedOrPtrPolicy<TContainers>...>;
+ using TValue = TValue_;
+ using TIteratorState = std::tuple<decltype(std::begin(std::declval<TContainers&>()))...>;
+ using TSentinelState = std::tuple<decltype(std::end(std::declval<TContainers&>()))...>;
+
+ struct TIterator;
+ struct TSentinelCandidate {
+ TSentinelState Iterators_;
+ std::size_t Position_;
+ THolders* HoldersPtr_;
+ };
+ using TSentinel = std::conditional_t<std::is_same_v<TIteratorState, TSentinelState>,
+ TIterator, TSentinelCandidate>;
+
+ struct TIterator {
+ private:
+ friend struct TConcatenatorWithIndex<I...>;
+
+ // important, that it is a static function, compiler better optimizes such code
+ template <std::size_t index = 0, typename TMaybeConstIteratorState>
+ static TValue GetCurrentValue(std::size_t position, TMaybeConstIteratorState& iterators) {
+ if constexpr (index >= sizeof...(TContainers)) {
+ // never happened when use of iterator is correct
+ return *std::get<0>(iterators);
+ } else {
+ if (position == index) {
+ return *std::get<index>(iterators);
+ } else {
+ return GetCurrentValue<index + 1>(position, iterators);
+ }
+ }
+ }
+
+ template <bool needIncrement, std::size_t index = 0>
+ void MaybeIncrementIteratorAndSkipExhaustedContainers() {
+ if constexpr (index >= sizeof...(TContainers)) {
+ return;
+ } else {
+ if (Position_ == index) {
+ if constexpr (needIncrement) {
+ ++std::get<index>(Iterators_);
+ }
+ if (!(std::get<index>(Iterators_) != std::end(*std::get<index>(*HoldersPtr_).Ptr()))) {
+ ++Position_;
+ MaybeIncrementIteratorAndSkipExhaustedContainers<false, index + 1>();
+ }
+ } else {
+ MaybeIncrementIteratorAndSkipExhaustedContainers<needIncrement, index + 1>();
+ }
+ }
+ }
+ public:
+ using difference_type = std::ptrdiff_t;
+ using value_type = TValue;
+ using pointer = std::remove_reference_t<TValue>*;
+ using reference = std::remove_reference_t<TValue>&;
+ using iterator_category = std::input_iterator_tag;
+
+ TValue operator*() {
+ return GetCurrentValue(Position_, Iterators_);
+ }
+ TValue operator*() const {
+ return GetCurrentValue(Position_, Iterators_);
+ }
TIterator& operator++() {
- MaybeIncrementIteratorAndSkipExhaustedContainers<true>();
+ MaybeIncrementIteratorAndSkipExhaustedContainers<true>();
return *this;
- }
- bool operator!=(const TSentinel& other) const {
- // give compiler an opportunity to optimize sentinel case (-70% of time)
- if (other.Position_ == sizeof...(TContainers)) {
- return Position_ < sizeof...(TContainers);
- } else {
- return (Position_ != other.Position_ ||
- ((std::get<I>(Iterators_) != std::get<I>(other.Iterators_)) || ...));
- }
- }
- bool operator==(const TSentinel& other) const {
- return !(*this != other);
- }
-
- TIteratorState Iterators_;
- std::size_t Position_;
- THolders* HoldersPtr_;
- };
- public:
- using iterator = TIterator;
- using const_iterator = TIterator;
+ }
+ bool operator!=(const TSentinel& other) const {
+ // give compiler an opportunity to optimize sentinel case (-70% of time)
+ if (other.Position_ == sizeof...(TContainers)) {
+ return Position_ < sizeof...(TContainers);
+ } else {
+ return (Position_ != other.Position_ ||
+ ((std::get<I>(Iterators_) != std::get<I>(other.Iterators_)) || ...));
+ }
+ }
+ bool operator==(const TSentinel& other) const {
+ return !(*this != other);
+ }
+
+ TIteratorState Iterators_;
+ std::size_t Position_;
+ THolders* HoldersPtr_;
+ };
+ public:
+ using iterator = TIterator;
+ using const_iterator = TIterator;
using value_type = typename TIterator::value_type;
using reference = typename TIterator::reference;
using const_reference = typename TIterator::reference;
-
- TIterator begin() const {
- TIterator iterator{TIteratorState{std::begin(*std::get<I>(Holders_).Ptr())...}, 0, &Holders_};
- iterator.template MaybeIncrementIteratorAndSkipExhaustedContainers<false>();
- return iterator;
- }
-
- TSentinel end() const {
- return {TSentinelState{std::end(*std::get<I>(Holders_).Ptr())...}, sizeof...(TContainers), &Holders_};
- }
-
- mutable THolders Holders_;
- };
-
- template <std::size_t... I>
- static auto Concatenate(TContainers&&... containers, std::index_sequence<I...>) {
- return TConcatenatorWithIndex<I...>{{std::forward<TContainers>(containers)...}};
- }
- };
-
-}
-
-
-//! Usage: for (auto x : Concatenate(a, b)) {...}
-template <typename TFirstContainer, typename... TContainers>
-auto Concatenate(TFirstContainer&& container, TContainers&&... containers) {
- return NPrivate::TConcatenator<decltype(*std::begin(container)), TFirstContainer, TContainers...>::Concatenate(
- std::forward<TFirstContainer>(container), std::forward<TContainers>(containers)...,
- std::make_index_sequence<sizeof...(TContainers) + 1>{});
-}
+
+ TIterator begin() const {
+ TIterator iterator{TIteratorState{std::begin(*std::get<I>(Holders_).Ptr())...}, 0, &Holders_};
+ iterator.template MaybeIncrementIteratorAndSkipExhaustedContainers<false>();
+ return iterator;
+ }
+
+ TSentinel end() const {
+ return {TSentinelState{std::end(*std::get<I>(Holders_).Ptr())...}, sizeof...(TContainers), &Holders_};
+ }
+
+ mutable THolders Holders_;
+ };
+
+ template <std::size_t... I>
+ static auto Concatenate(TContainers&&... containers, std::index_sequence<I...>) {
+ return TConcatenatorWithIndex<I...>{{std::forward<TContainers>(containers)...}};
+ }
+ };
+
+}
+
+
+//! Usage: for (auto x : Concatenate(a, b)) {...}
+template <typename TFirstContainer, typename... TContainers>
+auto Concatenate(TFirstContainer&& container, TContainers&&... containers) {
+ return NPrivate::TConcatenator<decltype(*std::begin(container)), TFirstContainer, TContainers...>::Concatenate(
+ std::forward<TFirstContainer>(container), std::forward<TContainers>(containers)...,
+ std::make_index_sequence<sizeof...(TContainers) + 1>{});
+}