[gcc/devel/c++-modules] libstdc++: Refactor filesystem::path string conversions
Nathan Sidwell
nathan@gcc.gnu.org
Wed Jun 10 16:42:33 GMT 2020
https://gcc.gnu.org/g:584d52b088f9fcf78704b504c3f1f07e17c1cded
commit 584d52b088f9fcf78704b504c3f1f07e17c1cded
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Sat May 23 09:00:32 2020 +0100
libstdc++: Refactor filesystem::path string conversions
This simplifies the logic of converting Source arguments and pairs of
InputIterator arguments into the native string format. For any input
that is a contiguous range of path::value_type (or char8_t for POSIX)
a string view can be created and the conversion can be done directly,
with no intermediate allocation. Previously some cases created a
basic_string unnecessarily, for example construction from a pair of
path::string_type::iterators, or a pair of non-const value_type*
pointers.
* include/bits/fs_path.h (__detail::_S_range_begin)
(__detail::_S_range_end, path::_S_string_from_iter): Replace with
overloaded function template __detail::__effective_range.
(__detail::__effective_range): New overloaded function template to
create a basic_string or basic_string_view for an effective range.
(__detail::__value_type_is_char): Use __detail::__effective_range.
Do not use remove_const on value type.
(__detail::__value_type_is_char_or_char8_t): Likewise.
(path::path(const Source&, format))
(path::path(const Source&, const locale&))
(path::operator/=(const Source&), path::append(const Source&))
(path::concat(const Source&)): Use __detail::__effective_range.
(path::_S_to_string(InputIterator, InputIterator)): New function
template to create a string view if possible, or string otherwise.
(path::_S_convert): Add overloads that convert a string returned
by __detail::__effective_range. Use if-constexpr to inline conversion
logic from all overloads of _Cvt::_S_convert.
(path::_S_convert_loc): Add overload that converts a string. Use
_S_to_string to avoid allocation when possible.
(path::_Cvt): Remove.
(path::operator+=(CharT)): Remove indirection through path::concat.
* include/experimental/bits/fs_path.h (path::_S_convert_loc): Add
overload for non-const pointers, to avoid constructing a std::string.
* src/c++17/fs_path.cc (path::_S_convert_loc): Replace conditional
compilation with call to _S_convert.
Diff:
---
libstdc++-v3/ChangeLog | 26 ++
libstdc++-v3/include/bits/fs_path.h | 356 +++++++++++------------
libstdc++-v3/include/experimental/bits/fs_path.h | 7 +
libstdc++-v3/src/c++17/fs_path.cc | 6 +-
4 files changed, 198 insertions(+), 197 deletions(-)
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index af52f143be8..08a2ad3330c 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,31 @@
2020-05-23 Jonathan Wakely <jwakely@redhat.com>
+ * include/bits/fs_path.h (__detail::_S_range_begin)
+ (__detail::_S_range_end, path::_S_string_from_iter): Replace with
+ overloaded function template __detail::__effective_range.
+ (__detail::__effective_range): New overloaded function template to
+ create a basic_string or basic_string_view for an effective range.
+ (__detail::__value_type_is_char): Use __detail::__effective_range.
+ Do not use remove_const on value type.
+ (__detail::__value_type_is_char_or_char8_t): Likewise.
+ (path::path(const Source&, format))
+ (path::path(const Source&, const locale&))
+ (path::operator/=(const Source&), path::append(const Source&))
+ (path::concat(const Source&)): Use __detail::__effective_range.
+ (path::_S_to_string(InputIterator, InputIterator)): New function
+ template to create a string view if possible, or string otherwise.
+ (path::_S_convert): Add overloads that convert a string returned
+ by __detail::__effective_range. Use if-constexpr to inline conversion
+ logic from all overloads of _Cvt::_S_convert.
+ (path::_S_convert_loc): Add overload that converts a string. Use
+ _S_to_string to avoid allocation when possible.
+ (path::_Cvt): Remove.
+ (path::operator+=(CharT)): Remove indirection through path::concat.
