2e54524955
PR-URL: https://github.com/nodejs/node/pull/35474 Reviewed-By: Ruy Adorno <ruyadorno@github.com> Reviewed-By: Ujjwal Sharma <ryzokuken@disroot.org> Reviewed-By: Ben Coe <bencoe@gmail.com> Reviewed-By: Geoffrey Booth <webmaster@geoffreybooth.com> Reviewed-By: Rich Trott <rtrott@gmail.com> Reviewed-By: Shelley Vohr <codebytere@gmail.com> Reviewed-By: Guy Bedford <guybedford@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
88 lines
1.7 KiB
JavaScript
88 lines
1.7 KiB
JavaScript
// Perform a depth-first walk of a tree, ONLY doing the descent (visit)
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//
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// This uses a stack rather than recursion, so that it can handle deeply
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// nested trees without call stack overflows. (My kingdom for proper TCO!)
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//
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// This is only used for cases where leave() is not specified.
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//
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// a
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// +-- b
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// | +-- 1
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// | +-- 2
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// +-- c
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// +-- 3
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// +-- 4
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//
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// Expect:
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// visit a
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// visit b
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// visit 1
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// visit 2
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// visit c
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// visit 3
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// visit 4
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//
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// stack.push(tree)
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// while stack not empty
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// pop T from stack
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// VISIT(T)
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// get children C of T
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// push each C onto stack
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const depth = ({
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visit,
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filter,
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getChildren,
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tree,
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}) => {
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const stack = []
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const seen = new Map()
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const next = () => {
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while (stack.length) {
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const node = stack.pop()
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const res = visitNode(node)
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if (isPromise(res)) {
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return res.then(() => next())
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}
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}
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return seen.get(tree)
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}
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const visitNode = (tree) => {
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if (seen.has(tree))
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return seen.get(tree)
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seen.set(tree, null)
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const res = visit ? visit(tree) : tree
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if (isPromise(res)) {
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const fullResult = res.then(res => {
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seen.set(tree, res)
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return kidNodes(tree)
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})
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seen.set(tree, fullResult)
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return fullResult
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} else {
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seen.set(tree, res)
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return kidNodes(tree)
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}
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}
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const kidNodes = (tree) => {
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const kids = getChildren(tree, seen.get(tree))
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return isPromise(kids) ? kids.then(processKids) : processKids(kids)
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}
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const processKids = (kids) => {
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kids = (kids || []).filter(filter)
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stack.push(...kids)
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}
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stack.push(tree)
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return next()
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}
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const isPromise = p => p && typeof p.then === 'function'
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module.exports = depth
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