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Code golf diffChildren size down by 33 B ⛳️ (#1580)
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Code golf diffChildren size down by 33 B ⛳️
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@marvinhagemeister
marvinhagemeister committed Apr 28, 2019
2 parents 47656bc + de71c11 commit cc4b770
Showing 1 changed file with 61 additions and 73 deletions.
134 changes: 61 additions & 73 deletions src/diff/children.js
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Expand Up @@ -24,11 +24,13 @@ import { removeNode } from '../util';
* Fragments that have siblings. In most cases, it starts out as `oldChildren[0]._dom`.
*/
export function diffChildren(parentDom, newParentVNode, oldParentVNode, context, isSvg, excessDomChildren, mounts, ancestorComponent, oldDom) {
let childVNode, i, j, p, index, oldVNode, newDom,
let childVNode, i, j, oldVNode, newDom,
nextDom, sibDom, focus;

let newChildren = newParentVNode._children || toChildArray(newParentVNode.props.children, newParentVNode._children=[], coerceToVNode, true);
let oldChildren = oldParentVNode!=null && oldParentVNode!=EMPTY_OBJ && oldParentVNode._children || EMPTY_ARR;
// This is a compression of oldParentVNode!=null && oldParentVNode != EMPTY_OBJ && oldParentVNode._children || EMPTY_ARR
// as EMPTY_OBJ._children should be `undefined`.
let oldChildren = oldParentVNode!=null && oldParentVNode._children || EMPTY_ARR;

let oldChildrenLength = oldChildren.length;

Expand All @@ -39,103 +41,89 @@ export function diffChildren(parentDom, newParentVNode, oldParentVNode, context,
if (oldDom == EMPTY_OBJ) {
oldDom = null;
if (excessDomChildren!=null) {
for (i = 0; i < excessDomChildren.length; i++) {
if (excessDomChildren[i]!=null) {
oldDom = excessDomChildren[i];
break;
}
for (i = 0; oldDom==null && i < excessDomChildren.length; i++) {
oldDom = excessDomChildren[i];
}
}
else {
for (i = 0; i < oldChildrenLength; i++) {
if (oldChildren[i] && oldChildren[i]._dom) {
oldDom = oldChildren[i]._dom;
break;
}
for (i = 0; oldDom==null && i < oldChildrenLength; i++) {
oldDom = oldChildren[i] && oldChildren[i]._dom;
}
}
}

for (i=0; i<newChildren.length; i++) {
childVNode = newChildren[i] = coerceToVNode(newChildren[i]);
oldVNode = index = null;

// Check if we find a corresponding element in oldChildren and store the
// index where the element was found.
p = oldChildren[i];


if (childVNode!=null) {
if (p===null || (p != null && (childVNode.key==null && p.key==null ? (childVNode.type === p.type) : (childVNode.key === p.key)))) {
index = i;
// Check if we find a corresponding element in oldChildren.
// If found, delete the array item by setting to `undefined`.
// We use `undefined`, as `null` is reserved for empty placeholders
// (holes).
oldVNode = oldChildren[i];

if (oldVNode===null || (oldVNode != null && (childVNode.key==null && oldVNode.key==null ? (childVNode.type === oldVNode.type) : (childVNode.key === oldVNode.key)))) {
oldChildren[i] = undefined;
}
else {
// Either oldVNode === undefined or oldChildrenLength > 0,
// so after this loop oldVNode == null or oldVNode is a valid value.
for (j=0; j<oldChildrenLength; j++) {
p = oldChildren[j];
if (p!=null) {
if (childVNode.key==null && p.key==null ? (childVNode.type === p.type) : (childVNode.key === p.key)) {
index = j;
break;
}
oldVNode = oldChildren[j];
if (oldVNode!=null && (childVNode.key==null && oldVNode.key==null ? (childVNode.type === oldVNode.type) : (childVNode.key === oldVNode.key))) {
oldChildren[j] = undefined;
break;
}
oldVNode = null;
}
}
}

// If we have found a corresponding old element we store it in a variable
// and delete it from the array. That way the next iteration can skip this
// element.
if (index!=null) {
oldVNode = oldChildren[index];
// We can't use `null` here because that is reserved for empty
// placeholders (holes)
oldChildren[index] = undefined;
}

nextDom = oldDom!=null && oldDom.nextSibling;
nextDom = oldDom!=null && oldDom.nextSibling;

// Morph the old element into the new one, but don't append it to the dom yet
newDom = diff(oldVNode==null ? null : oldVNode._dom, parentDom, childVNode, oldVNode, context, isSvg, excessDomChildren, mounts, ancestorComponent, null, oldDom);
// Morph the old element into the new one, but don't append it to the dom yet
newDom = diff(oldVNode && oldVNode._dom, parentDom, childVNode, oldVNode, context, isSvg, excessDomChildren, mounts, ancestorComponent, null, oldDom);

// Only proceed if the vnode has not been unmounted by `diff()` above.
if (childVNode!=null && newDom !=null) {
// Store focus in case moving children around changes it. Note that we
// can't just check once for every tree, because we have no way to
// differentiate wether the focus was reset by the user in a lifecycle
// hook or by reordering dom nodes.
focus = document.activeElement;
// Only proceed if the vnode has not been unmounted by `diff()` above.
if (newDom!=null) {
// Store focus in case moving children around changes it. Note that we
// can't just check once for every tree, because we have no way to
// differentiate wether the focus was reset by the user in a lifecycle
// hook or by reordering dom nodes.
focus = document.activeElement;

if (childVNode._lastDomChild != null) {
// Only Fragments or components that return Fragment like VNodes will
// have a non-null _lastDomChild. Continue the diff from the end of
// this Fragment's DOM tree.
newDom = childVNode._lastDomChild;
}
else if (excessDomChildren==oldVNode || newDom!=oldDom || newDom.parentNode==null) {
// NOTE: excessDomChildren==oldVNode above:
// This is a compression of excessDomChildren==null && oldVNode==null!
// The values only have the same type when `null`.

outer: if (oldDom==null || oldDom.parentNode!==parentDom) {
parentDom.appendChild(newDom);
if (childVNode._lastDomChild != null) {
// Only Fragments or components that return Fragment like VNodes will
// have a non-null _lastDomChild. Continue the diff from the end of
// this Fragment's DOM tree.
newDom = childVNode._lastDomChild;
}
else {
sibDom = oldDom;
j = 0;
while ((sibDom=sibDom.nextSibling) && j++<oldChildrenLength/2) {
if (sibDom===newDom) {
break outer;
else if (excessDomChildren==oldVNode || newDom!=oldDom || newDom.parentNode==null) {
// NOTE: excessDomChildren==oldVNode above:
// This is a compression of excessDomChildren==null && oldVNode==null!
// The values only have the same type when `null`.

outer: if (oldDom==null || oldDom.parentNode!==parentDom) {
parentDom.appendChild(newDom);
}
else {
sibDom = oldDom;
j = 0;
while ((sibDom=sibDom.nextSibling) && j++<oldChildrenLength/2) {
if (sibDom===newDom) {
break outer;
}
}
parentDom.insertBefore(newDom, oldDom);
}
parentDom.insertBefore(newDom, oldDom);
}
}

// Restore focus if it was changed
if (focus!==document.activeElement) {
focus.focus();
}
// Restore focus if it was changed
if (focus!==document.activeElement) {
focus.focus();
}

oldDom = newDom!=null ? newDom.nextSibling : nextDom;
oldDom = newDom!=null ? newDom.nextSibling : nextDom;
}
}
}

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