1 files changed, 50 insertions, 0 deletions
diff --git a/core/src/main/kotlin/ca/allanwang/kau/kotlin/LazyContext.kt b/core/src/main/kotlin/ca/allanwang/kau/kotlin/LazyContext.kt
new file mode 100644
index 0000000..8b59539
--- /dev/null
+++ b/core/src/main/kotlin/ca/allanwang/kau/kotlin/LazyContext.kt
@@ -0,0 +1,50 @@
+package ca.allanwang.kau.kotlin
+
+import android.content.Context
+import android.support.annotation.AnimatorRes
+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(@AnimatorRes id: Int) = lazyContext<Animation> { AnimationUtils.loadAnimation(it, id) }
+
+fun <T : Any> lazyContext(initializer: (context: Context) -> T): LazyContext<T> = LazyContext<T>(initializer)
+
+class LazyContext<out T : Any>(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
+            }
+        }
+    }
+
+}
+\ No newline at end of file