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| author | Dan Goodliffe <dan@randomdan.homeip.net> | 2022-03-18 01:46:46 +0000 |
|---|---|---|
| committer | Dan Goodliffe <dan@randomdan.homeip.net> | 2022-03-18 01:46:46 +0000 |
| commit | 8053a052ef29ca39bf972929c046f4c6a08c86f0 (patch) | |
| tree | 34c19ab12e0f308332db7022a0dd7edbe1dfbb11 | |
| parent | Lots of pass by value and perfect forwarding optimisations (diff) | |
| download | libdbpp-8053a052ef29ca39bf972929c046f4c6a08c86f0.tar.bz2 libdbpp-8053a052ef29ca39bf972929c046f4c6a08c86f0.tar.xz libdbpp-8053a052ef29ca39bf972929c046f4c6a08c86f0.zip | |
Simplify forEachField as a fold expression
| -rw-r--r-- | libdbpp/selectcommandUtil.impl.h | 18 |
1 files changed, 6 insertions, 12 deletions
diff --git a/libdbpp/selectcommandUtil.impl.h b/libdbpp/selectcommandUtil.impl.h index 9ef901e..cd64e7e 100644 --- a/libdbpp/selectcommandUtil.impl.h +++ b/libdbpp/selectcommandUtil.impl.h @@ -6,19 +6,13 @@ /// @cond namespace DB { - template<typename Fields, typename Func, unsigned int field, typename... Fn, typename... Args> + template<typename... Fn, std::size_t... I> inline void - forEachField(DB::SelectCommand * sel, const Func & func, Args &&... args) + forEachField(DB::SelectCommand * sel [[maybe_unused]], auto && func, std::index_sequence<I...>) { - if constexpr (field >= std::tuple_size<Fields>::value) { - (void)sel; - func(std::forward<Args>(args)...); - } - else { - typename std::tuple_element<field, Fields>::type a; - (*sel)[field] >> a; - forEachField<Fields, Func, field + 1, Fn...>(sel, func, args..., a); - } + std::tuple<Fn...> values; + (((*sel)[I] >> std::get<I>(values)), ...); + std::apply(func, values); } template<typename... Fn, typename Func> @@ -26,7 +20,7 @@ namespace DB { SelectCommand::forEachRow(const Func & func) { while (fetch()) { - forEachField<std::tuple<Fn...>, Func, 0>(this, func); + forEachField<Fn...>(this, func, std::make_index_sequence<sizeof...(Fn)> {}); } } |