093630eb5d
For C++17, if all the alternatives of a variant are formattable the variant is now also formattable. In addition 'std::monostate' is now formattable. The value of a variant is enclosed in '<' and '>', and the monostate is formatted as ' '.
44 lines
1.4 KiB
C++
44 lines
1.4 KiB
C++
// Formatting library for C++ - experimental variant API
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//
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// {fmt} support for variant interface.
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#include "fmt/variant.h"
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#include <string>
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#include "gtest/gtest.h"
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#if FMT_HAS_VARIANT
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TEST(variant_test, format_monostate) {
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EXPECT_EQ(fmt::format("{}", std::monostate{}), " ");
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}
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TEST(variant_test, format_variant) {
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using V0 = std::variant<int, float, std::string, char>;
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V0 v0(42);
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V0 v1(1.5f);
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V0 v2("hello");
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V0 v3('i');
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EXPECT_EQ(fmt::format("{}", v0), "<42>");
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EXPECT_EQ(fmt::format("{}", v1), "<1.5>");
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EXPECT_EQ(fmt::format("{}", v2), "<\"hello\">");
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EXPECT_EQ(fmt::format("{}", v3), "<'i'>");
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struct unformattable{};
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EXPECT_FALSE((fmt::is_formattable<unformattable>::value));
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EXPECT_FALSE((fmt::is_formattable<std::variant<unformattable>>::value));
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EXPECT_FALSE((fmt::is_formattable<std::variant<unformattable,int>>::value));
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EXPECT_FALSE((fmt::is_formattable<std::variant<int,unformattable>>::value));
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EXPECT_FALSE((fmt::is_formattable<std::variant<unformattable,unformattable>>::value));
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EXPECT_TRUE((fmt::is_formattable<std::variant<int,float>>::value));
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using V1 = std::variant<std::monostate, std::string, std::string>;
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V1 v4{};
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V1 v5{std::in_place_index<1>,"yes, this is variant"};
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EXPECT_EQ(fmt::format("{}", v4), "< >");
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EXPECT_EQ(fmt::format("{}", v5), "<\"yes, this is variant\">");
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}
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#endif // FMT_HAS_VARIANT
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