New ObservableValue class

1 files changed, 52 insertions, 0 deletions

diff --git a/src/main/kotlin/pl/treksoft/kvision/state/ObservableValue.kt b/src/main/kotlin/pl/treksoft/kvision/state/ObservableValue.kt
new file mode 100644
index 00000000..32fb07cc
--- /dev/null
+++ b/src/main/kotlin/pl/treksoft/kvision/state/ObservableValue.kt
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2017-present Robert Jaros
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package pl.treksoft.kvision.state
+
+import kotlin.properties.Delegates
+
+/**
+ * The observable value class.
+ * @param value the initial value
+ */
+class ObservableValue<T>(value: T) : ObservableState<T> {
+    private val observers = mutableListOf<(T) -> Unit>()
+
+    /**
+     * The observed variable.
+     */
+    var value: T by Delegates.observable(value) { _, _, new ->
+        observers.forEach { it(new) }
+    }
+
+    override fun getState(): T {
+        return value
+    }
+
+    override fun subscribe(observer: (T) -> Unit): () -> Unit {
+        observers += observer
+        observer(value)
+        return {
+            observers -= observer
+        }
+    }
+}