terminal.h

#ifndef SOURCEMETA_CORE_TERMINAL_H_
#define SOURCEMETA_CORE_TERMINAL_H_
 
#ifndef SOURCEMETA_CORE_TERMINAL_EXPORT
#include <sourcemeta/core/terminal_export.h>
#endif
 
#include <array>       // std::array
#include <cstdint>     // std::uint8_t
#include <iosfwd>      // std::ostream
#include <string>      // std::string
#include <string_view> // std::string_view
#include <type_traits> // std::underlying_type_t

 
namespace sourcemeta::core {

enum class TerminalStream : std::uint8_t {
  Stdin = 0,
  Stdout = 1,
  Stderr = 2
};

enum class TerminalColorPolicy : std::uint8_t {
  WhenInteractive,
  Disabled,
  Always
};

enum class TerminalStyle : std::uint8_t {
  None = 0,
  Bold = 1 << 0,
  Red = 1 << 1,
  Green = 1 << 2,
  Yellow = 1 << 3,
  Blue = 1 << 4,
  Cyan = 1 << 5
};

[[nodiscard]] constexpr auto operator|(TerminalStyle left,
                                       TerminalStyle right) noexcept
    -> TerminalStyle {
  using Underlying = std::underlying_type_t<TerminalStyle>;
  return static_cast<TerminalStyle>(static_cast<Underlying>(left) |
                                    static_cast<Underlying>(right));
}

[[nodiscard]] constexpr auto operator&(TerminalStyle left,
                                       TerminalStyle right) noexcept
    -> TerminalStyle {
  using Underlying = std::underlying_type_t<TerminalStyle>;
  return static_cast<TerminalStyle>(static_cast<Underlying>(left) &
                                    static_cast<Underlying>(right));
}

[[nodiscard]] constexpr auto operator~(TerminalStyle value) noexcept
    -> TerminalStyle {
  using Underlying = std::underlying_type_t<TerminalStyle>;
  return static_cast<TerminalStyle>(~static_cast<Underlying>(value));
}

[[nodiscard]] constexpr auto operator^(TerminalStyle left,
                                       TerminalStyle right) noexcept
    -> TerminalStyle {
  using Underlying = std::underlying_type_t<TerminalStyle>;
  return static_cast<TerminalStyle>(static_cast<Underlying>(left) ^
                                    static_cast<Underlying>(right));
}

[[nodiscard]] constexpr auto
terminal_style_is_valid(TerminalStyle style) noexcept -> bool {
  using Underlying = std::underlying_type_t<TerminalStyle>;
  constexpr Underlying DEFINED_MASK{
      static_cast<Underlying>(TerminalStyle::Bold) |
      static_cast<Underlying>(TerminalStyle::Red) |
      static_cast<Underlying>(TerminalStyle::Green) |
      static_cast<Underlying>(TerminalStyle::Yellow) |
      static_cast<Underlying>(TerminalStyle::Blue) |
      static_cast<Underlying>(TerminalStyle::Cyan)};
 
  const auto raw{static_cast<Underlying>(style)};
  if ((raw & ~DEFINED_MASK) != 0) {
    return false;
  }
 
  constexpr std::array<TerminalStyle, 5> COLORS{
      {TerminalStyle::Red, TerminalStyle::Green, TerminalStyle::Yellow,
       TerminalStyle::Blue, TerminalStyle::Cyan}};
 
  int color_count{0};
  for (const auto color : COLORS) {
    if ((style & color) != TerminalStyle::None) {
      ++color_count;
      if (color_count > 1) {
        return false;
      }
    }
  }
 
  return true;
}

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_is_interactive(TerminalStream stream) noexcept -> bool;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_is_interactive(int file_descriptor) noexcept -> bool;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_set_color_policy(TerminalColorPolicy policy) noexcept -> void;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_set_color_policy(TerminalStream stream,
                               TerminalColorPolicy policy) noexcept -> void;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_reset_color_policy() noexcept -> void;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_reset_color_policy(TerminalStream stream) noexcept -> void;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_color_policy(
    TerminalStream stream = TerminalStream::Stdout) noexcept
    -> TerminalColorPolicy;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_color_enabled(TerminalStream stream) noexcept -> bool;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_sgr_sequence(TerminalStyle style) noexcept -> std::string_view;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_sgr_reset() noexcept -> std::string_view;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_paint(std::string_view text, TerminalStyle style,
                    bool enabled = true) -> std::string;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_paint(TerminalStream stream, std::string_view text,
                    TerminalStyle style) -> std::string;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_paint(std::ostream &output, std::string_view text,
                    TerminalStyle style, bool enabled = true) -> std::ostream &;

SOURCEMETA_CORE_TERMINAL_EXPORT
auto terminal_paint(std::ostream &output, TerminalStream stream,
                    std::string_view text, TerminalStyle style)
    -> std::ostream &;
 
} // namespace sourcemeta::core
 
#endif