Provide semantic highlighting for operators in declarations

Adopts swiftlang/swift#60210

Resolves #595
rdar://97961816

Author: ahoppen

Sources/SourceKitD/sourcekitd_uids.swift

@@ -285,6 +285,7 @@ public struct sourcekitd_values {
   public let syntaxtype_doccomment: sourcekitd_uid_t
   public let syntaxtype_doccomment_field: sourcekitd_uid_t
   public let syntaxtype_keyword: sourcekitd_uid_t
+  public let syntaxtype_operator: sourcekitd_uid_t
   public let syntaxtype_number: sourcekitd_uid_t
   public let syntaxtype_string: sourcekitd_uid_t
   public let syntaxtype_string_interpolation_anchor: sourcekitd_uid_t
@@ -388,6 +389,7 @@ public struct sourcekitd_values {
     syntaxtype_doccomment = api.uid_get_from_cstr("source.lang.swift.syntaxtype.doccomment")!
     syntaxtype_doccomment_field = api.uid_get_from_cstr("source.lang.swift.syntaxtype.doccomment.field")!
     syntaxtype_keyword = api.uid_get_from_cstr("source.lang.swift.syntaxtype.keyword")!
+    syntaxtype_operator = api.uid_get_from_cstr("source.lang.swift.syntaxtype.operator")!
     syntaxtype_number = api.uid_get_from_cstr("source.lang.swift.syntaxtype.number")!
     syntaxtype_string = api.uid_get_from_cstr("source.lang.swift.syntaxtype.string")!
     syntaxtype_string_interpolation_anchor = api.uid_get_from_cstr("source.lang.swift.syntaxtype.string_interpolation_anchor")!

Sources/SourceKitLSP/Swift/SyntaxHighlightingTokenParser.swift

@@ -127,6 +127,8 @@ struct SyntaxHighlightingTokenParser {
          values.ref_function_destructor,
          values.ref_function_subscript:
       return (.method, [])
+    case values.syntaxtype_operator:
+      return (.operator, [])
     case values.decl_function_operator_prefix,
          values.decl_function_operator_postfix,
          values.decl_function_operator_infix:

Tests/SourceKitLSPTests/SemanticTokensTests.swift

@@ -348,6 +348,7 @@ final class SemanticTokensTests: XCTestCase {
       Token(line: 3, utf16index: 0, length: 3, kind: .keyword),
       Token(line: 3, utf16index: 4, length: 1, kind: .identifier),
       Token(line: 3, utf16index: 8, length: 1, kind: .variable),
+      Token(line: 3, utf16index: 10, length: 1, kind: .operator),
       Token(line: 3, utf16index: 12, length: 1, kind: .variable),
       // func a() {}
       Token(line: 5, utf16index: 0, length: 4, kind: .keyword),
@@ -488,6 +489,20 @@ final class SemanticTokensTests: XCTestCase {
     ])
   }
 
+
+  func testOperatorDeclaration() {
+    let text = """
+    infix operator ?= :ComparisonPrecedence
+    """
+    let tokens = openAndPerformSemanticTokensRequest(text: text)
+    XCTAssertEqual(tokens, [
+      Token(line: 0, utf16index: 0, length: 5, kind: .modifier),
+      Token(line: 0, utf16index: 6, length: 8, kind: .keyword),
+      Token(line: 0, utf16index: 15, length: 2, kind: .operator),
+      Token(line: 0, utf16index: 19, length: 20, kind: .identifier),
+    ])
+  }
+
   func testEmptyEdit() {
     let text = """
     let x: String = "test"