From 4cf1a466cdb0672341715ea72e34d6710c799023 Mon Sep 17 00:00:00 2001
From: Alexander Zinchuk <alx.zinchuk@gmail.com>
Date: Thu, 6 Jul 2023 14:25:40 +0200
Subject: [PATCH] Revert "[Perf] Teact: Performance optimizations"

This reverts commit fccdb019535c1eb23f6857ee97607cf39fbc48e8.
---
 src/lib/teact/teact.ts | 74 ++++++++++++++++++++++--------------------
 1 file changed, 38 insertions(+), 36 deletions(-)

diff --git a/src/lib/teact/teact.ts b/src/lib/teact/teact.ts
index 6c3ac85bd..d2c683716 100644
--- a/src/lib/teact/teact.ts
+++ b/src/lib/teact/teact.ts
@@ -1,13 +1,13 @@
 import type { ReactElement } from 'react';
+import { requestMeasure, requestMutation } from '../fasterdom/fasterdom';
 
 import { DEBUG, DEBUG_MORE } from '../../config';
+import { throttleWith } from '../../util/schedulers';
+import { orderBy } from '../../util/iteratees';
 import { logUnequalProps } from '../../util/arePropsShallowEqual';
 import { incrementOverlayCounter } from '../../util/debugOverlay';
-import { orderBy } from '../../util/iteratees';
-import safeExec from '../../util/safeExec';
-import { throttleWith } from '../../util/schedulers';
 import { isSignal } from '../../util/signals';
-import { requestMeasure, requestMutation } from '../fasterdom/fasterdom';
+import safeExec from '../../util/safeExec';
 
 export type Props = AnyLiteral;
 export type FC<P extends Props = any> = (props: P) => any;
@@ -170,6 +170,8 @@ function createElement(
   props: Props,
   ...children: any[]
 ): VirtualElementParent | VirtualElementChildren {
+  children = children.flat();
+
   if (source === Fragment) {
     return buildFragmentElement(children);
   } else if (typeof source === 'function') {
@@ -182,13 +184,18 @@ function createElement(
 function buildFragmentElement(children: any[]): VirtualElementFragment {
   return {
     type: VirtualElementTypesEnum.Fragment,
-    children: buildChildren(children, true),
+    children: dropEmptyTail(children, true).map(buildChildElement),
   };
 }
 
 function createComponentInstance(Component: FC, props: Props, children: any[]): VirtualElementComponent {
-  if (children?.length) {
-    props.children = children.length === 1 ? children[0] : children;
+  let parsedChildren: any | any[] | undefined;
+  if (children.length === 0) {
+    parsedChildren = undefined;
+  } else if (children.length === 1) {
+    [parsedChildren] = children;
+  } else {
+    parsedChildren = children;
   }
 
   const componentInstance: ComponentInstance = {
@@ -196,7 +203,10 @@ function createComponentInstance(Component: FC, props: Props, children: any[]):
     $element: {} as VirtualElementComponent,
     Component,
     name: Component.name,
-    props,
+    props: {
+      ...props,
+      ...(parsedChildren && { children: parsedChildren }),
+    },
     mountState: MountState.New,
     hooks: {
       state: {
@@ -225,13 +235,13 @@ function createComponentInstance(Component: FC, props: Props, children: any[]):
 
 function buildComponentElement(
   componentInstance: ComponentInstance,
-  children?: VirtualElementChildren,
+  children: VirtualElementChildren = [],
 ): VirtualElementComponent {
   return {
     type: VirtualElementTypesEnum.Component,
     componentInstance,
     props: componentInstance.props,
-    children: children ? buildChildren(children, true) : [],
+    children: dropEmptyTail(children, true).map(buildChildElement),
   };
 }
 
@@ -240,26 +250,10 @@ function buildTagElement(tag: string, props: Props, children: any[]): VirtualEle
     type: VirtualElementTypesEnum.Tag,
     tag,
     props,
-    children: buildChildren(children),
+    children: dropEmptyTail(children).map(buildChildElement),
   };
 }
 
-function buildChildren(children: any[], noEmpty = false): VirtualElement[] {
-  const cleanChildren = dropEmptyTail(children, noEmpty);
-  const newChildren = [];
-
-  for (let i = 0, l = cleanChildren.length; i < l; i++) {
-    const child = cleanChildren[i];
-    if (Array.isArray(child)) {
-      newChildren.push(...buildChildren(child, noEmpty));
-    } else {
-      newChildren.push(buildChildElement(child));
-    }
-  }
-
-  return newChildren;
-}
-
 // We only need placeholders in the middle of collection (to ensure other elements order).
 function dropEmptyTail(children: any[], noEmpty = false) {
   let i = children.length - 1;
@@ -282,22 +276,31 @@ function dropEmptyTail(children: any[], noEmpty = false) {
 }
 
 function isEmptyPlaceholder(child: any) {
-  return !child && child !== 0;
+  // eslint-disable-next-line no-null/no-null
+  return child === false || child === null || child === undefined;
 }
 
 function buildChildElement(child: any): VirtualElement {
   if (isEmptyPlaceholder(child)) {
-    return { type: VirtualElementTypesEnum.Empty };
+    return buildEmptyElement();
   } else if (isParentElement(child)) {
     return child;
   } else {
-    return {
-      type: VirtualElementTypesEnum.Text,
-      value: String(child),
-    };
+    return buildTextElement(child);
   }
 }
 
+function buildTextElement(value: any): VirtualElementText {
+  return {
+    type: VirtualElementTypesEnum.Text,
+    value: String(value),
+  };
+}
+
+function buildEmptyElement(): VirtualElementEmpty {
+  return { type: VirtualElementTypesEnum.Empty };
+}
+
 // eslint-disable-next-line @typescript-eslint/naming-convention
 const DEBUG_components: AnyLiteral = { TOTAL: { name: 'TOTAL', renders: 0 } };
 // eslint-disable-next-line @typescript-eslint/naming-convention
@@ -581,13 +584,12 @@ export function useState<T>(): [T | undefined, StateHookSetter<T | undefined>];
 export function useState<T>(initial: T, debugKey?: string): [T, StateHookSetter<T>];
 export function useState<T>(initial?: T, debugKey?: string): [T, StateHookSetter<T>] {
   const { cursor, byCursor } = renderingInstance.hooks.state;
-  const componentInstance = renderingInstance;
 
   if (byCursor[cursor] === undefined) {
     byCursor[cursor] = {
       value: initial,
       nextValue: initial,
-      setter: (newValue: ((current: T) => T) | T) => {
+      setter: ((componentInstance) => (newValue: ((current: T) => T) | T) => {
         if (componentInstance.mountState === MountState.Unmounted) {
           return;
         }
@@ -614,7 +616,7 @@ export function useState<T>(initial?: T, debugKey?: string): [T, StateHookSetter
             byCursor[cursor].nextValue,
           );
         }
-      },
+      })(renderingInstance),
     };
   }