+ * include/experimental/bits/fs_path.h (path::_S_convert_loc): Add
+ overload for non-const pointers, to avoid constructing a std::string.
+ * src/c++17/fs_path.cc (path::_S_convert_loc): Replace conditional
+ compilation with call to _S_convert.
+
* include/bits/fs_path.h (__detail::_S_range_begin)
(__detail::_S_range_end): Remove unintentional static specifiers.
* include/experimental/bits/fs_path.h (__detail::_S_range_begin)
diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index 818b5918927..2d2766ec62e 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -155,56 +155,61 @@ namespace __detail
template<typename _Iter, typename _Tr = __safe_iterator_traits<_Iter>>
using _Path2 = enable_if_t<__is_path_iter_src<_Tr>::value, path>;
- template<typename _Source>
- _Source
- _S_range_begin(_Source __begin) { return __begin; }
-
- struct __null_terminated { };
-
- template<typename _Source>
- __null_terminated
- _S_range_end(_Source) { return {}; }
-
- template<typename _CharT, typename _Traits, typename _Alloc>
- inline const _CharT*
- _S_range_begin(const basic_string<_CharT, _Traits, _Alloc>& __str)
- { return __str.data(); }
+ // The __effective_range overloads convert a Source parameter into
+ // either a basic_string_view or basic_string containing the
+ // effective range of the Source, as defined in [fs.path.req].
template<typename _CharT, typename _Traits, typename _Alloc>
- inline const _CharT*
- _S_range_end(const basic_string<_CharT, _Traits, _Alloc>& __str)
- { return __str.data() + __str.size(); }
+ inline basic_string_view<_CharT, _Traits>
+ __effective_range(const basic_string<_CharT, _Traits, _Alloc>& __source)
+ { return __source; }
template<typename _CharT, typename _Traits>
- inline const _CharT*
- _S_range_begin(const basic_string_view<_CharT, _Traits>& __str)
- { return __str.data(); }
+ inline const basic_string_view<_CharT, _Traits>&
+ __effective_range(const basic_string_view<_CharT, _Traits>& __source)
+ { return __source; }
- template<typename _CharT, typename _Traits>
- inline const _CharT*
- _S_range_end(const basic_string_view<_CharT, _Traits>& __str)
- { return __str.data() + __str.size(); }
-
- template<typename _Tp,
- typename _Iter = decltype(_S_range_begin(std::declval<_Tp>())),
- typename _Val = typename std::iterator_traits<_Iter>::value_type,
- typename _UnqualVal = std::remove_const_t<_Val>>
+ template<typename _Source>
+ inline auto
+ __effective_range(const _Source& __source)
+ {
+ if constexpr (is_pointer_v<decay_t<_Source>>)
+ return basic_string_view{&*__source};
+ else
+ {
+ // _Source is an input iterator that iterates over an NTCTS.
+ // Create a basic_string by reading until the null character.
+ using value_type
+ = typename iterator_traits<_Source>::value_type;
+ basic_string<value_type> __str;
+ _Source __it = __source;
+ for (value_type __ch = *__it; __ch != value_type(); __ch = *++__it)
+ __str.push_back(__ch);
+ return __str;
+ }
+ }
+
+ // The value type of a Source parameter's effective range.
+ template<typename _Tp>
+ using __value_t = typename remove_reference_t<
+ decltype(__detail::__effective_range(std::declval<_Tp>()))>::value_type;
+
+ // SFINAE helper to check that an effective range has value_type char,
+ // as required by path constructors taking a std::locale parameter.
+ // The type _Tp must have already been checked by _Path<Tp> or _Path2<_Tp>.
