From ad765ac771b8feeb1dc7a9d8412345a8198ae321 Mon Sep 17 00:00:00 2001
From: Anton Korzunov <thekashey@gmail.com>
Date: Fri, 25 May 2018 17:47:40 +1000
Subject: [PATCH] add a new option to control element comparison (#1007)

---
 src/options.js        | 11 +++++++++++
 src/vdom/component.js |  6 +++---
 src/vdom/diff.js      |  1 -
 src/vdom/index.js     | 13 ++++++++++++-
 4 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/options.js b/src/options.js
index 86c1b08b4d..f90febf605 100644
--- a/src/options.js
+++ b/src/options.js
@@ -18,6 +18,17 @@ export default {
 	 */
 	//vnode(vnode) { }
 
+	/**
+	 * Compares two Components
+	 * @param {Component} component1 First Component to compare
+	 * @param {Component} component2 Second Component to compare
+	 * @returns Boolean, true if components are equal
+   */
+	areComponentsEqual(component1, component2) {
+		// default implementation is 4x times faster than optional object property access
+		return component1 === component2;
+	}
+
 	/** Hook invoked after a component is mounted. */
 	// afterMount(component) { }
 
diff --git a/src/vdom/component.js b/src/vdom/component.js
index aa534358b2..72f2f9ea63 100644
--- a/src/vdom/component.js
+++ b/src/vdom/component.js
@@ -2,7 +2,7 @@ import { SYNC_RENDER, NO_RENDER, FORCE_RENDER, ASYNC_RENDER, ATTR_KEY } from '..
 import options from '../options';
 import { extend } from '../util';
 import { enqueueRender } from '../render-queue';
-import { getNodeProps } from './index';
+import { areComponentsEqual, getNodeProps } from './index';
 import { diff, mounts, diffLevel, flushMounts, recollectNodeTree, removeChildren } from './diff';
 import { createComponent, collectComponent } from './component-recycler';
 import { removeNode } from '../dom/index';
@@ -212,11 +212,11 @@ export function buildComponentFromVNode(dom, vnode, context, mountAll) {
 	let c = dom && dom._component,
 		originalComponent = c,
 		oldDom = dom,
-		isDirectOwner = c && dom._componentConstructor===vnode.nodeName,
+		isDirectOwner = c && areComponentsEqual(dom._componentConstructor, vnode.nodeName),
 		isOwner = isDirectOwner,
 		props = getNodeProps(vnode);
 	while (c && !isOwner && (c=c._parentComponent)) {
-		isOwner = c.constructor===vnode.nodeName;
+		isOwner = areComponentsEqual(c.constructor, vnode.nodeName);
 	}
 
 	if (c && isOwner && (!mountAll || c._component)) {
diff --git a/src/vdom/diff.js b/src/vdom/diff.js
index 8f740ea510..11f198012e 100644
--- a/src/vdom/diff.js
+++ b/src/vdom/diff.js
@@ -29,7 +29,6 @@ export function flushMounts() {
 	}
 }
 
-
 /**
  * Apply differences in a given vnode (and it's deep children) to a real DOM Node.
  * @param {Element} [dom=null] A DOM node to mutate into the shape of the `vnode`
diff --git a/src/vdom/index.js b/src/vdom/index.js
index d3a6e8199e..e4df3c6f27 100644
--- a/src/vdom/index.js
+++ b/src/vdom/index.js
@@ -1,5 +1,16 @@
 import { extend } from '../util';
+import options from '../options';
 
+/**
+ * Checks that two components are equal
+ * @param {Component} component1 First component to compare
+ * @param {Component} component2 Second component to compare
+ * @return {boolean}
+ * @private
+ */
+export function areComponentsEqual(component1, component2) {
+	return options.areComponentsEqual(component1, component2);
+}
 
 /**
  * Check if two nodes are equivalent.
@@ -16,7 +27,7 @@ export function isSameNodeType(node, vnode, hydrating) {
 	if (typeof vnode.nodeName==='string') {
 		return !node._componentConstructor && isNamedNode(node, vnode.nodeName);
 	}
-	return hydrating || node._componentConstructor===vnode.nodeName;
+	return hydrating || areComponentsEqual(node._componentConstructor, vnode.nodeName);
 }