PreferenceGroup.kt
/*
* Copyright 2018 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.
*/
@file:Suppress("NOTHING_TO_INLINE")
package androidx.preference
/**
* Returns the preference with `key`, or `null` if no preference with `key` is found.
*/
public inline operator fun <T : Preference> PreferenceGroup.get(key: CharSequence): T? =
findPreference(key)
/**
* Returns the preference at `index`.
*
* @throws IndexOutOfBoundsException if index is less than 0 or greater than or equal to the count.
*/
public operator fun PreferenceGroup.get(index: Int): Preference = getPreference(index)
/** Returns `true` if `preference` is found in this preference group. */
public operator fun PreferenceGroup.contains(preference: Preference): Boolean {
for (index in 0 until preferenceCount) {
if (getPreference(index) == preference) {
return true
}
}
return false
}
/** Adds `preference` to this preference group. */
public inline operator fun PreferenceGroup.plusAssign(preference: Preference) {
addPreference(preference)
}
/** Removes `preference` from this preference group. */
public inline operator fun PreferenceGroup.minusAssign(preference: Preference) {
removePreference(preference)
}
/** Returns the number of preferences in this preference group. */
public inline val PreferenceGroup.size: Int get() = preferenceCount
/** Returns true if this preference group contains no preferences. */
public inline fun PreferenceGroup.isEmpty(): Boolean = size == 0
/** Returns true if this preference group contains one or more preferences. */
public inline fun PreferenceGroup.isNotEmpty(): Boolean = size != 0
/** Performs the given action on each preference in this preference group. */
public inline fun PreferenceGroup.forEach(action: (preference: Preference) -> Unit) {
for (index in 0 until preferenceCount) {
action(get(index))
}
}
/**
* Performs the given action on each preference in this preference group,
* providing its sequential index.
*/
public inline fun PreferenceGroup.forEachIndexed(
action: (index: Int, preference: Preference) -> Unit
) {
for (index in 0 until preferenceCount) {
action(index, get(index))
}
}
/** Returns a [MutableIterator] over the preferences in this preference group. */
public operator fun PreferenceGroup.iterator(): Iterator<Preference> =
object : MutableIterator<Preference> {
private var index = 0
override fun hasNext() = index < size
override fun next() = getPreference(index++)
override fun remove() {
removePreference(getPreference(--index))
}
}
/** Returns a [Sequence] over the preferences in this preference group. */
public val PreferenceGroup.children: Sequence<Preference>
get() = object : Sequence<Preference> {
override fun iterator() = this@children.iterator()
}