From 93643d1741bd3eec1835d415318a87c7f2121162 Mon Sep 17 00:00:00 2001
From: Tim Culverhouse <tim@timculverhouse.com>
Date: Fri, 27 Sep 2024 22:22:22 -0500
Subject: [PATCH] sgr: add support for legacy double underline

SGR 21 is defined to be a double underline. This behavior is common
among many terminals, notably xterm.

References: https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-Functions-using-CSI-_-ordered-by-the-final-character_s_
---
 src/terminal/sgr.zig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/terminal/sgr.zig b/src/terminal/sgr.zig
index b23bd1514..67a4c05ea 100644
--- a/src/terminal/sgr.zig
+++ b/src/terminal/sgr.zig
@@ -165,6 +165,8 @@ pub const Parser = struct {
 
             9 => return Attribute{ .strikethrough = {} },
 
+            21 => return Attribute{ .underline = .double },
+
             22 => return Attribute{ .reset_bold = {} },
 
             23 => return Attribute{ .reset_italic = {} },