From 42067167e278fef921a07addf974f2b278944222 Mon Sep 17 00:00:00 2001
From: Hayleigh Thompson <me@hayleigh.dev>
Date: Wed, 19 Jul 2023 10:48:10 +0100
Subject: :alembic: Maybe we can just roll our own DOM patching?

---
 src/lustre.ffi.mjs  |   8 +-
 src/runtime.ffi.mjs | 988 ++++------------------------------------------------
 2 files changed, 79 insertions(+), 917 deletions(-)

diff --git a/src/lustre.ffi.mjs b/src/lustre.ffi.mjs
index 3a6556e..b57026f 100644
--- a/src/lustre.ffi.mjs
+++ b/src/lustre.ffi.mjs
@@ -1,4 +1,4 @@
-import { morphdom } from "./runtime.ffi.mjs";
+import { morph } from "./runtime.ffi.mjs";
 import { Ok, Error } from "./gleam.mjs";
 import { map } from "./lustre/element.mjs";
 
@@ -14,6 +14,10 @@ export class App {
   #willUpdate = false;
   #didUpdate = false;
 
+  #init = null;
+  #update = null;
+  #view = null;
+
   constructor(init, update, render) {
     this.#init = init;
     this.#update = update;
@@ -51,7 +55,7 @@ export class App {
     const node = this.#view(this.#state);
     const vdom = map(node, (msg) => this.dispatch(msg));
 
-    morphdom(this.#root.firstChild, vdom);
+    morph(this.#root, vdom);
   }
 
   #tick() {
diff --git a/src/runtime.ffi.mjs b/src/runtime.ffi.mjs
index c349a70..355c923 100644
--- a/src/runtime.ffi.mjs
+++ b/src/runtime.ffi.mjs
@@ -1,948 +1,106 @@
 import { h, t } from "./lustre/element.mjs";
+import { fold, each } from "../gleam_stdlib/gleam/list.mjs";
 
-// This file is vendored from https://github.com/patrick-steele-idem/morphdom/
-// and is licensed under the MIT license. For a copy of the original license
-// head on over to:
-//
-//   https://github.com/patrick-steele-idem/morphdom/blob/master/LICENSE
-//
+const Element = h("").constructor;
+const Text = t("").constructor;
 
-var DOCUMENT_FRAGMENT_NODE = 11;
+export function morph(prev, curr) {
+  if (curr instanceof Element) {
+    if (prev?.nodeType === 1 && prev.nodeName !== curr[0].toUpperCase()) {
+      return morphElement(prev, curr);
+    } else {
+      const el = document.createElement(curr[0]);
 
-function morphAttrs(fromNode, toNode) {
-  var toNodeAttrs = toNode.attributes;
-  var attr;
-  var attrName;
-  var attrNamespaceURI;
-  var attrValue;
-  var fromValue;
+      each(curr[1], (attr) => {
+        const name = attr[0];
+        const value = attr[1];
 
-  // document-fragments dont have attributes so lets not do anything
-  if (
-    toNode.nodeType === DOCUMENT_FRAGMENT_NODE ||
-    fromNode.nodeType === DOCUMENT_FRAGMENT_NODE
-  ) {
-    return;
-  }
+        morphAttr(el, name, value);
+      });
 
-  // update attributes on original DOM element
-  for (var i = toNodeAttrs.length - 1; i >= 0; i--) {
-    attr = toNodeAttrs[i];
-    attrName = attr.name;
-    attrNamespaceURI = attr.namespaceURI;
-    attrValue = attr.value;
+      each(curr[2], (child) => {
+        el.appendChild(morph(null, child));
+      });
 
-    if (attrNamespaceURI) {
-      attrName = attr.localName || attrName;
-      fromValue = fromNode.getAttributeNS(attrNamespaceURI, attrName);
+      if (prev) prev.replaceWith(el);
 
-      if (fromValue !== attrValue) {
-        if (attr.prefix === "xmlns") {
-          attrName = attr.name; // It's not allowed to set an attribute with the XMLNS namespace without specifying the `xmlns` prefix
-        }
-        fromNode.setAttributeNS(attrNamespaceURI, attrName, attrValue);
-      }
-    } else {
-      fromValue = fromNode.getAttribute(attrName);
-
-      if (fromValue !== attrValue) {
-        fromNode.setAttribute(attrName, attrValue);
-      }
+      return el;
     }
   }
 
