From f6d4821a688d173afa0cab4fdcdaaf5943f195ce Mon Sep 17 00:00:00 2001
From: notoria <notoria@users.noreply.github.com>
Date: Sun, 7 Mar 2021 18:38:04 +0100
Subject: [PATCH 1/2] Small improvement for mod in CLP(Z)

---
 src/lib/clpz.pl | 31 ++++++++++++++++++-------------
 tests/scryer.rs |  1 +
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index 0c561b92..367059b7 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -4972,19 +4972,24 @@ run_propagator(pmod(X,Y,Z), MState) -->
                 )
             ;   Z =:= 0 % Multiple solutions so do nothing special.
             ),
-            (   Z > 0 ->
-                { fd_get(Y, YD, YPs),
-                  YMin is Z + 1,
-                  domain_remove_smaller_than(YD, YMin, YD1) },
-                  fd_put(Y, YD1, YPs)
-                % queue_goal(Y #> Z)
-            ;   Z < 0 ->
-                { fd_get(Y, YD, YPs),
-                  YMax is Z - 1,
-                  domain_remove_greater_than(YD, YMax, YD1) },
-                  fd_put(Y, YD1, YPs)
-                % queue_goal(Y #< Z)
-            ;   true
+            (   { fd_get(Y, _, _, n(YU), _),
+                  YU < X, X =< 0 } -> kill(MState), Z =:= X
+            ;   { fd_get(Y, _, n(YL), _, _),
+                  YL > X, X >= 0 } -> kill(MState), Z =:= X
+            ;   (   Z > 0 ->
+                    { fd_get(Y, YD, YPs),
+                      YMin is Z + 1,
+                      domain_remove_smaller_than(YD, YMin, YD1) },
+                      fd_put(Y, YD1, YPs)
+                    % queue_goal(Y #> Z)
+                ;   Z < 0 ->
+                    { fd_get(Y, YD, YPs),
+                      YMax is Z - 1,
+                      domain_remove_greater_than(YD, YMax, YD1) },
+                      fd_put(Y, YD1, YPs)
+                    % queue_goal(Y #< Z)
+                ;   true
+                )
             )
         ;   run_propagator(pmodz(X,Y,Z), MState),
             run_propagator(pmody(X,Y,Z), MState),
diff --git a/tests/scryer.rs b/tests/scryer.rs
index 55d67a73..03c14c3e 100644
--- a/tests/scryer.rs
+++ b/tests/scryer.rs
@@ -60,6 +60,7 @@ fn setup_call_cleanup() {
 }
 
 #[test]
+#[ignore] // ignored as this does not terminate
 fn clpz() {
     test_file("src/tests/clpz/test_clpz.pl", Some(b""));
 }

From bd222ed2bf7d3911b2e9b569fbac1be38a6016f8 Mon Sep 17 00:00:00 2001
From: notoria <notoria@users.noreply.github.com>
Date: Wed, 10 Mar 2021 21:19:47 +0100
Subject: [PATCH 2/2] Added a test for mod in CLP(Z)

---
 src/tests/clpz/test_clpz.pl  |  2 +-
 src/tests/clpz/test_clpz2.pl | 80 ++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 1 deletion(-)
 create mode 100644 src/tests/clpz/test_clpz2.pl

diff --git a/src/tests/clpz/test_clpz.pl b/src/tests/clpz/test_clpz.pl
index 7d91f918..98fd827b 100644
--- a/src/tests/clpz/test_clpz.pl
+++ b/src/tests/clpz/test_clpz.pl
@@ -100,7 +100,7 @@ run :-
             Dss
         ),
         E,
-        (   write('caugth: '), write(E), nl,
+        (   write('caught: '), write(E), nl,
             portray_clause([N, Settings, Vs, Gs4, Dss]), nl,
             false
         )
diff --git a/src/tests/clpz/test_clpz2.pl b/src/tests/clpz/test_clpz2.pl
new file mode 100644
index 00000000..7ee94094
--- /dev/null
+++ b/src/tests/clpz/test_clpz2.pl
@@ -0,0 +1,80 @@
+:- use_module(library(debug)).
+:- use_module(library(clpz)).
+% :- use_module('../../lib/clpz').
+:- use_module(library(format)).
+:- use_module(library(lists)).
+:- use_module(library(time)).
+:- use_module(combination).
+:- use_module(permutation).
+
+nat(N) :-
+    nat(0, N).
+
+nat(N, N).
+nat(N0, N) :-
+    N1 is N0 + 1,
+    nat(N1, N).
+
+bound(X, L, U) :- L #=< X, X #=< U.
+
+/*
+ * This test stops only if there is an mistake in the propagator.
+ * This test is general enough to quickly test other operators.
+ * This test does not test if permutating the clause changes the final result.
+ */
+run(N) :-
+    Vs = [X0, X1, X2, L0, L1, L2, U0, U1, U2],
+
+    Xs = [X0, X1, X2],
+    Ls = [L0, L1, L2],
+    Us = [U0, U1, U2],
+
+    Bs = [L0, L1, L2, U0, U1, U2],
+
+    % maplist(#=<, Ls, Us),
+    maplist(#\=(0), [X1, L1, U1]),
+    maplist(bound, Xs, Ls, Us),
+
+    % nat(N),
+    format("~d\n", [N]),
+    NegN is -N - 1,
+    Domain = NegN..N,
+
+    I in 0..6,
+    indomain(I),
+    length(Is, I),
+    combination(Bs, Is),
+    Is ins Domain,
+    labeling([], Is),
+
+    (   % Every solution is generated and only solution.
+        X2 #= X0 mod X1,
+        Xs ins Domain,
+        labeling([], Xs),
+        (   catch(X2 is X0 mod X1, _, false) ->
+            true
+        ;   format("~q\n", [error0([N, Vs, Ys])]) % Found a non-solution.
+        )
+    ;   % Every solution is found and only solution.
+        copy_term(Xs, Ys),
+        Ys = [Y0, Y1, Y2],
+        Ys ins Domain,
+        labeling([], Ys),
+        (   catch(Y2 is Y0 mod Y1, _, false) ->
+            (   X2 #= X0 mod X1 ->
+                (   maplist(=, Ys, Xs) ->
+                    % Find a specific solution.
+                    true
+                ;   format("~q\n", [error1([N, Vs, Ys])])
+                )
+            ;   format("~q\n", [error2([N, Vs, Ys])])
+            )
+        ;   X2 #= X0 mod X1,
+            (   maplist(=, Ys, Xs) ->
+                % Found a non-solution.
+                format("~q\n", [error3([N, Vs, Ys])])
+            ;   true
+            )
+        )
+    ),
+    false.