Swift: Clearer, possibly more efficient implementation.

Author: geoffw0

swift/ql/lib/codeql/swift/security/SensitiveExprs.qll

@@ -155,14 +155,21 @@ class SensitiveExpr extends Expr {
   predicate isProbablySafe() { label.toLowerCase().regexpMatch(regexpProbablySafe()) }
 }
 
+/**
+ * A function that is likely used to encrypt or hash data.
+ */
+private class EncryptionFunction extends AbstractFunctionDecl {
+  EncryptionFunction() { this.getName().regexpMatch(".*(crypt|hash|encode|protect).*") }
+}
+
 /**
  * An expression that may be protected with encryption, for example an
  * argument to a function called "encrypt".
  */
 class EncryptedExpr extends Expr {
   EncryptedExpr() {
     exists(CallExpr call |
-      call.getStaticTarget().getName().regexpMatch(".*(crypt|hash|encode|protect).*") and
+      call.getStaticTarget() instanceof EncryptionFunction and
       call.getAnArgument().getExpr() = this
     )
   }