-  // Remove any extra attributes found on the original DOM element that
-  // weren't found on the target element.
-  var fromNodeAttrs = fromNode.attributes;
-
-  for (var d = fromNodeAttrs.length - 1; d >= 0; d--) {
-    attr = fromNodeAttrs[d];
-    attrName = attr.name;
-    attrNamespaceURI = attr.namespaceURI;
-
-    if (attrNamespaceURI) {
-      attrName = attr.localName || attrName;
-
-      if (!toNode.hasAttributeNS(attrNamespaceURI, attrName)) {
-        fromNode.removeAttributeNS(attrNamespaceURI, attrName);
-      }
+  if (curr instanceof Text) {
+    if (prev?.nodeType === 3) {
+      return morphText(prev, curr);
     } else {
-      if (!toNode.hasAttribute(attrName)) {
-        fromNode.removeAttribute(attrName);
-      }
+      const el = document.createTextNode(curr[0]);
+      if (prev) prev.replaceWith(el);
+      return el;
     }
   }
-}
-
-var range; // Create a range object for efficently rendering strings to elements.
-var NS_XHTML = "http://www.w3.org/1999/xhtml";
-
-var doc = typeof document === "undefined" ? undefined : document;
-var HAS_TEMPLATE_SUPPORT = !!doc && "content" in doc.createElement("template");
-var HAS_RANGE_SUPPORT =
-  !!doc && doc.createRange && "createContextualFragment" in doc.createRange();
-
-function createFragmentFromTemplate(str) {
-  var template = doc.createElement("template");
-  template.innerHTML = str;
-  return template.content.childNodes[0];
-}
-
-function createFragmentFromRange(str) {
-  if (!range) {
-    range = doc.createRange();
-    range.selectNode(doc.body);
-  }
-
-  var fragment = range.createContextualFragment(str);
-  return fragment.childNodes[0];
-}
-
-function createFragmentFromWrap(str) {
-  var fragment = doc.createElement("body");
-  fragment.innerHTML = str;
-  return fragment.childNodes[0];
-}
-
-/**
- * This is about the same
- * var html = new DOMParser().parseFromString(str, 'text/html');
- * return html.body.firstChild;
- *
- * @method toElement
- * @param {String} str
- */
-function toElement(str) {
-  str = str.trim();
-  if (HAS_TEMPLATE_SUPPORT) {
-    // avoid restrictions on content for things like `<tr><th>Hi</th></tr>` which
-    // createContextualFragment doesn't support
-    // <template> support not available in IE
-    return createFragmentFromTemplate(str);
-  } else if (HAS_RANGE_SUPPORT) {
-    return createFragmentFromRange(str);
-  }
 
-  return createFragmentFromWrap(str);
+  return null;
 }
 
-/**
- * Returns true if two node's names are the same.
- *
- * NOTE: We don't bother checking `namespaceURI` because you will never find two HTML elements with the same
- *       nodeName and different namespace URIs.
- *
- * @param {Element} a
- * @param {Element} b The target element
- * @return {boolean}
- */
-function compareNodeNames(fromEl, toEl) {
-  var fromNodeName = fromEl.nodeName;
-  var toNodeName = toEl.nodeName;
-  var fromCodeStart, toCodeStart;
+function morphElement(prev, curr) {
+  const prevAttrs = prev.attributes;
+  const currAttrs = fold(curr[1], new Map(), (acc, attr) => {
+    const name = attr[0];
+    const value = attr[1];
 
-  if (fromNodeName === toNodeName) {
-    return true;
-  }
+    acc.set(name, value);
+    return acc;
+  });
+  const currChildren = curr[2].toArray();
 
-  fromCodeStart = fromNodeName.charCodeAt(0);
-  toCodeStart = toNodeName.charCodeAt(0);
+  for (const { name, value: prevValue } of prevAttrs) {
+    if (!currAttrs.has(name)) prev.removeAttribute(name);
+    const value = currAttrs.get(name);
 
-  // If the target element is a virtual DOM node or SVG node then we may
-  // need to normalize the tag name before comparing. Normal HTML elements that are
-  // in the "http://www.w3.org/1999/xhtml"
-  // are converted to upper case
-  if (fromCodeStart <= 90 && toCodeStart >= 97) {
-    // from is upper and to is lower
-    return fromNodeName === toNodeName.toUpperCase();
-  } else if (toCodeStart <= 90 && fromCodeStart >= 97) {
-    // to is upper and from is lower
-    return toNodeName === fromNodeName.toUpperCase();
-  } else {
-    return false;
+    if (value !== prevValue) {
+      morphAttr(prev, name, value);
+      currAttrs.delete(name);
+    }
   }
-}
-
-/**
- * Create an element, optionally with a known namespace URI.
- *
- * @param {string} name the element name, e.g. 'div' or 'svg'
- * @param {string} [namespaceURI] the element's namespace URI, i.e. the value of
- * its `xmlns` attribute or its inferred namespace.
- *
- * @return {Element}
- */
-function createElementNS(name, namespaceURI) {
-  return !namespaceURI || namespaceURI === NS_XHTML
-    ? doc.createElement(name)
-    : doc.createElementNS(namespaceURI, name);
-}
 
