[m-rev.] for review: set__intersect_list

[Zoltan Somogyi]

For review by anyone.

Estimated hours taken: 0.5
Branches: main

library/set.m:
library/set_ordlist.m:
library/set_unordlist.m:
	Add a function for computing the intersection of a list of sets.

	There is already code to compute the intersection of a set of sets,
	but there should be no need to convert a list to a set, which can
	involve an expensive sorting process, unless you want the set of sets
	for some other reason.

Zoltan.

cvs diff: Diffing library
Index: library/set.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/set.m,v
retrieving revision 1.58
diff -u -b -r1.58 set.m
--- library/set.m	2001/06/27 05:04:39	1.58
+++ library/set.m	2001/11/18 09:38:48
@@ -221,6 +221,11 @@
 
 :- func set__power_intersect(set(set(T))) = set(T).
 
+	% `set__intersect_list(A, B)' is true iff `B' is the intersection of
+	% all the sets in `A'
+
+:- func set__intersect_list(list(set(T))) = set(T).
+
 	% `set__difference(SetA, SetB, Set)' is true iff `Set' is the
 	% set containing all the elements of `SetA' except those that
 	% occur in `SetB'
@@ -373,6 +378,8 @@
 
 set__power_intersect(Sets, Set) :-
 	set_ordlist__power_intersect(Sets, Set).
+
+set__intersect_list(Sets) = set_ordlist__intersect_list(Sets).
 
 set__difference(SetA, SetB, Set) :-
 	set_ordlist__difference(SetA, SetB, Set).
Index: library/set_ordlist.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/set_ordlist.m,v
retrieving revision 1.14
diff -u -b -r1.14 set_ordlist.m
--- library/set_ordlist.m	2001/04/24 03:59:13	1.14
+++ library/set_ordlist.m	2001/11/18 09:36:17
@@ -206,6 +206,11 @@
 :- func set_ordlist__power_intersect(set_ordlist(set_ordlist(T)))
 		= set_ordlist(T).
 
+	% `set_ordlist__intersect_list(A, B)' is true iff `B' is the
+	% intersection of all the sets in `A'.
+
+:- func set_ordlist__intersect_list(list(set_ordlist(T))) = set_ordlist(T).
+
 	% `set_ordlist__difference(SetA, SetB, Set)' is true iff `Set' is the
 	% set containing all the elements of `SetA' except those that
 	% occur in `SetB'.
@@ -418,6 +423,9 @@
 		set_ordlist__power_intersect(Ss, S1),
 		set_ordlist__intersect(S1, S0, S)
 	).
+
+set_ordlist__intersect_list(Sets) = S :-
+	set_ordlist__power_intersect(Sets, S).
 
 %--------------------------------------------------------------------------%
 
Index: library/set_unordlist.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/set_unordlist.m,v
retrieving revision 1.19
diff -u -b -r1.19 set_unordlist.m
--- library/set_unordlist.m	2001/04/24 03:59:13	1.19
+++ library/set_unordlist.m	2001/11/18 09:37:15
@@ -211,6 +211,12 @@
 :- func set_unordlist__power_intersect(set_unordlist(set_unordlist(T)))
 		= set_unordlist(T).
 
+	% `set_unordlist__intersect_list(A, B)' is true iff `B' is the
+	% intersection of all the sets in `A'
+
+:- func set_unordlist__intersect_list(list(set_unordlist(T)))
+		= set_unordlist(T).
+
 	% `set_unordlist__difference(SetA, SetB, Set)' is true iff `Set' is the
 	% set containing all the elements of `SetA' except those that
 	% occur in `SetB'
@@ -359,6 +365,9 @@
 		set_unordlist__power_intersect(Ss, S1),
 		set_unordlist__intersect(S1, S0, S)
 	).
+
+set_unordlist__intersect_list(Sets) = S :-
+	set_unordlist__power_intersect(Sets, S).
 
 %--------------------------------------------------------------------------%
 
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