From cef8dce18dc3fbc8577ccc038653a5f9118e5638 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Mon, 6 Sep 2021 10:26:21 +0200
Subject: [PATCH] enh(scala) add Scala 3 extension soft keyword

Based on https://github.com/scala/vscode-scala-syntax/blob/57e0829cd46980699570101a68c320a20330d36c/src/typescript/Scala.tmLanguage.ts#L1134.
Also see https://docs.scala-lang.org/scala3/reference/contextual/extension-methods.html#syntax.
---
 CHANGES.md                             |  1 +
 src/languages/scala.js                 | 12 ++++++++++++
 test/markup/scala/extension.expect.txt | 19 +++++++++++++++++++
 test/markup/scala/extension.txt        | 19 +++++++++++++++++++
 4 files changed, 51 insertions(+)
 create mode 100644 test/markup/scala/extension.expect.txt
 create mode 100644 test/markup/scala/extension.txt

diff --git a/CHANGES.md b/CHANGES.md
index 112ed8561b..09b2092c87 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -18,6 +18,7 @@ Grammars:
 - enh(scala) add missing `do` and `then` keyword (#3323) [Nicolas Stucki][]
 - enh(scala) add missing `enum`, `export` and `given` keywords (#3328) [Nicolas Stucki][]
 - enh(scala) remove symbol syntax and fix quoted code syntax (#3324) [Nicolas Stucki][]
+- enh(scala) add Scala 3 `extension` soft keyword (#3326) [Nicolas Stucki][]
 
 [Austin Schick]: https://github.com/austin-schick
 [Josh Goebel]: https://github.com/joshgoebel
diff --git a/src/languages/scala.js b/src/languages/scala.js
index ae84bff1f5..5671c6cb80 100644
--- a/src/languages/scala.js
+++ b/src/languages/scala.js
@@ -112,6 +112,17 @@ export default function(hljs) {
     contains: [ NAME ]
   };
 
+  const EXTENSION = {
+    begin: [
+      /^\s*/, // Is first token on the line
+      'extension',
+      /\s+(?=[\[\(])/, // followed by at least one space and `[` or `(`
+    ],
+    beginScope: {
+      2: "keyword",
+    }
+  };
+
   return {
     name: 'Scala',
     keywords: {
@@ -126,6 +137,7 @@ export default function(hljs) {
       METHOD,
       CLASS,
       hljs.C_NUMBER_MODE,
+      EXTENSION,
       ANNOTATION
     ]
   };
diff --git a/test/markup/scala/extension.expect.txt b/test/markup/scala/extension.expect.txt
new file mode 100644
index 0000000000..9daa346a91
--- /dev/null
+++ b/test/markup/scala/extension.expect.txt
@@ -0,0 +1,19 @@
+<span class="hljs-keyword">extension</span> (x: <span class="hljs-type">Int</span>) <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">plus</span></span>(y: <span class="hljs-type">Int</span>) = x + y
+
+<span class="hljs-keyword">extension</span> [<span class="hljs-type">T</span>](x: <span class="hljs-type">T</span>) <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">f</span> </span>= ()
+
+<span class="hljs-keyword">extension</span> (x: <span class="hljs-type">Int</span>)
+  <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">f</span> </span>= <span class="hljs-number">1</span>
+  <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">f</span> </span>= <span class="hljs-number">2</span>
+
+<span class="hljs-class"><span class="hljs-keyword">object</span> <span class="hljs-title">Foo</span> </span>{
+  <span class="hljs-keyword">extension</span> (x: <span class="hljs-type">Int</span>)
+    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">f</span> </span>= <span class="hljs-number">1</span>
+    <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">f</span> </span>= <span class="hljs-number">2</span>
+}
+
+<span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">extension</span></span>(file: <span class="hljs-type">File</span>) =
+  file.extension
+
+  file
+    .extension
diff --git a/test/markup/scala/extension.txt b/test/markup/scala/extension.txt
new file mode 100644
index 0000000000..75a6327980
--- /dev/null
+++ b/test/markup/scala/extension.txt
@@ -0,0 +1,19 @@
+extension (x: Int) def plus(y: Int) = x + y
+
+extension [T](x: T) def f = ()
+
+extension (x: Int)
+  def f = 1
+  def f = 2
+
+object Foo {
+  extension (x: Int)
+    def f = 1
+    def f = 2
+}
+
+def extension(file: File) =
+  file.extension
+
+  file
+    .extension