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TM::String::format and hex values formatted as float #2858

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Merged
herwinw merged 3 commits into from
Dec 19, 2025
Merged

TM::String::format and hex values formatted as float #2858

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85f63c9
Add test for current behaviour of hex formatting in TM::String
herwinw Dec 19, 2025
5069674
Limit hex format of TM::String to pointer and integral data types
herwinw Dec 19, 2025
564c5b4
Simplify type validation in format of TM::String
herwinw Dec 19, 2025
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18 changes: 16 additions & 2 deletions ext/tm/include/tm/string.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1577,6 +1577,20 @@ class String final {
* auto str = String::format("{} {}orld {}", cstr, c, num);
* assert_str_eq("hello world 999", str);
* ```
*
* Using `{h}`, an integral value or a pointer can be displayed as hex
* ```
* void *ptr = nullptr;
* int i = 255;
* auto str = String::format("Pointer = {h}, Integer = {h}", ptr, i);
* assert_str_eq("Pointer = 0x0, Integer = 0xff", str);
* ```
*
* A floating point in hex mode is floored to the integer value.
* ```should_abort
* float f = 10.5;
* String::format("{h}", f);
* ```
*/
template <typename... Args>
static String format(const char *const fmt, Args... args) {
Expand All @@ -1595,7 +1609,7 @@ class String final {
static void format(String &out, const char *fmt, T first, Args... rest) {
for (const char *c = fmt; *c != 0; c++) {
if (*c == '{' && *(c + 1) == 'h' && *(c + 2) == '}') {
if constexpr (std::is_arithmetic<T>::value || std::is_pointer<T>::value) {
if constexpr (std::is_integral_v<T> || std::is_pointer_v<T>) {
out += hex(first, HexFormat::LowercaseAndPrefixed);
format(out, c + 3, rest...);
return;
Expand All @@ -1604,7 +1618,7 @@ class String final {
abort();
}
} else if (*c == '{' && *(c + 1) == '}') {
if constexpr (std::is_pointer<T>::value && !std::is_same<const char *, T>::value && !std::is_same<char *, T>::value) {
if constexpr (std::is_pointer_v<T> && !std::is_same_v<const char *, T> && !std::is_same_v<char *, T>) {
fprintf(stderr, "String::format: T is a general pointer type but you didn't specify {h}\n");
abort();
} else {
Expand Down