Optimize text_style using bit packing
#4363
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@@ -205,121 +205,155 @@ struct rgb { | |
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| namespace detail { | ||
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| // a bit-packed variant of an RGB color, a terminal color, or unset color. | ||
| // see text_style for the bit-packing scheme. | ||
| struct color_type { | ||
| FMT_CONSTEXPR color_type() noexcept = default; | ||
| FMT_CONSTEXPR color_type(color rgb_color) noexcept | ||
| : value_(static_cast<uint32_t>(rgb_color) | (1 << 24)) {} | ||
| FMT_CONSTEXPR color_type(rgb rgb_color) noexcept | ||
| : color_type(static_cast<color>( | ||
| (static_cast<uint32_t>(rgb_color.r) << 16) | | ||
| (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b)) {} | ||
| FMT_CONSTEXPR color_type(terminal_color term_color) noexcept | ||
| : value_(static_cast<uint32_t>(term_color) | (3 << 24)) {} | ||
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| FMT_CONSTEXPR auto is_terminal_color() const noexcept -> bool { | ||
| return (value_ & (1 << 25)) != 0; | ||
| } | ||
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| FMT_CONSTEXPR auto value() const noexcept -> uint32_t { | ||
| return value_ & 0xFFFFFF; | ||
| } | ||
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| FMT_CONSTEXPR color_type(uint32_t value) noexcept : value_(value) {} | ||
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| uint32_t value_{}; | ||
| }; | ||
| } // namespace detail | ||
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| /// A text style consisting of foreground and background colors and emphasis. | ||
| class text_style { | ||
| // The information is packed as follows: | ||
| // ┌──┐ | ||
| // │ 0│─┐ | ||
| // │..│ ├── foreground color value | ||
| // │23│─┘ | ||
| // ├──┤ | ||
| // │24│─┬── discriminator for the above value. 00 if unset, 01 if it's | ||
| // │25│─┘ an RGB color, or 11 if it's a terminal color (10 is unused) | ||
| // ├──┤ | ||
| // │26│──── overflow bit, always zero (see below) | ||
| // ├──┤ | ||
| // │27│─┐ | ||
| // │..│ │ | ||
| // │50│ │ | ||
| // ├──┤ │ | ||
| // │51│ ├── background color (same format as the foreground color) | ||
| // │52│ │ | ||
| // ├──┤ │ | ||
| // │53│─┘ | ||
| // ├──┤ | ||
| // │54│─┐ | ||
| // │..│ ├── emphases | ||
| // │61│─┘ | ||
| // ├──┤ | ||
| // │62│─┬── unused | ||
| // │63│─┘ | ||
| // └──┘ | ||
| // The overflow bits are there to make operator|= efficient. | ||
| // When ORing, we must throw if, for either the foreground or background, | ||
| // one style specifies a terminal color and the other specifies any color | ||
| // (terminal or RGB); in other words, if one discriminator is 11 and the | ||
| // other is 11 or 01. | ||
| // | ||
| // We do that check by adding the styles. Consider what adding does to each | ||
| // possible pair of discriminators: | ||
| // 00 + 00 = 000 | ||
| // 01 + 00 = 001 | ||
| // 11 + 00 = 011 | ||
| // 01 + 01 = 010 | ||
| // 11 + 01 = 100 (!!) | ||
| // 11 + 11 = 110 (!!) | ||
| // In the last two cases, the ones we want to catch, the third bit——the | ||
| // overflow bit——is set. Bingo. | ||
| // | ||
| // We must take into account the possible carry bit from the bits | ||
| // before the discriminator. The only potentially problematic case is | ||
| // 11 + 00 = 011 (a carry bit would make it 100, not good!), but a carry | ||
| // bit is impossible in that case, because 00 (unset color) means the | ||
| // 24 bits that precede the discriminator are all zero. | ||
| // | ||
| // This test can be applied to both colors simultaneously. | ||
|
There was a problem hiding this comment. This is a very bit hacky algorithm; I hope the detailed explanation compensates for that. |
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| public: | ||
| FMT_CONSTEXPR text_style(emphasis em = emphasis()) noexcept | ||
| : style_(static_cast<uint64_t>(em) << 54) {} | ||
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| FMT_CONSTEXPR auto operator|=(text_style rhs) -> text_style& { | ||
| if (((style_ + rhs.style_) & ((1ULL << 26) | (1ULL << 53))) != 0) | ||
| report_error("can't OR a terminal color"); | ||
| style_ |= rhs.style_; | ||
| return *this; | ||
| } | ||
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| friend FMT_CONSTEXPR auto operator|(text_style lhs, text_style rhs) | ||
| -> text_style { | ||
| return lhs |= rhs; | ||
| } | ||
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| FMT_CONSTEXPR auto operator==(text_style rhs) const noexcept -> bool { | ||
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There was a problem hiding this comment.
