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Revert "Merge pull request #827 from saki7/modernize-skip"

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This reverts commit 4cd604abf6, reversing
changes made to 70f968ef6c.
This commit is contained in:
Nana Sakisaka
2025-09-13 08:56:54 +09:00
parent 49753e2515
commit ac6ed01642
2 changed files with 78 additions and 161 deletions
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228
include/boost/spirit/home/x3/directive/skip.hpp
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@@ -1,7 +1,7 @@
/*=============================================================================
Copyright (c) 2001-2014 Joel de Guzman
Copyright (c) 2013 Agustin Berge
Copyright (c) 2024-2025 Nana Sakisaka
Copyright (c) 2024 Nana Sakisaka
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -14,94 +14,67 @@
#include <boost/spirit/home/x3/support/expectation.hpp>
#include <boost/spirit/home/x3/core/skip_over.hpp>
#include <boost/spirit/home/x3/core/parser.hpp>
#include <boost/utility/enable_if.hpp>
#include <iterator>
#include <type_traits>
#include <utility>
namespace boost::spirit::x3
namespace boost { namespace spirit { namespace x3
{
template <typename Subject>
struct reskip_directive : unary_parser<Subject, reskip_directive<Subject>>
{
using base_type = unary_parser<Subject, reskip_directive<Subject>>;
static constexpr bool is_pass_through_unary = true;
static constexpr bool handles_container = Subject::handles_container;
typedef unary_parser<Subject, reskip_directive<Subject>> base_type;
static bool const is_pass_through_unary = true;
static bool const handles_container = Subject::handles_container;
template <typename SubjectT>
requires
(!std::is_same_v<std::remove_cvref_t<SubjectT>, reskip_directive>) &&
std::is_constructible_v<Subject, SubjectT>
constexpr reskip_directive(SubjectT&& subject)
noexcept(std::is_nothrow_constructible_v<Subject, SubjectT>)
: base_type(std::forward<SubjectT>(subject))
{}
constexpr reskip_directive(Subject const& subject)
: base_type(subject) {}
template <std::forward_iterator It, std::sentinel_for<It> Se, typename Context, typename RContext, typename Attribute>
requires has_skipper_v<Context>
[[nodiscard]] constexpr bool
parse(It& first, Se const& last, Context const& context, RContext& rcontext, Attribute& attr) const
noexcept(is_nothrow_parsable_v<Subject, It, Se, Context, RContext, Attribute>)
template <typename Iterator, typename Context
, typename RContext, typename Attribute>
typename disable_if<has_skipper<Context>, bool>::type
parse(Iterator& first, Iterator const& last
, Context& context, RContext& rcontext, Attribute& attr) const
{
static_assert(Parsable<Subject, It, Se, Context, RContext, Attribute>);
return this->subject.parse(first, last, context, rcontext, attr);
}
auto const& skipper =
detail::get_unused_skipper(x3::get<skipper_tag>(context));
private:
template <typename Context>
using context_t = x3::context<
skipper_tag,
decltype(detail::get_unused_skipper(x3::get<skipper_tag>(std::declval<Context const&>()))),
Context
>;
public:
template <std::forward_iterator It, std::sentinel_for<It> Se, typename Context, typename RContext, typename Attribute>
requires (!has_skipper_v<Context>)
[[nodiscard]] constexpr bool
parse(It& first, Se const& last, Context const& context, RContext& rcontext, Attribute& attr) const
// never noexcept (requires expectation failure modification)
{
static_assert(Parsable<Subject, It, Se, context_t<Context>, RContext, Attribute>);
auto const& skipper = detail::get_unused_skipper(x3::get<skipper_tag>(context));
auto const local_ctx = x3::make_context<skipper_tag>(skipper, context);
auto const local_ctx = make_context<skipper_tag>(skipper, context);
bool const r = this->subject.parse(first, last, local_ctx, rcontext, attr);
#if !BOOST_SPIRIT_X3_THROW_EXPECTATION_FAILURE
if (x3::has_expectation_failure(local_ctx))
if (has_expectation_failure(local_ctx))
{
x3::set_expectation_failure(x3::get_expectation_failure(local_ctx), context);
set_expectation_failure(get_expectation_failure(local_ctx), context);
}
#endif
return r;
}
template <typename Iterator, typename Context
, typename RContext, typename Attribute>
typename enable_if<has_skipper<Context>, bool>::type
parse(Iterator& first, Iterator const& last
, Context const& context, RContext& rcontext, Attribute& attr) const
{
return this->subject.parse(first, last, context, rcontext, attr);
}
};
template <typename Subject, typename Skipper>
struct skip_directive : unary_parser<Subject, skip_directive<Subject, Skipper>>
{
using base_type = unary_parser<Subject, skip_directive<Subject, Skipper>>;
static constexpr bool is_pass_through_unary = true;
static constexpr bool handles_container = Subject::handles_container;
typedef unary_parser<Subject, skip_directive<Subject, Skipper>> base_type;
static bool const is_pass_through_unary = true;
static bool const handles_container = Subject::handles_container;
