c-shell 0.3.0

An interactive shell for C: type an expression, a statement or a function and see what your real compiler does with it
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//! Terminal styling, centralised so `--no-color` has one switch to flip.

use crate::i18n::Language;

pub struct Ui {
    pub color: bool,
    /// Whether stdout is an interactive terminal that can consume terminal
    /// control sequences. OSC 8 is ignored by terminals that do not implement
    /// hyperlinks, while the linked URL remains visible as ordinary text.
    pub hyperlinks: bool,
    pub language: Language,
}

/// Startup banner, slant style. Kept under 60 columns so it survives
/// narrow terminals without wrapping.
const BANNER: &str = r#"   ______          _____    __  __    ______    __     __
  / ____/         / ___/   / / / /   / ____/   / /    / /
 / /      _____   \__ \   / /_/ /   / __/     / /    / /
/ /___   /_____/ ___/ /  / __  /   / /___    / /___ / /___
\____/          /____/  /_/ /_/   /_____/   /_____//_____/
"#;

impl Ui {
    pub fn text(&self, key: &str) -> String {
        crate::i18n::text_for(self.language, key)
    }

    pub fn text_with(&self, key: &str, values: &[(&'static str, String)]) -> String {
        crate::i18n::text_with_for(self.language, key, values)
    }

    fn paint(&self, code: &str, s: &str) -> String {
        if self.color {
            format!("\x1b[{code}m{s}\x1b[0m")
        } else {
            s.to_string()
        }
    }

    /// The startup ASCII art, colored when the terminal is.
    pub fn banner(&self) -> String {
        self.paint("1;36", BANNER)
    }

    /// The plain `In [n]:` prompt label, without the trailing space or color;
    /// reedline draws it and supplies both. Single source of truth for the
    /// prompt text, shared with [`Ui::prompt_width`].
    pub fn prompt_label(n: usize) -> String {
        format!("In [{n}]:")
    }

    /// Printable width of the full prompt (`In [n]: `, label plus its trailing
    /// space) — the column where the user's code starts, and the width the
    /// continuation-line indicator is padded to.
    pub fn prompt_width(n: usize) -> usize {
        Self::prompt_label(n).len() + 1
    }

    pub fn out_label(&self, n: usize) -> String {
        self.paint("1;31", &format!("Out[{n}]: "))
    }

    /// Marker shown only when c-shell, rather than the C program, has to end
    /// a partial terminal line before printing diagnostics, a value or prompt.
    pub fn inserted_newline_marker(&self) -> String {
        self.dim("↵")
    }

    pub fn err(&self, s: &str) -> String {
        self.paint("31", s)
    }

    pub fn warn(&self, s: &str) -> String {
        self.paint("33", s)
    }

    pub fn dim(&self, s: &str) -> String {
        self.paint("2", s)
    }

    pub fn bold(&self, s: &str) -> String {
        self.paint("1", s)
    }

    /// Make a visible URL clickable in terminals that implement OSC 8.
    ///
    /// Keeping the URL itself as the label means transcripts and terminals
    /// without hyperlink support still expose a useful address.
    pub fn hyperlink(&self, url: &str) -> String {
        if self.hyperlinks {
            format!("\x1b]8;;{url}\x1b\\{url}\x1b]8;;\x1b\\")
        } else {
            url.to_string()
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::i18n::Language;

    use super::Ui;

    #[test]
    fn hyperlinks_keep_the_url_visible_in_both_rendering_modes() {
        let url = "https://en.cppreference.com/c/header/stdio";
        let plain = Ui {
            color: false,
            hyperlinks: false,
            language: Language::English,
        };
        assert_eq!(plain.hyperlink(url), url);

        let interactive = Ui {
            color: false,
            hyperlinks: true,
            language: Language::English,
        };
        assert_eq!(
            interactive.hyperlink(url),
            format!("\x1b]8;;{url}\x1b\\{url}\x1b]8;;\x1b\\")
        );
    }
}