iterator.go

/*
Open Source Initiative OSI - The MIT License (MIT):Licensing

The MIT License (MIT)
Copyright (c) 2013 - 2022 Ralph Caraveo (deckarep@gmail.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

package mapset

// Iterator defines an iterator over a Set, its C channel can be used to range over the Set's
// elements.
type Iterator[T comparable] struct {
	C    <-chan T
	stop chan struct{}
}

// Stop stops the Iterator, no further elements will be received on C, C will be closed.
func (i *Iterator[T]) Stop() {
	// Allows for Stop() to be called multiple times
	// (close() panics when called on already closed channel)
	defer func() {
		recover()
	}()

	close(i.stop)

	// Exhaust any remaining elements.
	for range i.C {
	}
}

// newIterator returns a new Iterator instance together with its item and stop channels.
func newIterator[T comparable]() (*Iterator[T], chan<- T, <-chan struct{}) {
	itemChan := make(chan T)
	stopChan := make(chan struct{})
	return &Iterator[T]{
		C:    itemChan,
		stop: stopChan,
	}, itemChan, stopChan
}