Re: [PATCH, libstdc++, C++20] Implement P0457R2 String Prefix and Suffix Checking.
On 11/30/18 5:33 AM, Jonathan Wakely wrote:
On 29/11/18 21:35 -0500, Ed Smith-Rowland wrote:
Greetings,
This patch implements starts_with and ends_with for basic_string and
basic_string_view for C++20.
This was on my TODO list, thanks for taking care of it.
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const
noexcept
+ { return __sv_type(this->data(),
this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(),
this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const
This can be noexcept. It isn't in the standard, because it has a
narrow contract (there's a precondition that __x is null-terminated).
But since we can't reliably detect whether __x is null-terminated, and
even if we could we wouldn't want to throw an exception, we can just
make it noexcept. Same for the ends_with(const _CharT*) one, and the
equivalent members in the COW basic_string and basic_string_view.
Index: include/std/string_view
===
--- include/std/string_view (revision 266645)
+++ include/std/string_view (working copy)
@@ -227,7 +227,6 @@
__sv = __tmp;
}
-
// [string.view.ops], string operations:
size_type
@@ -387,6 +386,36 @@
traits_type::length(__str));
}
+#if __cplusplus > 201703L
+ constexpr bool
+ starts_with(basic_string_view __x) const noexcept
+ { return this->size() >= __x.size()
+ && this->compare(0, __x.size(), __x) == 0; }
Please put the opening and closing braces on their own lines, as for
ends_with below:
+ constexpr bool
+ ends_with(basic_string_view __x) const noexcept
+ {
+ return this->size() >= __x.size()
+ && this->compare(this->size() - __x.size(), npos, __x) == 0;
+ }
OK with those changes, thanks
Committed 266674.
New patch attached.
Ed
2018-11-30 Edward Smith-Rowland <3dw...@verizon.net>
Implement P0457R2 String Prefix and Suffix Checking.
* include/bits/basic_string.h: Add starts_with, ends_with members.
* include/std/string_view: Ditto.
* testsuite/21_strings/basic_string/operations/starts_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string/operations/starts_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string/operations/ends_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string/operations/ends_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/starts_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/starts_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/ends_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/ends_with/
wchar_t/1.cc: New test.
Index: include/bits/basic_string.h
===
--- include/bits/basic_string.h (revision 266671)
+++ include/bits/basic_string.h (working copy)
@@ -3038,6 +3038,32 @@
compare(size_type __pos, size_type __n1, const _CharT* __s,
size_type __n2) const;
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(const _CharT* __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+#endif // C++20
+
// Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
template friend class basic_stringbuf;
};
@@ -5884,6 +5910,32 @@
compare(size_type __pos, size_type __n1, const _CharT* __s,
size_type __n2) const;
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const noexcept
+ { return __sv_type(this->data(),
Re: [PATCH, libstdc++, C++20] Implement P0457R2 String Prefix and Suffix Checking.
On 29/11/18 21:35 -0500, Ed Smith-Rowland wrote:
Greetings,
This patch implements starts_with and ends_with for basic_string and
basic_string_view for C++20.
This was on my TODO list, thanks for taking care of it.
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const
This can be noexcept. It isn't in the standard, because it has a
narrow contract (there's a precondition that __x is null-terminated).
But since we can't reliably detect whether __x is null-terminated, and
even if we could we wouldn't want to throw an exception, we can just
make it noexcept. Same for the ends_with(const _CharT*) one, and the
equivalent members in the COW basic_string and basic_string_view.
Index: include/std/string_view
===
--- include/std/string_view (revision 266645)
+++ include/std/string_view (working copy)
@@ -227,7 +227,6 @@
__sv = __tmp;
}
-
// [string.view.ops], string operations:
size_type
@@ -387,6 +386,36 @@
traits_type::length(__str));
}
+#if __cplusplus > 201703L
+ constexpr bool
+ starts_with(basic_string_view __x) const noexcept
+ { return this->size() >= __x.size()
+ && this->compare(0, __x.size(), __x) == 0; }
Please put the opening and closing braces on their own lines, as for
ends_with below:
+ constexpr bool
+ ends_with(basic_string_view __x) const noexcept
+ {
+ return this->size() >= __x.size()
+ && this->compare(this->size() - __x.size(), npos, __x) == 0;
+ }
OK with those changes, thanks.
[PATCH, libstdc++, C++20] Implement P0457R2 String Prefix and Suffix Checking.
Greetings,
This patch implements starts_with and ends_with for basic_string and
basic_string_view for C++20.
This builds and tests cleanly on x86_64-linux.
Ed
2018-11-30 Edward Smith-Rowland <3dw...@verizon.net>
Implement P0457R2 String Prefix and Suffix Checking.
* include/bits/basic_string.h: Add starts_with, ends_with members.
* include/std/string_view: Ditto.
* testsuite/21_strings/basic_string/operations/starts_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string/operations/starts_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string/operations/ends_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string/operations/ends_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/starts_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/starts_with/
wchar_t/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/ends_with/
char/1.cc: New test.
* testsuite/21_strings/basic_string_view/operations/ends_with/
wchar_t/1.cc: New test.
Index: include/bits/basic_string.h
===
--- include/bits/basic_string.h (revision 266645)
+++ include/bits/basic_string.h (working copy)
@@ -3038,6 +3038,32 @@
compare(size_type __pos, size_type __n1, const _CharT* __s,
size_type __n2) const;
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(const _CharT* __x) const
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+#endif // C++20
+
// Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
template friend class basic_stringbuf;
};
@@ -5884,6 +5910,32 @@
compare(size_type __pos, size_type __n1, const _CharT* __s,
size_type __n2) const;
+#if __cplusplus > 201703L
+ bool
+ starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ starts_with(const _CharT* __x) const
+ { return __sv_type(this->data(), this->size()).starts_with(__x); }
+
+ bool
+ ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(_CharT __x) const noexcept
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+
+ bool
+ ends_with(const _CharT* __x) const
+ { return __sv_type(this->data(), this->size()).ends_with(__x); }
+#endif // C++20
+
# ifdef _GLIBCXX_TM_TS_INTERNAL
friend void
::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
Index: include/std/string_view
===
--- include/std/string_view (revision 266645)
+++ include/std/string_view (working copy)
@@ -227,7 +227,6 @@
__sv = __tmp;
}
-
// [string.view.ops], string operations:
size_type
@@ -387,6 +386,36 @@
traits_type::length(__str));
}
+#if __cplusplus > 201703L
+ constexpr bool
+ starts_with(basic_string_view __x) const noexcept
+ { return this->size() >= __x.size()
+ && this->compare(0, __x.size(), __x) == 0; }
+
+ constexpr bool
+ starts_with(_CharT __x) const noexcept
+ { return this->starts_with(basic_string_view(&__x, 1)); }
+
+ constexpr bool
+ starts_with(const _CharT* __x) const
+ { return this->starts_with(basic_string_view(__x)); }
+
+ constexpr bool
+ ends_with(basic_string_view __x) const noexcept
+ {
+ return this->size() >= __x.size()
+ && this->compare(this->size() - __x.size(), npos, __x) == 0;
+ }
+
+ constexpr bool
+ ends_with(_CharT __x) const noexcept
+ { return this->ends_with(basic_string_view(&__x, 1)); }
+
+ constexpr bool
+ ends_with(const _CharT* __x) const
+ { return
