[m-dev.] for review: switches via binary search

[Fergus Henderson]

On 30-Dec-1997, Zoltan Somogyi <zs at cs.mu.oz.au> wrote:
> 
> +:- pred tag_switch__divide_ptag_range(ptag_case_list, tag_bits,
> +	ptag_case_list, ptag_case_list).
> +:- mode tag_switch__divide_ptag_range(in, in, out, out) is det.
> +
> +tag_switch__divide_ptag_range([], _LowRangeEnd, [], []).
> +tag_switch__divide_ptag_range([PtagGroup | PtagGroups], LowRangeEnd,
> +		LowRange, HighRange) :-
> +	PtagGroup = Ptag - _,
> +	( Ptag > LowRangeEnd ->
> +		tag_switch__divide_ptag_range(PtagGroups, LowRangeEnd,
> +			LowRange, HighRange0),
> +		HighRange = [PtagGroup | HighRange0]
> +	;
> +		tag_switch__divide_ptag_range(PtagGroups, LowRangeEnd,
> +			LowRange0, HighRange),
> +		LowRange = [PtagGroup | LowRange0]
> +	).

It might be more elegant to implement this using list__filter/4.

> +:- pred tag_switch__divide_stag_range(stag_goal_list, int,
> +	stag_goal_list, stag_goal_list).
> +:- mode tag_switch__divide_stag_range(in, in, out, out) is det.
> +
> +tag_switch__divide_stag_range([], _LowRangeEnd, [], []).
> +tag_switch__divide_stag_range([PtagGroup | PtagGroups], LowRangeEnd,
> +		LowRange, HighRange) :-
> +	PtagGroup = Ptag - _,
> +	( Ptag > LowRangeEnd ->
> +		tag_switch__divide_stag_range(PtagGroups, LowRangeEnd,
> +			LowRange, HighRange0),
> +		HighRange = [PtagGroup | HighRange0]
> +	;
> +		tag_switch__divide_stag_range(PtagGroups, LowRangeEnd,
> +			LowRange0, HighRange),
> +		LowRange = [PtagGroup | LowRange0]
>  	).

Ditto.  Hang on, how does this differ from the previous one?
The fact that the variables are named Ptag* strongly suggests
a possible cut-and-paste error.

> +:- pred tag_switch__divide_ptag_range(ptag_case_list, tag_bits,
> +	ptag_case_list, ptag_case_list).
> +:- mode tag_switch__divide_ptag_range(in, in, out, out) is det.
> +
> +tag_switch__divide_ptag_range([], _LowRangeEnd, [], []).
> +tag_switch__divide_ptag_range([PtagGroup | PtagGroups], LowRangeEnd,
> +		LowRange, HighRange) :-

Hmm, didn't I see that already?

> +:- pred tag_switch__divide_stag_range(stag_goal_list, int,
> +	stag_goal_list, stag_goal_list).
> +:- mode tag_switch__divide_stag_range(in, in, out, out) is det.
> +
> +tag_switch__divide_stag_range([], _LowRangeEnd, [], []).
> +tag_switch__divide_stag_range([PtagGroup | PtagGroups], LowRangeEnd,
> +		LowRange, HighRange) :-

I'm getting serious deja vu here ;-)
I'm not sure why these are included twice in the diff.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>   |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>   |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3         |     -- the last words of T. S. Garp.