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StackNav.kt
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StackNav.kt
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/*
* Copyright 2021 Google LLC
*
* 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 com.tunjid.treenav
/**
* An immutable navigation [Node] whose children are represented with a stack like data structure
*/
data class StackNav(
val name: String,
override val children: List<Node> = listOf()
) : Node {
override val id: String get() = name
}
/**
* Swaps the top of the stack with the specified [Node]
*/
fun StackNav.swap(node: Node): StackNav =
if (children.lastOrNull() == node) this
else copy(children = children.dropLast(1) + node)
/**
* Pushes the [node] unto the top of the navigation stack if [current] is not equal to [node]
*/
fun StackNav.push(node: Node): StackNav =
if (children.lastOrNull() == node) this
else copy(children = children + node)
/**
* Pops the top node off if the stack is larger than 1 or [popLast] is true, otherwise it no ops
*/
fun StackNav.pop(popLast: Boolean = false) = when {
children.size == 1 && !popLast -> this
else -> copy(children = children.dropLast(1))
}
/**
* Indicates if there's a [Node] available to pop up to
*/
val StackNav.canPop get() = children.size > 1
val StackNav.current get() = children.lastOrNull()