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Made string_span details::string_length() generic (Fix issue #542) (#543)

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* Made string_span details::string_length() generic

removed overloads & specialized classes

Creating string_spans using `char16_t` and `char32_t` was not possible
without creating new specializations and function overloads.

This patch makes details::string_length() generic removing the need to
extend the overloads and specializations.

* added type aliases for string_span types char16_t and char32_t

* Added char16_t & char32_t overloads for ensure_z

* added string_span tests for char16_T & char32_t

* added zstring type aliases for char16_t & char32_t

* Added tests for char16_t & char31_t zstring and string_span types

* applies clang format to <gsl/string_span>

* Clang format tests/string_span_tests.cpp

* Removed ensure_z() overloads as they don't add functionality.
This commit is contained in:
Galik
2017-09-18 23:20:51 +01:00
committed by Neil MacIntosh
parent e7bcdf541b
commit 4c5fdb541f
2 changed files with 265 additions and 103 deletions
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150
include/gsl/string_span
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@ -39,8 +39,8 @@
#pragma push_macro("constexpr")
#define constexpr /*constexpr*/
#endif // _MSC_VER < 1910
#endif // _MSC_VER
#endif // _MSC_VER < 1910
#endif // _MSC_VER
// In order to test the library, we need it to throw exceptions that we can catch
#ifdef GSL_THROW_ON_CONTRACT_VIOLATION
@ -71,31 +71,32 @@ using czstring = basic_zstring<const char, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cwzstring = basic_zstring<const wchar_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cu16zstring = basic_zstring<const char16_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cu32zstring = basic_zstring<const char32_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using zstring = basic_zstring<char, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using wzstring = basic_zstring<wchar_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using u16zstring = basic_zstring<char16_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using u32zstring = basic_zstring<char32_t, Extent>;
namespace details
{
inline std::ptrdiff_t string_length(const char* str, std::ptrdiff_t n)
template <class CharT>
std::ptrdiff_t string_length(const CharT* str, std::ptrdiff_t n)
{
if (str == nullptr || n <= 0) return 0;
span<const char> str_span{str, n};
std::ptrdiff_t len = 0;
while (len < n && str_span[len]) len++;
return len;
}
inline std::ptrdiff_t wstring_length(const wchar_t* str, std::ptrdiff_t n)
{
if (str == nullptr || n <= 0) return 0;
span<const wchar_t> str_span{str, n};
span<const CharT> str_span{str, n};
std::ptrdiff_t len = 0;
while (len < n && str_span[len]) len++;
@ -122,48 +123,18 @@ span<T, dynamic_extent> ensure_sentinel(T* seq, std::ptrdiff_t max = PTRDIFF_MAX
}
//
// ensure_z - creates a span for a czstring or cwzstring.
// ensure_z - creates a span for a zero terminated strings.
// Will fail fast if a null-terminator cannot be found before
// the limit of size_type.
//
template <typename T>
inline span<T, dynamic_extent> ensure_z(T* const& sz, std::ptrdiff_t max = PTRDIFF_MAX)
template <typename CharT>
inline span<CharT, dynamic_extent> ensure_z(CharT* const& sz, std::ptrdiff_t max = PTRDIFF_MAX)
{
return ensure_sentinel<T, 0>(sz, max);
return ensure_sentinel<CharT, CharT(0)>(sz, max);
}
// TODO (neilmac) there is probably a better template-magic way to get the const and non-const
// overloads to share an implementation
inline span<char, dynamic_extent> ensure_z(char* const& sz, std::ptrdiff_t max)
{
auto len = details::string_length(sz, max);
Ensures(sz[len] == 0);
return {sz, len};
}
inline span<const char, dynamic_extent> ensure_z(const char* const& sz, std::ptrdiff_t max)
{
auto len = details::string_length(sz, max);
Ensures(sz[len] == 0);
return {sz, len};
}
inline span<wchar_t, dynamic_extent> ensure_z(wchar_t* const& sz, std::ptrdiff_t max)
{
auto len = details::wstring_length(sz, max);
