Re: CVS update: subversion/subversion/libsvn_fs structure

[Karl Fogel <kf...@galois.collab.net>]

Jim Blandy <ji...@zwingli.cygnus.com> writes:
> See the change I committed --- the empty string is the correct value.
> The grammar was wrong; the explanation of the `mutable' flag towards
> the top of the file specified that PARENT-ID is the empty string for
> the root directory.
> 
> Certainly one could do it either way, but I prefer it this way.  I
> think it's more graceful for the `mutable' flag to have a consistent
> structure for all nodes.  If the PARENT-ID field has a quiescent
> value, there's no need to propagate that fact up to the structure
> containing it.  It also makes it somewhat easier to add more possibly
> optional values to the end of the flag.

Sounds great.

Actually, the only reason I thought otherwise was that the commit
changing `structure' didn't also include the corresponding change to
the code of is_valid_flag().  But you committed that pretty soon
after, no big deal.

Hmm, now that I think about it, my original change to `structure' was
also not accompanied in the same commit by the change to
is_valid_flag().  Heh.

-K


> Karl Fogel <kf...@galois.ch.collab.net> writes:
> > jimb@tigris.org writes:
> > >   Log:
> > >   Tweak Karl's tweak of the syntax of the "mutable" flag.
> > 
> > Oh -- am I misunderstanding the BNF syntax?  I had thought that true
> > emptiness preceding a bar was the way to express actual absence, as
> > opposed to "", which would mean an atom representing the empty string.
> > It's the difference between these two:
> > 
> >    ("mutable")
> >    ("mutable" "")
> > 
> > where the former is a valid flag, and the latter is... well, at least
> > highly unlikely. :-)  (See the code in nodes-table.c:is_valid_flag().)
> > 
> > It would have to precede the bar, so it's clear it's not a typo, of
> > course.  I deduced that syntax from this entry a bit later in
> > `structure':
> > 
> >           list.body.opt ::=  | list.body ;
> > 
> > ?,
> > -K
> >    
> > >   Revision  Changes    Path
> > >   1.35      +1 -1      subversion/subversion/libsvn_fs/structure
> > >   
> > >   Index: structure
> > >   ===================================================================
> > >   RCS file: /cvs/subversion/subversion/libsvn_fs/structure,v
> > >   retrieving revision 1.34
> > >   retrieving revision 1.35
> > >   diff -u -r1.34 -r1.35
> > >   --- structure	2001/02/28 00:52:17	1.34
> > >   +++ structure	2001/02/28 22:07:10	1.35
> > >   @@ -634,7 +634,7 @@
> > >                     HEADER ::= (KIND PROPLIST FLAG ...) ;
> > >                       KIND ::= "file" | "dir" | "copy" ;
> > >                       FLAG ::= ("mutable" PARENT-ID) ;
> > >   -              PARENT-ID ::=  | node.revision-id ;
> > >   +              PARENT-ID ::= "" | node.revision-id ;
> > >            SOURCE-REVISION ::= number ;
> > >    
> > >    
> > >   
> > >   
> > >   
> >