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implementation.go
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implementation.go
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// Copyright 2018 Shift Devices AG
//
// 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 observable
import "github.com/digitalbitbox/bitbox-wallet-app/util/locker"
// Implementation can be embedded in implementations that are observable.
type Implementation struct {
counter int
observers map[int]func(Event)
observersLock locker.Locker
}
// Observe implements observable.Observe.
func (implementation *Implementation) Observe(observer func(Event)) func() {
defer implementation.observersLock.Lock()()
if implementation.observers == nil {
implementation.observers = make(map[int]func(Event))
}
// We need a variable for the returned function.
counter := implementation.counter
implementation.observers[counter] = observer
implementation.counter = counter + 1
return func() {
defer implementation.observersLock.Lock()()
delete(implementation.observers, counter)
}
}
// Notify notifies the registered observers about the given event.
// This method should only be called from the implementation itself.
func (implementation *Implementation) Notify(event Event) {
defer implementation.observersLock.RLock()()
for _, observer := range implementation.observers {
observer(event)
}
}