optimization: transform select into set as much as possible

Author: Andersama

Diff for: include/ctre/actions/options.inc.hpp

@@ -13,14 +13,24 @@ template <typename Parameters> static constexpr auto apply(pcre::push_empty, ctl
 
 // make_alternate (A|B)
 template <auto V, typename A, typename B, typename... Ts, typename Parameters> static constexpr auto apply(pcre::make_alternate, ctll::term<V>, pcre_context<ctll::list<B, A, Ts...>, Parameters> subject) {
-	return pcre_context{ctll::push_front(select<A,B>(), ctll::list<Ts...>()), subject.parameters};
+	if constexpr (MatchesCharacter<A>::template value<char32_t> && MatchesCharacter<B>::template value<char32_t>) {
+		auto new_set = push_back_into_set(A{}, B{});
+		return pcre_context{ ctll::push_front(new_set, ctll::list<Ts...>()), subject.parameters };
+	} else {
+		return pcre_context{ ctll::push_front(select<A,B>(), ctll::list<Ts...>()), subject.parameters };
+	}
 }
+
 // make_alternate (As..)|B => (As..|B)
-template <auto V, typename A, typename... Bs, typename... Ts, typename Parameters> static constexpr auto apply(pcre::make_alternate, ctll::term<V>, pcre_context<ctll::list<ctre::select<Bs...>, A, Ts...>, Parameters> subject) {
-	return pcre_context{ctll::push_front(select<A,Bs...>(), ctll::list<Ts...>()), subject.parameters};
+template <auto V, typename A, typename B, typename... Bs, typename... Ts, typename Parameters> static constexpr auto apply(pcre::make_alternate, ctll::term<V>, pcre_context<ctll::list<ctre::select<B, Bs...>, A, Ts...>, Parameters> subject) {
+	if constexpr (MatchesCharacter<A>::template value<char32_t> && MatchesCharacter<B>::template value<char32_t>) {
+		auto new_set = push_back_into_set(A{}, B{});
+		return pcre_context{ ctll::push_front(select<decltype(new_set),Bs...>(), ctll::list<Ts...>()), subject.parameters };
+	} else {
+		return pcre_context{ ctll::push_front(select<A,B,Bs...>(), ctll::list<Ts...>()), subject.parameters };
+	}
 }
 
-
 // make_optional
 template <auto V, typename A, typename... Ts, typename Parameters> static constexpr auto apply(pcre::make_optional, ctll::term<V>, pcre_context<ctll::list<A, Ts...>, Parameters> subject) {
 	return pcre_context{ctll::push_front(optional<A>(), ctll::list<Ts...>()), subject.parameters};

Diff for: include/ctre/actions/set.inc.hpp

@@ -4,7 +4,29 @@
 // UTILITY
 // add into set if not exists
 template <template <typename...> typename SetType, typename T, typename... As, bool Exists = (std::is_same_v<T, As> || ... || false)> static constexpr auto push_back_into_set(T, SetType<As...>) -> ctll::conditional<Exists, SetType<As...>, SetType<As...,T>> { return {}; }
+// merge two sets
+template<typename B, typename... As>
+static constexpr auto push_back_into_set(B, ctre::set<As...>) {
+	return push_back_into_set<ctre::set>(B{}, ctre::set<As...>{});
+}
+
+template<typename B, typename... As>
+static constexpr auto push_back_into_set(ctre::set<As...>, B) {
+	return push_back_into_set<ctre::set>(B{}, ctre::set<As...>{});
+}
 
+template<typename B, typename... Bs, typename... As>
+static constexpr auto push_back_into_set(ctre::set<B, Bs...>, ctre::set<As...>) {
+	if constexpr (sizeof...(Bs) == 0)
+		return push_back_into_set<ctre::set>(B{}, ctre::set<As...>{});
+	else
+		return push_back_into_set(ctre::set<Bs...>{}, push_back_into_set<ctre::set>(B{}, ctre::set<As...>{}));
+}
+
+template<typename A, typename B>
+static constexpr auto push_back_into_set(A, B) {
+	return push_back_into_set(A{}, ctre::set<B>{});
+}
 //template <template <typename...> typename SetType, typename A, typename BHead, typename... Bs> struct set_merge_helper {
 //	using step = decltype(push_back_into_set<SetType>(BHead(), A()));
 //	using type = ctll::conditional<(sizeof...(Bs) > 0), set_merge_helper<SetType, step, Bs...>, step>;