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| const oldCh = oldVnode.children // 老的儿子
const ch = vnode.children // 新的儿子
if (isUndef(vnode.text)) {
if (isDef(oldCh) && isDef(ch)) { // 比较孩子
if (oldCh !== ch) updateChildren(elm, oldCh, ch, insertedVnodeQueue, removeOnly)
} else if (isDef(ch)) { // 新的儿子有 老的没有
if (isDef(oldVnode.text)) {
nodeOps.setTextContent(elm, '') // 将老的清空
addVnodes(elm, null, ch, 0, ch.length - 1, insertedVnodeQueue)
}
} else if (isDef(oldCh)) { // 如果老的有新的没有 就删除
removeVnodes(oldCh, 0, oldCh.length - 1)
} else if (isDef(oldVnode.text)) { // 老的有文本 新的没文本
nodeOps.setTextContent(elm, '') // 将老的清空
}
} else if (oldVnode.text !== vnode.text) { // 文本不相同替换
nodeOps.setTextContent(elm, vnode.text)
}
function updateChildren(parentElm, oldCh, newCh, insertedVnodeQueue, removeOnly) {
let oldStartIdx = 0
let newStartIdx = 0
let oldEndIdx = oldCh.length - 1
let oldStartVnode = oldCh[0]
let oldEndVnode = oldCh[oldEndIdx]
let newEndIdx = newCh.length - 1
let newStartVnode = newCh[0]
let newEndVnode = newCh[newEndIdx]
let oldKeyToIdx, idxInOld, vnodeToMove, refElm
// removeOnly is a special flag used only by <transition-group>
// to ensure removed elements stay in correct relative positions
// during leaving transitions
const canMove = !removeOnly
if (process.env.NODE_ENV !== 'production') {
checkDuplicateKeys(newCh)
}
while (oldStartIdx <= oldEndIdx && newStartIdx <= newEndIdx) {
if (isUndef(oldStartVnode)) {
oldStartVnode = oldCh[++oldStartIdx] // Vnode has been moved left
} else if (isUndef(oldEndVnode)) {
oldEndVnode = oldCh[--oldEndIdx]
} else if (sameVnode(oldStartVnode, newStartVnode)) {
patchVnode(oldStartVnode, newStartVnode, insertedVnodeQueue, newCh, newStartIdx) oldStartVnode = oldCh[++
oldStartIdx] newStartVnode = newCh[++newStartIdx]
} else if (sameVnode(oldEndVnode, newEndVnode)) {
patchVnode(oldEndVnode, newEndVnode, insertedVnodeQueue, newCh, newEndIdx) oldEndVnode = oldCh[--oldEndIdx] newEndVnode =
newCh[--newEndIdx]
} else if (sameVnode(oldStartVnode, newEndVnode)) { // Vnode moved right
patchVnode(oldStartVnode, newEndVnode, insertedVnodeQueue, newCh, newEndIdx) canMove && nodeOps.insertBefore(
parentElm, oldStartVnode.elm, nodeOps.nextSibling(oldEndVnode.elm)) oldStartVnode = oldCh[++oldStartIdx] newEndVnode =
newCh[--newEndIdx]
} else if (sameVnode(oldEndVnode, newStartVnode)) { // Vnode moved left
patchVnode(oldEndVnode, newStartVnode, insertedVnodeQueue, newCh, newStartIdx) canMove && nodeOps.insertBefore(
parentElm, oldEndVnode.elm, oldStartVnode.elm) oldEndVnode = oldCh[--oldEndIdx] newStartVnode = newCh[++
newStartIdx]
} else {
if (isUndef(oldKeyToIdx)) oldKeyToIdx = createKeyToOldIdx(oldCh, oldStartIdx, oldEndIdx) idxInOld = isDef(
newStartVnode.key) ? oldKeyToIdx[newStartVnode.key] : findIdxInOld(newStartVnode, oldCh, oldStartIdx,
oldEndIdx) if (isUndef(idxInOld)) { // New element
createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm, false, newCh, newStartIdx)
} else {
vnodeToMove = oldCh[idxInOld]
if (sameVnode(vnodeToMove, newStartVnode)) {
patchVnode(vnodeToMove, newStartVnode, insertedVnodeQueue, newCh, newStartIdx) oldCh[idxInOld] = undefined canMove &&
nodeOps.insertBefore(parentElm, vnodeToMove.elm, oldStartVnode.elm)
} else { // same key but different element. treat as new element
createElm(newStartVnode, insertedVnodeQueue, parentElm, oldStartVnode.elm, false, newCh, newStartIdx)
}
} newStartVnode = newCh[++newStartIdx]
}
}
if (oldStartIdx > oldEndIdx) {
refElm = isUndef(newCh[newEndIdx + 1]) ? null : newCh[newEndIdx + 1].elm addVnodes(parentElm, refElm, newCh,
newStartIdx, newEndIdx, insertedVnodeQueue)
}
a
else if (newStartIdx > newEndIdx) {
removeVnodes(oldCh, oldStartIdx, oldEndIdx)
}
}
|