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| return style_ == rhs.style_; | ||
| } | ||
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| FMT_CONSTEXPR auto operator!=(text_style rhs) const noexcept -> bool { | ||
| return !(*this == rhs); | ||
| } | ||
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| FMT_CONSTEXPR auto has_foreground() const noexcept -> bool { | ||
| return (style_ & (1 << 24)) != 0; | ||
| } | ||
| FMT_CONSTEXPR auto has_background() const noexcept -> bool { | ||
| return (style_ & (1ULL << 51)) != 0; | ||
| } | ||
| FMT_CONSTEXPR auto has_emphasis() const noexcept -> bool { | ||
| return (style_ >> 54) != 0; | ||
| } | ||
| FMT_CONSTEXPR auto get_foreground() const noexcept -> detail::color_type { | ||
| FMT_ASSERT(has_foreground(), "no foreground specified for this style"); | ||
| return style_ & 0x3FFFFFF; | ||
| } | ||
| FMT_CONSTEXPR auto get_background() const noexcept -> detail::color_type { | ||
| FMT_ASSERT(has_background(), "no background specified for this style"); | ||
| return (style_ >> 27) & 0x3FFFFFF; | ||
| } | ||
| FMT_CONSTEXPR auto get_emphasis() const noexcept -> emphasis { | ||
| FMT_ASSERT(has_emphasis(), "no emphasis specified for this style"); | ||
| return static_cast<emphasis>(style_ >> 54); | ||
| } | ||
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| private: | ||
| FMT_CONSTEXPR text_style(uint64_t style) noexcept : style_(style) {} | ||
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| friend FMT_CONSTEXPR auto fg(detail::color_type foreground) noexcept | ||
| -> text_style; | ||
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| friend FMT_CONSTEXPR auto bg(detail::color_type background) noexcept | ||
| -> text_style; | ||
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| uint64_t style_{}; | ||
| }; | ||
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| /// Creates a text style from the foreground (text) color. | ||
| FMT_CONSTEXPR inline auto fg(detail::color_type foreground) noexcept | ||
| -> text_style { | ||
| return foreground.value_; | ||
| } | ||
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| /// Creates a text style from the background color. | ||
| FMT_CONSTEXPR inline auto bg(detail::color_type background) noexcept | ||
| -> text_style { | ||
| return static_cast<uint64_t>(background.value_) << 27; | ||
| } | ||
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| FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept | ||
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@@ -334,9 +368,9 @@ template <typename Char> struct ansi_color_escape { | |
| const char* esc) noexcept { | ||
| // If we have a terminal color, we need to output another escape code | ||
| // sequence. | ||
| if (text_color.is_terminal_color()) { | ||
| bool is_background = esc == string_view("\x1b[48;2;"); | ||
| uint32_t value = text_color.value(); | ||
| // Background ASCII codes are the same as the foreground ones but with | ||
| // 10 more. | ||
| if (is_background) value += 10u; | ||
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@@ -360,7 +394,7 @@ template <typename Char> struct ansi_color_escape { | |
| for (int i = 0; i < 7; i++) { | ||
| buffer[i] = static_cast<Char>(esc[i]); | ||
| } | ||
| rgb color(text_color.value()); | ||
| to_esc(color.r, buffer + 7, ';'); | ||
| to_esc(color.g, buffer + 11, ';'); | ||
| to_esc(color.b, buffer + 15, 'm'); | ||
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@@ -441,32 +475,26 @@ template <typename T> struct styled_arg : view { | |
| }; | ||
