Only use bold for keywords in novel tokens

This makes added/removed regions slightly less prominent, but easier
to read. It also makes them more consistent with the styling on the
surrounding text.

CHANGELOG.md

@@ -6,6 +6,10 @@ Every hunk is now shown with the file name and a hunk number. This
 makes it easier to see which file you're looking at when there are
 many changes.
 
+Keywords in added/removed regions are now shown in bold, to give
+modified regions basic syntax highlighting. Previously, all
+added/removed regions were bold.
+
 ### Command Line Interface
 
 The difftastic binary is now named `difft`, to reduce typing during

src/lines.rs

@@ -171,7 +171,9 @@ impl LineGroup {
 
         let opposite_pos: Vec<SingleLineSpan> = match &mp.kind {
             MatchKind::Unchanged { opposite_pos, .. } => opposite_pos.1.clone(),
-            MatchKind::Novel { prev_opposite_pos } => prev_opposite_pos.clone(),
+            MatchKind::Novel {
+                prev_opposite_pos, ..
+            } => prev_opposite_pos.clone(),
             MatchKind::UnchangedCommentPart { opposite_pos } => opposite_pos.clone(),
             MatchKind::ChangedCommentPart { prev_opposite_pos } => prev_opposite_pos.clone(),
         };
@@ -225,7 +227,9 @@ impl LineGroup {
                 // here?
                 opposite_pos.1.clone()
             }
-            MatchKind::Novel { prev_opposite_pos } => prev_opposite_pos.clone(),
+            MatchKind::Novel {
+                prev_opposite_pos, ..
+            } => prev_opposite_pos.clone(),
             MatchKind::UnchangedCommentPart { opposite_pos } => opposite_pos.clone(),
             MatchKind::ChangedCommentPart { prev_opposite_pos } => prev_opposite_pos.clone(),
         };
@@ -242,7 +246,9 @@ impl LineGroup {
                 // here?
                 opposite_pos.1.clone()
             }
-            MatchKind::Novel { prev_opposite_pos } => prev_opposite_pos.clone(),
+            MatchKind::Novel {
+                prev_opposite_pos, ..
+            } => prev_opposite_pos.clone(),
             MatchKind::UnchangedCommentPart { opposite_pos } => opposite_pos.clone(),
             MatchKind::ChangedCommentPart { prev_opposite_pos } => prev_opposite_pos.clone(),
         };

src/style.rs

@@ -110,14 +110,24 @@ pub fn apply_colors(s: &str, is_lhs: bool, positions: &[MatchedPos]) -> String {
                 bold: highlight == TokenKind::Atom(AtomKind::Keyword),
                 dimmed: highlight == TokenKind::Atom(AtomKind::Comment),
             },
-            MatchKind::Novel { .. } | MatchKind::ChangedCommentPart { .. } => Style {
+            MatchKind::Novel { highlight, .. } => Style {
                 foreground: if is_lhs {
                     Color::BrightRed
                 } else {
                     Color::BrightGreen
                 },
                 background: None,
-                bold: true,
+                bold: highlight == TokenKind::Atom(AtomKind::Keyword),
+                dimmed: false,
+            },
+            MatchKind::ChangedCommentPart { .. } => Style {
+                foreground: if is_lhs {
+                    Color::BrightRed
+                } else {
+                    Color::BrightGreen
+                },
+                background: None,
+                bold: false,
                 dimmed: false,
             },
             MatchKind::UnchangedCommentPart { .. } => Style {

src/syntax.rs

@@ -499,6 +499,7 @@ pub enum MatchKind {
         opposite_pos: (Vec<SingleLineSpan>, Vec<SingleLineSpan>),
     },
     Novel {
+        highlight: TokenKind,
         prev_opposite_pos: Vec<SingleLineSpan>,
     },
     UnchangedCommentPart {
@@ -641,6 +642,7 @@ impl MatchedPos {
                 }
             }
             Novel => MatchKind::Novel {
+                highlight,
                 prev_opposite_pos: prev_opposite_pos.to_vec(),
             },
         };