v. 1.0.1 - Added error handler and default error handling.

Took 1 hour 47 minutes

src/jsMain/kotlin/nl/astraeus/komp/ElementExtentions.kt

@@ -152,3 +152,15 @@ internal fun Element.getKompEvents(): MutableMap<String, (Event) -> Unit> {
   return this.asDynamic()["komp-events"] ?: mutableMapOf()
 }
 
+internal fun Element.findElementIndex(): Int {
+  val childNodes = parentElement?.children
+  if (childNodes != null) {
+    for (index in 0 until childNodes.length) {
+      if (childNodes[index] == this) {
+        return index
+      }
+    }
+  }
+
+  return 0
+}

src/jsMain/kotlin/nl/astraeus/komp/HtmlBuilder.kt

@@ -73,11 +73,13 @@ private fun ArrayList<ElementIndex>.replace(new: Node) {
 private fun Node.asElement() = this as? HTMLElement
 
 class HtmlBuilder(
+  val komponent: Komponent?,
   parent: Element,
-  childIndex: Int = 0
+  childIndex: Int = 0,
 ) : HtmlConsumer {
   private var currentPosition = arrayListOf<ElementIndex>()
   private var inDebug = false
+  private var exceptionThrown = false
   var currentNode: Node? = null
   var root: Element? = null
 
@@ -225,6 +227,10 @@ class HtmlBuilder(
   }
 
   override fun onTagEnd(tag: Tag) {
+    if (exceptionThrown) {
+      return
+    }
+
     while (currentPosition.currentElement() != null) {
       currentPosition.currentElement()?.let {
         it.parentElement?.removeChild(it)
@@ -237,31 +243,33 @@ class HtmlBuilder(
 
     currentPosition.pop()
 
-    val setAttrs: List<String> = currentElement.asDynamic()["komp-attributes"] ?: listOf()
+    if (currentElement != null) {
+      val setAttrs: List<String> = currentElement?.asDynamic()["komp-attributes"] ?: listOf()
 
-    // remove attributes that where not set
-    val element = currentElement
-    if (element?.hasAttributes() == true) {
-      for (index in 0 until element.attributes.length) {
-        val attr = element.attributes[index]
-        if (attr != null) {
+      // remove attributes that where not set
+      val element = currentElement
+      if (element?.hasAttributes() == true) {
+        for (index in 0 until element.attributes.length) {
+          val attr = element.attributes[index]
+          if (attr != null) {
 
-          if (element is HTMLElement && attr.name == "data-has-focus" && "true" == attr.value) {
-            element.focus()
-          }
+            if (element is HTMLElement && attr.name == "data-has-focus" && "true" == attr.value) {
+              element.focus()
+            }
 
-          if (attr.name != "style" && !setAttrs.contains(attr.name)) {
-            if (element is HTMLInputElement) {
-              if (attr.name == "checkbox") {
-                element.checked = false
-              } else if (attr.name == "value") {
-                element.value = ""
+            if (attr.name != "style" && !setAttrs.contains(attr.name)) {
+              if (element is HTMLInputElement) {
+                if (attr.name == "checkbox") {
+                  element.checked = false
+                } else if (attr.name == "value") {
+                  element.value = ""
+                }
+              } else {
+                if (Komponent.logReplaceEvent) {
+                  console.log("Clear attribute [${attr.name}]  on $element)")
+                }
+                element.removeAttribute(attr.name)
               }
-            } else {
-              if (Komponent.logReplaceEvent) {
-                console.log("Clear attribute [${attr.name}]  on $element)")
-              }
-              element.removeAttribute(attr.name)
             }
           }
         }
@@ -367,6 +375,43 @@ class HtmlBuilder(
     currentPosition.nextElement()
   }
 
+  override fun onTagError(tag: Tag, exception: Throwable) {
+    exceptionThrown = true
+
+    if (exception !is KomponentException) {
+      val position = mutableListOf<Element>()
+      var ce = currentElement
+      while(ce != null) {
+        position.add(ce)
+        ce = ce.parentElement
+      }
+      val builder = StringBuilder()
+      for (element in position.reversed()) {
+        builder.append("> ")
+        builder.append(element.tagName)
+        builder.append("[")
+        builder.append(element.findElementIndex())
+        builder.append("]")
+        if (element.hasAttribute("class")) {
+          builder.append("(")
+          builder.append(element.getAttribute("class"))
+          builder.append(")")
+        }
+        builder.append(" ")
+      }
+      throw KomponentException(
+        komponent,
+        currentElement,
+        tag,
+        builder.toString(),
+        exception.message ?: "error",
+        exception
+      )
+    } else {
+      throw exception
+    }
+  }
+
   override fun finalize(): Element {
     //logReplace"finalize, currentPosition: $currentPosition")
     return root ?: throw IllegalStateException("We can't finalize as there was no tags")
@@ -375,7 +420,7 @@ class HtmlBuilder(
   companion object {
     fun create(content: HtmlBuilder.() -> Unit): Element {
       val container = document.createElement("div") as HTMLElement
-      val consumer = HtmlBuilder(container, 0)
+      val consumer = HtmlBuilder(null, container, 0)
       content.invoke(consumer)
       return consumer.root ?: error("No root element found after render!")
     }

