From 93a71258ef5d52279edddc08b46b91cab6c9fa83 Mon Sep 17 00:00:00 2001
From: Mohamed Akram <mohd.akram@outlook.com>
Date: Sun, 1 Sep 2024 20:01:43 +0400
Subject: [PATCH] Improve rendering performance

Avoid unnecessary copies via Utils.extend in hot paths.
---
 lib/handlebars/helpers.js                     |  3 +-
 .../internal/create-new-lookup-object.js      | 11 -------
 lib/handlebars/internal/proto-access.js       | 32 +++++++++----------
 lib/handlebars/runtime.js                     | 20 ++++--------
 4 files changed, 24 insertions(+), 42 deletions(-)
 delete mode 100644 lib/handlebars/internal/create-new-lookup-object.js

diff --git a/lib/handlebars/helpers.js b/lib/handlebars/helpers.js
index 804796820..0a6e44024 100644
--- a/lib/handlebars/helpers.js
+++ b/lib/handlebars/helpers.js
@@ -20,7 +20,8 @@ export function moveHelperToHooks(instance, helperName, keepHelper) {
   if (instance.helpers[helperName]) {
     instance.hooks[helperName] = instance.helpers[helperName];
     if (!keepHelper) {
-      delete instance.helpers[helperName];
+      // Using delete is slow
+      instance.helpers[helperName] = undefined;
     }
   }
 }
diff --git a/lib/handlebars/internal/create-new-lookup-object.js b/lib/handlebars/internal/create-new-lookup-object.js
deleted file mode 100644
index 256f1eca1..000000000
--- a/lib/handlebars/internal/create-new-lookup-object.js
+++ /dev/null
@@ -1,11 +0,0 @@
-import { extend } from '../utils';
-
-/**
- * Create a new object with "null"-prototype to avoid truthy results on prototype properties.
- * The resulting object can be used with "object[property]" to check if a property exists
- * @param {...object} sources a varargs parameter of source objects that will be merged
- * @returns {object}
- */
-export function createNewLookupObject(...sources) {
-  return extend(Object.create(null), ...sources);
-}
diff --git a/lib/handlebars/internal/proto-access.js b/lib/handlebars/internal/proto-access.js
index 424e0a714..56cf12e6e 100644
--- a/lib/handlebars/internal/proto-access.js
+++ b/lib/handlebars/internal/proto-access.js
@@ -1,32 +1,30 @@
-import { createNewLookupObject } from './create-new-lookup-object';
+import { extend } from '../utils';
 import logger from '../logger';
 
 const loggedProperties = Object.create(null);
 
 export function createProtoAccessControl(runtimeOptions) {
-  let defaultMethodWhiteList = Object.create(null);
-  defaultMethodWhiteList['constructor'] = false;
-  defaultMethodWhiteList['__defineGetter__'] = false;
-  defaultMethodWhiteList['__defineSetter__'] = false;
-  defaultMethodWhiteList['__lookupGetter__'] = false;
-
-  let defaultPropertyWhiteList = Object.create(null);
+  // Create an object with "null"-prototype to avoid truthy results on
+  // prototype properties.
+  const propertyWhiteList = Object.create(null);
   // eslint-disable-next-line no-proto
-  defaultPropertyWhiteList['__proto__'] = false;
+  propertyWhiteList['__proto__'] = false;
+  extend(propertyWhiteList, runtimeOptions.allowedProtoProperties);
+
+  const methodWhiteList = Object.create(null);
+  methodWhiteList['constructor'] = false;
+  methodWhiteList['__defineGetter__'] = false;
+  methodWhiteList['__defineSetter__'] = false;
+  methodWhiteList['__lookupGetter__'] = false;
+  extend(methodWhiteList, runtimeOptions.allowedProtoMethods);
 
   return {
     properties: {
-      whitelist: createNewLookupObject(
-        defaultPropertyWhiteList,
-        runtimeOptions.allowedProtoProperties
-      ),
+      whitelist: propertyWhiteList,
       defaultValue: runtimeOptions.allowProtoPropertiesByDefault
     },
     methods: {
-      whitelist: createNewLookupObject(
-        defaultMethodWhiteList,
-        runtimeOptions.allowedProtoMethods
-      ),
+      whitelist: methodWhiteList,
       defaultValue: runtimeOptions.allowProtoMethodsByDefault
     }
   };
diff --git a/lib/handlebars/runtime.js b/lib/handlebars/runtime.js
index b9aec1e3b..554206d8b 100644
--- a/lib/handlebars/runtime.js
+++ b/lib/handlebars/runtime.js
@@ -74,17 +74,10 @@ export function template(templateSpec, env) {
     }
     partial = env.VM.resolvePartial.call(this, partial, context, options);
 
-    let extendedOptions = Utils.extend({}, options, {
-      hooks: this.hooks,
-      protoAccessControl: this.protoAccessControl
-    });
-
-    let result = env.VM.invokePartial.call(
-      this,
-      partial,
-      context,
-      extendedOptions
-    );
+    options.hooks = this.hooks;
+    options.protoAccessControl = this.protoAccessControl;
+
+    let result = env.VM.invokePartial.call(this, partial, context, options);
 
     if (result == null && env.compile) {
       options.partials[options.name] = env.compile(
@@ -92,7 +85,7 @@ export function template(templateSpec, env) {
         templateSpec.compilerOptions,
         env
       );
-      result = options.partials[options.name](context, extendedOptions);
+      result = options.partials[options.name](context, options);
     }
     if (result != null) {
       if (options.indent) {
@@ -438,6 +431,7 @@ function wrapHelpersToPassLookupProperty(mergedHelpers, container) {
 function passLookupPropertyOption(helper, container) {
   const lookupProperty = container.lookupProperty;
   return wrapHelper(helper, options => {
-    return Utils.extend({ lookupProperty }, options);
+    options.lookupProperty = lookupProperty;
+    return options;
   });
 }