[PATCH] Refactor std::basic_string_view members and add noexcept
Jonathan Wakely
jwakely@redhat.com
Tue Oct 24 13:18:00 GMT 2017
This applies 'noexcept' more liberally in our std::basic_string_view,
anywhere that can't actually throw (even if it has a narrow contract).
I've also refactored some members to remove complex conditional
expressions, because they're not needed with C++14 constexpr, we can
just write the code as normal.
* include/bits/string_view.tcc (find_first_of, find_last_of)
(find_first_not_of, find_last_not_of): Add noexcept.
* include/std/string_view (basic_string_view(const _CharT*))
(basic_string_view(const _CharT*, size_type))
(front, back, remove_prefix, remove_suffix, find, rfind)
(find_first_of, find_first_not_of): Add noexcept.
(at(size_type), _S_compare(size_type, size_type)): Replace conditional
expressions with if statements.
(copy(_CharT*, size_type, size_type), substr(size_type, size_type)):
Use _M_check for length checks.
(compare(basic_string_view)): Reformat.
(_M_check(size_type, const char)): Add noexcept(false).
(_M_limit(size_type, size_type)): Use noexcept not _GLIBCXX_NOEXCEPT.
Tested powerpc64le-linux, committed to trunk.
-------------- next part --------------
commit 0b6b569b442ab1837cecd140f07df969599eb51a
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue Oct 24 13:50:19 2017 +0100
Refactor std::basic_string_view members and add noexcept
* include/bits/string_view.tcc (find_first_of, find_last_of)
(find_first_not_of, find_last_not_of): Add noexcept.
* include/std/string_view (basic_string_view(const _CharT*))
(basic_string_view(const _CharT*, size_type))
(front, back, remove_prefix, remove_suffix, find, rfind)
(find_first_of, find_first_not_of): Add noexcept.
(at(size_type), _S_compare(size_type, size_type)): Replace conditional
expressions with if statements.
(copy(_CharT*, size_type, size_type), substr(size_type, size_type)):
Use _M_check for length checks.
(compare(basic_string_view)): Reformat.
(_M_check(size_type, const char)): Add noexcept(false).
(_M_limit(size_type, size_type)): Use noexcept not _GLIBCXX_NOEXCEPT.
diff --git a/libstdc++-v3/include/bits/string_view.tcc b/libstdc++-v3/include/bits/string_view.tcc
index 4d98f8668a0..5c53c584381 100644
--- a/libstdc++-v3/include/bits/string_view.tcc
+++ b/libstdc++-v3/include/bits/string_view.tcc
@@ -119,7 +119,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr typename basic_string_view<_CharT, _Traits>::size_type
basic_string_view<_CharT, _Traits>::
- find_first_of(const _CharT* __str, size_type __pos, size_type __n) const
+ find_first_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept
{
__glibcxx_requires_string_len(__str, __n);
for (; __n && __pos < this->_M_len; ++__pos)
@@ -135,7 +136,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr typename basic_string_view<_CharT, _Traits>::size_type
basic_string_view<_CharT, _Traits>::
- find_last_of(const _CharT* __str, size_type __pos, size_type __n) const
+ find_last_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept
{
__glibcxx_requires_string_len(__str, __n);
size_type __size = this->size();
@@ -156,7 +158,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr typename basic_string_view<_CharT, _Traits>::size_type
basic_string_view<_CharT, _Traits>::
- find_first_not_of(const _CharT* __str, size_type __pos, size_type __n) const
+ find_first_not_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept
{
__glibcxx_requires_string_len(__str, __n);
for (; __pos < this->_M_len; ++__pos)
@@ -179,7 +182,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _CharT, typename _Traits>
constexpr typename basic_string_view<_CharT, _Traits>::size_type
basic_string_view<_CharT, _Traits>::
- find_last_not_of(const _CharT* __str, size_type __pos, size_type __n) const
+ find_last_not_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept
{
__glibcxx_requires_string_len(__str, __n);
size_type __size = this->_M_len;
diff --git a/libstdc++-v3/include/std/string_view b/libstdc++-v3/include/std/string_view
index 110a235a4c0..1900b867841 100644
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -96,14 +96,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr basic_string_view(const basic_string_view&) noexcept = default;
- constexpr basic_string_view(const _CharT* __str)
+ constexpr basic_string_view(const _CharT* __str) noexcept
: _M_len{__str == nullptr ? 0 : traits_type::length(__str)},
_M_str{__str}
{ }
- constexpr basic_string_view(const _CharT* __str, size_type __len)
- : _M_len{__len},
- _M_str{__str}
+ constexpr
+ basic_string_view(const _CharT* __str, size_type __len) noexcept
+ : _M_len{__len}, _M_str{__str}
{ }
constexpr basic_string_view&
@@ -177,17 +177,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr const _CharT&
at(size_type __pos) const
{
- return __pos < this->_M_len
- ? *(this->_M_str + __pos)
- : (__throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
- "(which is %zu) >= this->size() "
- "(which is %zu)"),
- __pos, this->size()),
- *this->_M_str);
+ if (__pos >= _M_len)
+ __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
+ "(which is %zu) >= this->size() "
+ "(which is %zu)"), __pos, this->size());
+ return *(this->_M_str + __pos);
}
constexpr const _CharT&
- front() const
+ front() const noexcept
{
// TODO: Assert to restore in a way compatible with the constexpr.
// __glibcxx_assert(this->_M_len > 0);
@@ -195,7 +193,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
constexpr const _CharT&
- back() const
+ back() const noexcept
{
// TODO: Assert to restore in a way compatible with the constexpr.
