States with the gui

src/commonMain/kotlin/com/ewoudje/eggui/ContainerVerification.kt

@@ -69,6 +69,8 @@ object ContainerVerification {
         override val parent: EGGContainerParent,
         override val childId: Int
     ) : EGGFixedElement, EGGFillingElement {
+        override val attachment: EGGElementAttachment = EGGElementAttachment()
+
         override fun visit(ctx: EGGContext) {
             when (ctx.pass) {
                 is TestPass -> {

src/commonMain/kotlin/com/ewoudje/eggui/EGGPass.kt

@@ -1,6 +1,7 @@
 package com.ewoudje.eggui
 
-interface EGGPass {
-    data class Render(private val renderer: EGGRenderer) : EGGPass, EGGRenderer by renderer
-    data class BuildAssets(private val assetBuilder: EGGAssets): EGGPass, EGGAssets by assetBuilder
-}
+interface EGGPass
+interface EGGInitPass: EGGPass
+
+data class RenderPass(private val renderer: EGGRenderer) : EGGPass, EGGRenderer by renderer
+data class BuildAssetsPass(private val assetBuilder: EGGAssets): EGGInitPass, EGGAssets by assetBuilder

src/commonMain/kotlin/com/ewoudje/eggui/components/EGGComponent.kt

@@ -4,7 +4,19 @@ import com.ewoudje.eggui.*
 import com.ewoudje.eggui.frontend.EGGBuilderMarker
 
 @EGGBuilderMarker
-sealed interface EGGComponent
+sealed interface EGGComponent{
+    val attachment: EGGComponentAttachment
+}
+
+sealed interface EGGComponentAttachment
+open class EGGContainerAttachment(
+    var onEnter: (EGGPass) -> Boolean = {false},
+    var onExit: (EGGPass) -> Boolean = {false}
+): EGGComponentAttachment
+
+open class EGGElementAttachment(
+    var onVisit: (EGGPass) -> Boolean = {false}
+): EGGComponentAttachment
 
 sealed interface EGGChildComponent : EGGComponent {
     val parent: EGGContainerParent
@@ -26,6 +38,8 @@ sealed interface EGGChildComponent : EGGComponent {
 typealias EGGChildConstructor<T> = (EGGContainerParent, Int) -> T
 
 sealed interface EGGElement : EGGChildComponent {
+    override val attachment: EGGElementAttachment
+
     fun visit(context: EGGContext) {}
 }
 
@@ -38,6 +52,8 @@ sealed interface EGGContainerParent : EGGComponent {
 }
 
 sealed interface EGGContainer : EGGChildComponent, EGGContainerParent {
+    override val attachment: EGGContainerAttachment
+
     fun enter(context: EGGContext): EGGContext
     fun exit(context: EGGContext) {}
 }
@@ -67,6 +83,7 @@ interface EGGSingleContainer : EGGContainer {
 }
 
 class RootContainer : EGGContainerParent {
+    override val attachment = EGGContainerAttachment()
     var child: EGGChildComponent? = null
     var size = Size.EMPTY
 

src/commonMain/kotlin/com/ewoudje/eggui/components/containers/FixedContainer.kt

@@ -7,6 +7,7 @@ import com.ewoudje.eggui.frontend.ChildBuilder
 import com.ewoudje.eggui.frontend.EGGBuilderMarker
 
 class FixedContainer(override val parent: EGGContainerParent, override val childId: Int) : EGGSingleContainer {
+    override val attachment: EGGContainerAttachment = EGGContainerAttachment()
     override var child: EGGChildComponent? = null
         private set
     private var childSize = Size.FILL

src/commonMain/kotlin/com/ewoudje/eggui/components/containers/HorizontalContainer.kt

@@ -11,6 +11,7 @@ class HorizontalContainer(
     override val parent: EGGContainerParent,
     override val childId: Int
 ) : EGGMultipleContainer {
+    override val attachment: EGGContainerAttachment = EGGContainerAttachment()
     override val children = mutableListOf<EGGChildComponent>()
     private val sizes = mutableListOf<Size>()
 

src/commonMain/kotlin/com/ewoudje/eggui/components/containers/SquareContainer.kt

@@ -9,6 +9,7 @@ class SquareContainer(
     override val parent: EGGContainerParent,
     override val childId: Int
 ) : EGGSingleContainer {
+    override val attachment: EGGContainerAttachment = EGGContainerAttachment()
 
     override var child: EGGChildComponent? = null
         private set
@@ -21,9 +22,9 @@ class SquareContainer(
     }
 
     override fun getChildSize(): Size = childSize
-    override fun <T : EGGChildComponent> setChild(child: EGGChildConstructor<T>): T {
-        return child(this, 0).also { this.child = it }
-    }
+    override fun <T : EGGChildComponent> setChild(child: EGGChildConstructor<T>): T =
+        child(this, 0).also { this.child = it }
+
 
     override fun enter(context: EGGContext): EGGContext {
         var size = context.size

src/commonMain/kotlin/com/ewoudje/eggui/components/containers/StatefulContainer.kt