-/**
- * Copies the children of one DOM element to another DOM element
- */
-function moveChildren(fromEl, toEl) {
-  var curChild = fromEl.firstChild;
-  while (curChild) {
-    var nextChild = curChild.nextSibling;
-    toEl.appendChild(curChild);
-    curChild = nextChild;
+  for (const [name, value] of currAttrs) {
+    morphAttr(prev, name, value);
   }
-  return toEl;
-}
 
-function syncBooleanAttrProp(fromEl, toEl, name) {
-  if (fromEl[name] !== toEl[name]) {
-    fromEl[name] = toEl[name];
-    if (fromEl[name]) {
-      fromEl.setAttribute(name, "");
+  for (let child = prev.firstChild; child; child = child.nextSibling) {
+    if (currChildren.length) {
+      morph(child, currChildren.shift());
     } else {
-      fromEl.removeAttribute(name);
+      prev.removeChild(child);
     }
   }
-}
-
-var specialElHandlers = {
-  OPTION: function (fromEl, toEl) {
-    var parentNode = fromEl.parentNode;
-    if (parentNode) {
-      var parentName = parentNode.nodeName.toUpperCase();
-      if (parentName === "OPTGROUP") {
-        parentNode = parentNode.parentNode;
-        parentName = parentNode && parentNode.nodeName.toUpperCase();
-      }
-      if (parentName === "SELECT" && !parentNode.hasAttribute("multiple")) {
-        if (fromEl.hasAttribute("selected") && !toEl.selected) {
-          // Workaround for MS Edge bug where the 'selected' attribute can only be
-          // removed if set to a non-empty value:
-          // https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/12087679/
-          fromEl.setAttribute("selected", "selected");
-          fromEl.removeAttribute("selected");
-        }
-        // We have to reset select element's selectedIndex to -1, otherwise setting
-        // fromEl.selected using the syncBooleanAttrProp below has no effect.
-        // The correct selectedIndex will be set in the SELECT special handler below.
-        parentNode.selectedIndex = -1;
-      }
-    }
-    syncBooleanAttrProp(fromEl, toEl, "selected");
-  },
-  /**
-   * The "value" attribute is special for the <input> element since it sets
-   * the initial value. Changing the "value" attribute without changing the
-   * "value" property will have no effect since it is only used to the set the
-   * initial value.  Similar for the "checked" attribute, and "disabled".
-   */
-  INPUT: function (fromEl, toEl) {
-    syncBooleanAttrProp(fromEl, toEl, "checked");
-    syncBooleanAttrProp(fromEl, toEl, "disabled");
-
-    if (fromEl.value !== toEl.value) {
-      fromEl.value = toEl.value;
-    }
-
-    if (!toEl.hasAttribute("value")) {
-      fromEl.removeAttribute("value");
-    }
-  },
-
-  TEXTAREA: function (fromEl, toEl) {
-    var newValue = toEl.value;
-    if (fromEl.value !== newValue) {
-      fromEl.value = newValue;
-    }
-
-    var firstChild = fromEl.firstChild;
-    if (firstChild) {
-      // Needed for IE. Apparently IE sets the placeholder as the
-      // node value and vise versa. This ignores an empty update.
-      var oldValue = firstChild.nodeValue;
 
