Add syntax highlighting for parameter labels

Author: ahoppen

Sources/SwiftIDEUtils/SyntaxClassification.swift

@@ -47,6 +47,8 @@ public enum SyntaxClassification {
   case stringLiteral
   /// An identifier referring to a type.
   case type
+  /// The label of a function parameter or a function call argument.
+  case parameterLabel
 }
 
 extension SyntaxClassification {
@@ -83,6 +85,10 @@ extension SyntaxClassification {
       return (.keyword, false)
     case \SimpleTypeIdentifierSyntax.name:
       return (.type, false)
+    case \FunctionParameterSyntax.firstName:
+      return (.parameterLabel, false)
+    case \LabeledExprSyntax.label:
+      return (.parameterLabel, false)
     default:
       return nil
     }

Tests/SwiftIDEUtilsTest/ClassificationTests.swift

@@ -577,4 +577,29 @@ public class ClassificationTests: XCTestCase {
       ]
     )
   }
+
+  public func testParameterLabel() {
+    assertClassification(
+      """
+      func foo(arg: Int) {}
+      """,
+      expected: [
+        ClassificationSpec(source: "func", kind: .keyword),
+        ClassificationSpec(source: "foo", kind: .identifier),
+        ClassificationSpec(source: "arg", kind: .parameterLabel),
+        ClassificationSpec(source: "Int", kind: .type),
+      ]
+    )
+
+    assertClassification(
+      """
+      foo(arg: 1)
+      """,
+      expected: [
+        ClassificationSpec(source: "foo", kind: .identifier),
+        ClassificationSpec(source: "arg", kind: .parameterLabel),
+        ClassificationSpec(source: "1", kind: .integerLiteral),
+      ]
+    )
+  }
 }