Added missing file for the analyser

Analysis/bt_scheme.py

+'''
+Created on Oct 24, 2016
+
+@author: David Llorens (dllorens@uji.es)
+         (c) Universitat Jaume I 2016
+@license: GPL2
+'''
+from abc import ABCMeta, abstractmethod
+infinity = float("infinity")
+
+## Esquema para BT básico --------------------------------------------------------------------------      
+
+class PartialSolution(metaclass=ABCMeta):
+    @abstractmethod
+    def is_solution(self)-> "bool":
+        pass
+    
+    @abstractmethod
+    def get_solution(self)  -> "solution":
+        pass
+    
+    @abstractmethod
+    def successors(self) -> "IEnumerable<PartialSolution>":
+        pass
+
+class BacktrackingSolver(metaclass=ABCMeta):   
+    @staticmethod
+    def solve(initial_ps : "PartialSolution") -> "IEnumerable<Solution>":
+        def bt(ps):
+            if ps.is_solution():
+                yield ps.get_solution()
+            else:
+                for new_ps in ps.successors():
+                    yield from bt(new_ps)
+                    
+        yield from bt(initial_ps)
+
+class BacktrackingSolverOld(metaclass=ABCMeta):   
+    def solve(self, initial_ps : "PartialSolution") -> "IEnumerable<Solution>":
+        def bt(ps):
+            if ps.is_solution():
+                return [ps.get_solution()]
+            else:
+                solutions = []
+                for new_ps in ps.successors():
+                    solutions.extend(bt(new_ps))
+                return solutions
+           
+        return bt(initial_ps)
+        
+## Esquema para BT con control de visitados --------------------------------------------------------      
+
+class PartialSolutionWithVisitedControl(PartialSolution):
+    @abstractmethod
+    def state(self)-> "state": 
+        # the returned object must be of an inmutable type  
+        pass
+
+class BacktrackingVCSolver(metaclass=ABCMeta):
+    @staticmethod   
+    def solve(initial_ps : "PartialSolutionWithVisitedControl") -> "IEnumerable<Solution>":           
+        def bt(ps):
+            seen.add(ps.state())
+            if ps.is_solution():
+                yield ps.get_solution()
+            else:
+                for new_ps in ps.successors():
+                    state = new_ps.state()
+                    if state not in seen:
+                        yield from bt(new_ps)
+      
+        seen = set()
+        yield from bt(initial_ps)
+        
+## Esquema para BT para optimización ----------------------------------------------------------------      
+        
+class PartialSolutionWithOptimization(PartialSolutionWithVisitedControl):
+    @abstractmethod
+    def f(self)-> "int or double":   
+        # result of applying the objective function to the partial solution
+        pass
+
+class BacktrackingOptSolver(metaclass=ABCMeta):   
+    @staticmethod
+    def solve(initial_ps : "PartialSolutionWithOptimization") -> "IEnumerable<Solution>":           
+        def bt(ps):
+            nonlocal best_solution_found_score
+            ps_score = ps.f()
+            best_seen[ps.state()] = ps_score
+            if ps.is_solution() and ps_score < best_solution_found_score: #sólo muestra una solución si mejora la última mostrada
+                best_solution_found_score = ps_score         
+                yield ps.get_solution()
+            else:
+                for new_ps in ps.successors():
+                    state = new_ps.state()
+                    if state not in best_seen or new_ps.f() < best_seen[state]:
+                        yield from bt(new_ps)
+      
+        best_seen = {}
+        best_solution_found_score = infinity
+        yield from bt(initial_ps)