regexp to match formatted time string?

regexp to match formatted time string?

[Drew Adams]

Anyone have a function that takes, as its argument, a string that is
acceptable as input to `format-time-string' (i.e. a value like
`display-time-format'), and returns a regexp that will match all such
formatted times, that is, whatever `format-time-string' would return for the
same input, for any time?

IOW, (foo ARG UNIVERSAL) would return a regexp that matches
(format-time-string ARG TIME UNIVERSAL), for all values of TIME.

I searched the source code a bit, but didn't find anything. Seems like this
would be useful. For instance, I would use it in some font-locking code, to
match a time/date field, based on the user's preferred time format.

Re: regexp to match formatted time string?

[Miles Bader]

"Drew Adams" <drew.adams@oracle.com> writes:
> Anyone have a function that takes, as its argument, a string that is
> acceptable as input to `format-time-string' (i.e. a value like
> `display-time-format'), and returns a regexp that will match all such
> formatted times, that is, whatever `format-time-string' would return for the
> same input, for any time?

It does sound kind of useful, but wouldn't it be rather hard for some of
the formats format-time-string supports -- e.g., %c, %a, or %b?

Maybe that doesn't matter for the typical uses of such a function...
(formats embedded in a file being font-locked would tend to be more
portable ones, perhaps)

-Miles

-- 
Carefully crafted initial estimates reward you not only with
reduced computational effort, but also with understanding and
increased self-esteem.         -- Numerical methods in C,
  Chapter 9. "Root Finding and Nonlinear Sets of Equations"

RE: regexp to match formatted time string?

[Drew Adams]

> > Anyone have a function that takes, as its argument, a string that is
> > acceptable as input to `format-time-string' (i.e. a value like
> > `display-time-format'), and returns a regexp that will 
> > match all such formatted times, that is, whatever
> > `format-time-string' would return for the same input,
> > for any time?
> 
> It does sound kind of useful, but wouldn't it be rather hard 
> for some of the formats format-time-string supports -- e.g.,
> %c, %a, or %b?
> 
> Maybe that doesn't matter for the typical uses of such a function...
> (formats embedded in a file being font-locked would tend to be more
> portable ones, perhaps)

Good point.

I would be interested even if such a function were limited wrt the formats
it supported - some well-defined subset of what `format-time-string'
accepts.

The alternative, as I see it, is code that supports only one or a few
hard-coded time formats.