Surprisingly, every escape sequence can also be used as an argument

delimiter for an outer escape sequence, in which case the delimiting
escape sequence retains its syntax but usually ignores its argument
and loses its inherent effect.  Add rudimentary support for this
syntax quirk in order to improve parsing compatibility with groff.

1 files changed, 52 insertions, 0 deletions

diff --git a/regress/char/N/delim.out_ascii b/regress/char/N/delim.out_ascii
new file mode 100644
index 00000000..4e7cb1c2
--- /dev/null
+++ b/regress/char/N/delim.out_ascii
@@ -0,0 +1,52 @@
+N-DELIM(1)                  General Commands Manual                 N-DELIM(1)
+
+NNAAMMEE
+     NN--ddeelliimm - argument delimiters for the N escape sequence
+
+DDEESSCCRRIIPPTTIIOONN
+     unsupported \!: *u
+     unsupported \r: 42u
+     ignored \%: *u
+     ignored \&: *u
+     ignored \): *u
+     ignored \,: 42u
+     ignored \/: *u
+     ignored \^: 42u
+     ignored \a: 42u
+     ignored \d: 42u
+     ignored \t: 42u
+     ignored \u: 42u
+     ignored \{: *u
+     ignored \|: 42u
+     ignored \}: *u
+     useless \.: 42.u
+     invalid \G: *u
+     special \ : 42 u
+     special \': *u
+     special \-: *u
+     special \0: 42 u
+     special \:: *u
+     special \_: *u
+     special \`: *u
+     special \e: *u
+     special \~: 42 u
+     break \p: *u
+     nospace \c: *u
+     string expansion: *u
+     register expansion: 3u
+     ignored \O: 42u
+     ignored \Y: 42u
+     ignored \k: *u
+     special character: *u
+     ignored \D: 42u
+     ignored \L: 42u
+     ignored \X: 42u
+     ignored \Z: 42u
+     ignored \b: 42u
+     ignored \v: 42u
+     ignored \x: 42u
+     horizontal motion: 42   u
+     horizontal line: 42__u
+     overstrike: 42cdu
+
+OpenBSD                          June 8, 2022                          OpenBSD