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Refactor ansi_color_escape to track size instead of using a null terminator #4511

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Merged
vitaut merged 1 commit into from
Aug 9, 2025
Merged

Refactor ansi_color_escape to track size instead of using a null terminator #4511

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33 changes: 15 additions & 18 deletions include/fmt/color.h
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Original file line number Diff line number Diff line change
Expand Up @@ -375,19 +375,17 @@ template <typename Char> struct ansi_color_escape {
// 10 more.
if (is_background) value += 10u;

size_t index = 0;
buffer[index++] = static_cast<Char>('\x1b');
buffer[index++] = static_cast<Char>('[');
buffer[size++] = static_cast<Char>('\x1b');
buffer[size++] = static_cast<Char>('[');

if (value >= 100u) {
buffer[index++] = static_cast<Char>('1');
buffer[size++] = static_cast<Char>('1');
value %= 100u;
}
buffer[index++] = static_cast<Char>('0' + value / 10u);
buffer[index++] = static_cast<Char>('0' + value % 10u);
buffer[size++] = static_cast<Char>('0' + value / 10u);
buffer[size++] = static_cast<Char>('0' + value % 10u);

buffer[index++] = static_cast<Char>('m');
buffer[index++] = static_cast<Char>('\0');
buffer[size++] = static_cast<Char>('m');
return;
}

Expand All @@ -398,7 +396,7 @@ template <typename Char> struct ansi_color_escape {
to_esc(color.r, buffer + 7, ';');
to_esc(color.g, buffer + 11, ';');
to_esc(color.b, buffer + 15, 'm');
buffer[19] = static_cast<Char>(0);
size = 19;
}
FMT_CONSTEXPR ansi_color_escape(emphasis em) noexcept {
uint8_t em_codes[num_emphases] = {};
Expand All @@ -411,26 +409,25 @@ template <typename Char> struct ansi_color_escape {
if (has_emphasis(em, emphasis::conceal)) em_codes[6] = 8;
if (has_emphasis(em, emphasis::strikethrough)) em_codes[7] = 9;

size_t index = 0;
for (size_t i = 0; i < num_emphases; ++i) {
if (!em_codes[i]) continue;
buffer[index++] = static_cast<Char>('\x1b');
buffer[index++] = static_cast<Char>('[');
buffer[index++] = static_cast<Char>('0' + em_codes[i]);
buffer[index++] = static_cast<Char>('m');
buffer[size++] = static_cast<Char>('\x1b');
buffer[size++] = static_cast<Char>('[');
buffer[size++] = static_cast<Char>('0' + em_codes[i]);
buffer[size++] = static_cast<Char>('m');
}
buffer[index++] = static_cast<Char>(0);
}
FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }

FMT_CONSTEXPR auto begin() const noexcept -> const Char* { return buffer; }
FMT_CONSTEXPR20 auto end() const noexcept -> const Char* {
return buffer + basic_string_view<Char>(buffer).size();
FMT_CONSTEXPR auto end() const noexcept -> const Char* {
return buffer + size;
}

private:
static constexpr size_t num_emphases = 8;
Char buffer[7u + 4u * num_emphases + 1u];
Char buffer[7u + 4u * num_emphases];
size_t size = 0;

static FMT_CONSTEXPR void to_esc(uint8_t c, Char* out,
char delimiter) noexcept {
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