| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | #pragma once | ||
| 2 | |||
| 3 | #include <vector> | ||
| 4 | #include <utility> | ||
| 5 | #include <optional> | ||
| 6 | #include <unordered_map> | ||
| 7 | |||
| 8 | #include "../Common.h" | ||
| 9 | #include "../sources/ContainerSources.h" | ||
| 10 | #include "../util/TraitImpl.h" | ||
| 11 | |||
| 12 | namespace CXXIter { | ||
| 13 | |||
| 14 | // ################################################################################################ | ||
| 15 | // GROUP BY | ||
| 16 | // ################################################################################################ | ||
| 17 | namespace op { | ||
| 18 | /** @private */ | ||
| 19 | template<typename TChainInput, typename TGroupIdentifierFn, typename TGroupIdent> | ||
| 20 | class [[nodiscard(CXXITER_CHAINER_NODISCARD_WARNING)]] GroupBy : public IterApi<GroupBy<TChainInput, TGroupIdentifierFn, TGroupIdent>> { | ||
| 21 | friend struct trait::Iterator<GroupBy<TChainInput, TGroupIdentifierFn, TGroupIdent>>; | ||
| 22 | private: | ||
| 23 | using OwnedInputItem = typename TChainInput::ItemOwned; | ||
| 24 | using GroupCache = SrcMov<std::unordered_map<TGroupIdent, std::vector<OwnedInputItem>>>; | ||
| 25 | |||
| 26 | TChainInput input; | ||
| 27 | TGroupIdentifierFn groupIdentFn; | ||
| 28 | std::optional<GroupCache> groupCache; | ||
| 29 | public: | ||
| 30 | 10 | constexpr GroupBy(TChainInput&& input, TGroupIdentifierFn groupIdentFn) : input(std::move(input)), groupIdentFn(groupIdentFn) {} | |
| 31 | }; | ||
| 32 | } | ||
| 33 | // ------------------------------------------------------------------------------------------------ | ||
| 34 | /** @private */ | ||
| 35 | template<typename TChainInput, typename TGroupIdentifierFn, typename TGroupIdent> | ||
| 36 | struct trait::Iterator<op::GroupBy<TChainInput, TGroupIdentifierFn, TGroupIdent>> { | ||
| 37 | using ChainInputIterator = trait::Iterator<TChainInput>; | ||
| 38 | using OwnedInputItem = typename TChainInput::ItemOwned; | ||
| 39 | // CXXIter Interface | ||
| 40 | using Self = op::GroupBy<TChainInput, TGroupIdentifierFn, TGroupIdent>; | ||
| 41 | using Item = std::pair<const TGroupIdent, std::vector<OwnedInputItem>>; | ||
| 42 | |||
| 43 | 20 | static constexpr inline IterValue<Item> next(Self& self) { | |
| 44 | // we have to drain the input in order to be able to calculate the groups | ||
| 45 | // so we do that on the first invocation, and then yield from the calculated result. | ||
| 46 |
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20 | if(!self.groupCache.has_value()) [[unlikely]] { |
| 47 | 8 | std::unordered_map<TGroupIdent, std::vector<OwnedInputItem>> groupCache; | |
| 48 |
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28 | while(true) { |
| 49 |
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26 | auto item = ChainInputIterator::next(self.input); |
| 50 |
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26 | if(!item.has_value()) [[unlikely]] { break; } // group cache building complete |
| 51 |
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18 | TGroupIdent itemGroup = self.groupIdentFn(item.value()); |
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18 | if(groupCache.contains(itemGroup)) { |
| 53 |
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6 | groupCache[itemGroup].push_back(item.value()); |
| 54 | } else { | ||
| 55 |
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24 | groupCache[itemGroup] = { item.value() }; |
| 56 | } | ||
| 57 | } | ||
| 58 |
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8 | self.groupCache.emplace(std::move(groupCache)); |
| 59 | 8 | } | |
| 60 | |||
| 61 | using GroupCacheIterator = trait::Iterator<typename Self::GroupCache>; | ||
| 62 | 20 | typename Self::GroupCache& groupedItems = self.groupCache.value(); | |
| 63 | 20 | return GroupCacheIterator::next(groupedItems); | |
| 64 | } | ||
| 65 | 5 | static constexpr inline SizeHint sizeHint(const Self& self) { | |
| 66 | 5 | SizeHint input = ChainInputIterator::sizeHint(self.input); | |
| 67 | 8 | return SizeHint(1, input.upperBound); | |
| 68 | } | ||
| 69 | static constexpr inline size_t advanceBy(Self& self, size_t n) { return util::advanceByPull(self, n); } | ||
| 70 | }; | ||
| 71 | |||
| 72 | } | ||
| 73 |