core/ktx/src/main/java/androidx/core/content/Context.kt

/*
 * Copyright (C) 2017 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.core.content

import android.content.Context
import android.content.res.TypedArray
import android.util.AttributeSet
import androidx.annotation.AttrRes
import androidx.annotation.StyleRes

/**
 * Return the handle to a system-level service by class.
 *
 * The return type of this function intentionally uses a
 * [platform type](https://kotlinlang.org/docs/reference/java-interop.html#null-safety-and-platform-types)
 * to allow callers to decide whether they require a service be present or can tolerate its absence.
 *
 * @see Context.getSystemService(Class)
 */
inline fun <reified T> Context.getSystemService(): T? =
        ContextCompat.getSystemService(this, T::class.java)

/**
 * Executes [block] on a [TypedArray] receiver. The [TypedArray] holds the attribute
 * values in [set] that are listed in [attrs]. In addition, if the given [AttributeSet]
 * specifies a style class (through the `style` attribute), that style will be applied
 * on top of the base attributes it defines.
 *
 * @param set The base set of attribute values.
 * @param attrs The desired attributes to be retrieved. These attribute IDs must be
 *              sorted in ascending order.
 * @param defStyleAttr An attribute in the current theme that contains a reference to
 *                     a style resource that supplies defaults values for the [TypedArray].
 *                     Can be 0 to not look for defaults.
 * @param defStyleRes A resource identifier of a style resource that supplies default values
 *                    for the [TypedArray], used only if [defStyleAttr] is 0 or can not be found
 *                     in the theme. Can be 0 to not look for defaults.
 *
 * @see Context.obtainStyledAttributes
 * @see android.content.res.Resources.Theme.obtainStyledAttributes
 */
inline fun Context.withStyledAttributes(
    set: AttributeSet? = null,
    attrs: IntArray,
    @AttrRes defStyleAttr: Int = 0,
    @StyleRes defStyleRes: Int = 0,
    block: TypedArray.() -> Unit
) {
    obtainStyledAttributes(set, attrs, defStyleAttr, defStyleRes).apply(block).recycle()
}

/**
 * Executes [block] on a [TypedArray] receiver. The [TypedArray] holds the the values
 * defined by the style resource [resourceId] which are listed in [attrs].
 *
 * @param attrs The desired attributes. These attribute IDs must be sorted in ascending order.
 *
 * @see Context.obtainStyledAttributes
 * @see android.content.res.Resources.Theme.obtainStyledAttributes
 */
inline fun Context.withStyledAttributes(
    @StyleRes resourceId: Int,
    attrs: IntArray,
    block: TypedArray.() -> Unit
) {
    obtainStyledAttributes(resourceId, attrs).apply(block).recycle()
}