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| template <typename Char> | ||
| void vformat_to(buffer<Char>& buf, text_style ts, basic_string_view<Char> fmt, | ||
| basic_format_args<buffered_context<Char>> args) { | ||
| if (ts.has_emphasis()) { | ||
| auto emphasis = make_emphasis<Char>(ts.get_emphasis()); | ||
| buf.append(emphasis.begin(), emphasis.end()); | ||
| } | ||
| if (ts.has_foreground()) { | ||
| auto foreground = make_foreground_color<Char>(ts.get_foreground()); | ||
| buf.append(foreground.begin(), foreground.end()); | ||
| } | ||
| if (ts.has_background()) { | ||
| auto background = make_background_color<Char>(ts.get_background()); | ||
| buf.append(background.begin(), background.end()); | ||
| } | ||
| vformat_to(buf, fmt, args); | ||
| if (ts != text_style{}) reset_color<Char>(buf); | ||
| } | ||
| } // namespace detail | ||
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| inline void vprint(FILE* f, text_style ts, string_view fmt, format_args args) { | ||
| auto buf = memory_buffer(); | ||
| detail::vformat_to(buf, ts, fmt, args); | ||
| print(f, FMT_STRING("{}"), string_view(buf.begin(), buf.size())); | ||
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@@ -482,8 +510,7 @@ inline void vprint(FILE* f, const text_style& ts, string_view fmt, | |
| * "Elapsed time: {0:.2f} seconds", 1.23); | ||
| */ | ||
| template <typename... T> | ||
| void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) { | ||
| vprint(f, ts, fmt.str, vargs<T...>{{args...}}); | ||
| } | ||
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@@ -497,11 +524,11 @@ void print(FILE* f, const text_style& ts, format_string<T...> fmt, | |
| * "Elapsed time: {0:.2f} seconds", 1.23); | ||
| */ | ||
| template <typename... T> | ||
| void print(text_style ts, format_string<T...> fmt, T&&... args) { | ||
| return print(stdout, ts, fmt, std::forward<T>(args)...); | ||
| } | ||
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| inline auto vformat(text_style ts, string_view fmt, format_args args) | ||
| -> std::string { | ||
| auto buf = memory_buffer(); | ||
| detail::vformat_to(buf, ts, fmt, args); | ||
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@@ -521,16 +548,16 @@ inline auto vformat(const text_style& ts, string_view fmt, format_args args) | |
| * ``` | ||
| */ | ||
| template <typename... T> | ||
| inline auto format(text_style ts, format_string<T...> fmt, T&&... args) | ||
| -> std::string { | ||
| return fmt::vformat(ts, fmt.str, vargs<T...>{{args...}}); | ||
| } | ||
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| /// Formats a string with the given text_style and writes the output to `out`. | ||
| template <typename OutputIt, | ||
| FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)> | ||
| auto vformat_to(OutputIt out, text_style ts, string_view fmt, format_args args) | ||
| -> OutputIt { | ||
| auto&& buf = detail::get_buffer<char>(out); | ||
| detail::vformat_to(buf, ts, fmt, args); | ||
| return detail::get_iterator(buf, out); | ||
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@@ -548,8 +575,8 @@ auto vformat_to(OutputIt out, const text_style& ts, string_view fmt, | |
| */ | ||
| template <typename OutputIt, typename... T, | ||
| FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)> | ||
| inline auto format_to(OutputIt out, text_style ts, format_string<T...> fmt, | ||
| T&&... args) -> OutputIt { | ||
| return vformat_to(out, ts, fmt.str, vargs<T...>{{args...}}); | ||
| } | ||
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Clever =)