-      if (
-        oldValue == newValue ||
-        (!newValue && oldValue == fromEl.placeholder)
-      ) {
-        return;
-      }
-
-      firstChild.nodeValue = newValue;
-    }
-  },
-  SELECT: function (fromEl, toEl) {
-    if (!toEl.hasAttribute("multiple")) {
-      var selectedIndex = -1;
-      var i = 0;
-      // We have to loop through children of fromEl, not toEl since nodes can be moved
-      // from toEl to fromEl directly when morphing.
-      // At the time this special handler is invoked, all children have already been morphed
-      // and appended to / removed from fromEl, so using fromEl here is safe and correct.
-      var curChild = fromEl.firstChild;
-      var optgroup;
-      var nodeName;
-      while (curChild) {
-        nodeName = curChild.nodeName && curChild.nodeName.toUpperCase();
-        if (nodeName === "OPTGROUP") {
-          optgroup = curChild;
-          curChild = optgroup.firstChild;
-        } else {
-          if (nodeName === "OPTION") {
-            if (curChild.hasAttribute("selected")) {
-              selectedIndex = i;
-              break;
-            }
-            i++;
-          }
-          curChild = curChild.nextSibling;
-          if (!curChild && optgroup) {
-            curChild = optgroup.nextSibling;
-            optgroup = null;
-          }
-        }
-      }
-
-      fromEl.selectedIndex = selectedIndex;
-    }
-  },
-};
-
-export const ELEMENT_NODE = 1;
-export const DOCUMENT_FRAGMENT_NODE$1 = 11;
-export const TEXT_NODE = 3;
-export const COMMENT_NODE = 8;
-
-function noop() {}
-
-function defaultGetNodeKey(node) {
-  if (node) {
-    return (node.getAttribute && node.getAttribute("id")) || node.id;
+  for (const child of currChildren) {
+    prev.appendChild(morph(null, child));
   }
-}
-
-function morphdomFactory(morphAttrs) {
-  return function morphdom(fromNode, toNode, options) {
-    if (!options) {
-      options = {};
-    }
-
-    if (typeof toNode === "string") {
-      if (
-        fromNode.nodeName === "#document" ||
-        fromNode.nodeName === "HTML" ||
-        fromNode.nodeName === "BODY"
-      ) {
-        var toNodeHtml = toNode;
-        toNode = doc.createElement("html");
-        toNode.innerHTML = toNodeHtml;
-      } else {
-        toNode = toElement(toNode);
-      }
-    } else if (toNode.nodeType === DOCUMENT_FRAGMENT_NODE$1) {
-      toNode = toNode.firstElementChild;
-    }
-
-    var getNodeKey = options.getNodeKey || defaultGetNodeKey;
-    var onBeforeNodeAdded = options.onBeforeNodeAdded || noop;
-    var onNodeAdded = options.onNodeAdded || noop;
-    var onBeforeElUpdated = options.onBeforeElUpdated || noop;
-    var onElUpdated = options.onElUpdated || noop;
-    var onBeforeNodeDiscarded = options.onBeforeNodeDiscarded || noop;
-    var onNodeDiscarded = options.onNodeDiscarded || noop;
-    var onBeforeElChildrenUpdated = options.onBeforeElChildrenUpdated || noop;
-    var skipFromChildren = options.skipFromChildren || noop;
-    var addChild =
-      options.addChild ||
-      function (parent, child) {
-        return parent.appendChild(child);
-      };
-    var childrenOnly = options.childrenOnly === true;
-
-    // This object is used as a lookup to quickly find all keyed elements in the original DOM tree.
-    var fromNodesLookup = Object.create(null);
-    var keyedRemovalList = [];
-
-    function addKeyedRemoval(key) {
-      keyedRemovalList.push(key);
-    }
-
-    function walkDiscardedChildNodes(node, skipKeyedNodes) {
-      if (node.nodeType === ELEMENT_NODE) {
-        var curChild = node.firstChild;
-        while (curChild) {
-          var key = undefined;
-
-          if (skipKeyedNodes && (key = getNodeKey(curChild))) {
-            // If we are skipping keyed nodes then we add the key
-            // to a list so that it can be handled at the very end.
-            addKeyedRemoval(key);
-          } else {
-            // Only report the node as discarded if it is not keyed. We do this because
-            // at the end we loop through all keyed elements that were unmatched
-            // and then discard them in one final pass.
-            onNodeDiscarded(curChild);
-            if (curChild.firstChild) {
-              walkDiscardedChildNodes(curChild, skipKeyedNodes);
-            }
-          }
-
-          curChild = curChild.nextSibling;
-        }
-      }
-    }
-
-    /**
-     * Removes a DOM node out of the original DOM
-     *
-     * @param  {Node} node The node to remove
-     * @param  {Node} parentNode The nodes parent
-     * @param  {Boolean} skipKeyedNodes If true then elements with keys will be skipped and not discarded.
-     * @return {undefined}
-     */
-    function removeNode(node, parentNode, skipKeyedNodes) {
-      if (onBeforeNodeDiscarded(node) === false) {
-        return;
-      }
-
-      if (parentNode) {
-        parentNode.removeChild(node);
-      }
-
-      onNodeDiscarded(node);
-      walkDiscardedChildNodes(node, skipKeyedNodes);
-    }
-
-    function indexTree(node) {
-      if (
-        node.nodeType === ELEMENT_NODE ||
-        node.nodeType === DOCUMENT_FRAGMENT_NODE$1
-      ) {
-        var curChild = node.firstChild;
-        while (curChild) {
-          var key = getNodeKey(curChild);
-          if (key) {
-            fromNodesLookup[key] = curChild;
-          }
-
-          // Walk recursively
-          indexTree(curChild);
-
-          curChild = curChild.nextSibling;
-        }
-      }
-    }
-
-    indexTree(fromNode);
-
-    function handleNodeAdded(el) {
-      onNodeAdded(el);
-
-      var curChild = el.firstChild;
-      while (curChild) {
-        var nextSibling = curChild.nextSibling;
-
-        var key = getNodeKey(curChild);
-        if (key) {
-          var unmatchedFromEl = fromNodesLookup[key];
-          // if we find a duplicate #id node in cache, replace `el` with cache value
-          // and morph it to the child node.
-          if (unmatchedFromEl && compareNodeNames(curChild, unmatchedFromEl)) {
-            curChild.parentNode.replaceChild(unmatchedFromEl, curChild);
-            morphEl(unmatchedFromEl, curChild);
-          } else {
-            handleNodeAdded(curChild);
-          }
-        } else {
-          // recursively call for curChild and it's children to see if we find something in
-          // fromNodesLookup
-          handleNodeAdded(curChild);
-        }
-
-        curChild = nextSibling;
-      }
-    }
-
-    function cleanupFromEl(fromEl, curFromNodeChild, curFromNodeKey) {
-      // We have processed all of the "to nodes". If curFromNodeChild is
-      // non-null then we still have some from nodes left over that need
-      // to be removed
-      while (curFromNodeChild) {
-        var fromNextSibling = curFromNodeChild.nextSibling;
-        if ((curFromNodeKey = getNodeKey(curFromNodeChild))) {
-          // Since the node is keyed it might be matched up later so we defer
-          // the actual removal to later
-          addKeyedRemoval(curFromNodeKey);
-        } else {
-          // NOTE: we skip nested keyed nodes from being removed since there is
-          //       still a chance they will be matched up later
-          removeNode(curFromNodeChild, fromEl, true /* skip keyed nodes */);
-        }
-        curFromNodeChild = fromNextSibling;
-      }
-    }
-
-    function morphEl(fromEl, toEl, childrenOnly) {
-      var toElKey = getNodeKey(toEl);
 
