colorchoice/
lib.rs

1//! Global override of color control
2
3#![cfg_attr(not(test), no_std)]
4#![cfg_attr(docsrs, feature(doc_auto_cfg))]
5#![warn(missing_docs)]
6#![warn(clippy::print_stderr)]
7#![warn(clippy::print_stdout)]
8
9use core::sync::atomic::{AtomicUsize, Ordering};
10
11/// Selection for overriding color output
12#[allow(clippy::exhaustive_enums)]
13#[derive(Copy, Clone, Debug, PartialEq, Eq)]
14pub enum ColorChoice {
15    /// Use colors if the output device appears to support them
16    Auto,
17    /// Like `Always`, except it never tries to use anything other than emitting ANSI
18    /// color codes.
19    AlwaysAnsi,
20    /// Try very hard to emit colors.
21    ///
22    /// This includes emitting ANSI colors on Windows if the console API is unavailable.
23    Always,
24    /// Never emit colors.
25    Never,
26}
27
28impl ColorChoice {
29    /// Get the current [`ColorChoice`] state
30    pub fn global() -> Self {
31        USER.get()
32    }
33
34    /// Override the detected [`ColorChoice`]
35    pub fn write_global(self) {
36        USER.set(self);
37    }
38}
39
40impl Default for ColorChoice {
41    fn default() -> Self {
42        Self::Auto
43    }
44}
45
46static USER: AtomicChoice = AtomicChoice::new();
47
48#[derive(Debug)]
49pub(crate) struct AtomicChoice(AtomicUsize);
50
51impl AtomicChoice {
52    pub(crate) const fn new() -> Self {
53        Self(AtomicUsize::new(Self::from_choice(ColorChoice::Auto)))
54    }
55
56    pub(crate) fn get(&self) -> ColorChoice {
57        let choice = self.0.load(Ordering::SeqCst);
58        Self::to_choice(choice).expect("Only `ColorChoice` values can be `set`")
59    }
60
61    pub(crate) fn set(&self, choice: ColorChoice) {
62        let choice = Self::from_choice(choice);
63        self.0.store(choice, Ordering::SeqCst);
64    }
65
66    const fn from_choice(choice: ColorChoice) -> usize {
67        match choice {
68            ColorChoice::Auto => 0,
69            ColorChoice::AlwaysAnsi => 1,
70            ColorChoice::Always => 2,
71            ColorChoice::Never => 3,
72        }
73    }
74
75    const fn to_choice(choice: usize) -> Option<ColorChoice> {
76        match choice {
77            0 => Some(ColorChoice::Auto),
78            1 => Some(ColorChoice::AlwaysAnsi),
79            2 => Some(ColorChoice::Always),
80            3 => Some(ColorChoice::Never),
81            _ => None,
82        }
83    }
84}
85
86impl Default for AtomicChoice {
87    fn default() -> Self {
88        Self::new()
89    }
90}
91
92#[cfg(test)]
93mod test {
94    use super::*;
95
96    #[test]
97    fn choice_serialization() {
98        let expected = vec![
99            ColorChoice::Auto,
100            ColorChoice::AlwaysAnsi,
101            ColorChoice::Always,
102            ColorChoice::Never,
103        ];
104        let values: Vec<_> = expected
105            .iter()
106            .cloned()
107            .map(AtomicChoice::from_choice)
108            .collect();
109        let actual: Vec<_> = values
110            .iter()
111            .cloned()
112            .filter_map(AtomicChoice::to_choice)
113            .collect();
114        assert_eq!(expected, actual);
115    }
116}
colorchoice/lib.rs

colorchoice/
lib.rs
