[OctDev] Regular Expressions

[Stefan v. d. W. <st...@su...>]

Hi Paul

Is there a way to make the regexps less greedy?

For example, the regexp

A.*A

on a string like

AbbbbbbbbAbbbbbbbbbbbbbbA

will match the whole string.

In Python, you can use the regexp

A.*?A which is less greedy, and only will match

AbbbbbbbbA

Is there a way to do this with the current implementation?

Regards
Stefan

On Wed, Jun 02, 2004 at 08:03:35AM -0400, Paul Kienzle wrote:
> I added some regexp support a couple of releases back (shortly before
> the first matlab release with regexps --- of course it isn't=20
> compatible).
> Look in main/strings.
>=20
> - Paul
>=20
> On Jun 2, 2004, at 3:31 AM, Stefan van der Walt wrote:
>=20
> >If we add enough supporting functions, each package can be distributed=
=20
> >with an install.m file?
> >
> >Supporting functions would, for example, be
> >
> >add_toolbox(id, description)
> >add_category(id, description, parent_toolbox)
> >add_function([category1 category2 ...])
> >rebuild()
> >
> >The install.m file can then be renamed to <package>-install.m and=20
> >stored in a directory -- needed for rebuilding the index from scratch=20
> >later on.
> >
> >Every time a function is added the appropriate toolbox contents.m=20
> >should be rebuilt, using the descriptions extracted by an octave=20
> >function. What is the current level of regular expression support? =20
> >With regular expressions this problem becomes a lot simpler.
> >
> >Comments and ideas?
> >
> >Regards
> >St=E9fan
> >
> >Paul Kienzle wrote:
> >>Here are some features that I consider important:
> >>(1) distributed description --- adding a package to the system
> >>should automatically update the indices to reflect the presence
> >>of that package.   E.g., adding octave forge should add a number
> >>of functions to Octave's existing string categories, amongst others.
> >>An install=3Dtime step is sufficient --- it doesn't need to happen
> >>every time a directory is added to the path, though it's okay if it
> >>does so.  A single function can belong to multiple subcategories in
> >>different toolboxes.
> >>(2) easy syntax --- it is hard to get more minimal than the INDEX
> >>file format that make_index is using.
> >>(3) minimal tools --- you cannot require python on user
> >>systems.   For developer systems, the fewer languages
> >>required the better.  I guess beating Octave's string
> >>handling into shape so that it is up to the task itself is a bit
> >>too ambitious.
> >>(4) multiple output targets, including matlab-style contents.m.
> >>I'm sure there's others, but not that I can think of tonight.
> >>- Paul
> >>On Jun 1, 2004, at 12:20 PM, Stefan van der Walt wrote:
> >>>Hi Paul
> >>>
> >>>I started working on this today.  Wrote a python script similar in
> >>>functionality to make_index. It uses octave to provide the function
> >>>descriptions, however -- which means that you can build indeces=20
> >>>having
> >>>only a binary distribution available.
> >>>
> >>>An example config file looks like this:
> >>>
> >>>---
> >>>
> >>>octave =3D "/usr/share/octave/2.1.57/m"
> >>>forge =3D "/usr/share/octave/2.1.57/site/m/octave-forge/"
> >>>
> >>>signal {
> >>>  name =3D "Signal Processing Toolbox"
> >>>  add_dirs =3D "signal"
> >>>  add_files =3D "ifft ifft2"
> >>>  unsupported =3D "nosup neithersup"
> >>>  sub =3D "numeric"
> >>>}
> >>>
> >>>numeric {
> >>>  name =3D "Numerical Games"
> >>>  add_dirs =3D "blah"
> >>>}
> >>>
> >>>---
> >>>
> >>>It scans all the directories specified in "add_dirs" directives for=20
> >>>.m
> >>>files and then queries octave for their descriptions, doing some
> >>>gung-ho parsing to take care of all the different comment formats ou=
t
> >>>there.
> >>>
> >>>The generated file signal.m can be generated (note: I havn't include=
d
> >>>any sub-categories here):
> >>>
> >>>##
> >>>## Signal Processing Toolbox
> >>>##
> >>>## arburg       - fits an AR (p)-model using Burg method (a so=20
> >>>called maximum entropy model).
> >>>## arch_fit     - Fit an ARCH regression model to the time series Y=20
> >>>using the scoring algorithm in Engle's original ARCH paper.
> >>>## arch_rnd     - Simulate an ARCH sequence of length T with AR=20
> >>>coefficients B and CH coefficients A.
> >>>## arch_test    - For a linear regression model
> >>>## arma_rnd     - Return a simulation of the ARMA model
> >>>## aryule       - fits an AR (p)-model with Yule-Walker estimates.
> >>>## autocor      - Return the autocorrelations from lag 0 to H of=20
> >>>vector X.
> >>>.
> >>>.
> >>>.
> >>>## zplane       - Plot the poles and zeros.
> >>>##
> >>>## Unsupported functions:
> >>>##
> >>>## nosup
> >>>## neithersup
> >>>##
> >>>
> >>>It would also be easy to factor this out into a module so that only
> >>>the front-end changes with every other method of presentation.  This
> >>>way you can generate a web page index, category descriptions like
> >>>signal.m or anything else you want in any format.
> >>>
> >>>If the generated category descriptions are in the loadpath, calling
> >>>"help signal" should do the job.  It will be trivial to generate a
> >>>toolbox.m for "help toolbox" to get a list of all toolboxes.
> >>>
> >>>Also, a toolbox can "contain" any other toolbox.  You can, for
> >>>example, make an image processing toolbox and include the signal=20
> >>>processing
> >>>toolbox if you so wish.
> >>>
> >>>Is this going in the right direction?  If not, I would appreciate a
> >>>few pointers!
> >>>
> >>>I attach the scripts.
> >>>
> >>>Regards
> >>>Stefan
> >>>
> >>>On Sun, May 30, 2004 at 12:00:46AM -0400, Paul Kienzle wrote:
> >>>
> >>>>Stefan,
> >>>>
> >>>>I've extended dispatch() so that even functions called with no
> >>>>parameters can be dispatched so octave-forge could now provide
> >>>>categorical help independent of octave if we so choose.
> >>>>
> >>>>There's a small caveat in that dispatch already dispatches on help,=
=20
> >>>>so
> >>>>we need to remove it and call our own
> >>>>
> >>>>    ##PKG_ADD: dispatch('help','string')
> >>>>    ##PKG_ADD: dispatch('help','cathelp','any')
> >>>>    function cathelp(varargin)
> >>>>      ...
> >>>>      dispatch_help(pars{:})
> >>>>
> >>>>The call to dispatch_help at the end in order to fill in base help=20
> >>>>for
> >>>>dispatched functions.
> >>>>
> >>>>Are you still interested?
> >>>>
> >>>>My rule lately has been to not do anything too sophisticated=20
> >>>>otherwise
> >>>>nothing ever gets done.  At least that's my excuse for not fixing=20
> >>>>the
> >>>>problem I just noticed in dispatch which is that dispatches can't
> >>>>chain.  You could
> >>>>fake it if dispatch('name','type') returned the dispatch function=20
> >>>>for
> >>>>that type, or if dispatch('name','new','type') returned the old
> >>>>dispatch function for that type.
> >>>>
> >>>>- Paul
> >
> >
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>=20