Start on include/inn/confparse.h

[Aidan Cully]

On Wed, Jun 28, 2000 at 07:31:32PM, Russ Allbery said:
> One thing I noticed when designing the interface is that the return of
> conf_parse is going to be minorly annoying to deal with for configuration
> files with nested groups.  For example, with incoming.conf, all you really
> care about is the array of structs corresponding to peer groups; those may
> be grouped into other groups, though, and what you'll actually get out of
> conf_parse is a tree of conf_data structs, with pointers to the structs
> that you care about in the data members.  Basically, the interesting part
> will be all the leaves.  The best way of handling this may be to write a
> conf_collapse function that takes a conf_data tree and returns a list of
> just the leaves, freeing everything at a higher level.

You've got start and finish handlers...  They can deal with storing
config info in a flat place somewhere, without needing to worry about
a conf_collapse()...  It ends up meaning the returned conf_data are
useless for that application, though.

I'd advocate relying on 'finish' callbacks for committing conf data,
rather than returning and reading the conf_data structure from
conf_parse.  I think it punts on the issues you raise...

> /* Parameters are collected into parameter groups, which are defined by the
>    following struct.  init and finish are callbacks used to do various
>    initialization, cleanup, or programmatic defaults for the result struct
>    of a parse of a configuration file. */
> struct conf_group {
>     char *              name;
>     size_t              struct_size;
>     void *              defaults;
>     conf_callback_t     init;
>     conf_callback_t     finish;
> 
>     struct conf_group *         parent;
>     struct conf_group **        subgroups;
>     struct conf_parameter **    parameters;
> };
...
> /* The public parse function.  Takes the name of a file to parse and a
>    pointer to a conf_group tree that specifies the semantic structure of the
>    file.  Returns a pointer to a conf_data tree containing the results of
>    the parse. */
> extern struct conf_data *conf_parse(const char *file,
>                                     const struct conf_group *structure);

I'm not sure how you intend to specify arbitrarily nested 'group'
declarations, like in incoming.conf...  The structure would look
something like (and in the interest of simplicity, the C-code is
incorrect):
conf_group example_conf_children[] = {
	{
	  "group", 0, 0, 0, 0,	/* just give it a name, for this example */

	  &example_conf,	/* is this supposed to be filled in manually? */
	  &example_conf_children,
	    /* somehowe include a pointer to our own
	     * structure? does that work? the defaults change
	     * when we nest further...  would a callback
	     * function fill this in? */
	  0
	}
};
conf_group example_conf = {
	0, 0, 0, 0, 0,	/* top level node has no associated data, for this
			 * example */
	0,
	&example_conf_children, /* how to indicate size of array? */
	0
};

I guess you can tell I'm a bit confused, for this case, if I
understand everything else correctly...

--aidan
-- 
Aidan Cully       "You can lead a whore to culture, but you can't make her
Not Panix Staff    think."
aidan at panix.com        --Dorothy Parker