Ensures(sz[len] == 0);
return {sz, len};
}
inline span<const wchar_t, dynamic_extent> ensure_z(const wchar_t* const& sz, std::ptrdiff_t max)
{
auto len = details::wstring_length(sz, max);
Ensures(sz[len] == 0);
return {sz, len};
}
template <typename T, std::size_t N>
span<T, dynamic_extent> ensure_z(T (&sz)[N])
template <typename CharT, std::size_t N>
span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N])
{
return ensure_z(&sz[0], static_cast<std::ptrdiff_t>(N));
}
@ -194,47 +165,6 @@ namespace details
struct is_basic_string_span : is_basic_string_span_oracle<std::remove_cv_t<T>>
{
};
template <typename T>
struct length_func
{
};
template <>
struct length_func<char>
{
std::ptrdiff_t operator()(const char* const ptr, std::ptrdiff_t length) GSL_NOEXCEPT
{
return details::string_length(ptr, length);
}
};
template <>
struct length_func<wchar_t>
{
std::ptrdiff_t operator()(const wchar_t* const ptr, std::ptrdiff_t length) GSL_NOEXCEPT
{
return details::wstring_length(ptr, length);
}
};
template <>
struct length_func<const char>
{
std::ptrdiff_t operator()(const char* const ptr, std::ptrdiff_t length) GSL_NOEXCEPT
{
return details::string_length(ptr, length);
}
};
template <>
struct length_func<const wchar_t>
{
std::ptrdiff_t operator()(const wchar_t* const ptr, std::ptrdiff_t length) GSL_NOEXCEPT
{
return details::wstring_length(ptr, length);
}
};
}
//
@ -262,13 +192,13 @@ public:
// copy
constexpr basic_string_span(const basic_string_span& other) GSL_NOEXCEPT = default;
// move
// move
constexpr basic_string_span(basic_string_span&& other) GSL_NOEXCEPT = default;
// assign
constexpr basic_string_span& operator=(const basic_string_span& other) GSL_NOEXCEPT = default;
// move assign
// move assign
constexpr basic_string_span& operator=(basic_string_span&& other) GSL_NOEXCEPT = default;
// from nullptr
@ -399,7 +329,7 @@ public:
private:
static impl_type remove_z(pointer const& sz, std::ptrdiff_t max)
{
return {sz, details::length_func<element_type>()(sz, max)};
return {sz, details::string_length(sz, max)};
}
template <std::size_t N>
@ -423,6 +353,18 @@ using wstring_span = basic_string_span<wchar_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cwstring_span = basic_string_span<const wchar_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using u16string_span = basic_string_span<char16_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cu16string_span = basic_string_span<const char16_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using u32string_span = basic_string_span<char32_t, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent>
using cu32string_span = basic_string_span<const char32_t, Extent>;
//
// to_string() allow (explicit) conversions from string_span to string
//
@ -468,13 +410,13 @@ public:
// copy
constexpr basic_zstring_span(const basic_zstring_span& other) = default;
// move
// move
constexpr basic_zstring_span(basic_zstring_span&& other) = default;
// assign
constexpr basic_zstring_span& operator=(const basic_zstring_span& other) = default;
// move assign
// move assign
constexpr basic_zstring_span& operator=(basic_zstring_span&& other) = default;
constexpr bool empty() const GSL_NOEXCEPT { return span_.size() == 0; }
@ -499,12 +441,24 @@ using zstring_span = basic_zstring_span<char, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using wzstring_span = basic_zstring_span<wchar_t, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using u16zstring_span = basic_zstring_span<char16_t, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using u32zstring_span = basic_zstring_span<char32_t, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using czstring_span = basic_zstring_span<const char, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using cwzstring_span = basic_zstring_span<const wchar_t, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using cu16zstring_span = basic_zstring_span<const char16_t, Max>;
template <std::ptrdiff_t Max = dynamic_extent>
using cu32zstring_span = basic_zstring_span<const char32_t, Max>;
// operator ==
template <class CharT, std::ptrdiff_t Extent, class T,
class = std::enable_if_t<