Define a scala.scm of highlighting queries

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 Difftastic no longer shows "1/1" when a file only has a single hunk.
 
+Improved Scala syntax highlighting.
+
 ## 0.24 (release 26th March 2022)
 
 ### Diffing

sample_files/compare.expected

@@ -86,7 +86,7 @@ sample_files/ruby_before.rb sample_files/ruby_after.rb
 4a9847a91e32ec6afdc2f0b01e28d2d6  -
 
 sample_files/scala_before.scala sample_files/scala_after.scala
-738f973ea0c3468e1db277116cf12516  -
+0a7e7cf903bf816deda37f9a6871c94d  -
 
 sample_files/simple_before.js sample_files/simple_after.js
 e4df6957f8e1d5f58cf9a72d18ee1193  -

src/tree_sitter_parser.rs

@@ -434,7 +434,11 @@ pub fn from_language(language: guess::Language) -> TreeSitterConfig {
                 language,
                 atom_nodes: (vec!["string", "template_string"]).into_iter().collect(),
                 delimiter_tokens: (vec![("{", "}"), ("(", ")"), ("[", "]")]),
-                highlight_query: ts::Query::new(language, "").unwrap(),
+                highlight_query: ts::Query::new(
+                    language,
+                    include_str!("../vendor/highlights/scala.scm"),
+                )
+                .unwrap(),
             }
         }
         TypeScript => {

vendor/highlights/scala.scm

@@ -0,0 +1,77 @@
+;; TODO: upstream this.
+
+;; Largely based on java.scm.
+
+; Annotations
+
+"@" @operator
+
+; Types
+
+(class_definition
+  name: (identifier) @type)
+(trait_definition
+  name: (identifier) @type)
+(object_definition
+  name: (identifier) @type)
+
+(type_identifier) @type
+
+;; Variables
+
+((identifier) @constant
+ (#match? @constant "^_*[A-Z][A-Z\\d_]+$"))
+
+(identifier) @variable
+
+; Literals
+
+[
+  (integer_literal)
+  (floating_point_literal)
+] @number
+
+[
+  (character_literal)
+  (string)
+] @string
+
+[
+  (boolean_literal)
+  (null_literal)
+] @constant.builtin
+
+(comment) @comment
+
+; Keywords
+
+[
+  "abstract"
+  "case"
+  "catch"
+  "class"
+  "def"
+  "do"
+  "else"
+  "extends"
+  "final"
+  "finally"
+  "for"
+  "if"
+  "implicit"
+  "import"
+  "lazy"
+  "new"
+  "object"
+  "override"
+  "package"
+  "private"
+  "protected"
+  "return"
+  "sealed"
+  "throw"
+  "trait"
+  "try"
+  "while"
+  "with"
+] @keyword