rs-rich 0.0.8

//! Emoji shortcode replacement.
//!
//! Port of upstream `rich/_emoji_replace.py` + the full `rich/_emoji_codes.py`
//! table (see `emoji_codes.rs`). [`replace`] turns `:name:` shortcodes into
//! emoji, with optional `:name-emoji:` / `:name-text:` variant selectors.
//! Unknown codes are left untouched (matching upstream).

const VARIANT_EMOJI: &str = "\u{fe0f}";
const VARIANT_TEXT: &str = "\u{fe0e}";

/// An emoji presentation variant. Mirrors `rich.emoji.EmojiVariant`
/// (`"emoji"` or `"text"`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum EmojiVariant {
    /// Emoji presentation: appends U+FE0F.
    Emoji,
    /// Text presentation: appends U+FE0E.
    Text,
}

impl EmojiVariant {
    /// Parse upstream's variant name (`"emoji"` or `"text"`).
    pub fn parse(name: &str) -> Option<EmojiVariant> {
        match name {
            "emoji" => Some(EmojiVariant::Emoji),
            "text" => Some(EmojiVariant::Text),
            _ => None,
        }
    }

    /// The variant's name, as upstream spells it.
    pub fn name(self) -> &'static str {
        match self {
            EmojiVariant::Emoji => "emoji",
            EmojiVariant::Text => "text",
        }
    }

    /// The variation selector this variant appends.
    fn selector(self) -> &'static str {
        match self {
            EmojiVariant::Emoji => VARIANT_EMOJI,
            EmojiVariant::Text => VARIANT_TEXT,
        }
    }
}

/// Replace `:name:` emoji shortcodes in `text`. Port of `_emoji_replace`.
///
/// Mirrors one `re.sub` over `(:(\S*?)(?:(?:\-)(emoji|text))?:)`: every match,
/// including an unknown code or an empty `::`, is consumed, and scanning
/// resumes after its closing colon.
pub fn replace(text: &str) -> String {
    replace_with_variant(text, None)
}

/// [`replace`] with upstream's `default_variant`: the selector appended to a
/// code that names no variant of its own. Port of
/// `_emoji_replace(text, default_variant=…)`.
pub fn replace_with_variant(text: &str, default_variant: Option<EmojiVariant>) -> String {
    let chars: Vec<char> = text.chars().collect();
    let len = chars.len();
    let mut out = String::with_capacity(text.len());
    let mut index = 0;

    while index < len {
        if chars[index] == ':' {
            // The lazy `\S*?` stops at the first ':' that follows only
            // non-whitespace characters.
            let mut end = index + 1;
            while end < len && !is_python_space(chars[end]) && chars[end] != ':' {
                end += 1;
            }
            if end < len && chars[end] == ':' {
                let body: String = chars[index + 1..end].iter().collect();
                match lookup(&body, default_variant) {
                    Some(replacement) => out.push_str(&replacement),
                    None => out.extend(&chars[index..=end]),
                }
                index = end + 1;
                continue;
            }
        }
        out.push(chars[index]);
        index += 1;
    }
    out
}

/// Python's `str.isspace()`, which `\s` follows for `str` patterns. Unlike
/// `char::is_whitespace` it includes the separators U+001C..=U+001F.
fn is_python_space(c: char) -> bool {
    c.is_whitespace() || ('\u{1c}'..='\u{1f}').contains(&c)
}

/// Resolve a shortcode body (with optional variant suffix) to its replacement.
///
/// The suffix is matched case-sensitively, as upstream's `(emoji|text)` group
/// is; only the name is lowercased (`get_emoji(emoji_name.lower())`).
fn lookup(body: &str, default_variant: Option<EmojiVariant>) -> Option<String> {
    let default = default_variant.map_or("", EmojiVariant::selector);
    let (name, variant) = if let Some(name) = body.strip_suffix("-emoji") {
        (name, VARIANT_EMOJI)
    } else if let Some(name) = body.strip_suffix("-text") {
        (name, VARIANT_TEXT)
    } else {
        (body, default)
    };
    emoji_code(&name.to_lowercase()).map(|code| format!("{code}{variant}"))
}

/// Resolve an emoji name to its glyph(s) from the full vendored table.
fn emoji_code(name: &str) -> Option<&'static str> {
    crate::emoji_codes::emoji_code(name)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn replaces_known_codes() {
        // Captured from real rich 15.0.0 `_emoji_replace`.
        assert_eq!(replace(":rocket:"), "\u{1f680}");
        assert_eq!(replace("hello :thumbs_up: world"), "hello \u{1f44d} world");
        assert_eq!(replace(":rocket: to :moon:"), "\u{1f680} to \u{1f314}");
    }

    #[test]
    fn leaves_unknown_and_bare_colons() {
        assert_eq!(replace(":not_a_real_emoji:"), ":not_a_real_emoji:");
        assert_eq!(replace("no emoji"), "no emoji");
        assert_eq!(replace("ratio 3:4 done"), "ratio 3:4 done");
    }

    #[test]
    fn variant_selectors() {
        assert_eq!(replace(":rocket-emoji:"), "\u{1f680}\u{fe0f}");
        assert_eq!(replace(":rocket-text:"), "\u{1f680}\u{fe0e}");
    }

    #[test]
    fn default_variant_and_case_sensitive_suffix() {
        // Captured from real rich 15.0.0 `_emoji_replace`.
        assert_eq!(replace(":rocket-EMOJI:"), ":rocket-EMOJI:");
        assert_eq!(replace(":ROCKET-text:"), "\u{1f680}\u{fe0e}");
        assert_eq!(
            replace_with_variant(":rocket: :rocket-text:", Some(EmojiVariant::Emoji)),
            "\u{1f680}\u{fe0f} \u{1f680}\u{fe0e}"
        );
        assert_eq!(
            replace_with_variant(":rocket:", Some(EmojiVariant::Text)),
            "\u{1f680}\u{fe0e}"
        );
    }

    #[test]
    fn scanning_resumes_after_every_match() {
        // Captured from real rich 15.0.0 `_emoji_replace` (#448).
        assert_eq!(replace(" -:界[ba:b: x"), " -:界[ba:b: x");
        assert_eq!(replace("::rocket:"), "::rocket:");
        assert_eq!(replace(":x:rocket:"), "\u{274c}rocket:");
        assert_eq!(replace(":rocket:rocket:"), "\u{1f680}rocket:");
        assert_eq!(replace(":ROCKET:"), "\u{1f680}");
        assert_eq!(replace("a:\u{1c}rocket:"), "a:\u{1c}rocket:");
        assert_eq!(replace(":\u{212a}rocket:"), ":\u{212a}rocket:");
    }
}