Hi Dan,
nice piece of work, thank you.
On Mon, Feb 07, 2005 at 03:55:49PM -0500, Dan Manthey wrote:
> > 3) ad: the implementation of non-recursive substitution:
> >
> > All the hacks with |[EMAIL PROTECTED]@#| are too complicated and not
> > general enough.
> > There is a better solution.
> >
> I agree that your solution works and makes non-recursion invisible
> to the user, but I think it's actually benefitial to have the wacky string
> that gets deleted (for instance, to disabiguate [EMAIL PROTECTED]@bar@' by
> [EMAIL PROTECTED]@|#_!!_#|bar@'), so I have not taken your suggestion here.
You are right, this is a good solution.
> I just surround all `@'s with the deleted string, and also put it at the
> beginning of each output value.
I think adding the string _after_ each `@' would be enough; IOW I propose
to change
s/@/|#_!!_#|@|#_!!_#|/g
to
s/@/@|#_!!_#|/g
To prove formally that it is correct, we have to prove that each [EMAIL
PROTECTED]@'
which appears in any stage, was already in the original input.
Proof: Let's have an occurence of [EMAIL PROTECTED]@'. If its left `@' wasn't
in the
original input, then it has to be followed by |#_!!_#|, so it's not [EMAIL
PROTECTED]',
contradiction. So the left `@' had to be inthe original line.
If some characters of this occurence [EMAIL PROTECTED]@' were inserted by a
previous
substitution, then there would have to be the |#_!!_#| from the beginning
of the substituted value.
Thus the whole [EMAIL PROTECTED]@' had to be in the original line, q.e.d.
> Note that I changed the deleted string to
> be a palendrome, since that allows it to be inserted at its own center.
What? IIRC, the previous suggestion was |#_!_#|, which is also a
palendrome. No big deal, of course.
One more comment:
I notice that your patch contains
m4_define([_AC_SED_CMDS],m4_defn([_AC_SED_CMDS])[| sed 's/|#_!!_#|//g' ])
As I have admitted before, I don't (yet) fully understand your patch,
but this seems a bit suspicious to me. Does this mean that you use one
more `sed' call in the pipe to remove these tokens?
It's clear that you cannot put s/|#_!!_#|//g at the end of each fragment,
But I think you can put it as the very last command of the last fragment.
Oh yes, you have to change the last fragment to:
/@[a-zA-Z_][a-zA-Z_0-9]*@/!b end
...
:end
s/|#_!!_#|//g
but I think it's worth it. (Perhaps it would help to put the label `:end'
at the end of each fragment, so that the first command of each fragment
will be the same. You can decrease the number of commands for each segment
by 2 (the label plus possibly s/|#_!!_#|//g). All this is still better
than having one more process in the pipe.
Will you find time to implement these improvements?
> My thanks go to Stepan for all the help he's given with this.
I'm glad to generate hints. But I have stated several times that I cannot
keep pace with you and I actually don't understand your code. ;-)
Thank you for this, Dan. It's really inspiring work!
Have a nice day,
Stepan
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