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[libc] Allow construction of const span from mutable span

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This commit is contained in:
Guillaume Chatelet 2022-08-22 08:54:13 +00:00
parent 1d66c5ebbc
commit e5d5146323
3 changed files with 33 additions and 37 deletions
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8
libc/src/__support/CPP/span.h
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@ -11,7 +11,7 @@
#include <stddef.h> // For size_t
#include "array.h" // For array
#include "type_traits.h" // For remove_cv_t
#include "type_traits.h" // For remove_cv_t, enable_if_t, is_same_v, is_const_v
namespace __llvm_libc::cpp {
@ -52,6 +52,12 @@ public:
constexpr span(array<T, N> &arr)
: span_data(arr.data()), span_size(arr.size()) {}
template <typename U,
cpp::enable_if_t<!cpp::is_const_v<U> && cpp::is_const_v<T> &&
cpp::is_same_v<U, value_type>,
bool> = true>
constexpr span(span<U> &s) : span(s.data(), s.size()) {}
constexpr span(const span &s) = default;
constexpr span &operator=(const span &s) = default;
~span() = default;

52
libc/src/__support/CPP/type_traits.h
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@ -15,9 +15,7 @@ namespace __llvm_libc {
namespace cpp {
template <bool B, typename T> struct enable_if;
template <typename T> struct enable_if<true, T> {
using type = T;
};
template <typename T> struct enable_if<true, T> { using type = T; };
template <bool B, typename T = void>
using enable_if_t = typename enable_if<B, T>::type;
@ -28,15 +26,17 @@ template <typename T, T v> struct integral_constant {
using true_type = cpp::integral_constant<bool, true>;
using false_type = cpp::integral_constant<bool, false>;
template <typename T> struct type_identity {
using type = T;
};
template <typename T> struct type_identity { using type = T; };
template <typename T, typename U> struct is_same : cpp::false_type {};
template <typename T> struct is_same<T, T> : cpp::true_type {};
template <typename T, typename U>
inline constexpr bool is_same_v = is_same<T, U>::value;
template <class T> struct is_const : cpp::false_type {};
template <class T> struct is_const<const T> : cpp::true_type {};
template <class T> inline constexpr bool is_const_v = is_const<T>::value;
template <typename T> struct remove_cv : public type_identity<T> {};
template <typename T> struct remove_cv<const T> : public type_identity<T> {};
template <typename T> struct remove_cv<volatile T> : public type_identity<T> {};
@ -114,46 +114,26 @@ template <typename T> struct is_signed {
template <typename T> inline constexpr bool is_signed_v = is_signed<T>::value;
template <typename T> struct make_unsigned;
template <> struct make_unsigned<char> {
using type = unsigned char;
};
template <> struct make_unsigned<signed char> {
using type = unsigned char;
};
template <> struct make_unsigned<short> {
using type = unsigned short;
};
template <> struct make_unsigned<int> {
using type = unsigned int;
};
template <> struct make_unsigned<long> {
using type = unsigned long;
};
template <> struct make_unsigned<char> { using type = unsigned char; };
template <> struct make_unsigned<signed char> { using type = unsigned char; };
template <> struct make_unsigned<short> { using type = unsigned short; };
template <> struct make_unsigned<int> { using type = unsigned int; };
template <> struct make_unsigned<long> { using type = unsigned long; };
template <> struct make_unsigned<long long> {
using type = unsigned long long;
};
template <> struct make_unsigned<unsigned char> {
using type = unsigned char;
};
template <> struct make_unsigned<unsigned char> { using type = unsigned char; };
template <> struct make_unsigned<unsigned short> {
using type = unsigned short;
};
template <> struct make_unsigned<unsigned int> {
using type = unsigned int;
};
template <> struct make_unsigned<unsigned long> {
using type = unsigned long;
};
template <> struct make_unsigned<unsigned int> { using type = unsigned int; };
template <> struct make_unsigned<unsigned long> { using type = unsigned long; };
template <> struct make_unsigned<unsigned long long> {
using type = unsigned long long;
};
#ifdef __SIZEOF_INT128__
template <> struct make_unsigned<__int128_t> {
using type = __uint128_t;
};
template <> struct make_unsigned<__uint128_t> {
using type = __uint128_t;
};
template <> struct make_unsigned<__int128_t> { using type = __uint128_t; };
template <> struct make_unsigned<__uint128_t> { using type = __uint128_t; };
#endif
template <typename T> using make_unsigned_t = typename make_unsigned<T>::type;

10
libc/test/src/__support/CPP/span_test.cpp
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@ -56,6 +56,16 @@ TEST(LlvmLibcSpanTest, InitializeArray) {
ASSERT_EQ(s[2], 3);
}
TEST(LlvmLibcSpanTest, ConstFromMutable) {
array<int, 3> a = {1, 2, 3};
span<int> mutable_view(a);
span<const int> const_view(mutable_view);
ASSERT_EQ(const_view.size(), size_t(3));
ASSERT_EQ(const_view[0], 1);
ASSERT_EQ(const_view[1], 2);
ASSERT_EQ(const_view[2], 3);
}
TEST(LlvmLibcSpanTest, Modify) {
int a[] = {1, 2, 3};
span<int> s(a);