framework/fsm/transition.go

// Copyright (C) 2016 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package fsm

type internalEvent string

const (
	// Next is the event attempted if a state exits with no pending transition
	Next internalEvent = "next"
	// exit is the event generated by a controller quitting with an error
	controllerError internalEvent = "exit"
)

// Event is the type for events that get delivered to the state machine, causing transitions.
type Event interface{}

// Transition describes a set of possible transitions in an fsm.
// When being compiled, this will generate one CompiledTransition per state this Transition matches.
type Transition struct {
	// From matches all the states this transition is allowed to start in.
	// See Match for details on how this is used.
	From interface{}
	// Event is the event that triggers this transition.
	Event Event
	// To is the state this should transition to.
	To StateID
}

// CompiledTransition is a compiled Transition.
type CompiledTransition struct {
	// From is the state this transition comes from.
	From *CompiledState
	// Event is the event that triggers this transition.
	Event Event
	// To is the state this should transition to.
	To *CompiledState
	// Hooks are the hooks to invoke when this transition occurs.
	Hooks []HookBuilder
}

// runningTransition is a transition entry in a runningState
type runningTransition struct {
	to    *runningState
	hooks []HookFunc
}