+ template<typename _Tp, typename _Val = __value_t<_Tp>>
using __value_type_is_char
- = std::enable_if_t<std::is_same_v<_UnqualVal, char>,
- _UnqualVal>;
+ = std::enable_if_t<std::is_same_v<_Val, char>, _Val>;
- template<typename _Tp,
- typename _Iter = decltype(_S_range_begin(std::declval<_Tp>())),
- typename _Val = typename std::iterator_traits<_Iter>::value_type,
- typename _UnqualVal = std::remove_const_t<_Val>>
+ // As above, but also allows char8_t, as required by u8path
+ // C++20 [depr.fs.path.factory]
+ template<typename _Tp, typename _Val = __value_t<_Tp>>
using __value_type_is_char_or_char8_t
- = std::enable_if_t<__or_v<
- std::is_same<_UnqualVal, char>
+ = std::enable_if_t<std::is_same_v<_Val, char>
#ifdef _GLIBCXX_USE_CHAR8_T
- , std::is_same<_UnqualVal, char8_t>
+ || std::is_same_v<_Val, char8_t>
#endif
- >,
- _UnqualVal>;
+ , _Val>;
} // namespace __detail
/// @endcond
@@ -251,8 +256,7 @@ namespace __detail
template<typename _Source,
typename _Require = __detail::_Path<_Source>>
path(_Source const& __source, format = auto_format)
- : _M_pathname(_S_convert(__detail::_S_range_begin(__source),
- __detail::_S_range_end(__source)))
+ : _M_pathname(_S_convert(__detail::__effective_range(__source)))
{ _M_split_cmpts(); }
template<typename _InputIterator,
@@ -264,9 +268,8 @@ namespace __detail
template<typename _Source,
typename _Require = __detail::_Path<_Source>,
typename _Require2 = __detail::__value_type_is_char<_Source>>
- path(_Source const& __source, const locale& __loc, format = auto_format)
- : _M_pathname(_S_convert_loc(__detail::_S_range_begin(__source),
- __detail::_S_range_end(__source), __loc))
+ path(_Source const& __src, const locale& __loc, format = auto_format)
+ : _M_pathname(_S_convert_loc(__detail::__effective_range(__src), __loc))
{ _M_split_cmpts(); }
template<typename _InputIterator,
@@ -309,8 +312,7 @@ namespace __detail
__detail::_Path<_Source>&
operator/=(_Source const& __source)
{
- _M_append(_S_convert(__detail::_S_range_begin(__source),
- __detail::_S_range_end(__source)));
+ _M_append(_S_convert(__detail::__effective_range(__source)));
return *this;
}
@@ -318,8 +320,7 @@ namespace __detail
__detail::_Path<_Source>&
append(_Source const& __source)
{
- _M_append(_S_convert(__detail::_S_range_begin(__source),
- __detail::_S_range_end(__source)));
+ _M_append(_S_convert(__detail::__effective_range(__source)));
return *this;
}
@@ -351,8 +352,7 @@ namespace __detail
__detail::_Path<_Source>&
concat(_Source const& __x)
{
- _M_concat(_S_convert(__detail::_S_range_begin(__x),
- __detail::_S_range_end(__x)));
+ _M_concat(_S_convert(__detail::__effective_range(__x)));
return *this;
}
@@ -523,22 +523,6 @@ namespace __detail
return __result;
}
- /// @cond undocumented
- // Create a basic_string by reading until a null character.
- template<typename _InputIterator,
- typename _Traits = std::iterator_traits<_InputIterator>,
- typename _CharT
- = typename std::remove_cv_t<typename _Traits::value_type>>
- static std::basic_string<_CharT>
- _S_string_from_iter(_InputIterator __source)
- {
- std::basic_string<_CharT> __str;
- for (_CharT __ch = *__source; __ch != _CharT(); __ch = *++__source)
- __str.push_back(__ch);
- return __str;
- }
- /// @endcond
-
private:
enum class _Type : unsigned char {
_Multi = 0, _Root_name, _Root_dir, _Filename
@@ -558,43 +542,67 @@ namespace __detail
pair<const string_type*, size_t> _M_find_extension() const noexcept;
- template<typename _CharT>
- struct _Cvt;
-
- static basic_string_view<value_type>
- _S_convert(value_type* __src, __detail::__null_terminated)
- { return __src; }
+ // Create a string or string view from an iterator range.
