math_opt: update from google3

ortools/math_opt/python/model.py

@@ -1279,6 +1279,12 @@ class LinearConstraint:
                 ),
             )
 
+    def as_bounded_linear_expression(self) -> BoundedLinearExpression:
+        """Returns the bounded expression from lower_bound, upper_bound and terms."""
+        return BoundedLinearExpression(
+            self.lower_bound, LinearSum(self.terms()), self.upper_bound
+        )
+
     def __str__(self):
         """Returns the name, or a string containing the id if the name is empty."""
         return self.name if self.name else f"linear_constraint_{self.id}"

ortools/math_opt/python/model_test.py

@@ -160,6 +160,20 @@ class ModelTest(compare_proto.MathOptProtoAssertions, parameterized.TestCase):
         self.assertEqual(c, mod.get_linear_constraint(0))
         self.assertEqual(d, mod.get_linear_constraint(1))
 
+    def test_linear_constraint_as_bounded_expression(
+        self, storage_class: StorageClass
+    ) -> None:
+        mod = model.Model(name="test_model", storage_class=storage_class)
+        x = mod.add_binary_variable(name="x")
+        y = mod.add_binary_variable(name="y")
+        c = mod.add_linear_constraint(lb=-1.0, ub=2.5, name="c", expr=3 * x - 2 * y)
+        bounded_expr = c.as_bounded_linear_expression()
+        self.assertEqual(bounded_expr.lower_bound, -1.0)
+        self.assertEqual(bounded_expr.upper_bound, 2.5)
+        expr = model.as_flat_linear_expression(bounded_expr.expression)
+        self.assertEqual(expr.offset, 0.0)
+        self.assertDictEqual(dict(expr.terms), {x: 3.0, y: -2.0})
+
     def test_get_linear_constraint_does_not_exist_key_error(
         self, storage_class: StorageClass
     ) -> None: