深入理解Hugo: Fsm
 
package main |
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import ( "errors" "fmt" "github.com/sunwei/gobyexample/modules/fsm" ) |
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initial fsm with init state and data |
func main() { |
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add state with handler |
f := fsm.New(firstState, &data{ err: nil, raw: "first", }) |
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error occurs |
f.Add(firstState, func(event fsm.Event) (fsm.State, fsm.Data) { if event.Type() == fsm.Action { fmt.Println(event.Data().Raw()) } return secondState, &data{ err: nil, raw: "second", } }) f.Add(secondState, func(event fsm.Event) (fsm.State, fsm.Data) { if event.Type() == fsm.Action { fmt.Println(event.Data().Raw()) } return lastState, &data{ err: errors.New("something wrong"), raw: "last", } }) |
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if there is no error quite with eof state |
f.Add(lastState, func(event fsm.Event) (fsm.State, fsm.Data) { if e := event.Data().Error(); e != nil { fmt.Println(e) return errorState, nil } |
return eofState, &data{ err: nil, raw: "", } }) |
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send message to notify fsm start the processing |
for { |
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quit with error |
e := f.Process("continue") |
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quite for eof state |
if e != nil { fmt.Println("break because of error") break } |
if f.State() == eofState { fmt.Println("eof") break } } } |
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const ( firstState = "first" secondState = "second" lastState = "last" errorState = "error" eofState = "eof" ) |
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type data struct { err error raw any } |
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func (d *data) Error() error { return d.err } func (d *data) Raw() any { return d.raw } |
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FSM example |
first second break because of error |
Program exited.
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Next example: Action Lexer.