src/jsMain/kotlin/nl/astraeus/komp/Komponent.kt

@@ -5,7 +5,6 @@ import kotlinx.html.FlowOrMetaDataOrPhrasingContent
 import org.w3c.dom.Element
 import org.w3c.dom.HTMLElement
 import org.w3c.dom.get
-import kotlin.reflect.KProperty
 
 private var currentKomponent: Komponent? = null
 fun FlowOrMetaDataOrPhrasingContent.currentKomponent(): Komponent =
@@ -38,13 +37,19 @@ abstract class Komponent {
   open fun create(parent: Element, childIndex: Int? = null) {
     onBeforeUpdate()
     val builder = HtmlBuilder(
+      this,
       parent,
       childIndex ?: parent.childNodes.length
     )
 
-    currentKomponent = this
-    builder.render()
-    currentKomponent = null
+    try {
+      currentKomponent = this
+      builder.render()
+    } catch(e: KomponentException) {
+      errorHandler(e)
+    } finally {
+      currentKomponent = null
+    }
 
     element = builder.root
     updateMemoizeHash()
@@ -117,7 +122,7 @@ abstract class Komponent {
    */
   open fun generateMemoizeHash(): Int? = null
 
-  internal fun refresh() {
+  private fun refresh() {
     val currentElement = element
 
     check(currentElement != null) {
@@ -131,14 +136,19 @@ abstract class Komponent {
         childIndex = index
       }
     }
-    val consumer = HtmlBuilder(parent, childIndex)
-    consumer.root = null
+    val builder = HtmlBuilder(this, parent, childIndex)
+    builder.root = null
 
-    currentKomponent = this
-    consumer.render()
-    currentKomponent = null
+    try {
+      currentKomponent = this
+      builder.render()
+    } catch(e: KomponentException) {
+      errorHandler(e)
+    } finally {
+      currentKomponent = null
+    }
 
-    element = consumer.root
+    element = builder.root
     dirty = false
   }
 
@@ -149,6 +159,18 @@ abstract class Komponent {
   companion object {
     private var nextCreateIndex: Int = 1
     private var updateCallback: Int? = null
+    private var errorHandler: (KomponentException) -> Unit = { ke ->
+      console.error("Render error in Komponent", ke)
+
+      ke.element?.innerHTML = """<div class="komponent-error">Render error!</div>"""
+
+      window.alert("""
+        Error in Komponent '${ke.komponent}', ${ke.message}
+        Tag: ${ke.tag.tagName}
+        See console log for details
+        Position: ${ke.position}""".trimIndent()
+      )
+    }
     private var scheduledForUpdate = mutableSetOf<Komponent>()
     private var interceptor: (Komponent, () -> Unit) -> Unit = { _, block -> block() }
 
@@ -161,6 +183,10 @@ abstract class Komponent {
       component.create(parent)
     }
 
+    fun setErrorHandler(handler: (KomponentException) -> Unit) {
+      errorHandler = handler
+    }
+
     fun setUpdateInterceptor(block: (Komponent, () -> Unit) -> Unit) {
       interceptor = block
     }

src/jsMain/kotlin/nl/astraeus/komp/KomponentException.kt

@@ -0,0 +1,18 @@
+package nl.astraeus.komp
+
+import kotlinx.html.Tag
+import org.w3c.dom.Element
+
+class KomponentException(
+  val komponent: Komponent?,
+  val element: Element?,
+  val tag: Tag,
+  val position: String,
+  message: String,
+  cause: Throwable
+) : RuntimeException(message, cause) {
+
+  override fun toString(): String {
+    return "KompException(message='$message', tag='$tag', position='$position')"
+  }
+}

src/jsTest/kotlin/nl/astraeus/komp/TestUpdate.kt

@@ -61,6 +61,8 @@ class SimpleKomponent : Komponent() {
         if (hello) {
           div {
             +"Hello"
+
+            throw IllegalStateException("Bloe")
           }
         } else {
           span {