IndexBasedArrayIterator.kt
/*
* Copyright 2020 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 androidx.collection
internal abstract class IndexBasedArrayIterator<T>(startingSize: Int) : MutableIterator<T> {
private var size = startingSize
private var index = 0
private var canRemove = false
protected abstract fun elementAt(index: Int): T
protected abstract fun removeAt(index: Int)
override fun hasNext(): Boolean = index < size
override fun next(): T {
if (!hasNext()) {
throw NoSuchElementException()
}
val res = elementAt(index)
index++
canRemove = true
return res
}
override fun remove() {
check(canRemove) { "Call next() before removing an element." }
// Attempt removal first so an UnsupportedOperationException retains a valid state.
removeAt(--index)
size--
canRemove = false
}
}