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perf: remove err-msg from combinator

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Generate error message in `parse_something()`, not in `lex_something`.
Since the error message generated by `lex_something` is too difficult to
read for humans, I've disabled the error message generation for the sake
of efficiency (it takes time to generate error message that will never
be read). I think now the error message generation itself safely can be
removed from combinators. At this stage, `lex_something` does not need
to return `result<T, E>` because all the error type would be discarded.
Now it is turned out that returing `optional<T>` from lex_* is enough.
Maybe later I would change the return type itself, but currently I
changed the error type from std::string to char because implementing
optional takes time and effort. It makes the parsing process a bit
faster.
This commit is contained in:
ToruNiina
2019-05-30 20:08:37 +09:00
parent 8bba3c8a14
commit 81abb6c9d7
2 changed files with 52 additions and 88 deletions
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106
toml/combinator.hpp
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@@ -56,24 +56,19 @@ struct character
static constexpr char target = C;
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
if(loc.iter() == loc.end()) {return err("not sufficient characters");}
if(loc.iter() == loc.end()) {return err('\0');}
const auto first = loc.iter();
const char c = *(loc.iter());
if(c != target)
{
if(msg)
{
return err(concat_to_string("expected '", show_char(target),
"' but got '", show_char(c), "'."));
}
return err("");
return err(c);
}
loc.advance(); // update location
@@ -94,25 +89,19 @@ struct in_range
static constexpr char lower = Low;
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
if(loc.iter() == loc.end()) {return err("not sufficient characters");}
if(loc.iter() == loc.end()) {return err('\0');}
const auto first = loc.iter();
const char c = *(loc.iter());
if(c < lower || upper < c)
{
if(msg)
{
return err(concat_to_string("expected character in range "
"[", show_char(lower), ", ", show_char(upper), "] but got ",
"'", show_char(c), "'."));
}
return err("");
return err(c);
}
loc.advance();
@@ -128,25 +117,20 @@ template<typename Combinator>
struct exclude
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
if(loc.iter() == loc.end()) {return err("not sufficient characters");}
if(loc.iter() == loc.end()) {return err('\0');}
auto first = loc.iter();
auto rslt = Combinator::invoke(loc, msg);
auto rslt = Combinator::invoke(loc);
if(rslt.is_ok())
{
loc.reset(first);
if(msg)
{
return err(concat_to_string("invalid pattern appeared ",
rslt.unwrap().str()));
}
return err("");
return err(*first);
}
loc.reset(std::next(first)); // XXX maybe loc.advance() is okay but...
return ok(region<Cont>(loc, first, loc.iter()));
@@ -158,13 +142,13 @@ template<typename Combinator>
struct maybe
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
const auto rslt = Combinator::invoke(loc, msg);
const auto rslt = Combinator::invoke(loc);
if(rslt.is_ok())
{
return rslt;
@@ -180,36 +164,35 @@ template<typename Head, typename ... Tail>
struct sequence<Head, Tail...>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
const auto first = loc.iter();
const auto rslt = Head::invoke(loc, msg);
const auto rslt = Head::invoke(loc);
if(rslt.is_err())
{
loc.reset(first);
return err(rslt.unwrap_err());
}
return sequence<Tail...>::invoke(loc, std::move(rslt.unwrap()), first, msg);
return sequence<Tail...>::invoke(loc, std::move(rslt.unwrap()), first);
}
// called from the above function only, recursively.
template<typename Cont, typename Iterator>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, region<Cont> reg, Iterator first,
const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc, region<Cont> reg, Iterator first)
{
const auto rslt = Head::invoke(loc, msg);
const auto rslt = Head::invoke(loc);
if(rslt.is_err())
{
loc.reset(first);
return err(rslt.unwrap_err());
}
reg += rslt.unwrap(); // concat regions
return sequence<Tail...>::invoke(loc, std::move(reg), first, msg);
return sequence<Tail...>::invoke(loc, std::move(reg), first);
}
};
@@ -218,11 +201,10 @@ struct sequence<Head>
{
// would be called from sequence<T ...>::invoke only.
template<typename Cont, typename Iterator>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, region<Cont> reg, Iterator first,
const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc, region<Cont> reg, Iterator first)
{
const auto rslt = Head::invoke(loc, msg);
const auto rslt = Head::invoke(loc);
if(rslt.is_err())
{
loc.reset(first);
@@ -240,27 +222,27 @@ template<typename Head, typename ... Tail>
struct either<Head, Tail...>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
const auto rslt = Head::invoke(loc, msg);
const auto rslt = Head::invoke(loc);
if(rslt.is_ok()) {return rslt;}
return either<Tail...>::invoke(loc, msg);
return either<Tail...>::invoke(loc);
}
};
template<typename Head>
struct either<Head>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
static_assert(std::is_same<char, typename Cont::value_type>::value,
"internal error: container::value_type should be `char`.");
return Head::invoke(loc, msg);
return Head::invoke(loc);
}
};
@@ -275,14 +257,14 @@ template<typename T, std::size_t N>
struct repeat<T, exactly<N>>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
region<Cont> retval(loc);
const auto first = loc.iter();
for(std::size_t i=0; i<N; ++i)
{
auto rslt = T::invoke(loc, msg);
auto rslt = T::invoke(loc);
if(rslt.is_err())
{
loc.reset(first);
@@ -298,15 +280,15 @@ template<typename T, std::size_t N>
struct repeat<T, at_least<N>>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
region<Cont> retval(loc);
const auto first = loc.iter();
for(std::size_t i=0; i<N; ++i)
{
auto rslt = T::invoke(loc, msg);
auto rslt = T::invoke(loc);
if(rslt.is_err())
{
loc.reset(first);
@@ -316,7 +298,7 @@ struct repeat<T, at_least<N>>
}
while(true)
{
auto rslt = T::invoke(loc, msg);
auto rslt = T::invoke(loc);
if(rslt.is_err())
{
return ok(std::move(retval));
@@ -330,13 +312,13 @@ template<typename T>
struct repeat<T, unlimited>
{
template<typename Cont>
static result<region<Cont>, std::string>
invoke(location<Cont>& loc, const bool msg = false)
static result<region<Cont>, char>
invoke(location<Cont>& loc)
{
region<Cont> retval(loc);
while(true)
{
auto rslt = T::invoke(loc, msg);
auto rslt = T::invoke(loc);
if(rslt.is_err())
{
return ok(std::move(retval));