[m-rev.] for review: debugging tabling procedures

[Fergus Henderson]

On 08-Nov-2002, Zoltan Somogyi <zs at cs.mu.OZ.AU> wrote:
> @@ -3417,6 +3506,666 @@
>  }
>  
>  static MR_Next
> +MR_trace_cmd_table(char **words, int word_count,
> +	MR_Trace_Cmd_Info *cmd, MR_Event_Info *event_info,
> +	MR_Event_Details *event_details, MR_Code **jumpaddr)
> +{
...
> +	MR_register_all_modules_and_procs(MR_mdb_out, MR_TRUE);
> +	matches = MR_search_for_matching_procedures(&spec);
> +	if (matches.match_proc_next == 0) {
> +		fflush(MR_mdb_out);
> +		fprintf(MR_mdb_err,
> +			"mdb: there is no such procedure.\n");
> +		return KEEP_INTERACTING;
> +	} else if (matches.match_proc_next == 1) {
> +		proc = matches.match_procs[0];
> +	} else {
> +		char	buf[100];
> +		char	*line2;
> +
> +		fflush(MR_mdb_out);
> +		fprintf(MR_mdb_err, "Ambiguous procedure specification. "
> +			"The matches are:\n");
> +		for (i = 0; i < matches.match_proc_next; i++)
> +		{
> +			fprintf(MR_mdb_out, "%d: ", i);
> +			MR_print_proc_id_and_nl(MR_mdb_out,
> +				matches.match_procs[i]);
> +		}
> +
> +		sprintf(buf, "\nWhich procedure's table do you want to print "
> +			"(0-%d)? ",
> +			matches.match_proc_next - 1);
> +		line2 = MR_trace_getline(buf, MR_mdb_in, MR_mdb_out);
> +		n = -1;
> +		if (line2 == NULL || !MR_trace_is_natural_number(line2, &n)) {
> +			n = -1;
> +			fprintf(MR_mdb_out, "none of them\n");
> +		} else if (n < 0 || n >= matches.match_proc_next) {
> +			n = -1;
> +			fprintf(MR_mdb_out, "invalid choice\n");
> +		}
> +
> +		if (line2 != NULL) {
> +			MR_free(line2);
> +		}
> +
> +		if (n >= 0) {
> +			proc = matches.match_procs[n];
> +		} else {
> +			return KEEP_INTERACTING;
> +		}
> +	}

It would be nicer to abstract that part out into a separate subroutine, IMHO.
It does a single, easily describable thing -- select a single matching
procedure -- and the coupling between the part and the rest of the routine
is quite minor.

	MR_Proc_Entry *
	MR_select_matching_procedure(const MR_Proc_Spec *spec,
		const char *ambiguity_question)
	{
		...
	}

	static MR_Next
	MR_trace_cmd_table(...)
	{

		proc = MR_select_matching_procedure(&spec,
			"Which procedure's table do you want to print");
		if (proc == NULL) {
			return KEEP_INTERACTING;
		}

		...
	}

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