Move highlighting into new IDE module

1 files changed, 308 insertions, 0 deletions

diff --git a/src/ide/highlight.rs b/src/ide/highlight.rs
new file mode 100644
index 00000000..75539a3b
--- /dev/null
+++ b/src/ide/highlight.rs
@@ -0,0 +1,308 @@
+//! Syntax highlighting for Typst source code.
+
+use crate::syntax::{LinkedNode, SyntaxKind};
+
+/// Syntax highlighting categories.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Category {
+    /// A line or block comment.
+    Comment,
+    /// Punctuation in code.
+    Punctuation,
+    /// An escape sequence, shorthand or symbol notation.
+    Escape,
+    /// Strong markup.
+    Strong,
+    /// Emphasized markup.
+    Emph,
+    /// A hyperlink.
+    Link,
+    /// Raw text.
+    Raw,
+    /// A label.
+    Label,
+    /// A reference to a label.
+    Ref,
+    /// A section heading.
+    Heading,
+    /// A marker of a list, enumeration, or description list.
+    ListMarker,
+    /// A term in a description list.
+    ListTerm,
+    /// The delimiters of a math formula.
+    MathDelimiter,
+    /// An operator with special meaning in a math formula.
+    MathOperator,
+    /// A keyword.
+    Keyword,
+    /// An operator in code.
+    Operator,
+    /// A numeric literal.
+    Number,
+    /// A string literal.
+    String,
+    /// A function or method name.
+    Function,
+    /// An interpolated variable in markup or math.
+    Interpolated,
+    /// A syntax error.
+    Error,
+}
+
+impl Category {
+    /// Return the recommended TextMate grammar scope for the given highlighting
+    /// category.
+    pub fn tm_scope(&self) -> &'static str {
+        match self {
+            Self::Comment => "comment.typst",
+            Self::Punctuation => "punctuation.typst",
+            Self::Escape => "constant.character.escape.typst",
+            Self::Strong => "markup.bold.typst",
+            Self::Emph => "markup.italic.typst",
+            Self::Link => "markup.underline.link.typst",
+            Self::Raw => "markup.raw.typst",
+            Self::MathDelimiter => "punctuation.definition.math.typst",
+            Self::MathOperator => "keyword.operator.math.typst",
+            Self::Heading => "markup.heading.typst",
+            Self::ListMarker => "punctuation.definition.list.typst",
+            Self::ListTerm => "markup.list.term.typst",
+            Self::Label => "entity.name.label.typst",
+            Self::Ref => "markup.other.reference.typst",
+            Self::Keyword => "keyword.typst",
+            Self::Operator => "keyword.operator.typst",
+            Self::Number => "constant.numeric.typst",
+            Self::String => "string.quoted.double.typst",
+            Self::Function => "entity.name.function.typst",
+            Self::Interpolated => "meta.interpolation.typst",
+            Self::Error => "invalid.typst",
+        }
+    }
+}
+
+/// Highlight a linked syntax node.
+///
+/// Produces a highlighting category or `None` if the node should not be
+/// highlighted.
+pub fn highlight(node: &LinkedNode) -> Option<Category> {
+    match node.kind() {
+        SyntaxKind::LineComment => Some(Category::Comment),
+        SyntaxKind::BlockComment => Some(Category::Comment),
+        SyntaxKind::Space { .. } => None,
+
+        SyntaxKind::LeftBrace => Some(Category::Punctuation),
+        SyntaxKind::RightBrace => Some(Category::Punctuation),
+        SyntaxKind::LeftBracket => Some(Category::Punctuation),
+        SyntaxKind::RightBracket => Some(Category::Punctuation),
+        SyntaxKind::LeftParen => Some(Category::Punctuation),
+        SyntaxKind::RightParen => Some(Category::Punctuation),
+        SyntaxKind::Comma => Some(Category::Punctuation),
+        SyntaxKind::Semicolon => Some(Category::Punctuation),
+        SyntaxKind::Colon => Some(Category::Punctuation),
+        SyntaxKind::Star => match node.parent_kind() {
+            Some(SyntaxKind::Strong) => None,
+            _ => Some(Category::Operator),
+        },
