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package ca.allanwang.kau.kotlin
import android.content.Context
import android.support.annotation.AnimRes
import android.support.annotation.InterpolatorRes
import android.view.animation.Animation
import android.view.animation.AnimationUtils
import android.view.animation.Interpolator
/**
* Created by Allan Wang on 2017-05-30.
*
* Lazy retrieval of context based items
* Items are retrieved using delegateName(context)
*
*/
fun lazyInterpolator(@InterpolatorRes id: Int) = lazyContext<Interpolator> { AnimationUtils.loadInterpolator(it, id) }
fun lazyAnimation(@AnimRes id: Int) = lazyContext<Animation> { AnimationUtils.loadAnimation(it, id) }
fun <T> lazyContext(initializer: (context: Context) -> T): LazyContext<T> = LazyContext(initializer)
class LazyContext<out T>(private val initializer: (context: Context) -> T, lock: Any? = null) {
@Volatile
private var _value: Any? = UNINITIALIZED
private val lock = lock ?: this
fun invalidate() {
_value = UNINITIALIZED
}
operator fun invoke(context: Context): T {
val _v1 = _value
if (_v1 !== UNINITIALIZED)
@Suppress("UNCHECKED_CAST")
return _v1 as T
return synchronized(lock) {
val _v2 = _value
if (_v2 !== UNINITIALIZED) {
@Suppress("UNCHECKED_CAST")
_v2 as T
} else {
val typedValue = initializer(context)
_value = typedValue
typedValue
}
}
}
}
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