Jade Lovelace
292567e0b0
This will stop printing stuff to dumb terminals that they don't support. I've overall audited usage of isatty and replaced the ones with intent to mean "is a Real terminal" with checking for that. I've also caught a case of carelessly assuming "is a tty" means "should be colour" in nix-env. Change-Id: I6d83725d9a2d932ac94ff2294f92c0a1100d23c9
73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
#pragma once
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///@file
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#include <limits>
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#include <string>
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namespace nix {
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enum class StandardOutputStream {
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Stdout = 1,
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Stderr = 2,
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};
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/**
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* Determine whether the output is a real terminal (i.e. not dumb, not a pipe).
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*
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* This is probably not what you want, you may want shouldANSI() or something
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* more specific. Think about how the output should work with a pager or
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* entirely non-interactive scripting use.
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*
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* The user may be redirecting the Lix output to a pager, but have stderr
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* connected to a terminal. Think about where you are outputting the text when
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* deciding whether to use STDERR_FILENO or STDOUT_FILENO.
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*
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* \param fileno file descriptor number to check if it is a tty
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*/
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bool isOutputARealTerminal(StandardOutputStream fileno);
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/**
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* Determine whether ANSI escape sequences are appropriate for the
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* present output.
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*
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* This follows the rules described on https://bixense.com/clicolors/
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* with CLICOLOR defaulted to enabled (and thus ignored).
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*
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* That is to say, the following procedure is followed in order:
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* - NO_COLOR or NOCOLOR set -> always disable colour
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* - CLICOLOR_FORCE or FORCE_COLOR set -> enable colour
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* - The output is a tty; TERM != "dumb" -> enable colour
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* - Otherwise -> disable colour
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*
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* \param fileno which file descriptor number to consider. Use the one you are outputting to
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*/
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bool shouldANSI(StandardOutputStream fileno = StandardOutputStream::Stderr);
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/**
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* Truncate a string to 'width' printable characters. If 'filterAll'
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* is true, all ANSI escape sequences are filtered out. Otherwise,
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* some escape sequences (such as colour setting) are copied but not
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* included in the character count. Also, tabs are expanded to
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* spaces.
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*/
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std::string filterANSIEscapes(std::string_view s,
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bool filterAll = false,
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unsigned int width = std::numeric_limits<unsigned int>::max(),
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bool eatTabs = true);
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/**
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* Recalculate the window size, updating a global variable. Used in the
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* `SIGWINCH` signal handler.
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*/
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void updateWindowSize();
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/**
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* @return the number of rows and columns of the terminal.
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*
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* The value is cached so this is quick. The cached result is computed
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* by `updateWindowSize()`.
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*/
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std::pair<unsigned short, unsigned short> getWindowSize();
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}
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