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| <!-- traverseAllChildren函数 -->
/**
*
*
* @param {*} children 传递的props.children
* @param {*} callback 为传递进来的mapSingleChildIntoContext函数
* @param {*} traverseContext 从对象池中获取的对象，也是执行的上下文
* @returns
*/
function traverseAllChildren(children, callback, traverseContext) {
if (children == null) {
return 0;
}
return traverseAllChildrenImpl(children, '', callback, traverseContext);
}
<!-- traverseAllChildrenImpl函数 -->
/**
*
*
* @param {*} children 初始值 props.children，后续为递归传递的子节点
* @param {*} nameSoFar 初始值 ''
* @param {*} callback mapSingleChildIntoContext
* @param {*} traverseContext 这里的context为对象池中获取的对象
*/
function traverseAllChildrenImpl(
children,
nameSoFar,
callback,
traverseContext,
) {
const type = typeof children;
let invokeCallback = false;
if (type === "undefined" || type === "boolean") {
invokeCallback = true;
} else {
switch (type) {
case 'string':
case 'number':
invokeCallback = true;
break;
case 'object':
switch (children.$$typeof) {
case REACT_ELEMENT_TYPE:
case REACT_PORTAL_TYPE:
invokeCallback = true;
}
}
}
if (invokeCallback) {
callback(
traverseContext,
children,
nameSoFar === '' ? SEPARATOR + getComponentKey(children, 0) : nameSoFar,
);
return 1;
}
let child;
let nextName;
let subtreeCount = 0;
const nextNamePrefix =
nameSoFar === '' ? SEPARATOR : nameSoFar + SUBSEPARATOR;//初始值为'.:'
if (Array.isArray(children)) {
for (let i = 0; i < children.length; i++) {
child = children[i];
nextName = nextNamePrefix + getComponentKey(child, i);
subtreeCount += traverseAllChildrenImpl(
child,
nextName,
callback,
traverseContext,
);
}
} else {
const iteratorFn = getIteratorFn(children);
if (typeof iteratorFn === 'function') {
const iterator = iteratorFn.call(children);
let step;
let ii = 0;
while (!(step = iterator.next()).done) {
child = step.value;
nextName = nextNamePrefix + getComponentKey(child, ii++);
subtreeCount += traverseAllChildrenImpl(
child,
nextName,
callback,
traverseContext,
);
}
} else if (type === 'object') {
let addendum = '';
const childrenString = '' + children;
invariant(
false,
'Objects are not valid as a React child (found: %s).%s',
childrenString === '[object Object]'
? 'object with keys {' + Object.keys(children).join(', ') + '}'
: childrenString,
addendum,
);
}
}
return subtreeCount;
}
const POOL_SIZE = 10;
const traverseContextPool = [];
function getPooledTraverseContext(
mapResult,
keyPrefix,
mapFunction,
mapContext,
) {
if (traverseContextPool.length) {
const traverseContext = traverseContextPool.pop();
traverseContext.result = mapResult;
traverseContext.keyPrefix = keyPrefix;
traverseContext.func = mapFunction;
traverseContext.context = mapContext;
traverseContext.count = 0;
return traverseContext;
} else {
return {
result: mapResult,
keyPrefix: keyPrefix,
func: mapFunction,
context: mapContext,
count: 0,
};
}
}
|