+        SyntaxKind::Underscore => match node.parent_kind() {
+            Some(SyntaxKind::Script) => Some(Category::MathOperator),
+            _ => None,
+        },
+        SyntaxKind::Dollar => Some(Category::MathDelimiter),
+        SyntaxKind::Plus => Some(match node.parent_kind() {
+            Some(SyntaxKind::EnumItem) => Category::ListMarker,
+            _ => Category::Operator,
+        }),
+        SyntaxKind::Minus => Some(match node.parent_kind() {
+            Some(SyntaxKind::ListItem) => Category::ListMarker,
+            _ => Category::Operator,
+        }),
+        SyntaxKind::Slash => Some(match node.parent_kind() {
+            Some(SyntaxKind::DescItem) => Category::ListMarker,
+            Some(SyntaxKind::Frac) => Category::MathOperator,
+            _ => Category::Operator,
+        }),
+        SyntaxKind::Hat => Some(Category::MathOperator),
+        SyntaxKind::Amp => Some(Category::MathOperator),
+        SyntaxKind::Dot => Some(Category::Punctuation),
+        SyntaxKind::Eq => match node.parent_kind() {
+            Some(SyntaxKind::Heading) => None,
+            _ => Some(Category::Operator),
+        },
+        SyntaxKind::EqEq => Some(Category::Operator),
+        SyntaxKind::ExclEq => Some(Category::Operator),
+        SyntaxKind::Lt => Some(Category::Operator),
+        SyntaxKind::LtEq => Some(Category::Operator),
+        SyntaxKind::Gt => Some(Category::Operator),
+        SyntaxKind::GtEq => Some(Category::Operator),
+        SyntaxKind::PlusEq => Some(Category::Operator),
+        SyntaxKind::HyphEq => Some(Category::Operator),
+        SyntaxKind::StarEq => Some(Category::Operator),
+        SyntaxKind::SlashEq => Some(Category::Operator),
+        SyntaxKind::Dots => Some(Category::Operator),
+        SyntaxKind::Arrow => Some(Category::Operator),
+
+        SyntaxKind::Not => Some(Category::Keyword),
+        SyntaxKind::And => Some(Category::Keyword),
+        SyntaxKind::Or => Some(Category::Keyword),
+        SyntaxKind::None => Some(Category::Keyword),
+        SyntaxKind::Auto => Some(Category::Keyword),
+        SyntaxKind::Let => Some(Category::Keyword),
+        SyntaxKind::Set => Some(Category::Keyword),
+        SyntaxKind::Show => Some(Category::Keyword),
+        SyntaxKind::If => Some(Category::Keyword),
+        SyntaxKind::Else => Some(Category::Keyword),
+        SyntaxKind::For => Some(Category::Keyword),
+        SyntaxKind::In => Some(Category::Keyword),
+        SyntaxKind::While => Some(Category::Keyword),
+        SyntaxKind::Break => Some(Category::Keyword),
+        SyntaxKind::Continue => Some(Category::Keyword),
+        SyntaxKind::Return => Some(Category::Keyword),
+        SyntaxKind::Import => Some(Category::Keyword),
+        SyntaxKind::Include => Some(Category::Keyword),
+        SyntaxKind::From => Some(Category::Keyword),
+
+        SyntaxKind::Markup { .. }
+            if node.parent_kind() == Some(&SyntaxKind::DescItem)
+                && node.next_sibling_kind() == Some(&SyntaxKind::Colon) =>
+        {
+            Some(Category::ListTerm)
+        }
+        SyntaxKind::Markup { .. } => None,
+
+        SyntaxKind::Text(_) => None,
+        SyntaxKind::Linebreak => Some(Category::Escape),
+        SyntaxKind::Escape(_) => Some(Category::Escape),
+        SyntaxKind::Shorthand(_) => Some(Category::Escape),
+        SyntaxKind::Symbol(_) => Some(Category::Escape),
+        SyntaxKind::SmartQuote { .. } => None,
+        SyntaxKind::Strong => Some(Category::Strong),
+        SyntaxKind::Emph => Some(Category::Emph),
+        SyntaxKind::Raw(_) => Some(Category::Raw),
+        SyntaxKind::Link(_) => Some(Category::Link),
+        SyntaxKind::Label(_) => Some(Category::Label),
+        SyntaxKind::Ref(_) => Some(Category::Ref),
+        SyntaxKind::Heading => Some(Category::Heading),
+        SyntaxKind::ListItem => None,
+        SyntaxKind::EnumItem => None,
+        SyntaxKind::EnumNumbering(_) => Some(Category::ListMarker),
+        SyntaxKind::DescItem => None,