-      if (toElKey) {
-        // If an element with an ID is being morphed then it will be in the final
-        // DOM so clear it out of the saved elements collection
-        delete fromNodesLookup[toElKey];
-      }
-
-      if (!childrenOnly) {
-        // optional
-        if (onBeforeElUpdated(fromEl, toEl) === false) {
-          return;
-        }
-
-        // update attributes on original DOM element first
-        morphAttrs(fromEl, toEl);
-        // optional
-        onElUpdated(fromEl);
-
-        if (onBeforeElChildrenUpdated(fromEl, toEl) === false) {
-          return;
-        }
-      }
-
-      if (fromEl.nodeName !== "TEXTAREA") {
-        morphChildren(fromEl, toEl);
-      } else {
-        specialElHandlers.TEXTAREA(fromEl, toEl);
-      }
-    }
-
-    function morphChildren(fromEl, toEl) {
-      var skipFrom = skipFromChildren(fromEl);
-      var curToNodeChild = toEl.firstChild;
-      var curFromNodeChild = fromEl.firstChild;
-      var curToNodeKey;
-      var curFromNodeKey;
-
-      var fromNextSibling;
-      var toNextSibling;
-      var matchingFromEl;
-
-      // walk the children
-      outer: while (curToNodeChild) {
-        toNextSibling = curToNodeChild.nextSibling;
-        curToNodeKey = getNodeKey(curToNodeChild);
-
-        // walk the fromNode children all the way through
-        while (!skipFrom && curFromNodeChild) {
-          fromNextSibling = curFromNodeChild.nextSibling;
-
-          if (
-            curToNodeChild.isSameNode &&
-            curToNodeChild.isSameNode(curFromNodeChild)
-          ) {
-            curToNodeChild = toNextSibling;
-            curFromNodeChild = fromNextSibling;
-            continue outer;
-          }
-
-          curFromNodeKey = getNodeKey(curFromNodeChild);
-
-          var curFromNodeType = curFromNodeChild.nodeType;
-
-          // this means if the curFromNodeChild doesnt have a match with the curToNodeChild
-          var isCompatible = undefined;
-
-          if (curFromNodeType === curToNodeChild.nodeType) {
-            if (curFromNodeType === ELEMENT_NODE) {
-              // Both nodes being compared are Element nodes
-
-              if (curToNodeKey) {
-                // The target node has a key so we want to match it up with the correct element
-                // in the original DOM tree
-                if (curToNodeKey !== curFromNodeKey) {
-                  // The current element in the original DOM tree does not have a matching key so
-                  // let's check our lookup to see if there is a matching element in the original
-                  // DOM tree
-                  if ((matchingFromEl = fromNodesLookup[curToNodeKey])) {
-                    if (fromNextSibling === matchingFromEl) {
-                      // Special case for single element removals. To avoid removing the original
-                      // DOM node out of the tree (since that can break CSS transitions, etc.),
-                      // we will instead discard the current node and wait until the next
-                      // iteration to properly match up the keyed target element with its matching
-                      // element in the original tree
-                      isCompatible = false;
-                    } else {
-                      // We found a matching keyed element somewhere in the original DOM tree.
-                      // Let's move the original DOM node into the current position and morph
-                      // it.
-
-                      // NOTE: We use insertBefore instead of replaceChild because we want to go through
-                      // the `removeNode()` function for the node that is being discarded so that
-                      // all lifecycle hooks are correctly invoked
-                      fromEl.insertBefore(matchingFromEl, curFromNodeChild);
-
-                      // fromNextSibling = curFromNodeChild.nextSibling;
-
-                      if (curFromNodeKey) {
-                        // Since the node is keyed it might be matched up later so we defer
-                        // the actual removal to later
-                        addKeyedRemoval(curFromNodeKey);
-                      } else {
-                        // NOTE: we skip nested keyed nodes from being removed since there is
-                        //       still a chance they will be matched up later
-                        removeNode(
-                          curFromNodeChild,
-                          fromEl,
-                          true /* skip keyed nodes */
-                        );
-                      }
-
-                      curFromNodeChild = matchingFromEl;
-                    }
-                  } else {
-                    // The nodes are not compatible since the "to" node has a key and there
-                    // is no matching keyed node in the source tree
-                    isCompatible = false;
-                  }
-                }
-              } else if (curFromNodeKey) {
-                // The original has a key
-                isCompatible = false;
-              }
-
-              isCompatible =
-                isCompatible !== false &&
-                compareNodeNames(curFromNodeChild, curToNodeChild);
-              if (isCompatible) {
-                // We found compatible DOM elements so transform
-                // the current "from" node to match the current
-                // target DOM node.
-                // MORPH
-                morphEl(curFromNodeChild, curToNodeChild);
-              }
-            } else if (
-              curFromNodeType === TEXT_NODE ||
-              curFromNodeType == COMMENT_NODE
-            ) {
-              // Both nodes being compared are Text or Comment nodes
-              isCompatible = true;
-              // Simply update nodeValue on the original node to
-              // change the text value
-              if (curFromNodeChild.nodeValue !== curToNodeChild.nodeValue) {
