mostly-dom/lib.es2015/updateChildren.js

A virtual-dom for TypeScript

import { addVNodes } from './addVNodes';
import { createElement } from './createElement';
import { patchVNode } from './patchVNode';
import { removeVNodes } from './removeVNodes';
import { vNodesAreEqual } from './helpers';
export function updateChildren(parentElement, formerChildren, children, moduleCallbacks, insertedVNodeQueue) {
    // indexes
    var formerStartIndex = 0;
    var startIndex = 0;
    var formerEndIndex = formerChildren.length - 1;
    var endIndex = children.length - 1;
    // VNodes
    var formerStartVNode = formerChildren[formerStartIndex];
    var startVNode = children[startIndex];
    var formerEndVNode = formerChildren[formerEndIndex];
    var endVNode = children[endIndex];
    // an object mapping keys to indexes in formerChildren array
    var mappedKeyToFormerIndex;
    while (formerStartIndex <= formerEndIndex && startIndex <= endIndex) {
        if (!formerStartVNode)
            formerStartVNode = formerChildren[++formerStartIndex];
        else if (!formerEndVNode)
            formerEndVNode = formerChildren[--formerEndIndex];
        else if (vNodesAreEqual(formerStartVNode, startVNode)) {
            patchVNode(formerStartVNode, startVNode, moduleCallbacks, insertedVNodeQueue);
            formerStartVNode = formerChildren[++formerStartIndex];
            startVNode = children[++startIndex];
        }
        else if (vNodesAreEqual(formerEndVNode, endVNode)) {
            patchVNode(formerEndVNode, endVNode, moduleCallbacks, insertedVNodeQueue);
            formerEndVNode = formerChildren[--formerEndIndex];
            endVNode = children[--endIndex];
        }
        else if (vNodesAreEqual(formerStartVNode, endVNode)) {
            patchVNode(formerStartVNode, endVNode, moduleCallbacks, insertedVNodeQueue);
            parentElement.insertBefore(formerStartVNode.element, formerEndVNode.element.nextSibling);
            formerStartVNode = formerChildren[++formerStartIndex];
            endVNode = children[--endIndex];
        }
        else if (vNodesAreEqual(formerEndVNode, startVNode)) {
            patchVNode(formerEndVNode, startVNode, moduleCallbacks, insertedVNodeQueue);
            parentElement.insertBefore(formerEndVNode.element, formerStartVNode.element);
            formerEndVNode = formerChildren[--formerEndIndex];
            startVNode = children[++startIndex];
        }
        else {
            if (!mappedKeyToFormerIndex)
                mappedKeyToFormerIndex =
                    mapKeyToFormerIndex(formerChildren, formerStartIndex, formerEndIndex);
            var formerIndexKey = mappedKeyToFormerIndex[startVNode.key];
            if (!formerIndexKey) { // new element
                var element = createElement(startVNode, moduleCallbacks, insertedVNodeQueue).element;
                parentElement.insertBefore(element, formerStartVNode.element);
                startVNode = children[++startIndex];
            }
            else {
                var reorderableVNode = formerChildren[formerIndexKey];
                patchVNode(reorderableVNode, startVNode, moduleCallbacks, insertedVNodeQueue);
                // WARNING: hack for performance optimization
                formerChildren[formerIndexKey] = void 0;
                parentElement.insertBefore(reorderableVNode.element, formerStartVNode.element);
                startVNode = children[++startIndex];
            }
        }
    }
    if (formerStartIndex > formerEndIndex) {
        var referenceNode = children[endIndex + 1] ? children[endIndex + 1].element : null;
        addVNodes(parentElement, referenceNode, children, startIndex, endIndex, moduleCallbacks, insertedVNodeQueue);
    }
    else if (startIndex > endIndex)
        removeVNodes(parentElement, formerChildren, formerStartIndex, formerEndIndex, moduleCallbacks);
}
function mapKeyToFormerIndex(children, startIndex, endIndex) {
    var index = startIndex;
    var map = {};
    var key;
    for (; index <= endIndex; ++index) {
        key = children[index].key;
        if (key)
            map[key] = index;
    }
    return map;
}
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