+        SyntaxKind::Math => None,
+        SyntaxKind::Atom(_) => None,
+        SyntaxKind::Script => None,
+        SyntaxKind::Frac => None,
+        SyntaxKind::AlignPoint => None,
+
+        SyntaxKind::Ident(_) => match node.parent_kind() {
+            Some(
+                SyntaxKind::Markup { .. }
+                | SyntaxKind::Math
+                | SyntaxKind::Script
+                | SyntaxKind::Frac,
+            ) => Some(Category::Interpolated),
+            Some(SyntaxKind::FuncCall) => Some(Category::Function),
+            Some(SyntaxKind::MethodCall) if node.prev_sibling().is_some() => {
+                Some(Category::Function)
+            }
+            Some(SyntaxKind::Closure) if node.prev_sibling().is_none() => {
+                Some(Category::Function)
+            }
+            Some(SyntaxKind::SetRule) => Some(Category::Function),
+            Some(SyntaxKind::ShowRule)
+                if node.prev_sibling_kind() == Some(&SyntaxKind::Show) =>
+            {
+                Some(Category::Function)
+            }
+            _ => None,
+        },
+        SyntaxKind::Bool(_) => Some(Category::Keyword),
+        SyntaxKind::Int(_) => Some(Category::Number),
+        SyntaxKind::Float(_) => Some(Category::Number),
+        SyntaxKind::Numeric(_, _) => Some(Category::Number),
+        SyntaxKind::Str(_) => Some(Category::String),
+        SyntaxKind::CodeBlock => None,
+        SyntaxKind::ContentBlock => None,
+        SyntaxKind::Parenthesized => None,
+        SyntaxKind::Array => None,
+        SyntaxKind::Dict => None,
+        SyntaxKind::Named => None,
+        SyntaxKind::Keyed => None,
+        SyntaxKind::Unary => None,
+        SyntaxKind::Binary => None,
+        SyntaxKind::FieldAccess => None,
+        SyntaxKind::FuncCall => None,
+        SyntaxKind::MethodCall => None,
+        SyntaxKind::Args => None,
+        SyntaxKind::Spread => None,
+        SyntaxKind::Closure => None,
+        SyntaxKind::Params => None,
+        SyntaxKind::LetBinding => None,
+        SyntaxKind::SetRule => None,
+        SyntaxKind::ShowRule => None,
+        SyntaxKind::Conditional => None,
+        SyntaxKind::WhileLoop => None,
+        SyntaxKind::ForLoop => None,
+        SyntaxKind::ForPattern => None,
+        SyntaxKind::ModuleImport => None,
+        SyntaxKind::ImportItems => None,
+        SyntaxKind::ModuleInclude => None,
+        SyntaxKind::LoopBreak => None,
+        SyntaxKind::LoopContinue => None,
+        SyntaxKind::FuncReturn => None,
+
+        SyntaxKind::Error(_, _) => Some(Category::Error),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::ops::Range;
+
+    use super::*;
+    use crate::syntax::Source;
+
+    #[test]
+    fn test_highlighting() {
+        use Category::*;
+
+        #[track_caller]
+        fn test(text: &str, goal: &[(Range<usize>, Category)]) {
+            let mut vec = vec![];
+            let source = Source::detached(text);
+            highlight_tree(&mut vec, &LinkedNode::new(source.root()));
+            assert_eq!(vec, goal);
+        }
+
+        fn highlight_tree(tags: &mut Vec<(Range<usize>, Category)>, node: &LinkedNode) {
+            if let Some(tag) = highlight(node) {
+                tags.push((node.range(), tag));
+            }
+
+            for child in node.children() {
+                highlight_tree(tags, &child);
+            }
+        }
+
+        test("= *AB*", &[(0..6, Heading), (2..6, Strong)]);
+
+        test(
+            "#f(x + 1)",
+            &[
+                (0..2, Function),
+                (2..3, Punctuation),
+                (5..6, Operator),
+                (7..8, Number),
+                (8..9, Punctuation),
+            ],
+        );
+
+        test(
+            "#let f(x) = x",
+            &[
+                (0..4, Keyword),
+                (5..6, Function),
+                (6..7, Punctuation),
+                (8..9, Punctuation),
+                (10..11, Operator),
+            ],
+        );
+    }
+}