[latex3-commits] [git/LaTeX3-latex3-latex3] main: Better way to handle \exp_not:n in \text_expand:n (fixes #875) (9bc2aae8d)
Joseph Wright
joseph.wright at morningstar2.co.uk
Mon Apr 26 11:57:50 CEST 2021
Repository : https://github.com/latex3/latex3
On branch : main
Link : https://github.com/latex3/latex3/commit/9bc2aae8d936eff5818c0a45fd348347aaedaa2d
>---------------------------------------------------------------
commit 9bc2aae8d936eff5818c0a45fd348347aaedaa2d
Author: Bruno Le Floch <blflatex at gmail.com>
Date: Mon Apr 26 11:37:06 2021 +0200
Better way to handle \exp_not:n in \text_expand:n (fixes #875)
>---------------------------------------------------------------
9bc2aae8d936eff5818c0a45fd348347aaedaa2d
l3kernel/l3text.dtx | 61 +++++++++++++++++++++++++++++++---------
l3kernel/testfiles/m3text001.lvt | 1 +
l3kernel/testfiles/m3text001.tlg | 3 ++
3 files changed, 51 insertions(+), 14 deletions(-)
diff --git a/l3kernel/l3text.dtx b/l3kernel/l3text.dtx
index b5133dacb..dd8c1a4a8 100644
--- a/l3kernel/l3text.dtx
+++ b/l3kernel/l3text.dtx
@@ -637,8 +637,10 @@
% \begin{macro}[EXP]{\@@_expand_replace:N}
% \begin{macro}[EXP]{\@@_expand_replace:n}
% \begin{macro}[EXP]{\@@_expand_cs_expand:N}
-% \begin{macro}[EXP]{\@@_expand_noexpand:w}
-% \begin{macro}[EXP]{\@@_expand_noexpand:nn}
+% \begin{macro}[EXP]{\@@_expand_unexpanded:w}
+% \begin{macro}[EXP]{\@@_expand_unexpanded_test:w}
+% \begin{macro}[EXP]{\@@_expand_unexpanded:N}
+% \begin{macro}[EXP]{\@@_expand_unexpanded:n}
% After precautions against |&| tokens, start a simple loop: that of
% course means that \enquote{text} cannot contain the two recursion
% quarks. The loop here must be \texttt{f}-type expandable; we have
@@ -997,19 +999,13 @@
% Finally, expand any macros which can be: this then loops back around to
% deal with what they produce. The only issue is if the token is
% \cs{exp_not:n}, as that must apply to the following balanced text.
-% Expand everything that follows such an \cs{exp_not:n} (in principle
-% we should actually expand tokens and discard any spaces or \cs{scan_stop:},
-% but this is messy to ensure safely).
% \begin{macrocode}
\cs_new:Npn \@@_expand_cs_expand:N #1
{
\@@_if_expandable:NTF #1
{
\token_if_eq_meaning:NNTF #1 \exp_not:n
- {
- \exp_after:wN \@@_expand_noexpand:w
- \exp:w \exp_end_continue_f:w
- }
+ { \@@_expand_unexpanded:w }
{ \exp_after:wN \@@_expand_loop:w #1 }
}
{
@@ -1017,12 +1013,47 @@
\@@_expand_loop:w
}
}
-\cs_new:Npn \@@_expand_noexpand:w #1#
- { \@@_expand_noexpand:nn {#1} }
-\cs_new:Npn \@@_expand_noexpand:nn #1#2
+% \end{macrocode}
+% Since \cs{exp_not:n} is actually a primitive, it allows a strange syntax
+% and it particular the primitive expands what follows and discards spaces
+% and \cs{scan_stop:} until finding a braced argument (the opening brace
+% can be implicit but we will not support this here). Here, we repeatedly
+% |f|-expand after such an \cs{exp_not:n}, and test what follows. If
+% it is a brace group, then we found the intended argument of
+% \cs{exp_not:n}. If it is a space, then the next |f|-expansion will
+% eliminate it. If it is an |N|-type token then
+% \cs{@@_expand_unexpanded:N} leaves the token to be expanded if it is
+% expandable, and otherwise removes it, assuming that it is
+% \cs{scan_stop:}. This silently hides errors when \cs{exp_not:n} is
+% incorrectly followed by some non-expandable token other than
+% \cs{scan_stop:}, but this should be pretty rare, and there is no good
+% error recovery anyways.
+% \begin{macrocode}
+\cs_new:Npn \@@_expand_unexpanded:w
+ {
+ \exp_after:wN \@@_expand_unexpanded_test:w
+ \exp:w \exp_end_continue_f:w
+ }
+\cs_new:Npn \@@_expand_unexpanded_test:w #1 \q_@@_recursion_stop
{
- \exp_after:wN \@@_expand_store:n \exp_after:wN
- { \__kernel_exp_not:w #1 {#2} }
+ \tl_if_head_is_group:nTF {#1}
+ { \@@_expand_unexpanded:n }
+ {
+ \@@_expand_unexpanded:w
+ \tl_if_head_is_N_type:nT {#1} { \@@_expand_unexpanded:N }
+ }
+ #1 \q_@@_recursion_stop
+ }
+\cs_new:Npn \@@_expand_unexpanded:N #1
+ {
+ \exp_after:wN \if_meaning:w \exp_not:N #1 #1
+ \else:
+ \exp_after:wN #1
+ \fi:
+ }
+\cs_new:Npn \@@_expand_unexpanded:n #1
+ {
+ \@@_expand_store:n {#1}
\@@_expand_loop:w
}
% \end{macrocode}
@@ -1058,6 +1089,8 @@
% \end{macro}
% \end{macro}
% \end{macro}
+% \end{macro}
+% \end{macro}
%
% \begin{macro}
% {
diff --git a/l3kernel/testfiles/m3text001.lvt b/l3kernel/testfiles/m3text001.lvt
index 1b328c16c..cdd66f177 100644
--- a/l3kernel/testfiles/m3text001.lvt
+++ b/l3kernel/testfiles/m3text001.lvt
@@ -87,6 +87,7 @@
{
\tl_show:x { \text_expand:n { \exp_not:n { ~ \abc \foo } } }
\tl_show:x { \text_expand:n { \tl_tail:n { ~ \abc \foo } } }
+ \tl_show:x { \text_expand:n { \exp_not:n \scan_stop: \use:n { ~ \use_none:n } { X } { \foo } } }
}
\END
diff --git a/l3kernel/testfiles/m3text001.tlg b/l3kernel/testfiles/m3text001.tlg
index b6a56f57d..e7b0a95bf 100644
--- a/l3kernel/testfiles/m3text001.tlg
+++ b/l3kernel/testfiles/m3text001.tlg
@@ -60,4 +60,7 @@ l. ... }
> \foo .
<recently read> }
l. ... }
+> \foo .
+<recently read> }
+l. ... }
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