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, 95 insertions, 3 deletions

diff --git a/regress/roff/esc/B.in b/regress/roff/esc/B.in
index 40cd2ecb..aab552b5 100644
--- a/regress/roff/esc/B.in
+++ b/regress/roff/esc/B.in
@@ -1,5 +1,5 @@
-.\" $OpenBSD: B.in,v 1.3 2017/07/04 14:53:27 schwarze Exp $
-.Dd $Mdocdate: July 4 2017 $
+.\" $OpenBSD: B.in,v 1.4 2022/06/08 13:08:00 schwarze Exp $
+.Dd $Mdocdate: June 8 2022 $
 .Dt ESC-B 1
 .Os
 .Sh NAME
@@ -33,5 +33,97 @@ parentheses containing number: \B'(42)'
 complex expression: \B'3+(3*(5==5*2)*4)+(3*5)/2'
 .br
 other delimiter: \Bx1+1x
+.Ss Argument delimiters
+unsupported \e!: \B\!42\!u
 .br
-no closing delimiter: \B'1+1
+unsupported \er: \B\r42u
+.br
+ignored \e%: \B\%42\%u
+.br
+ignored \e&: \B\&42\&u
+.br
+ignored \e): \B\)42\)u
+.br
+ignored \e,: \B\,42\,u
+.br
+ignored \e/: \B\/42\/u
+.br
+ignored \e^: \B\^42\^u
+.br
+ignored \ea: \B\a42\au
+.br
+ignored \ed: \B\d42\du
+.br
+ignored \et: \B\t42\tu
+.br
+ignored \eu: \B\u42\uu
+.br
+ignored \e{: \B\{42\{u
+.br
+ignored \e|: \B\|42\|u
+.br
+ignored \e}: \B\}42\}u
+.br
+useless \e.: \B\.42.u
+.\".br
+.\"XXX useless \e\e: \B\\42\\u
+.br
+invalid \eG: \B\G42Gu
+.br
+special \e\ : \B\ 42\ u
+.br
+special \e\(aq: \B\'42\'u
+.br
+special \e-: \B\-42\-u
+.br
+special \e0: \B\042\0u
+.br
+special \e:: \B\:42\:u
+.br
+special \e_: \B\_42\_u
+.br
+special \e\(ga: \B\`42\`u
+.br
+special \ee: \B\e42\eu
+.br
+special \e~: \B\~42\~u
+.br
+break \ep: \B\p42\pu
+.br
+nospace \ec: \B\c42\cu
+.\".br
+.\"XXX skipchar \ec: \B\z42\zu
+.br
+.ds mystr x42xu
+string expansion: \B\*[mystr]
+.br
+.nr myreg 23
+register expansion: \B\n[myreg]u
+.br
+ignored \eO: \B\O142\O2u
+.br
+ignored \eY: \B\Y[mystr]42\Y[mystr]u
+.br
+ignored \ek: \B\k[myreg]42\k[myreg]u
+.br
+special character: \B\(hy42\(hyu
+.br
+ignored \eD: \B\D't 1'42\D't 2'u
+.br
+ignored \eL: \B\L'2'42u
+.br
+ignored \eX: \B\X'foo'42\X'bar'u
+.br
+ignored \eZ: \B\Z'foo'42\Z''u
+.br
+ignored \eb: \B\b'2'42\b''u
+.br
+ignored \ev: \B\v'2'42\v'0'u
+.br
+ignored \ex: \B\x'2'42\v'0'u
+.br
+horizontal motion: \B\h'1'42\h'3'u
+.br
+horizontal line: \B\l'4'42\l'2'u
+.br
+overstrike: \B\o'ab'42\o'cd'u