terminal.hh File Reference

#include <limits>
#include <string>

Go to the source code of this file.

Enumerations
enum class	StandardOutputStream { Stdout = 1 , Stderr = 2 }

Functions
bool	nix::isOutputARealTerminal (StandardOutputStream fileno)
bool	nix::shouldANSI (StandardOutputStream fileno)
std::string	nix::filterANSIEscapes (std::string_view s, bool filterAll, unsigned int width, bool eatTabs)
void	nix::updateWindowSize ()
std::pair< unsigned short, unsigned short >	nix::getWindowSize ()

Function Documentation

filterANSIEscapes()

std::string nix::filterANSIEscapes	(	std::string_view	s,
		bool	filterAll = false,
		unsigned int	width = std::numeric_limits< unsigned int >::max(),
		bool	eatTabs = true )

Truncate a string to 'width' printable characters. If 'filterAll' is true, all ANSI escape sequences are filtered out. Otherwise, some escape sequences (such as colour setting) are copied but not included in the character count. Also, tabs are expanded to spaces.

getWindowSize()

std::pair< unsigned short, unsigned short > nix::getWindowSize

(

)

Returns

the number of rows and columns of the terminal.

The value is cached so this is quick. The cached result is computed by updateWindowSize().

isOutputARealTerminal()

bool nix::isOutputARealTerminal

(

StandardOutputStream

fileno

)

Determine whether the output is a real terminal (i.e. not dumb, not a pipe).

This is probably not what you want, you may want shouldANSI() or something more specific. Think about how the output should work with a pager or entirely non-interactive scripting use.

The user may be redirecting the Lix output to a pager, but have stderr connected to a terminal. Think about where you are outputting the text when deciding whether to use STDERR_FILENO or STDOUT_FILENO.

Parameters

fileno

file descriptor number to check if it is a tty

shouldANSI()

bool nix::shouldANSI

(

StandardOutputStream

fileno = StandardOutputStream::Stderr

)

Determine whether ANSI escape sequences are appropriate for the present output.

This follows the rules described on https://bixense.com/clicolors/ with CLICOLOR defaulted to enabled (and thus ignored).

That is to say, the following procedure is followed in order:

• NO_COLOR or NOCOLOR set -> always disable colour
• CLICOLOR_FORCE or FORCE_COLOR set -> enable colour
• The output is a tty; TERM != "dumb" -> enable colour
• Otherwise -> disable colour

Parameters

fileno

which file descriptor number to consider. Use the one you are outputting to

updateWindowSize()

void nix::updateWindowSize

(

)

Recalculate the window size, updating a global variable. Used in the SIGWINCH signal handler.