template <typename SubjectT, typename SkipperT>
requires std::is_constructible_v<Subject, SubjectT> && std::is_constructible_v<Skipper, SkipperT>
constexpr skip_directive(SubjectT&& subject, SkipperT&& skipper)
noexcept(std::is_nothrow_constructible_v<Subject, SubjectT> && std::is_nothrow_constructible_v<Skipper, SkipperT>)
: base_type(std::forward<SubjectT>(subject))
, skipper_(skipper)
constexpr skip_directive(Subject const& subject, Skipper const& skipper)
: base_type(subject)
, skipper(skipper)
{}
template <std::forward_iterator It, std::sentinel_for<It> Se, typename RContext, typename Attribute>
[[nodiscard]] constexpr bool
parse(It& first, Se const& last, unused_type const&, RContext& rcontext, Attribute& attr) const
noexcept(is_nothrow_parsable_v<Subject, It, Se, x3::context<skipper_tag, Skipper>, RContext, Attribute>)
template <typename Iterator, typename RContext, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, unused_type const&, RContext& rcontext, Attribute& attr) const
{
static_assert(Parsable<Subject, It, Se, x3::context<skipper_tag, Skipper>, RContext, Attribute>);
// It is perfectly fine to omit the expectation_failure context
// even in non-throwing mode if and only if the skipper itself
// is expectation-less.
@@ -121,126 +94,73 @@ namespace boost::spirit::x3
// Anyways, we don't need to repack the expectation context
// into our brand new skipper context, in contrast to the
// repacking process done in `x3::skip_over`.
return this->subject.parse(
first, last, x3::make_context<skipper_tag>(skipper_), rcontext, attr
);
return this->subject.parse(first, last,
make_context<skipper_tag>(skipper), rcontext, attr);
}
template <std::forward_iterator It, std::sentinel_for<It> Se, typename Context, typename RContext, typename Attribute>
[[nodiscard]] constexpr bool
parse(It& first, Se const& last, Context const& context, RContext& rcontext, Attribute& attr) const
// never noexcept (requires expectation failure modification)
template <typename Iterator, typename Context, typename RContext, typename Attribute>
bool parse(Iterator& first, Iterator const& last
, Context const& context, RContext& rcontext, Attribute& attr) const
{
static_assert(Parsable<Subject, It, Se, x3::context<skipper_tag, Context>, RContext, Attribute>);
#if BOOST_SPIRIT_X3_THROW_EXPECTATION_FAILURE
return this->subject.parse(first, last, x3::make_context<skipper_tag>(skipper_, context), rcontext, attr);
return this->subject.parse(first, last, make_context<skipper_tag>(skipper, context), rcontext, attr);
#else
static_assert(
!std::is_same_v<expectation_failure_t<Context>, unused_type>,
"Context type was not specified for x3::expectation_failure_tag. "
"You probably forgot: `x3::with<x3::expectation_failure_tag>(failure)[p]`. "
"Note that you must also bind the context to your skipper."
);
"Note that you must also bind the context to your skipper.");
// This logic is heavily related to the instantiation chain;
// see `x3::skip_over` for details.
auto const local_ctx = x3::make_context<skipper_tag>(skipper_, context);
auto const local_ctx = make_context<skipper_tag>(skipper, context);
bool const r = this->subject.parse(first, last, local_ctx, rcontext, attr);
if (x3::has_expectation_failure(local_ctx))
if (has_expectation_failure(local_ctx))
{
x3::set_expectation_failure(x3::get_expectation_failure(local_ctx), context);
set_expectation_failure(get_expectation_failure(local_ctx), context);
}
return r;
#endif
}
private:
Skipper skipper_;
};
namespace detail
{
template <X3Subject Skipper>
struct skip_gen_impl
{
// Unreference rvalue reference, but hold lvalue reference as-is
using skipper_type = std::conditional_t<
std::is_rvalue_reference_v<Skipper>,
std::remove_reference_t<Skipper>,
Skipper
>;
template <typename SkipperT>
requires std::is_same_v<std::remove_cvref_t<SkipperT>, std::remove_cvref_t<Skipper>>
constexpr skip_gen_impl(SkipperT&& skipper)
noexcept(std::is_nothrow_constructible_v<skipper_type, SkipperT>)
: skipper_(std::forward<SkipperT>(skipper))
{}
template <X3Subject Subject>
[[nodiscard]] constexpr skip_directive<as_parser_plain_t<Subject>, std::remove_cvref_t<Skipper>>
operator[](Subject&& subject) const
noexcept(
is_parser_nothrow_castable_v<Subject> &&
std::is_nothrow_constructible_v<
skip_directive<as_parser_plain_t<Subject>, std::remove_cvref_t<Skipper>>,
as_parser_t<Subject>,
skipper_type const&
>
)
{
return { as_parser(std::forward<Subject>(subject)), skipper_ };
}
private:
skipper_type skipper_;
};
struct skip_gen
{
template <X3Subject Skipper>
[[nodiscard]]
static constexpr skip_gen_impl<as_parser_t<Skipper>>
operator()(Skipper&& skipper)
noexcept(
is_parser_nothrow_castable_v<Skipper> &&
std::is_nothrow_constructible_v<skip_gen_impl<as_parser_t<Skipper>>, as_parser_t<Skipper>>
)
{
return { as_parser(std::forward<Skipper>(skipper)) };
}
template <typename Subject>
[[nodiscard, deprecated("Use `x3::reskip[p]`.")]]
