RE: [jamboost] Header scanning change

From: Mark Sheppard (msheppard_at_[hidden])
Date: 2003-10-20 06:07:53

Vladimir Prus wrote:
> Mark Sheppard wrote:
> > I made the following change so that the rule specified
> > by $(HDRRULE) gets the bound name of the source/header
> > file:
> >
[...]
> 
> Mark,
> I have two remarks.
> 
> First, I believe that V2 already handles "" includes. In 
> fact, I believe V1 handles them as well, since I've added
> that code to it a long time ago.

So it does. I hadn't looked at V2 (or even V1) before, only
the Perforce Jambase.

> Second, your change is very interesting. For example, to find 
> out the location of the scanned target, V2 has to store
> binding and later retrive it. I though about adding "BINDING"
> variable, which will be automatically set. Passing boundname
> as 'target' is an interesting idea.
> 
> But there's a problem, though. V2, V2 and Perforce Jambase 
> use grist on header targets to distinguish between different
> scans of the same file. And with your change, grist is no
> longer available in scanner. I'm not sure how to handle this.

Yes, I ran into this problem after using my change. The way
I've fixed it is to pass both the name and the boundname to
$(HDRRULE):

--- jam_src.orig/headers.c 2002-05-28 21:35:12.000000000 +0100
+++ jam_src/headers.c 2003-10-20 11:43:08.000000000 +0100
@@ -87,13 +87,14 @@
FRAME frame[1];
frame_init( frame );
lol_add( frame->args, list_new( L0, t->name ) );
+ lol_add( frame->args, list_new( L0, t->boundname ) );
#ifdef OPT_HEADER_CACHE_EXT
lol_add( frame->args, hcache( t, rec, re, hdrscan ) );
#else
lol_add( frame->args, headers1( headlist, t->boundname, rec, re )
);
#endif

- if( lol_get( frame->args, 1 ) )
+ if( lol_get( frame->args, 2 ) )
evaluate_rule( hdrrule->string, frame );

/* Clean up */

Then in Jambase I do this:

rule AddGrist ( paths + : grist )
{
return $(paths:G=$(grist)) ;
}

rule HdrRule ( source : bound-source : headers + )
{
local search-path ;
if $(SEARCH) {
# propagate search path to nested headers
search-path = $(bound-source:D) $(SEARCH[2-]) ;
}
else if $(INCPATH) {
# set the search path on included headers
search-path = $(bound-source:D) $(INCPATH) ;
}

headers = [ AddGrist $(headers) : [ MD5 $(search-path) ] ] ;
SEARCH on $(headers) = $(search-path) ;

Obviously this breaks backwards compatibility so isn't something you'd want
to do in the mainline Boost Jam. Alternatives I thought of would be adding
a BOUND_NAME builtin or a variable modifier (e.g. $(source:Z), unfortunately
B is taken) which would return nothing before a target is bound.

Mark.