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export function reconcileChildren(workInProgress, elements) { | ||
let index = 0; // 当前遍历的子元素在父节点下的下标 | ||
let prevSibling = null; // 记录上一个兄弟节点 | ||
let oldFiber = workInProgress?.alternate?.child; // 对应的旧 fiber | ||
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while (index < elements.length) { | ||
// 遍历子元素 | ||
while (index < elements.length || oldFiber) { | ||
// 遍历 elements 和 oldFiber | ||
const element = elements[index]; | ||
// 创建新的 fiber | ||
const newFiber = { | ||
element, | ||
return: workInProgress, | ||
stateNode: null, | ||
}; | ||
let newFiber = null; | ||
const isSameType = | ||
element?.type && | ||
oldFiber?.element?.type && | ||
element.type === oldFiber.element.type; | ||
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// 添加 flag 副作用 | ||
if (isSameType) { | ||
// type相同,表示更新 | ||
newFiber = { | ||
element: { | ||
...element, | ||
props: element.props, | ||
}, | ||
stateNode: oldFiber.stateNode, | ||
return: workInProgress, | ||
alternate: oldFiber, | ||
flag: 'Update', | ||
}; | ||
} else { | ||
// type 不同,表示添加或者删除 | ||
if (element || element === 0) { | ||
// element 存在,表示添加 | ||
newFiber = { | ||
element, | ||
stateNode: null, | ||
return: workInProgress, | ||
alternate: null, | ||
flag: 'Placement', | ||
index, | ||
}; | ||
} | ||
if (oldFiber) { | ||
// oldFiber存在,删除 oldFiber | ||
oldFiber.flag = 'Deletion'; | ||
} | ||
} | ||
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if (oldFiber) { | ||
// oldFiber 存在,则继续遍历其 sibling | ||
oldFiber = oldFiber.sibling; | ||
} | ||
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if (index === 0) { | ||
// 如果下标为 0,则将当前fiber设置为父 fiber 的 child | ||
workInProgress.child = newFiber; | ||
} else { | ||
// 否则通过 sibling 作为兄弟 fiber 连接 | ||
prevSibling = newFiber; | ||
} else if (newFiber) { | ||
// newFiber 和 prevSibling 存在,通过 sibling 作为兄弟 fiber 连接 | ||
prevSibling.sibling = newFiber; | ||
prevSibling = newFiber; | ||
} | ||
prevSibling = newFiber; | ||
index++; | ||
} | ||
} |