Swift: Add a couple of standard Comment subclasses.

Author: MathiasVP

swift/ql/lib/codeql/swift/elements/Comment.qll

@@ -4,3 +4,32 @@ class Comment extends CommentBase {
   /** toString */
   override string toString() { result = getText() }
 }
+
+class SingleLineComment extends Comment {
+  SingleLineComment() {
+    this.getText().matches("//%") and
+    not this instanceof SingleLineDocComment
+  }
+}
+
+class MultiLineComment extends Comment {
+  MultiLineComment() {
+    this.getText().matches("/*%") and
+    not this instanceof MultiLineDocComment
+  }
+}
+
+class DocComment extends Comment {
+  DocComment() {
+    this instanceof SingleLineDocComment or
+    this instanceof MultiLineDocComment
+  }
+}
+
+class SingleLineDocComment extends Comment {
+  SingleLineDocComment() { this.getText().matches("///%") }
+}
+
+class MultiLineDocComment extends Comment {
+  MultiLineDocComment() { this.getText().matches("/**%") }
+}