FIN INIT

node_modules/preact/src/diff/children.js

@@ -0,0 +1,351 @@
+import { diff, unmount, applyRef } from './index';
+import { createVNode, Fragment } from '../create-element';
+import { EMPTY_OBJ, EMPTY_ARR } from '../constants';
+import { getDomSibling } from '../component';
+
+/**
+ * Diff the children of a virtual node
+ * @param {import('../internal').PreactElement} parentDom The DOM element whose
+ * children are being diffed
+ * @param {import('../internal').ComponentChildren[]} renderResult
+ * @param {import('../internal').VNode} newParentVNode The new virtual
+ * node whose children should be diff'ed against oldParentVNode
+ * @param {import('../internal').VNode} oldParentVNode The old virtual
+ * node whose children should be diff'ed against newParentVNode
+ * @param {object} globalContext The current context object - modified by getChildContext
+ * @param {boolean} isSvg Whether or not this DOM node is an SVG node
+ * @param {Array<import('../internal').PreactElement>} excessDomChildren
+ * @param {Array<import('../internal').Component>} commitQueue List of components
+ * which have callbacks to invoke in commitRoot
+ * @param {import('../internal').PreactElement} oldDom The current attached DOM
+ * element any new dom elements should be placed around. Likely `null` on first
+ * render (except when hydrating). Can be a sibling DOM element when diffing
+ * Fragments that have siblings. In most cases, it starts out as `oldChildren[0]._dom`.
+ * @param {boolean} isHydrating Whether or not we are in hydration
+ */
+export function diffChildren(
+	parentDom,
+	renderResult,
+	newParentVNode,
+	oldParentVNode,
+	globalContext,
+	isSvg,
+	excessDomChildren,
+	commitQueue,
+	oldDom,
+	isHydrating
+) {
+	let i, j, oldVNode, childVNode, newDom, firstChildDom, refs;
+
+	// This is a compression of oldParentVNode!=null && oldParentVNode != EMPTY_OBJ && oldParentVNode._children || EMPTY_ARR
+	// as EMPTY_OBJ._children should be `undefined`.
+	let oldChildren = (oldParentVNode && oldParentVNode._children) || EMPTY_ARR;
+
+	let oldChildrenLength = oldChildren.length;
+
+	newParentVNode._children = [];
+	for (i = 0; i < renderResult.length; i++) {
+		childVNode = renderResult[i];
+
+		if (childVNode == null || typeof childVNode == 'boolean') {
+			childVNode = newParentVNode._children[i] = null;
+		}
+		// If this newVNode is being reused (e.g. <div>{reuse}{reuse}</div>) in the same diff,
+		// or we are rendering a component (e.g. setState) copy the oldVNodes so it can have
+		// it's own DOM & etc. pointers
+		else if (
+			typeof childVNode == 'string' ||
+			typeof childVNode == 'number' ||
+			// eslint-disable-next-line valid-typeof
+			typeof childVNode == 'bigint'
+		) {
+			childVNode = newParentVNode._children[i] = createVNode(
+				null,
+				childVNode,
+				null,
+				null,
+				childVNode
+			);
+		} else if (Array.isArray(childVNode)) {
+			childVNode = newParentVNode._children[i] = createVNode(
+				Fragment,
+				{ children: childVNode },
+				null,
+				null,
+				null
+			);
+		} else if (childVNode._depth > 0) {
+			// VNode is already in use, clone it. This can happen in the following
+			// scenario:
+			//   const reuse = <div />
+			//   <div>{reuse}<span />{reuse}</div>
+			childVNode = newParentVNode._children[i] = createVNode(
+				childVNode.type,
+				childVNode.props,
+				childVNode.key,
+				childVNode.ref ? childVNode.ref : null,
+				childVNode._original
+			);
+		} else {
+			childVNode = newParentVNode._children[i] = childVNode;
+		}
+
+		// Terser removes the `continue` here and wraps the loop body
+		// in a `if (childVNode) { ... } condition
+		if (childVNode == null) {
+			continue;
+		}
+
+		childVNode._parent = newParentVNode;
+		childVNode._depth = newParentVNode._depth + 1;
+
+		// 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 &&
+				childVNode.key == oldVNode.key &&
+				childVNode.type === oldVNode.type)
+		) {
+			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++) {
+				oldVNode = oldChildren[j];
+				// If childVNode is unkeyed, we only match similarly unkeyed nodes, otherwise we match by key.
+				// We always match by type (in either case).
+				if (
+					oldVNode &&
+					childVNode.key == oldVNode.key &&
+					childVNode.type === oldVNode.type
+				) {
+					oldChildren[j] = undefined;
+					break;
+				}
+				oldVNode = null;
+			}
+		}
+
+		oldVNode = oldVNode || EMPTY_OBJ;
+
+		// Morph the old element into the new one, but don't append it to the dom yet
+		diff(
+			parentDom,
+			childVNode,
+			oldVNode,
+			globalContext,
+			isSvg,
+			excessDomChildren,
+			commitQueue,
+			oldDom,
+			isHydrating
+		);
+
+		newDom = childVNode._dom;
+
+		if ((j = childVNode.ref) && oldVNode.ref != j) {
+			if (!refs) refs = [];
+			if (oldVNode.ref) refs.push(oldVNode.ref, null, childVNode);
+			refs.push(j, childVNode._component || newDom, childVNode);
+		}
+
+		if (newDom != null) {
+			if (firstChildDom == null) {
+				firstChildDom = newDom;
+			}
+
+			if (
+				typeof childVNode.type == 'function' &&
+				childVNode._children === oldVNode._children
+			) {
+				childVNode._nextDom = oldDom = reorderChildren(
+					childVNode,
+					oldDom,
+					parentDom
+				);
+			} else {
+				oldDom = placeChild(
+					parentDom,
+					childVNode,
+					oldVNode,
+					oldChildren,
+					newDom,
+					oldDom
+				);
+			}
+
+			if (typeof newParentVNode.type == 'function') {
+				// Because the newParentVNode is Fragment-like, we need to set it's
+				// _nextDom property to the nextSibling of its last child DOM node.