+ template<typename _InputIterator>
+ static auto
+ _S_to_string(_InputIterator __first, _InputIterator __last)
+ {
+ using _EcharT
+ = typename std::iterator_traits<_InputIterator>::value_type;
+ static_assert(__detail::__is_encoded_char<_EcharT>);
- static basic_string_view<value_type>
- _S_convert(const value_type* __src, __detail::__null_terminated)
- { return __src; }
+#if __cpp_lib_concepts
+ constexpr bool __contiguous = std::contiguous_iterator<_InputIterator>;
+#else
+ constexpr bool __contiguous
+ = is_pointer_v<decltype(std::__niter_base(__first))>;
+#endif
+ if constexpr (__contiguous)
+ {
+ // For contiguous iterators we can just return a string view.
+ const auto* __f = std::__to_address(std::__niter_base(__first));
+ const auto* __l = std::__to_address(std::__niter_base(__last));
+ return basic_string_view<_EcharT>(__f, __l - __f);
+ }
+ else
+ // Conversion requires contiguous characters, so create a string.
+ return basic_string<_EcharT>(__first, __last);
+ }
- static basic_string_view<value_type>
- _S_convert(value_type* __first, value_type* __last)
- { return {__first, __last - __first}; }
+ // path::_S_convert creates a basic_string<value_type> or
+ // basic_string_view<value_type> from a range (either the effective
+ // range of a Source parameter, or a pair of InputIterator parameters),
+ // performing the conversions required by [fs.path.type.cvt].
+ // If the value_type of the range value type is path::value_type,
+ // no encoding conversion is performed. If the range is contiguous
+ // a string_view
- static basic_string_view<value_type>
- _S_convert(const value_type* __first, const value_type* __last)
- { return {__first, __last - __first}; }
+ static string_type
+ _S_convert(string_type __str)
+ { return __str; }
- template<typename _Iter>
- static string_type
- _S_convert(_Iter __first, _Iter __last)
+ template<typename _Tp>
+ static auto
+ _S_convert(const _Tp& __str)
{
- using __value_type = typename std::iterator_traits<_Iter>::value_type;
- return _Cvt<typename remove_cv<__value_type>::type>::
- _S_convert(__first, __last);
+ if constexpr (is_same_v<_Tp, string_type>)
+ return __str;
+ else if constexpr (is_same_v<_Tp, basic_string_view<value_type>>)
+ return __str;
+ else if constexpr (is_same_v<typename _Tp::value_type, value_type>)
+ return basic_string_view<value_type>(__str.data(), __str.size());
+ else
+ return _S_convert(__str.data(), __str.data() + __str.size());
}
- template<typename _InputIterator>
- static string_type
- _S_convert(_InputIterator __src, __detail::__null_terminated)
- {
- // Read from iterator into basic_string until a null value is seen:
- auto __s = _S_string_from_iter(__src);
- // Convert (if needed) from iterator's value type to path::value_type:
- return string_type(_S_convert(__s.data(), __s.data() + __s.size()));
- }
+ template<typename _EcharT>
+ static auto
+ _S_convert(const _EcharT* __first, const _EcharT* __last);
+
+ template<typename _Iter>
+ static auto
+ _S_convert(_Iter __first, _Iter __last)
+ { return _S_convert(_S_to_string(__first, __last)); }
static string_type
_S_convert_loc(const char* __first, const char* __last,
@@ -604,16 +612,14 @@ namespace __detail
static string_type
_S_convert_loc(_Iter __first, _Iter __last, const std::locale& __loc)
{
- const std::string __str(__first, __last);
