lib/solve.rb in solve-1.2.1 vs lib/solve.rb in solve-2.0.0

@@ -5,16 +5,46 @@
   require_relative 'solve/demand'
   require_relative 'solve/dependency'
   require_relative 'solve/version'
   require_relative 'solve/errors'
   require_relative 'solve/graph'
-  require_relative 'solve/solver'
+  require_relative 'solve/ruby_solver'
+  require_relative 'solve/gecode_solver'
 
   class << self
     # @return [Solve::Formatter]
     attr_reader :tracer
 
+    @engine = :ruby
+
+    # Returns the currently configured engine.
+    # @see #engine=
+    # @return [Symbol]
+    attr_reader :engine
+
+
+    # Sets the solving backend engine. Solve supports 2 engines:
+    # * `:ruby` - Molinillo, a pure ruby solver
+    # * `:gecode` - dep-selector, a wrapper around the Gecode CSP solver library
+    #
+    # Note that dep-selector is an optional dependency and may therefore not be
+    # available.
+    #
+    # @param [Symbol] selected_engine
+    # @return [Symbol] selected_engine
+    # @raise [Solve::Errors::EngineNotAvailable] when the selected engine's deps aren't installed.
+    # @raise [Solve::Errors::InvalidEngine] when `selected_engine` is invalid.
+    def engine=(selected_engine)
+      engine_class = solver_for_engine(selected_engine)
+      if engine_class.nil?
+        raise Errors::InvalidEngine, "Engine `#{selected_engine}` is not supported. Valid values are `:ruby`, `:gecode`"
+      else
+        engine_class.activate
+      end
+      @engine = selected_engine
+    end
+
     # A quick solve. Given the "world" as we know it (the graph) and a list of
     # requirements (demands) which must be met. Return me the best solution of
     # artifacts and verisons that I should use.
     #
     # If a ui object is passed in, the resolution will be traced
@@ -27,9 +57,20 @@
     #
     # @raise [NoSolutionError]
     #
     # @return [Hash]
     def it!(graph, demands, options = {})
-      Solver.new(graph, demands).resolve(options)
+      solver_for_engine(engine).new(graph, demands, options).resolve(options)
     end
+
+    def solver_for_engine(engine_name)
+      case engine_name
+      when :ruby
+        RubySolver
+      when :gecode
+        GecodeSolver
+      end
+    end
+
+    private :solver_for_engine
   end
 end