lumis-core 2.4.0

//! Highlight event types for the rendering pipeline.
//!
//! These events represent the output of syntax highlighting (from tree-sitter or any other source)
//! in a format that is independent of tree-sitter's C FFI types. Formatters in lumis-core consume
//! these events to produce HTML, terminal output, etc.

/// A single step in rendering a syntax-highlighted document.
///
/// This enum mirrors tree-sitter's `HighlightEvent` but uses plain Rust types,
/// making it usable without any tree-sitter dependency.
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum HighlightEvent {
    /// A highlight scope begins.
    ///
    /// `scope_index` is an index into the `HIGHLIGHT_NAMES` array.
    /// `language` is the language name this highlight belongs to (e.g., "rust", "markdown").
    Start {
        scope_index: usize,
        language: String,
    },
    /// A range of the source text that should be included in the output.
    ///
    /// `start` and `end` are byte offsets into the source string.
    Source { start: usize, end: usize },
    /// A highlight scope ends.
    End,
}

impl HighlightEvent {
    /// The scope name a `Start` opens, e.g. `keyword.function`.
    ///
    /// JavaScript's `HighlightEvent` carries the name directly; Rust carries an
    /// index into [`HIGHLIGHT_NAMES`](crate::highlights::HIGHLIGHT_NAMES)
    /// because resolving it per event costs more than the formatters need. This
    /// resolves it, so a custom formatter reads the same value in both.
    ///
    /// Returns `None` for `Source` and `End`, and for a `scope_index` outside
    /// `HIGHLIGHT_NAMES` — an event built by hand rather than by highlighting.
    pub fn scope(&self) -> Option<&'static str> {
        match self {
            Self::Start { scope_index, .. } => crate::highlights::HIGHLIGHT_NAMES
                .get(*scope_index)
                .copied(),
            Self::Source { .. } | Self::End => None,
        }
    }

    /// The language a `Start` belongs to, e.g. `rust`.
    ///
    /// Returns `None` for `Source` and `End`.
    pub fn language(&self) -> Option<&str> {
        match self {
            Self::Start { language, .. } => Some(language),
            Self::Source { .. } | Self::End => None,
        }
    }
}