From f0c1ebe85e66619bc0cd2e7dcd8d621ab8b0f30a Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Fri, 9 Jul 2021 12:24:51 +0200
Subject: [PATCH] Add isNil for Preserve

Not a ref type, but add `isNil` for checking if a Perserve is
zero-initialized.
---
 src/preserves.nim | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/preserves.nim b/src/preserves.nim
index 7e0fe09..a06f765 100644
--- a/src/preserves.nim
+++ b/src/preserves.nim
@@ -59,6 +59,10 @@ proc assertValid*(prs: Preserve) =
   else:
     discard
 
+proc isNil*(prs: Preserve): bool =
+  ## Check if ``prs`` is equivalent to the zero-initialized ``Preserve``.
+  prs.kind == pkBoolean and prs.bool == false
+
 proc `<`(x, y: string | seq[byte]): bool =
   for i in 0 .. min(x.high, y.high):
     if x[i] < y[i]: