any.go

/*
   Copyright 2021 Joseph Cumines

   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 behaviortree

import "sync"

// Any wraps a tick such that non-error non-running statuses will be overridden with a success if at least one child
// succeeded - which is achieved by encapsulation of children, before passing them into the wrapped tick. Nil will be
// returned if tick is nil, and nil children will be passed through as such.
func Any(tick Tick) Tick {
	if tick == nil {
		return nil
	}
	var (
		mutex   sync.Mutex
		success bool
	)
	return func(children []Node) (Status, error) {
		children = copyNodes(children)
		for i := range children {
			child := children[i]
			if child == nil {
				continue
			}
			children[i] = func() (Tick, []Node) {
				tick, nodes := child()
				if tick == nil {
					return nil, nodes
				}
				return func(children []Node) (Status, error) {
					status, err := tick(children)
					if err == nil && status == Success {
						mutex.Lock()
						success = true
						mutex.Unlock()
					}
					return status, err
				}, nodes
			}
		}
		status, err := tick(children)
		if err != nil {
			return Failure, err
		}
		if status == Running {
			return Running, nil
		}
		mutex.Lock()
		defer mutex.Unlock()
		if !success {
			return Failure, nil
		}
		success = false
		return Success, nil
	}
}

func copyNodes(src []Node) (dst []Node) {
	if src == nil {
		return
	}
	dst = make([]Node, len(src))
	copy(dst, src)
	return
}