// __glibcxx_assert(this->_M_len > 0);
@@ -209,7 +207,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// [string.view.modifiers], modifiers:
constexpr void
- remove_prefix(size_type __n)
+ remove_prefix(size_type __n) noexcept
{
__glibcxx_assert(this->_M_len >= __n);
this->_M_str += __n;
@@ -217,7 +215,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
constexpr void
- remove_suffix(size_type __n)
+ remove_suffix(size_type __n) noexcept
{ this->_M_len -= __n; }
constexpr void
@@ -235,38 +233,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
copy(_CharT* __str, size_type __n, size_type __pos = 0) const
{
__glibcxx_requires_string_len(__str, __n);
- if (__pos > this->_M_len)
- __throw_out_of_range_fmt(__N("basic_string_view::copy: __pos "
- "(which is %zu) > this->size() "
- "(which is %zu)"),
- __pos, this->size());
- size_type __rlen{std::min(__n, size_type{this->_M_len - __pos})};
+ __pos = _M_check(__pos, "basic_string_view::copy");
+ const size_type __rlen = std::min(__n, _M_len - __pos);
for (auto __begin = this->_M_str + __pos,
__end = __begin + __rlen; __begin != __end;)
*__str++ = *__begin++;
return __rlen;
}
-
- // [string.view.ops], string operations:
-
constexpr basic_string_view
- substr(size_type __pos, size_type __n=npos) const
+ substr(size_type __pos, size_type __n = npos) const noexcept(false)
{
- return __pos <= this->_M_len
- ? basic_string_view{this->_M_str + __pos,
- std::min(__n, size_type{this->_M_len - __pos})}
- : (__throw_out_of_range_fmt(__N("basic_string_view::substr: __pos "
- "(which is %zu) > this->size() "
- "(which is %zu)"),
- __pos, this->size()), basic_string_view{});
+ __pos = _M_check(__pos, "basic_string_view::substr");
+ const size_type __rlen = std::min(__n, _M_len - __pos);
+ return basic_string_view{_M_str + __pos, __rlen};
}
constexpr int
compare(basic_string_view __str) const noexcept
{
- int __ret = traits_type::compare(this->_M_str, __str._M_str,
- std::min(this->_M_len, __str._M_len));
+ const size_type __rlen = std::min(this->_M_len, __str._M_len);
+ int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
if (__ret == 0)
__ret = _S_compare(this->_M_len, __str._M_len);
return __ret;
@@ -279,7 +266,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr int
compare(size_type __pos1, size_type __n1,
basic_string_view __str, size_type __pos2, size_type __n2) const
- { return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2)); }
+ {
+ return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
+ }
constexpr int
compare(const _CharT* __str) const noexcept
@@ -291,7 +280,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr int
compare(size_type __pos1, size_type __n1,
- const _CharT* __str, size_type __n2) const
+ const _CharT* __str, size_type __n2) const noexcept(false)
{
return this->substr(__pos1, __n1)
.compare(basic_string_view(__str, __n2));
@@ -302,13 +291,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return this->find(__str._M_str, __pos, __str._M_len); }
constexpr size_type
- find(_CharT __c, size_type __pos=0) const noexcept;
+ find(_CharT __c, size_type __pos = 0) const noexcept;
constexpr size_type
find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
constexpr size_type
- find(const _CharT* __str, size_type __pos=0) const noexcept
+ find(const _CharT* __str, size_type __pos = 0) const noexcept
{ return this->find(__str, __pos, traits_type::length(__str)); }
constexpr size_type
@@ -350,7 +339,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return this->rfind(__c, __pos); }
constexpr size_type
- find_last_of(const _CharT* __str, size_type __pos, size_type __n) const;
+ find_last_of(const _CharT* __str, size_type __pos,
+ size_type __n) const noexcept;
constexpr size_type
find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
@@ -366,7 +356,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr size_type
find_first_not_of(const _CharT* __str,
- size_type __pos, size_type __n) const;
+ size_type __pos, size_type __n) const noexcept;
constexpr size_type
find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
@@ -385,7 +375,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr size_type
find_last_not_of(const _CharT* __str,
- size_type __pos, size_type __n) const;
+ size_type __pos, size_type __n) const noexcept;
constexpr size_type
find_last_not_of(const _CharT* __str,
@@ -396,7 +386,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
constexpr size_type
- _M_check(size_type __pos, const char* __s) const
+ _M_check(size_type __pos, const char* __s) const noexcept(false)
{
if (__pos > this->size())
__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
@@ -407,7 +397,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// NB: _M_limit doesn't check for a bad __pos value.
constexpr size_type
- _M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
+ _M_limit(size_type __pos, size_type __off) const noexcept
{
const bool __testoff = __off < this->size() - __pos;
return __testoff ? __off : this->size() - __pos;
@@ -418,11 +408,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
static constexpr int
_S_compare(size_type __n1, size_type __n2) noexcept
{
- return difference_type{__n1 - __n2} > std::numeric_limits<int>::max()
- ? std::numeric_limits<int>::max()
- : difference_type{__n1 - __n2} < std::numeric_limits<int>::min()
- ? std::numeric_limits<int>::min()
- : static_cast<int>(difference_type{__n1 - __n2});
+ const difference_type __diff{__n1 - __n2};
+ if (__diff > std::numeric_limits<int>::max())
+ return std::numeric_limits<int>::max();
+ if (__diff < std::numeric_limits<int>::min())
+ return std::numeric_limits<int>::min();
+ return static_cast<int>(__diff);
}
size_t _M_len;
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