/* static */ constexpr reskip_directive<as_parser_plain_t<Subject>>
operator[](Subject&& subject) const // MSVC 2022 bug: cannot define `static operator[]` even in C++26 mode
noexcept(is_parser_nothrow_constructible_v<reskip_directive<as_parser_plain_t<Subject>>, Subject>)
{
return { as_parser(std::forward<Subject>(subject)) };
}
Skipper const skipper;
};
struct reskip_gen
{
template <X3Subject Subject>
[[nodiscard]]
/* static */ constexpr reskip_directive<as_parser_plain_t<Subject>>
operator[](Subject&& subject) const // MSVC 2022 bug: cannot define `static operator[]` even in C++26 mode
noexcept(is_parser_nothrow_constructible_v<reskip_directive<as_parser_plain_t<Subject>>, Subject>)
template <typename Skipper>
struct skip_gen
{
return { as_parser(std::forward<Subject>(subject)) };
constexpr skip_gen(Skipper const& skipper)
: skipper_(skipper) {}
template <typename Subject>
constexpr skip_directive<typename extension::as_parser<Subject>::value_type, Skipper>
operator[](Subject const& subject) const
{
return { as_parser(subject), skipper_ };
}
Skipper skipper_;
};
template <typename Skipper>
constexpr skip_gen<Skipper> const operator()(Skipper const& skipper) const
{
return { skipper };
}
template <typename Subject>
constexpr reskip_directive<typename extension::as_parser<Subject>::value_type>
operator[](Subject const& subject) const
{
return { as_parser(subject) };
}
};
} // detail
inline namespace cpos
{
inline constexpr detail::skip_gen skip{};
inline constexpr detail::reskip_gen reskip{};
}
} // boost::spirit::x3
constexpr auto skip = reskip_gen{};
}}}
#endif

21
test/x3/skip.cpp
View File

@@ -1,25 +1,24 @@
/*=============================================================================
Copyright (c) 2001-2015 Joel de Guzman
Copyright (c) 2013 Agustin Berge
Copyright (c) 2025 Nana Sakisaka
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#include "test.hpp"
#include <boost/spirit/home/x3.hpp>
#include <iostream>
#include "test.hpp"
int main()
int
main()
{
using spirit_test::test;
using spirit_test::test_attr;
using boost::spirit::x3::standard::space;
using boost::spirit::x3::standard::space_type;
using boost::spirit::x3::standard::char_;
using boost::spirit::x3::standard::alpha;
using boost::spirit::x3::ascii::space;
using boost::spirit::x3::ascii::space_type;
using boost::spirit::x3::ascii::char_;
using boost::spirit::x3::ascii::alpha;
using boost::spirit::x3::lexeme;
using boost::spirit::x3::skip;
using boost::spirit::x3::lit;
@@ -30,15 +29,13 @@ int main()
BOOST_TEST((test("a b c d", skip(space)[*char_])));
}
{
// test attribute
{ // test attribute
std::string s;
BOOST_TEST((test_attr("a b c d", skip(space)[*char_], s)));
BOOST_TEST(s == "abcd");
}
{
// reskip
{ // reskip
BOOST_TEST((test("ab c d", lexeme[lit('a') >> 'b' >> skip[lit('c') >> 'd']], space)));
BOOST_TEST((test("abcd", lexeme[lit('a') >> 'b' >> skip[lit('c') >> 'd']], space)));
BOOST_TEST(!(test("a bcd", lexeme[lit('a') >> 'b' >> skip[lit('c') >> 'd']], space)));