Draft `Highlighter` API

2 files changed, 65 insertions, 0 deletions

diff --git a/core/src/text/editor.rs b/core/src/text/editor.rs
index 003557c1..0f439c8d 100644
--- a/core/src/text/editor.rs
+++ b/core/src/text/editor.rs
@@ -1,3 +1,4 @@
+use crate::text::highlighter::{self, Highlighter};
 use crate::text::LineHeight;
 use crate::{Pixels, Point, Rectangle, Size};
 
@@ -29,6 +30,14 @@ pub trait Editor: Sized + Default {
         new_font: Self::Font,
         new_size: Pixels,
         new_line_height: LineHeight,
+        new_highlighter: &mut impl Highlighter,
+    );
+
+    fn highlight<H: Highlighter>(
+        &mut self,
+        font: Self::Font,
+        highlighter: &mut H,
+        format_highlight: impl Fn(&H::Highlight) -> highlighter::Format<Self::Font>,
     );
 }
 
diff --git a/core/src/text/highlighter.rs b/core/src/text/highlighter.rs
new file mode 100644
index 00000000..1f9ac840
--- /dev/null
+++ b/core/src/text/highlighter.rs
@@ -0,0 +1,56 @@
+use crate::Color;
+
+use std::hash::Hash;
+use std::ops::Range;
+
+pub trait Highlighter: Clone + 'static {
+    type Settings: Hash;
+    type Highlight;
+
+    type Iterator<'a>: Iterator<Item = (Range<usize>, Self::Highlight)>
+    where
+        Self: 'a;
+
+    fn new(settings: &Self::Settings) -> Self;
+
+    fn change_line(&mut self, line: usize);
+
+    fn highlight_line(&mut self, line: &str) -> Self::Iterator<'_>;
+
+    fn current_line(&self) -> usize;
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Style {
+    pub color: Color,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct PlainText;
+
+impl Highlighter for PlainText {
+    type Settings = ();
+    type Highlight = ();
+
+    type Iterator<'a> = std::iter::Empty<(Range<usize>, Self::Highlight)>;
+
+    fn new(_settings: &Self::Settings) -> Self {
+        Self
+    }
+
+    fn change_line(&mut self, _line: usize) {}
+
+    fn highlight_line(&mut self, _line: &str) -> Self::Iterator<'_> {
+        std::iter::empty()
+    }
+
+    fn current_line(&self) -> usize {
+        usize::MAX
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Format<Font> {
+    pub color: Option<Color>,
+    pub font: Option<Font>,
+}