-                curFromNodeChild.nodeValue = curToNodeChild.nodeValue;
-              }
-            }
-          }
-
-          if (isCompatible) {
-            // Advance both the "to" child and the "from" child since we found a match
-            // Nothing else to do as we already recursively called morphChildren above
-            curToNodeChild = toNextSibling;
-            curFromNodeChild = fromNextSibling;
-            continue outer;
-          }
-
-          // No compatible match so remove the old node from the DOM and continue trying to find a
-          // match in the original DOM. However, we only do this if the from node is not keyed
-          // since it is possible that a keyed node might match up with a node somewhere else in the
-          // target tree and we don't want to discard it just yet since it still might find a
-          // home in the final DOM tree. After everything is done we will remove any keyed nodes
-          // that didn't find a home
-          if (curFromNodeKey) {
-            // Since the node is keyed it might be matched up later so we defer
-            // the actual removal to later
-            addKeyedRemoval(curFromNodeKey);
-          } else {
-            // NOTE: we skip nested keyed nodes from being removed since there is
-            //       still a chance they will be matched up later
-            removeNode(curFromNodeChild, fromEl, true /* skip keyed nodes */);
-          }
-
-          curFromNodeChild = fromNextSibling;
-        } // END: while(curFromNodeChild) {}
-
-        // If we got this far then we did not find a candidate match for
-        // our "to node" and we exhausted all of the children "from"
-        // nodes. Therefore, we will just append the current "to" node
-        // to the end
-        if (
-          curToNodeKey &&
-          (matchingFromEl = fromNodesLookup[curToNodeKey]) &&
-          compareNodeNames(matchingFromEl, curToNodeChild)
-        ) {
-          // MORPH
-          if (!skipFrom) {
-            addChild(fromEl, matchingFromEl);
-          }
-          morphEl(matchingFromEl, curToNodeChild);
-        } else {
-          var onBeforeNodeAddedResult = onBeforeNodeAdded(curToNodeChild);
-          if (onBeforeNodeAddedResult !== false) {
-            if (onBeforeNodeAddedResult) {
-              curToNodeChild = onBeforeNodeAddedResult;
-            }
-
-            if (curToNodeChild.actualize) {
-              curToNodeChild = curToNodeChild.actualize(
-                fromEl.ownerDocument || doc
-              );
-            }
-            addChild(fromEl, curToNodeChild);
-            handleNodeAdded(curToNodeChild);
-          }
-        }
-
-        curToNodeChild = toNextSibling;
-        curFromNodeChild = fromNextSibling;
-      }
-
-      cleanupFromEl(fromEl, curFromNodeChild, curFromNodeKey);
-
-      var specialElHandler = specialElHandlers[fromEl.nodeName];
-      if (specialElHandler) {
-        specialElHandler(fromEl, toEl);
-      }
-    } // END: morphChildren(...)
-
-    var morphedNode = fromNode;
-    var morphedNodeType = morphedNode.nodeType;
-    var toNodeType = toNode.nodeType;
-
-    if (!childrenOnly) {
-      // Handle the case where we are given two DOM nodes that are not
-      // compatible (e.g. <div> --> <span> or <div> --> TEXT)
-      if (morphedNodeType === ELEMENT_NODE) {
-        if (toNodeType === ELEMENT_NODE) {
-          if (!compareNodeNames(fromNode, toNode)) {
-            onNodeDiscarded(fromNode);
-            morphedNode = moveChildren(
-              fromNode,
-              createElementNS(toNode.nodeName, toNode.namespaceURI)
-            );
-          }
-        } else {
-          // Going from an element node to a text node
-          morphedNode = toNode;
-        }
-      } else if (
-        morphedNodeType === TEXT_NODE ||
-        morphedNodeType === COMMENT_NODE
-      ) {
-        // Text or comment node
-        if (toNodeType === morphedNodeType) {
-          if (morphedNode.nodeValue !== toNode.nodeValue) {
-            morphedNode.nodeValue = toNode.nodeValue;
-          }
-
-          return morphedNode;
-        } else {
-          // Text node to something else
-          morphedNode = toNode;
-        }
-      }
-    }
-
-    if (morphedNode === toNode) {
-      // The "to node" was not compatible with the "from node" so we had to
-      // toss out the "from node" and use the "to node"
-      onNodeDiscarded(fromNode);
-    } else {
-      if (toNode.isSameNode && toNode.isSameNode(morphedNode)) {
-        return;
-      }
-
-      morphEl(morphedNode, toNode, childrenOnly);
-
-      // We now need to loop over any keyed nodes that might need to be
-      // removed. We only do the removal if we know that the keyed node
-      // never found a match. When a keyed node is matched up we remove
-      // it out of fromNodesLookup and we use fromNodesLookup to determine
-      // if a keyed node has been matched up or not
-      if (keyedRemovalList) {
-        for (var i = 0, len = keyedRemovalList.length; i < len; i++) {
-          var elToRemove = fromNodesLookup[keyedRemovalList[i]];
-          if (elToRemove) {
-            removeNode(elToRemove, elToRemove.parentNode, false);
-          }
-        }
-      }
-    }
-
-    if (!childrenOnly && morphedNode !== fromNode && fromNode.parentNode) {
-      if (morphedNode.actualize) {
-        morphedNode = morphedNode.actualize(fromNode.ownerDocument || doc);
-      }
-      // If we had to swap out the from node with a new node because the old
-      // node was not compatible with the target node then we need to
-      // replace the old DOM node in the original DOM tree. This is only
-      // possible if the original DOM node was part of a DOM tree which
-      // we know is the case if it has a parent node.
-      fromNode.parentNode.replaceChild(morphedNode, fromNode);
-    }
-
-    return morphedNode;
-  };
+  return prev;
 }
 