- return _S_convert_loc(__str.data(), __str.data()+__str.size(), __loc);
+ const auto __s = _S_to_string(__first, __last);
+ return _S_convert_loc(__s.data(), __s.data() + __s.size(), __loc);
}
- template<typename _InputIterator>
+ template<typename _Tp>
static string_type
- _S_convert_loc(_InputIterator __src, __detail::__null_terminated,
- const std::locale& __loc)
+ _S_convert_loc(const _Tp& __s, const std::locale& __loc)
{
- const std::string __s = _S_string_from_iter(__src);
return _S_convert_loc(__s.data(), __s.data() + __s.size(), __loc);
}
@@ -803,100 +809,66 @@ namespace __detail
size_t _M_pos;
};
- // specialize _Cvt for degenerate 'noconv' case
- template<>
- struct path::_Cvt<path::value_type>
- {
- template<typename _Iter>
- static string_type
- _S_convert(_Iter __first, _Iter __last)
- { return string_type{__first, __last}; }
- };
-
-#if !defined _GLIBCXX_FILESYSTEM_IS_WINDOWS && defined _GLIBCXX_USE_CHAR8_T
- // For POSIX converting from char8_t to char is also 'noconv'
- template<>
- struct path::_Cvt<char8_t>
+ template<typename _EcharT>
+ auto
+ path::_S_convert(const _EcharT* __f, const _EcharT* __l)
{
- template<typename _Iter>
- static string_type
- _S_convert(_Iter __first, _Iter __last)
- { return string_type(__first, __last); }
- };
+ static_assert(__detail::__is_encoded_char<_EcharT>);
+
+ if constexpr (is_same_v<_EcharT, value_type>)
+ return basic_string_view<value_type>(__f, __l - __f);
+#if !defined _GLIBCXX_FILESYSTEM_IS_WINDOWS && defined _GLIBCXX_USE_CHAR8_T
+ else if constexpr (is_same_v<_EcharT, char8_t>)
+ // For POSIX converting from char8_t to char is also 'noconv'
+ return string_view(reinterpret_cast<const char*>(__f), __l - __f);
#endif
-
- template<typename _CharT>
- struct path::_Cvt
- {
- static string_type
- _S_convert(const _CharT* __f, const _CharT* __l)
- {
+ else
+ {
#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
- std::wstring __wstr;
- if constexpr (is_same_v<_CharT, char>)
- {
- struct _UCvt : std::codecvt<wchar_t, char, std::mbstate_t>
- { } __cvt;
- if (__str_codecvt_in_all(__f, __l, __wstr, __cvt))
- return __wstr;
- }
+ std::wstring __wstr;
+ if constexpr (is_same_v<_EcharT, char>)
+ {
+ struct _UCvt : std::codecvt<wchar_t, char, std::mbstate_t>
+ { } __cvt;
+ if (__str_codecvt_in_all(__f, __l, __wstr, __cvt))
+ return __wstr;
+ }
#ifdef _GLIBCXX_USE_CHAR8_T
- else if constexpr (is_same_v<_CharT, char8_t>)
- {
- const char* __f2 = (const char*)__f;
- const char* __l2 = (const char*)__l;
- std::codecvt_utf8_utf16<wchar_t> __wcvt;
- if (__str_codecvt_in_all(__f2, __l2, __wstr, __wcvt))
- return __wstr;
- }
+ else if constexpr (is_same_v<_EcharT, char8_t>)
+ {
+ const char* __f2 = (const char*)__f;
+ const char* __l2 = (const char*)__l;
+ std::codecvt_utf8_utf16<wchar_t> __wcvt;
+ if (__str_codecvt_in_all(__f2, __l2, __wstr, __wcvt))
+ return __wstr;
+ }
#endif
- else // char16_t or char32_t
- {
- struct _UCvt : std::codecvt<_CharT, char, std::mbstate_t>
- { } __cvt;
- std::string __str;
- if (__str_codecvt_out_all(__f, __l, __str, __cvt))
- {
- const char* __f2 = __str.data();
- const char* __l2 = __f2 + __str.size();
- std::codecvt_utf8_utf16<wchar_t> __wcvt;
- if (__str_codecvt_in_all(__f2, __l2, __wstr, __wcvt))
- return __wstr;
- }
- }
+ else // char16_t or char32_t
+ {
+ struct _UCvt : std::codecvt<_EcharT, char, std::mbstate_t>
