Hello again,
on a second thought, I see my yesterday ideas can be improved. That's why
I answer to my own mail, sorry.
1) I wrote:
> ... s/x\{23\}/yes/ ... is not portable
Does anyone know whether I was true or not? The autoconf manual doesn't
mention this problem, and \{23\} is required by POSIX for BRE's.
2) ad
> AC_SUBST(ac_delim) can cause an endless loop
My proposal indeed fixed this, yet I think a safety belt cannot hurt.
We could change the simple infinite loop to something like:
ac_iter=""
ac_delim='%!_!#_ '
while :; do
...
test `grep -c "$ac_delim"'$' ` = 74 && break
ac_iter=x$ac_iter
if test $ac_iter = xxxxxxxx; then
AC_MSG_ERROR([Eight was not enough???])
fi
ac_delim="$ac_delim$ac_delim !_$ac_delim"
done
3) ad: the implementation of non-recursive substitution:
All the hacks with |#@!@#| are too complicated and not general enough.
There is a better solution.
Let's choose yet another escape character, say '?'. And let's define:
?q -- for a literal '?'
?a -- for @
Then the resulting sed fragments, as executed by config.status, should
look like this:
/@[a-zA-Z_][a-zA-Z_0-9]*@/!b
s/?/?q/g
s,@bindir@,/usr/local/bin,g
...
s/?a/@/g
s/?q/?/g
Which means that you have to compute _AC_SED_SUBS_LIMIT as
_AC_SED_CMD_LIMIT - 4 - 4*_AC_SED_SUBS
and that if the variables are listed as
_AC_Var!$_AC_Var$ac_delim
then the postprocessing sed script would look like this:
sed ':s
/'"$ac_delim"'$/b ok
N
b s
:ok
s/?/?q/g
s/@/?a/g
s/[\\&,]/\\&/g
s/\n/\\&/g
s/^/s,@/
s/!/@,/
s/'"$ac_delim"'$/,g/'
4) When reading parts of your patch, I cannot understand why it is
necessary to use diversions.
I'd suggest this:
- write the file substitutions sed fragments
- if the last one has space for at least five commands, leave it open
- open a file for var substs, unless we have the open file from
the previous step
- write the preamble:
/@[a-zA-Z_][a-zA-Z_0-9]*@/!b
s/?/?q/g
...
- start a loop which processes the subst variables
I find this approach quite straightforward, and I don't see any need
for diversions.
I think it might be easier to count `sed commands' instead of
`substitutions' in this case. Each file subst would increment it by 4,
while, variable subst would still increment it by 1.
5) I've noticed a typo: there is "frament" twice.
Have a nice day,
Stepan Kasal
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