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#include <format>
#include "gtest.h"
TEST(StdFormatTest, Escaping) {
using namespace std;
string s = format("{0}-{{", 8); // s == "8-{"
EXPECT_EQ(s, "8-{");
}
TEST(StdFormatTest, Indexing) {
using namespace std;
string s0 = format("{} to {}", "a", "b"); // OK: automatic indexing
string s1 = format("{1} to {0}", "a", "b"); // OK: manual indexing
EXPECT_EQ(s0, "a to b");
EXPECT_EQ(s1, "b to a");
// Error: mixing automatic and manual indexing
EXPECT_THROW(string s2 = format("{0} to {}", "a", "b"), std::format_error);
// Error: mixing automatic and manual indexing
EXPECT_THROW(string s3 = format("{} to {1}", "a", "b"), std::format_error);
}
TEST(StdFormatTest, Alignment) {
using namespace std;
char c = 120;
string s0 = format("{:6}", 42); // s0 == " 42"
string s1 = format("{:6}", 'x'); // s1 == "x "
string s2 = format("{:*<6}", 'x'); // s2 == "x*****"
string s3 = format("{:*>6}", 'x'); // s3 == "*****x"
string s4 = format("{:*^6}", 'x'); // s4 == "**x***"
// Error: '=' with charT and no integer presentation type
EXPECT_THROW(string s5 = format("{:=6}", 'x'), std::format_error);
string s6 = format("{:6d}", c); // s6 == " 120"
string s7 = format("{:6}", true); // s9 == "true "
EXPECT_EQ(s0, " 42");
EXPECT_EQ(s1, "x ");
EXPECT_EQ(s2, "x*****");
EXPECT_EQ(s3, "*****x");
EXPECT_EQ(s4, "**x***");
EXPECT_EQ(s6, " 120");
EXPECT_EQ(s7, "true ");
}
TEST(StdFormatTest, Float) {
using namespace std;
double inf = numeric_limits<double>::infinity();
double nan = numeric_limits<double>::quiet_NaN();
string s0 = format("{0:} {0:+} {0:-} {0: }", 1); // s0 == "1 +1 1 1"
string s1 = format("{0:} {0:+} {0:-} {0: }", -1); // s1 == "-1 -1 -1 -1"
string s2 =
format("{0:} {0:+} {0:-} {0: }", inf); // s2 == "inf +inf inf inf"
string s3 =
format("{0:} {0:+} {0:-} {0: }", nan); // s3 == "nan +nan nan nan"
EXPECT_EQ(s0, "1 +1 1 1");
EXPECT_EQ(s1, "-1 -1 -1 -1");
EXPECT_EQ(s2, "inf +inf inf inf");
EXPECT_EQ(s3, "nan +nan nan nan");
}
TEST(StdFormatTest, Int) {
using namespace std;
string s0 = format("{}", 42); // s0 == "42"
string s1 = format("{0:b} {0:d} {0:o} {0:x}", 42); // s1 == "101010 42 52 2a"
string s2 = format("{0:#x} {0:#X}", 42); // s2 == "0x2a 0X2A"
string s3 = format("{:L}", 1234); // s3 == "1234" (depends on the locale)
EXPECT_EQ(s0, "42");
EXPECT_EQ(s1, "101010 42 52 2a");
EXPECT_EQ(s2, "0x2a 0X2A");
EXPECT_EQ(s3, "1234");
}
#include <format>
enum color { red, green, blue };
const char* color_names[] = {"red", "green", "blue"};
template <> struct std::formatter<color> : std::formatter<const char*> {
auto format(color c, format_context& ctx) {
return formatter<const char*>::format(color_names[c], ctx);
}
};
struct err {};
TEST(StdFormatTest, Formatter) {
std::string s0 = std::format("{}", 42); // OK: library-provided formatter
// std::string s1 = std::format("{}", L"foo"); // Ill-formed: disabled
// formatter
std::string s2 = std::format("{}", red); // OK: user-provided formatter
// std::string s3 = std::format("{}", err{}); // Ill-formed: disabled
// formatter
EXPECT_EQ(s0, "42");
EXPECT_EQ(s2, "red");
}
struct S {
int value;
};
template <> struct std::formatter<S> {
size_t width_arg_id = 0;
// Parses a width argument id in the format { <digit> }.
constexpr auto parse(format_parse_context& ctx) {
auto iter = ctx.begin();
// auto get_char = [&]() { return iter != ctx.end() ? *iter : 0; };
auto get_char = [&]() { return iter != ctx.end() ? *iter : '\0'; };
if (get_char() != '{') return iter;
++iter;
char c = get_char();
if (!isdigit(c) || (++iter, get_char()) != '}')
throw format_error("invalid format");
width_arg_id = c - '0';
ctx.check_arg_id(width_arg_id);
return ++iter;
}
// Formats S with width given by the argument width_arg_id.
auto format(S s, format_context& ctx) {
int width = visit_format_arg(
[](auto value) -> int {
using type = decltype(value);
if constexpr (!is_integral_v<type> || is_same_v<type, bool>)
throw format_error("width is not integral");
// else if (value < 0 || value > numeric_limits<int>::max())
else if (fmt::detail::is_negative(value) ||
value > numeric_limits<int>::max())
throw format_error("invalid width");
else
return static_cast<int>(value);
},
ctx.arg(width_arg_id));
return format_to(ctx.out(), "{0:{1}}", s.value, width);
}
};
TEST(StdFormatTest, Parsing) {
std::string s = std::format("{0:{1}}", S{42}, 10); // s == " 42"
EXPECT_EQ(s, " 42");
}
#if FMT_USE_INT128
template <> struct std::formatter<__int128_t> : std::formatter<long long> {
auto format(__int128_t n, format_context& ctx) {
// Format as a long long since we only want to check if it is possible to
// specialize formatter for __int128_t.
return formatter<long long>::format(static_cast<long long>(n), ctx);
}
};
TEST(StdFormatTest, Int128) {
__int128_t n = 42;
auto s = std::format("{}", n);
EXPECT_EQ(s, "42");
}
#endif // FMT_USE_INT128
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