State machine

Ploop-state.lua

package.path = package.path .. ";../?/init.lua;../?.lua"
require "PLoop"(function (_ENV)

  class "__State_Machine__" (function(_ENV)
    extend "IApplyAttribute"

    function ApplyAttribute(self, target, targettype, manager, owner, name, stack)
        if manager then
            Environment.Apply(manager, function(_ENV)
                property "State" { default = self.State }
            end)
        end
    end

    property "AttributeTarget" { default = AttributeTargets.Interface + AttributeTargets.Class }

    property "State" { }
    -- TODO allowed states
  end)

  class "__State__"(function(_ENV)
    extend "IInitAttribute"


    function InitDefinition(self, target, targettype, definition, owner, name, stack)
      return function (o, ...)
        print(o .. " [" .. (o.State or "nil") .. "] --> [" .. (self.To or "nil") .. "]")
        if o.State == self.From then
          definition(o, ...) 
          print(" [" .. (o.State or "nil") .. "] --> [" .. (self.To or "nil") .. "]")
          o.State = self.To
        else
          throw("Cannot start with a state [" .. (o.State or "nil") .. "], expected state [" .. (self.From or "nil") .. "]")
        end
      end
    end

    property "From" {}
    property "To" {}
  end)

  __State_Machine__{ State = "Start" }
  class "MyMachine"(function(_ENV)
    __State__{ From = "Start", To = "Stop" }
    function SetState()
    end
  end)
  local instance = MyMachine()
  print("iz "..instance.State)
  MyMachine:SetState()
  MyMachine:SetState()


end)

require "PLoop"(function (_ENV)

  class "__State_Machine__" (function(_ENV)
    extend "IApplyAttribute"

    function ApplyAttribute(self, target, targettype, manager, owner, name, stack)
      -- make the self not the upvalue of the anonymous function, so it can be collcted
      -- but in this example, use self.State is ok, since the anonymous function will also be collcted
      local defaultState = self.State

        Environment.Apply(manager, function(_ENV)
            property "State" { default = defaultState }
        end)
    end

    property "AttributeTarget" { default = AttributeTargets.Interface + AttributeTargets.Class }

    property "State" { }
    -- TODO allowed states
  end)

  class "__State__"(function(_ENV)
    extend "IInitAttribute"


    function InitDefinition(self, target, targettype, definition, owner, name, stack)
      -- Since the anonymous function won't be collcted, don't use self in it, that will make the
      -- attr object can't be collected.
      local from = self.From
      local to = self.To

      return function (self, ...)
        print(tostring(self) .. " [" .. (self.State or "nil") .. "] --> [" .. (to or "nil") .. "]")

        if self.State == from then
          definition(self, ...)

          print(" [" .. (self.State or "nil") .. "] --> [" .. (to or "nil") .. "]")
          self.State = to
        else
          -- Throw will use an object as error, but it can only be catched by a pcall/xpcall,
          -- Here the stack is clear, so, just use the error is ok
          error("Cannot start with a state [" .. (self.State or "nil") .. "], expected state [" .. (from or "nil") .. "]", 2)
        end
      end
    end

    property "From" {}
    property "To" {}
  end)

  __State_Machine__{ State = "Start" }
  class "MyMachine"(function(_ENV)
    __State__{ From = "Start", To = "Stop" }
    function SetState()
    end
  end)

  local instance = MyMachine()
  print("iz "..instance.State)
  instance:SetState()
  instance:SetState()


end)