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https://github.com/ToruNiina/toml11.git
synced 2024-09-19 15:19:54 +00:00
feat: use detail::none_t instead of char
Although the error value from combinators currently does not have any information, it can have an information because it is a char value. It is better to use no-information-type explicitly to make it clear that it does not have any information. So I added none_t in toml::detai and use it in combinators and parsers as an error value from combinators.
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ToruNiina
parent
81abb6c9d7
commit
717f5929c2
@ -56,19 +56,19 @@ struct character
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static constexpr char target = C;
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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"internal error: container::value_type should be `char`.");
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if(loc.iter() == loc.end()) {return err('\0');}
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if(loc.iter() == loc.end()) {return none();}
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const auto first = loc.iter();
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const char c = *(loc.iter());
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if(c != target)
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{
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return err(c);
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return none();
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}
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loc.advance(); // update location
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@ -89,19 +89,19 @@ struct in_range
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static constexpr char lower = Low;
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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"internal error: container::value_type should be `char`.");
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if(loc.iter() == loc.end()) {return err('\0');}
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if(loc.iter() == loc.end()) {return none();}
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const auto first = loc.iter();
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const char c = *(loc.iter());
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if(c < lower || upper < c)
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{
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return err(c);
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return none();
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}
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loc.advance();
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@ -117,20 +117,20 @@ template<typename Combinator>
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struct exclude
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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"internal error: container::value_type should be `char`.");
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if(loc.iter() == loc.end()) {return err('\0');}
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if(loc.iter() == loc.end()) {return none();}
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auto first = loc.iter();
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auto rslt = Combinator::invoke(loc);
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if(rslt.is_ok())
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{
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loc.reset(first);
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return err(*first);
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return none();
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}
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loc.reset(std::next(first)); // XXX maybe loc.advance() is okay but...
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return ok(region<Cont>(loc, first, loc.iter()));
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@ -142,7 +142,7 @@ template<typename Combinator>
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struct maybe
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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@ -164,7 +164,7 @@ template<typename Head, typename ... Tail>
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struct sequence<Head, Tail...>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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@ -175,21 +175,21 @@ struct sequence<Head, Tail...>
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if(rslt.is_err())
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{
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loc.reset(first);
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return err(rslt.unwrap_err());
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return none();
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}
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return sequence<Tail...>::invoke(loc, std::move(rslt.unwrap()), first);
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}
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// called from the above function only, recursively.
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template<typename Cont, typename Iterator>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc, region<Cont> reg, Iterator first)
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{
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const auto rslt = Head::invoke(loc);
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if(rslt.is_err())
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{
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loc.reset(first);
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return err(rslt.unwrap_err());
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return none();
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}
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reg += rslt.unwrap(); // concat regions
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return sequence<Tail...>::invoke(loc, std::move(reg), first);
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@ -201,14 +201,14 @@ struct sequence<Head>
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{
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// would be called from sequence<T ...>::invoke only.
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template<typename Cont, typename Iterator>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc, region<Cont> reg, Iterator first)
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{
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const auto rslt = Head::invoke(loc);
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if(rslt.is_err())
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{
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loc.reset(first);
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return err(rslt.unwrap_err());
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return none();
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}
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reg += rslt.unwrap(); // concat regions
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return ok(reg);
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@ -222,7 +222,7 @@ template<typename Head, typename ... Tail>
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struct either<Head, Tail...>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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@ -237,7 +237,7 @@ template<typename Head>
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struct either<Head>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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static_assert(std::is_same<char, typename Cont::value_type>::value,
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@ -257,7 +257,7 @@ template<typename T, std::size_t N>
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struct repeat<T, exactly<N>>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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region<Cont> retval(loc);
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@ -268,7 +268,7 @@ struct repeat<T, exactly<N>>
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if(rslt.is_err())
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{
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loc.reset(first);
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return err(rslt.unwrap_err());
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return none();
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}
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retval += rslt.unwrap();
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}
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@ -280,7 +280,7 @@ template<typename T, std::size_t N>
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struct repeat<T, at_least<N>>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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region<Cont> retval(loc);
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@ -292,7 +292,7 @@ struct repeat<T, at_least<N>>
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if(rslt.is_err())
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{
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loc.reset(first);
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return err(rslt.unwrap_err());
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return none();
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}
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retval += rslt.unwrap();
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}
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@ -312,7 +312,7 @@ template<typename T>
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struct repeat<T, unlimited>
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{
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template<typename Cont>
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static result<region<Cont>, char>
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static result<region<Cont>, none_t>
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invoke(location<Cont>& loc)
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{
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region<Cont> retval(loc);
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@ -376,7 +376,7 @@ parse_ml_basic_string(location<Container>& loc)
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// immediate newline is ignored (if exists)
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/* discard return value */ lex_newline::invoke(inner_loc);
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delim = err('\0');
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delim = none();
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while(!delim)
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{
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using lex_unescaped_seq = repeat<
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@ -432,7 +432,7 @@ parse_basic_string(location<Container>& loc)
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std::string retval;
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retval.reserve(token.unwrap().size());
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quot = err('\0');
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quot = none();
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while(!quot)
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{
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using lex_unescaped_seq = repeat<lex_basic_unescaped, unlimited>;
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@ -692,5 +692,26 @@ void swap(result<T, E>& lhs, result<T, E>& rhs)
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// return lhs.is_ok() ? lhs : rhs;
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// }
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// ----------------------------------------------------------------------------
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// re-use result<T, E> as a optional<T> with none_t
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namespace detail
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{
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struct none_t {};
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inline bool operator==(const none_t&, const none_t&) noexcept {return true;}
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inline bool operator!=(const none_t&, const none_t&) noexcept {return false;}
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inline bool operator< (const none_t&, const none_t&) noexcept {return false;}
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inline bool operator<=(const none_t&, const none_t&) noexcept {return true;}
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inline bool operator> (const none_t&, const none_t&) noexcept {return false;}
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inline bool operator>=(const none_t&, const none_t&) noexcept {return true;}
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template<typename charT, typename traitsT>
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std::basic_ostream<charT, traitsT>&
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operator<<(std::basic_ostream<charT, traitsT>& os, const none_t&)
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{
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os << "none";
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return os;
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}
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inline failure<none_t> none() noexcept {return failure<none_t>{none_t{}};}
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} // detail
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} // toml11
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#endif// TOML11_RESULT_H
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