+				//
+				// `oldDom` contains the correct value here because if the last child
+				// is a Fragment-like, then oldDom has already been set to that child's _nextDom.
+				// If the last child is a DOM VNode, then oldDom will be set to that DOM
+				// node's nextSibling.
+				newParentVNode._nextDom = oldDom;
+			}
+		} else if (
+			oldDom &&
+			oldVNode._dom == oldDom &&
+			oldDom.parentNode != parentDom
+		) {
+			// The above condition is to handle null placeholders. See test in placeholder.test.js:
+			// `efficiently replace null placeholders in parent rerenders`
+			oldDom = getDomSibling(oldVNode);
+		}
+	}
+
+	newParentVNode._dom = firstChildDom;
+
+	// Remove remaining oldChildren if there are any.
+	for (i = oldChildrenLength; i--; ) {
+		if (oldChildren[i] != null) {
+			if (
+				typeof newParentVNode.type == 'function' &&
+				oldChildren[i]._dom != null &&
+				oldChildren[i]._dom == newParentVNode._nextDom
+			) {
+				// If the newParentVNode.__nextDom points to a dom node that is about to
+				// be unmounted, then get the next sibling of that vnode and set
+				// _nextDom to it
+				newParentVNode._nextDom = getLastDom(oldParentVNode).nextSibling;
+			}
+
+			unmount(oldChildren[i], oldChildren[i]);
+		}
+	}
+
+	// Set refs only after unmount
+	if (refs) {
+		for (i = 0; i < refs.length; i++) {
+			applyRef(refs[i], refs[++i], refs[++i]);
+		}
+	}
+}
+
+function reorderChildren(childVNode, oldDom, parentDom) {
+	// Note: VNodes in nested suspended trees may be missing _children.
+	let c = childVNode._children;
+	let tmp = 0;
+	for (; c && tmp < c.length; tmp++) {
+		let vnode = c[tmp];
+		if (vnode) {
+			// We typically enter this code path on sCU bailout, where we copy
+			// oldVNode._children to newVNode._children. If that is the case, we need
+			// to update the old children's _parent pointer to point to the newVNode
+			// (childVNode here).
+			vnode._parent = childVNode;
+
+			if (typeof vnode.type == 'function') {
+				oldDom = reorderChildren(vnode, oldDom, parentDom);
+			} else {
+				oldDom = placeChild(parentDom, vnode, vnode, c, vnode._dom, oldDom);
+			}
+		}
+	}
+
+	return oldDom;
+}
+
+/**
+ * Flatten and loop through the children of a virtual node
+ * @param {import('../index').ComponentChildren} children The unflattened
+ * children of a virtual node
+ * @returns {import('../internal').VNode[]}
+ */
+export function toChildArray(children, out) {
+	out = out || [];
+	if (children == null || typeof children == 'boolean') {
+	} else if (Array.isArray(children)) {
+		children.some(child => {
+			toChildArray(child, out);
+		});
+	} else {
+		out.push(children);
+	}
+	return out;
+}
+
+function placeChild(
+	parentDom,
+	childVNode,
+	oldVNode,
+	oldChildren,
+	newDom,
+	oldDom
+) {
+	let nextDom;
+	if (childVNode._nextDom !== undefined) {
+		// Only Fragments or components that return Fragment like VNodes will
+		// have a non-undefined _nextDom. Continue the diff from the sibling
+		// of last DOM child of this child VNode
+		nextDom = childVNode._nextDom;
+
+		// Eagerly cleanup _nextDom. We don't need to persist the value because
+		// it is only used by `diffChildren` to determine where to resume the diff after
+		// diffing Components and Fragments. Once we store it the nextDOM local var, we
+		// can clean up the property
+		childVNode._nextDom = undefined;
+	} else if (
+		oldVNode == null ||
+		newDom != oldDom ||
+		newDom.parentNode == null
+	) {
+		outer: if (oldDom == null || oldDom.parentNode !== parentDom) {
+			parentDom.appendChild(newDom);
+			nextDom = null;
+		} else {
+			// `j<oldChildrenLength; j+=2` is an alternative to `j++<oldChildrenLength/2`
+			for (
+				let sibDom = oldDom, j = 0;
+				(sibDom = sibDom.nextSibling) && j < oldChildren.length;
+				j += 1
+			) {
+				if (sibDom == newDom) {
+					break outer;
+				}
+			}
+			parentDom.insertBefore(newDom, oldDom);
+			nextDom = oldDom;
+		}
+	}
+
+	// If we have pre-calculated the nextDOM node, use it. Else calculate it now
+	// Strictly check for `undefined` here cuz `null` is a valid value of `nextDom`.
+	// See more detail in create-element.js:createVNode
+	if (nextDom !== undefined) {
+		oldDom = nextDom;
+	} else {
+		oldDom = newDom.nextSibling;
+	}
+
+	return oldDom;
+}
+
+/**
+ * @param {import('../internal').VNode} vnode
+ */
+function getLastDom(vnode) {
+	if (vnode.type == null || typeof vnode.type === 'string') {
+		return vnode._dom;
+	}
+
+	if (vnode._children) {
+		for (let i = vnode._children.length - 1; i >= 0; i--) {
+			let child = vnode._children[i];
+			if (child) {
+				let lastDom = getLastDom(child);
+				if (lastDom) {
+					return lastDom;
+				}
+			}
+		}
+	}
+
+	return null;
+}