@@ -0,0 +1,78 @@
+package com.ewoudje.eggui.components.containers
+
+import com.ewoudje.eggui.*
+import com.ewoudje.eggui.components.*
+import com.ewoudje.eggui.frontend.ChildBuilder
+import com.ewoudje.eggui.frontend.EGGBuilderMarker
+import com.ewoudje.eggui.frontend.invoke
+import kotlin.reflect.KProperty
+
+class StatefulContainer(
+    val block: StatefulContainer.() -> Unit,
+    override val parent: EGGContainerParent,
+    override val childId: Int,
+): EGGSingleContainer {
+    override val attachment: EGGContainerAttachment = EGGContainerAttachment()
+    override var child: EGGChildComponent? = null
+        private set
+    private var childSize = Size.FILL
+    private val map = mutableMapOf<KProperty<*>, Any?>()
+    private val inits = mutableListOf<EGGInitPass>()
+    private var dirty = false
+
+    override fun <T : EGGChildComponent> setChild(child: EGGChildConstructor<T>): T =
+        child(this, 0).also { this.child = it }
+
+    override fun updateChildSize(size: Size) {
+        this.childSize = size
+    }
+
+    override fun getChildSize(): Size = childSize
+
+    override fun enter(context: EGGContext): EGGContext {
+        if (dirty) updateChild(context.position, context.size)
+        return context.new(listOf(context.position), listOf(context.size))
+    }
+
+    fun <T> newState(v: T) = StatePreparer(v, this)
+
+    private fun updateChild(pos: Pos, size: CalculatedSize) {
+        child = null
+        block()
+
+        child?.let {
+            for (pass in inits) {
+                EGGContext.traverse(it, EGGContext(listOf(pos), listOf(size), pass))
+            }
+        }
+        dirty = false
+    }
+
+    class StatePreparer<T>(private val defaultVal: T, private val container: StatefulContainer) {
+        operator fun provideDelegate(
+            thisRef: Any?,
+            prop: KProperty<*>
+        ): State<T> {
+            val value = (container.map[prop] ?: defaultVal) as T
+            return State(value, container)
+        }
+    }
+
+    class State<T>(
+        private var value: T,
+        private val container: StatefulContainer
+    ) {
+        operator fun getValue(thisRef: Any?, property: KProperty<*>): T = value
+        operator fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
+            this.value = value
+            container.map[property] = value
+            container.dirty = true
+        }
+    }
+}
+
+
+
+@EGGBuilderMarker
+fun <T: EGGContainer> T.stateful(block: StatefulContainer.() -> Unit): Unit =
+    ChildBuilder(this) { parent, id -> StatefulContainer(block, parent, id) }.invoke { block() }

src/commonMain/kotlin/com/ewoudje/eggui/components/containers/VerticalContainer.kt

@@ -11,6 +11,7 @@ class VerticalContainer(
     override val parent: EGGContainerParent,
     override val childId: Int
 ) : EGGMultipleContainer {
+    override val attachment: EGGContainerAttachment = EGGContainerAttachment()
     override val children = mutableListOf<EGGChildComponent>()
     private val sizes = mutableListOf<Size>()
 

src/commonMain/kotlin/com/ewoudje/eggui/components/elements/RectangleElement.kt

@@ -1,10 +1,7 @@
 package com.ewoudje.eggui.components.elements
 
 import com.ewoudje.eggui.*
-import com.ewoudje.eggui.components.EGGContainer
-import com.ewoudje.eggui.components.EGGContainerParent
-import com.ewoudje.eggui.components.EGGFillingElement
-import com.ewoudje.eggui.components.EGGFixedElement
+import com.ewoudje.eggui.components.*
 import com.ewoudje.eggui.frontend.ChildBuilder
 import com.ewoudje.eggui.frontend.EGGBuilderMarker
 import java.util.UUID
@@ -13,11 +10,13 @@ import kotlin.random.Random
 data class RectangleAsset(val size: CalculatedSize, val color: Int): EGGRenderAsset
 
 class RectangleElement(override val parent: EGGContainerParent, override val childId: Int) : EGGFillingElement, EGGFixedElement {
+    override val attachment: EGGElementAttachment = EGGElementAttachment()
+
     var color = 0
 
     override fun visit(context: EGGContext) {
         when (context.pass) {
-            is EGGPass.Render -> {
+            is RenderPass -> {
                 val renderer = context.pass
                 renderer.renderAsset(RectangleAsset(context.size, color), context.position)
             }
@@ -28,8 +27,4 @@ class RectangleElement(override val parent: EGGContainerParent, override val chi
 
