search.rb in gecoder-0.3.0

- old
+ new
@@ -10,14 +10,51 @@
 
     # Finds the first solution to the modelled problem and updates the variables
     # to that solution. Returns the model if a solution was found, nil 
     # otherwise.
     def solve!
-      stop = Gecode::Raw::Search::Stop.new
-      dfs = Gecode::Raw::DFS.new(@base_space, COPY_DIST, ADAPTATION_DIST, stop)
-      space = dfs.next
+      space = dfs_engine.next
       return nil if space.nil?
       @active_space = space
       return self
+    end
+    
+    # Returns to the original state, before any search was made (but propagation 
+    # might have been performed). Returns the reset model.
+    def reset!
+      @active_space = base_space
+      return self
+    end
+    
+    # Yields the first solution (if any) to the block. If no solution is found
+    # then the block is not used. Returns the result of the block (nil in case
+    # the block wasn't run). 
+    def solution(&block)
+      solution = self.solve!
+      res = yield solution unless solution.nil?
+      self.reset!
+      return res
+    end
+    
+    # Yields each solution that the model has.
+    def each_solution(&block)
+      dfs = dfs_engine
+      while not (@active_space = dfs.next).nil?
+        yield self
+      end
+      self.reset!
+    end
+    
+    private
+    
+    # Creates an DFS engine for the search, executing any unexecuted 
+    # constraints first.
+    def dfs_engine
+      # Execute constraints.
+      constraints.each{ |con| con.post }
+      constraints.clear # Empty the queue.
+    
+      stop = Gecode::Raw::Search::Stop.new
+      Gecode::Raw::DFS.new(active_space, COPY_DIST, ADAPTATION_DIST, stop)
     end
   end
 end