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Fix StringLike for non-string-like range #48

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Merged
saki7 merged 2 commits into from
Mar 5, 2026
Merged

Fix StringLike for non-string-like range #48

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3ecb3af
Add test for `StringLike`
saki7 Mar 5, 2026
ed72668
Fix `StringLike` for non-string-like range
saki7 Mar 5, 2026
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18 changes: 15 additions & 3 deletions include/iris/string.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,15 +3,27 @@

// SPDX-License-Identifier: MIT

#include <concepts>
#include <string>
#include <string_view>

namespace iris {

template<class T>
concept StringLike = requires(T t) {
std::basic_string_view{t};
};
concept CharLike =
std::same_as<T, char> ||
std::same_as<T, char32_t> ||
std::same_as<T, wchar_t> ||
std::same_as<T, char8_t> ||
std::same_as<T, char16_t>;

template<class T>
concept StringLike =
std::convertible_to<T, std::basic_string_view<char>> ||
std::convertible_to<T, std::basic_string_view<char32_t>> ||
std::convertible_to<T, std::basic_string_view<wchar_t>> ||
std::convertible_to<T, std::basic_string_view<char8_t>> ||
std::convertible_to<T, std::basic_string_view<char16_t>>;

template<class T>
concept NotStringLike = !StringLike<T>;
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42 changes: 42 additions & 0 deletions test/core.cpp
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Expand Up @@ -5,11 +5,14 @@
#include <iris/type_traits.hpp>
#include <iris/requirements.hpp>
#include <iris/compare.hpp>
#include <iris/string.hpp>
#include <iris/fixed_string.hpp>
#include <iris/exception.hpp>
#include <iris/hash.hpp>

#include <concepts>
#include <string>
#include <string_view>
#include <utility>
#include <type_traits>
#include <ranges>
Expand Down Expand Up @@ -448,6 +451,45 @@ TEST_CASE("synth_three_way")
STATIC_CHECK(iris::cmp::synth_three_way{}(NoThreeWay{0}, NoThreeWay{1}) == std::weak_ordering::less);
}

TEST_CASE("StringLike")
{
STATIC_CHECK(iris::StringLike<char const*>);
STATIC_CHECK(iris::StringLike<wchar_t const*>);
STATIC_CHECK(iris::StringLike<char8_t const*>);
STATIC_CHECK(iris::StringLike<char16_t const*>);
STATIC_CHECK(iris::StringLike<char32_t const*>);

STATIC_CHECK(iris::StringLike<std::string>);
STATIC_CHECK(iris::StringLike<std::wstring>);
STATIC_CHECK(iris::StringLike<std::u8string>);
STATIC_CHECK(iris::StringLike<std::u16string>);
STATIC_CHECK(iris::StringLike<std::u32string>);

STATIC_CHECK(iris::StringLike<std::string_view>);
STATIC_CHECK(iris::StringLike<std::wstring_view>);
STATIC_CHECK(iris::StringLike<std::u8string_view>);
STATIC_CHECK(iris::StringLike<std::u16string_view>);
STATIC_CHECK(iris::StringLike<std::u32string_view>);

struct InvalidValueRange
{
struct Invalid { Invalid(Invalid const&) = delete; };

using value_type = Invalid;
value_type const* begin() const { return nullptr; }
value_type const* end() const { return nullptr; }
std::size_t size() const { return 0; }
};
static_assert(std::ranges::sized_range<InvalidValueRange>);
static_assert(std::ranges::contiguous_range<InvalidValueRange>);

// hard error as per [strings.general]/1
//std::basic_string_view sv{InvalidValueRange{}};

// should NOT yield hard error
STATIC_CHECK(!iris::StringLike<InvalidValueRange>);
}

TEST_CASE("fixed_string")
{
using namespace std::string_view_literals;
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