+ { } __cvt;
+ std::string __str;
+ if (__str_codecvt_out_all(__f, __l, __str, __cvt))
+ {
+ const char* __f2 = __str.data();
+ const char* __l2 = __f2 + __str.size();
+ std::codecvt_utf8_utf16<wchar_t> __wcvt;
+ if (__str_codecvt_in_all(__f2, __l2, __wstr, __wcvt))
+ return __wstr;
+ }
+ }
#else // ! windows
- struct _UCvt : std::codecvt<_CharT, char, std::mbstate_t>
- { } __cvt;
- std::string __str;
- if (__str_codecvt_out_all(__f, __l, __str, __cvt))
- return __str;
+ struct _UCvt : std::codecvt<_EcharT, char, std::mbstate_t>
+ { } __cvt;
+ std::string __str;
+ if (__str_codecvt_out_all(__f, __l, __str, __cvt))
+ return __str;
#endif
- _GLIBCXX_THROW_OR_ABORT(filesystem_error(
- "Cannot convert character sequence",
- std::make_error_code(errc::illegal_byte_sequence)));
- }
-
- static string_type
- _S_convert(_CharT* __f, _CharT* __l)
- {
- return _S_convert(const_cast<const _CharT*>(__f),
- const_cast<const _CharT*>(__l));
- }
-
- template<typename _Iter>
- static string_type
- _S_convert(_Iter __first, _Iter __last)
- {
- const std::basic_string<_CharT> __str(__first, __last);
- return _S_convert(__str.data(), __str.data() + __str.size());
+ _GLIBCXX_THROW_OR_ABORT(filesystem_error(
+ "Cannot convert character sequence",
+ std::make_error_code(errc::illegal_byte_sequence)));
}
-
- template<typename _Iter, typename _Cont>
- static string_type
- _S_convert(__gnu_cxx::__normal_iterator<_Iter, _Cont> __first,
- __gnu_cxx::__normal_iterator<_Iter, _Cont> __last)
- { return _S_convert(__first.base(), __last.base()); }
- };
+ }
/// @endcond
@@ -1030,10 +1002,10 @@ namespace __detail
template<typename _CharT>
inline __detail::_Path2<_CharT*>&
- path::operator+=(_CharT __x)
+ path::operator+=(const _CharT __x)
{
- auto* __addr = std::__addressof(__x);
- return concat(__addr, __addr + 1);
+ _M_concat(_S_convert(&__x, &__x + 1));
+ return *this;
}
inline path&
diff --git a/libstdc++-v3/include/experimental/bits/fs_path.h b/libstdc++-v3/include/experimental/bits/fs_path.h
index 69b823a3466..c91937c66d8 100644
--- a/libstdc++-v3/include/experimental/bits/fs_path.h
+++ b/libstdc++-v3/include/experimental/bits/fs_path.h
@@ -495,6 +495,13 @@ namespace __detail
_S_convert_loc(const char* __first, const char* __last,
const std::locale& __loc);
+ static string_type
+ _S_convert_loc(char* __first, char* __last, const std::locale& __loc)
+ {
+ return _S_convert_loc(const_cast<const char*>(__first),
+ const_cast<const char*>(__last), __loc);
+ }
+
template<typename _Iter>
static string_type
_S_convert_loc(_Iter __first, _Iter __last, const std::locale& __loc)
diff --git a/libstdc++-v3/src/c++17/fs_path.cc b/libstdc++-v3/src/c++17/fs_path.cc
index 5ff17741f81..cea7aa08601 100644
--- a/libstdc++-v3/src/c++17/fs_path.cc
+++ b/libstdc++-v3/src/c++17/fs_path.cc
@@ -1949,11 +1949,7 @@ path::_S_convert_loc(const char* __first, const char* __last,
_GLIBCXX_THROW_OR_ABORT(filesystem_error(
"Cannot convert character sequence",
std::make_error_code(errc::illegal_byte_sequence)));
-#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
- return __ws;
-#else
- return _Cvt<wchar_t>::_S_convert(__ws.data(), __ws.data() + __ws.size());
-#endif
+ return _S_convert(std::move(__ws));
#else
return {__first, __last};
#endif
More information about the Libstdc++-cvs
mailing list