non working rewrite of LNS for python + example

examples/python/pyls_api.py

@@ -0,0 +1,52 @@
+from ortools.constraint_solver import pywrapcp
+from google.apputils import app
+import gflags
+import random
+
+class OneVarLns(pywrapcp.PyLns):
+  """One Var LNS."""
+
+  def __init__(self, vars):
+    pywrapcp.PyLns.__init__(self, vars)
+    self.__index = 0
+
+  def InitFragments(self):
+    self.__index = 0
+    print 'OneVarLns::InitFragments'
+
+  def NextFragment(self):
+    if self.__index < self.Size():
+      self.__index += 1
+      return [self.__index - 1]
+    else:
+      return []
+
+
+def Solve(type):
+  solver = pywrapcp.Solver('Solve')
+  vars = [solver.IntVar(0, 4) for _ in range(4)]
+  sum_var = solver.Sum(vars)
+  obj = solver.Minimize(sum_var, 1)
+  db = solver.Phase(vars, solver.CHOOSE_FIRST_UNBOUND, solver.ASSIGN_MAX_VALUE)
+  ls = None
+
+  if type == 0:  # LNS
+    print 'Large Neighborhood Search'
+    one_var_lns = OneVarLns(vars)
+    ls_params = solver.LocalSearchPhaseParameters(one_var_lns, db)
+    ls = solver.LocalSearchPhase(vars, db, ls_params)
+
+  collector = solver.LastSolutionCollector()
+  collector.Add(vars)
+  collector.AddObjective(sum_var)
+  log = solver.SearchLog(1000, obj)
+  solver.Solve(ls, [collector, obj, log])
+  print 'Objective value = %d' % collector.ObjectiveValue()
+
+
+def main(_):
+  Solve(0)
+
+
+if __name__ == '__main__':
+  app.run()

src/constraint_solver/python/constraint_solver.swig

@@ -141,6 +141,12 @@ static bool PyCallbackBool(PyObject* pyfunc) {
 %feature("director") operations_research::SearchMonitor;
 %feature("director") operations_research::Constraint;
 %feature("director") operations_research::Demon;
+%feature("director") operations_research::BaseLNS;
+%feature("director") operations_research::LocalSearchOperator;
+%feature("director") operations_research::PathOperator;
+%feature("director") operations_research::IntVarLocalSearchOperator;
+%feature("director") operations_research::SequenceVarLocalSearchOperator;
+%feature("director") operations_research::IntVarLocalSearchFilter;
 
 // We *do* need to use SWIGTYPE_... descriptor directly in embedded C++ code:
 // the recommended replacement $descriptor(...) is only available within
@@ -385,7 +391,7 @@ flags.DEFINE_string('cp_profile_file', '',
 %rename (InitialPropagateWrapper)
     operations_research::Constraint::InitialPropagate;
 %rename (RunWrapper) operations_research::Demon::Run;
-
+%rename (NextFragmentWrapper) operations_research::BaseLNS::NextFragment;
 
 // Rename rules on SolutionCollector.
 %rename (Branches) operations_research::SolutionCollector::branches;
@@ -1183,8 +1189,9 @@ class PyDecisionBuilder(object):
 
 
 class PyConstraint(Constraint):
+
   def __init__(self, solver):
-    pywrapcp.Constraint.__init__(self, solver)
+    Constraint.__init__(self, solver)
 
   def InitialPropagateWrapper(self):
     try:
@@ -1197,8 +1204,9 @@ class PyConstraint(Constraint):
 
 
 class PyDemon(Demon):
+
   def __init__(self):
-    pywrapcp.Demon.__init__(self)
+    Demon.__init__(self)
 
   def RunWrapper(self, solver):
     try:
@@ -1209,4 +1217,29 @@ class PyDemon(Demon):
   def DebugString(self):
     return "PyDemon"
 
+
+class PyLns(BaseLNS):
+
+  def __init__(self, vars):
+    BaseLNS.__init__(self, vars)
+
+  def NextFragment(self):
+    print 'in PyLns.NextFragment'
+    return []
+
+  def InitFragments(self):
+    print 'in PyLns.InitFragments'
+    pass
+
+  def NextFragmentWrapper(self, fragment):
+    print 'in PyLns.NextFragmentWrapper'
+    print 'in NextFragmentWrapper'
+    fragment.clear()
+    f = self.NextFragment()
+    if not f:
+      return False
+    else:
+      for v in f:
+        fragment.push_back(v)
+      return True
 }