1 files changed, 88 insertions, 0 deletions
diff --git a/src/main/kotlin/pl/treksoft/kvision/state/StateBinding.kt b/src/main/kotlin/pl/treksoft/kvision/state/StateBinding.kt
new file mode 100644
index 00000000..7df82adc
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+++ b/src/main/kotlin/pl/treksoft/kvision/state/StateBinding.kt
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2019. Robert Jaros
+ */
+package pl.treksoft.kvision.state
+
+import pl.treksoft.kvision.core.Container
+import pl.treksoft.kvision.core.Widget
+
+/**
+ * A class which binds the given container to the observable state.
+ *
+ * @constructor Creates StateBinding which binds the given container to the observable state.
+ * @param S the state type
+ * @param CONT container type
+ * @param observableState the state
+ * @param container the container
+ * @param factory a function which re-creates the view based on the given state
+ */
+class StateBinding<S : Any, CONT : Container, CONTENT>(
+    observableState: ObservableState<S>,
+    private val container: CONT,
+    private val factory: (CONT.(S) -> CONTENT)
+) : Widget(setOf()) {
+
+    init {
+        observableState.subscribe { update(it) }
+    }
+
+    private var updateState: ((S, CONTENT) -> Unit)? = null
+    private var content: CONTENT? = null
+
+    /**
+     * Updates view based on the current state.
+     */
+    @Suppress("ComplexMethod")
+    fun update(state: S) {
+        singleRender {
+            if (updateState == null || content == null) {
+                container.removeAll()
+                container.add(this)
+                content = container.factory(state)
+            } else {
+                content?.let {
+                    updateState?.invoke(state, it)
+                }
+            }
+        }
+    }
+
+    private fun setUpdateState(updateState: (S, CONTENT) -> Unit) {
+        this.updateState = updateState
+    }
+
+    companion object {
+        /**
+         * DSL builder extension function.
+         *
+         * It takes the same parameters as the constructor of the built component.
+         */
+        fun <S : Any, CONT : Container> CONT.stateBinding(
+            observableState: ObservableState<S>,
+            factory: (CONT.(S) -> Unit)
+        ): StateBinding<S, CONT, Unit> {
+            return StateBinding(observableState, this, factory)
+        }
+
+        /**
+         * DSL builder extension function for updateable redux content.
+         *
+         * It takes the same parameters as the constructor of the built component.
+         */
+        fun <S : Any, CONT : Container, CONTENT> CONT.stateUpdate(
+            observableState: ObservableState<S>,
+            factory: (CONT.(S) -> CONTENT)
+        ): Updateable<S, CONTENT> {
+            return Updateable(StateBinding(observableState, this, factory)::setUpdateState)
+        }
+    }
+}
+
+/**
+ * A helper class for updateable content.
+ */
+class Updateable<S : Any, CONTENT>(private val setUpdateState: ((S, CONTENT) -> Unit) -> Unit) {
+    infix fun updateWith(updateState: (S, CONTENT) -> Unit) {
+        setUpdateState(updateState)
+    }
+}