move iterator over all solutions to _BijectionistMILP

Author: mantepse

src/sage/combinat/bijectionist.py

@@ -2499,17 +2499,7 @@ def solutions_iterator(self):
         """
         if self._bmilp is None:
             self._bmilp = _BijectionistMILP(self)
-        bmilp = self._bmilp
-        index = 0
-        while True:
-            solution = bmilp.solution(False, [], index)
-            if solution is None:
-                return
-            index += 1
-            yield solution
-            if get_verbose() >= 2:
-                print("after vetoing")
-                bmilp.show(variables=False)
+        yield from self._bmilp
 
 
 class _BijectionistMILP():
@@ -2843,6 +2833,32 @@ def solution(self, on_blocks, constraints, index=0):
                     break
         return mapping
 
+    def __iter__(self):
+        r"""
+        Iterate over all solutions of the MILP.
+
+        EXAMPLES::
+
+            sage: A = B = 'abc'
+            sage: bij = Bijectionist(A, B, lambda x: B.index(x) % 2, solver="GLPK")
+            sage: from sage.combinat.bijectionist import _BijectionistMILP
+            sage: list(_BijectionistMILP(bij))
+            [{'a': 0, 'b': 1, 'c': 0},
+             {'a': 1, 'b': 0, 'c': 0},
+             {'a': 0, 'b': 0, 'c': 1}]
+
+        """
+        index = 0
+        while True:
+            solution = self.solution(False, [], index)
+            if solution is None:
+                return
+            index += 1
+            yield solution
+            if get_verbose() >= 2:
+                print("after vetoing")
+                self.show(variables=False)
+
     def add_alpha_beta_constraints(self):
         r"""
         Add constraints enforcing that `(alpha, s)` is equidistributed