 @EGGBuilderMarker
 val <T: EGGContainer> T.rectangle get() =
-    ChildBuilder(this, ::RectangleElement)
-
-@EGGBuilderMarker
-fun <T: EGGContainer> T.rectangle(color: Int = Random.nextInt()) =
-    ChildBuilder(this, ::RectangleElement).wrap { it.color = color }
+    ChildBuilder(this, ::RectangleElement)

src/commonMain/kotlin/com/ewoudje/eggui/frontend/EGGBuilder.kt

@@ -6,7 +6,7 @@ import com.ewoudje.eggui.components.*
 annotation class EGGBuilderMarker
 
 @EGGBuilderMarker
-class ChildBuilder< C: EGGContainer, T: EGGComponent>(
+class ChildBuilder<C: EGGContainer, T: EGGComponent>(
     val parent: C,
     val constructor: EGGChildConstructor<T>
 ) {
@@ -33,4 +33,16 @@ operator fun <C, T> ChildBuilder<C, T>.invoke(block: T.() -> Unit): Unit
 operator fun <C, T> ChildBuilder<C, T>.invoke(block: T.() -> Unit): Unit
         where C: EGGSingleContainer,
               T: EGGChildComponent
-        = parent.setChild(constructor).block()
+        = parent.setChild(constructor).block()
+
+
+@EGGBuilderMarker
+@JvmName("unknownContainerInvoke")
+operator fun <C, T> ChildBuilder<C, T>.invoke(block: T.() -> Unit): Unit
+        where C: EGGContainer,
+              T: EGGChildComponent
+        = when(parent) {
+            is EGGMultipleContainer -> parent.addChild(constructor).block()
+            is EGGSingleContainer -> parent.setChild(constructor).block()
+            else -> throw IllegalStateException("Unknown container type")
+        }

src/commonMain/kotlin/com/ewoudje/eggui/frontend/EGGCompiler.kt

@@ -47,6 +47,9 @@ private class Trace {
 private fun traverse(comp: EGGComponent, ctx: EGGContext, trace: Trace) {
     when (comp) {
         is EGGMultipleContainer -> {
+
+            if (comp.attachment.onEnter(ctx.pass)) return
+
             val newCtx = try {
                 comp.enter(ctx)
             } catch (e: Exception) {
@@ -62,9 +65,13 @@ private fun traverse(comp: EGGComponent, ctx: EGGContext, trace: Trace) {
                 throw trace.exitError(e, comp)
             }
 
+            if (comp.attachment.onExit(ctx.pass)) return
+
             trace.exit(comp)
         }
         is EGGSingleContainer -> {
+            if (comp.attachment.onEnter(ctx.pass)) return
+
             val newCtx = try {
                 comp.enter(ctx)
             } catch (e: Exception) {
@@ -74,6 +81,8 @@ private fun traverse(comp: EGGComponent, ctx: EGGContext, trace: Trace) {
             trace.enter(comp)
             comp.child?.let { traverse(it, newCtx, trace) }
 
+            if (comp.attachment.onExit(ctx.pass)) return
+
             try {
                 comp.exit(newCtx)
             } catch (e: Exception) {
@@ -83,6 +92,7 @@ private fun traverse(comp: EGGComponent, ctx: EGGContext, trace: Trace) {
         }
         is EGGElement -> {
             try {
+                if (comp.attachment.onVisit(ctx.pass)) return
                 comp.visit(ctx)
             } catch (e: Exception) {
                 throw trace.visitError(e, comp)

src/commonMain/kotlin/com/ewoudje/eggui/frontend/EGGEvents.kt

@@ -0,0 +1,20 @@
+package com.ewoudje.eggui.frontend
+
+import com.ewoudje.eggui.EGGPass
+import com.ewoudje.eggui.components.EGGContainer
+import com.ewoudje.eggui.components.EGGElement
+
+fun EGGContainer.catchEnter(block: (EGGPass) -> Boolean) {
+    val visit = attachment.onEnter
+    attachment.onEnter = { block(it) || visit(it) }
+}
+
+fun EGGContainer.catchExit(block: (EGGPass) -> Boolean) {
+    val visit = attachment.onExit
+    attachment.onExit = { block(it) || visit(it) }
+}
+
+fun EGGElement.catchVisit(block: (EGGPass) -> Boolean): Unit {
+    val visit = attachment.onVisit
+    attachment.onVisit = { block(it) || visit(it) }
+}