-export const morphdom = morphdomFactory(morphAttrs);
-
-export default morphdom;
-
-// VDOM HACKS ------------------------------------------------------------------
-
-// Whew this is some Naughty Stuff™. Our `Element` Gleam type is opaque so the
-// class constructors are not exposed and we can't import them. We need to
-// massage these classes into a shape that morphdom knows how to deal with, and
-// because we can't get at the constructors directly we're going to be sneaky and
-// get in by constructing some dummy elements and stealing their prototypes.
-//
-// Morphdom expects the following properties/methods to exist on a valid VDOM
-// node:
-//
-//   - firstChild;
-//   - nextSibling;
-//   - nodeType;
-//   - nodeName;
-//   - namespaceURI;
-//   - nodeValue;
-//   - attributes;
-//   - value;
-//   - selected;
-//   - disabled;
-//   - hasAttributeNS(namespaceURI, name);
-//   - actualize(document);
-//
-// See more here: https://github.com/patrick-steele-idem/morphdom/blob/master/docs/virtual-dom.md
-//
-
-Object.defineProperties(h("").constructor.prototype, {
-  firstChild: {
-    get() {
-      // If this is the first time `firstChild` is being accessed, we need to
-      // create the children array first.
-      if (!this.children) this.children = this[2].toArray();
-
-      const child = this.children[0];
-
-      if (child) {
-        child.parentElement = this;
-        child.index = 0;
-      }
-
-      return child;
-    },
-  },
-
-  nextSibling: {
-    get() {
-      const sibling = this.parentElement?.children[this.index + 1];
-
-      if (sibling) {
-        sibling.parentElement = this.parentElement;
-        sibling.index = this.index + 1;
-      }
-
-      return sibling;
-    },
-  },
-
-  nodeType: {
-    value: ELEMENT_NODE,
-  },
-
-  nodeName: {
-    get() {
-      return this[0].toUpperCase();
-    },
-  },
-
-  namespaceURI: {
-    value: undefined,
-  },
-
-  nodeValue: {
-    value: null,
-  },
-
-  attributes: {
-    get() {
-      if (!this._attributes) {
-        this._attributes = Object.fromEntries(this[1].toArray());
-      }
-
-      return this._attributes;
-    },
-  },
-
-  value: {
-    get() {
-      return this.attributes.value;
-    },
-  },
-
-  selected: {
-    get() {
-      return !!this.attributes.selected;
-    },
-  },
-
-  disabled: {
-    get() {
-      return !!this.attributes.disabled;
-    },
-  },
-
-  hasAttributeNS: {
-    value: function (_, name) {
-      return name in this.attributes;
-    },
-  },
-
-  actualize: {
-    value: function (document) {
-      const el = document.createElement(this[0]);
-
-      for (const key in this.attributes) {
-        el[key] = this.attributes[key];
-      }
-
-      for (let child = this.firstChild; !!child; child = child.nextSibling) {
-        el.appendChild(child.actualize(document));
-      }
-
-      return el;
-    },
-  },
-});
-
-Object.defineProperties(t("").constructor.prototype, {
-  nextSibling: {
-    get() {
-      const sibling = this.parentElement?.children[this.index + 1];
-
-      if (sibling) {
-        sibling.parentElement = this.parentElement;
-        sibling.index = this.index + 1;
-      }
-
-      return sibling;
-    },
-  },
-
-  nodeType: {
-    get() {
-      return TEXT_NODE;
-    },
-  },
-
-  nodeName: {
-    value: "#text",
-  },
-
-  nodeValue: {
-    get() {
-      return this[0];
-    },
-  },
+function morphText(prev, curr) {
+  if (prev.nodeValue !== curr[0]) prev.nodeValue = curr[0];
+  return prev;
+}
 
-  actualize: {
-    value: function (document) {
-      return document.createTextNode(this[0]);
-    },
-  },
-});
+function morphAttr(el, name, value) {
+  switch (typeof value) {
+    case "string":
+      el.setAttribute(name, value);
+      break;
+
+    // Boolean attributes work a bit differently in HTML. Their presence always
+    // implies true: to set an attribute to false you need to remove it entirely.
+    case "boolean":
+      value ? el.setAttribute(name, name) : el.removeAttribute(name);
+      break;
+
+    // For properties, we're leaning on reference equality to avoid unnecessary
+    // updates.
+    default:
+      if (el[name] !== value) el[name] = value;
+  }
+}
-- 
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