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// Internal methods used by buildIdealTree.
// Answer the question: "can I put this dep here?"
//
// IMPORTANT: *nothing* in this class should *ever* modify or mutate the tree
// at all. The contract here is strictly limited to read operations. We call
// this in the process of walking through the ideal tree checking many
// different potential placement targets for a given node. If a change is made
// to the tree along the way, that can cause serious problems!
//
// In order to enforce this restriction, in debug mode, canPlaceDep() will
// snapshot the tree at the start of the process, and then at the end, will
// verify that it still matches the snapshot, and throw an error if any changes
// occurred.
//
// The algorithm is roughly like this:
// - check the node itself:
// - if there is no version present, and no conflicting edges from target,
// OK, provided all peers can be placed at or above the target.
// - if the current version matches, KEEP
// - if there is an older version present, which can be replaced, then
// - if satisfying and preferDedupe? KEEP
// - else: REPLACE
// - if there is a newer version present, and preferDedupe, REPLACE
// - if the version present satisfies the edge, KEEP
// - else: CONFLICT
// - if the node is not in conflict, check each of its peers:
// - if the peer can be placed in the target, continue
// - else if the peer can be placed in a parent, and there is no other
// conflicting version shadowing it, continue
// - else CONFLICT
// - If the peers are not in conflict, return the original node's value
//
// An exception to this logic is that if the target is the deepest location
// that a node can be placed, and the conflicting node can be placed deeper,
// then we will return REPLACE rather than CONFLICT, and Arborist will queue
// the replaced node for resolution elsewhere.
const localeCompare = require('@isaacs/string-locale-compare')('en')
const semver = require('semver')
const debug = require('./debug.js')
const peerEntrySets = require('./peer-entry-sets.js')
const deepestNestingTarget = require('./deepest-nesting-target.js')
const CONFLICT = Symbol('CONFLICT')
const OK = Symbol('OK')
const REPLACE = Symbol('REPLACE')
const KEEP = Symbol('KEEP')
class CanPlaceDep {
// dep is a dep that we're trying to place. it should already live in
// a virtual tree where its peer set is loaded as children of the root.
// target is the actual place where we're trying to place this dep
// in a node_modules folder.
// edge is the edge that we're trying to satisfy with this placement.
// parent is the CanPlaceDep object of the entry node when placing a peer.
constructor (options) {
const {
dep,
target,
edge,
preferDedupe,
parent = null,
peerPath = [],
explicitRequest = false,
} = options
debug(() => {
if (!dep) {
throw new Error('no dep provided to CanPlaceDep')
}
if (!target) {
throw new Error('no target provided to CanPlaceDep')
}
if (!edge) {
throw new Error('no edge provided to CanPlaceDep')
}
this._treeSnapshot = JSON.stringify([...target.root.inventory.entries()]
.map(([loc, { packageName, version, resolved }]) => {
return [loc, packageName, version, resolved]
}).sort(([a], [b]) => localeCompare(a, b)))
})
// the result of whether we can place it or not
this.canPlace = null
// if peers conflict, but this one doesn't, then that is useful info
this.canPlaceSelf = null
this.dep = dep
this.target = target
this.edge = edge
this.explicitRequest = explicitRequest
// preventing cycles when we check peer sets
this.peerPath = peerPath
// we always prefer to dedupe peers, because they are trying
// a bit harder to be singletons.
this.preferDedupe = !!preferDedupe || edge.peer
this.parent = parent
this.children = []
this.isSource = target === this.peerSetSource
this.name = edge.name
this.current = target.children.get(this.name)
this.targetEdge = target.edgesOut.get(this.name)
this.conflicts = new Map()
// check if this dep was already subject to a peerDep override while
// building the peerSet.
this.edgeOverride = !dep.satisfies(edge)
this.canPlace = this.checkCanPlace()
if (!this.canPlaceSelf) {
this.canPlaceSelf = this.canPlace
}
debug(() => {
const treeSnapshot = JSON.stringify([...target.root.inventory.entries()]
.map(([loc, { packageName, version, resolved }]) => {
return [loc, packageName, version, resolved]
}).sort(([a], [b]) => localeCompare(a, b)))
/* istanbul ignore if */
if (this._treeSnapshot !== treeSnapshot) {
throw Object.assign(new Error('tree changed in CanPlaceDep'), {
expect: this._treeSnapshot,
actual: treeSnapshot,
})
}
})
}
checkCanPlace () {
const { target, targetEdge, current, dep } = this
// if the dep failed to load, we're going to fail the build or
// prune it out anyway, so just move forward placing/replacing it.
if (dep.errors.length) {
return current ? REPLACE : OK
}
// cannot place peers inside their dependents, except for tops
if (targetEdge && targetEdge.peer && !target.isTop) {
return CONFLICT
}
// skip this test if there's a current node, because we might be able
// to dedupe against it anyway
if (!current &&
targetEdge &&
!dep.satisfies(targetEdge) &&
targetEdge !== this.edge) {
return CONFLICT
}
return current ? this.checkCanPlaceCurrent() : this.checkCanPlaceNoCurrent()
}
// we know that the target has a dep by this name in its node_modules
// already. Can return KEEP, REPLACE, or CONFLICT.
checkCanPlaceCurrent () {
const { preferDedupe, explicitRequest, current, target, edge, dep } = this
if (dep.matches(current)) {
if (current.satisfies(edge) || this.edgeOverride) {
return explicitRequest ? REPLACE : KEEP
}
}
const { version: curVer } = current
const { version: newVer } = dep
const tryReplace = curVer && newVer && semver.gte(newVer, curVer)
if (tryReplace && dep.canReplace(current)) {
// It's extremely rare that a replaceable node would be a conflict, if
// the current one wasn't a conflict, but it is theoretically possible
// if peer deps are pinned. In that case we treat it like any other
// conflict, and keep trying.
const cpp = this.canPlacePeers(REPLACE)
if (cpp !== CONFLICT) {
return cpp
}
}
// ok, can't replace the current with new one, but maybe current is ok?
if (current.satisfies(edge) && (!explicitRequest || preferDedupe)) {
return KEEP
}
// if we prefer deduping, then try replacing newer with older
if (preferDedupe && !tryReplace && dep.canReplace(current)) {
const cpp = this.canPlacePeers(REPLACE)
if (cpp !== CONFLICT) {
return cpp
}
}
// Check for interesting cases!
// First, is this the deepest place that this thing can go, and NOT the
// deepest place where the conflicting dep can go? If so, replace it,
// and let it re-resolve deeper in the tree.
const myDeepest = this.deepestNestingTarget
// ok, i COULD be placed deeper, so leave the current one alone.
if (target !== myDeepest) {
return CONFLICT
}
// if we are not checking a peerDep, then we MUST place it here, in the
// target that has a non-peer dep on it.
if (!edge.peer && target === edge.from) {
return this.canPlacePeers(REPLACE)
}
// if we aren't placing a peer in a set, then we're done here.
// This is ignored because it SHOULD be redundant, as far as I can tell,
// with the deepest target and target===edge.from tests. But until we
// can prove that isn't possible, this condition is here for safety.
/* istanbul ignore if - allegedly impossible */
if (!this.parent && !edge.peer) {
return CONFLICT
}
// check the deps in the peer group for each edge into that peer group
// if ALL of them can be pushed deeper, or if it's ok to replace its
// members with the contents of the new peer group, then we're good.
let canReplace = true
for (const [entryEdge, currentPeers] of peerEntrySets(current)) {
if (entryEdge === this.edge || entryEdge === this.peerEntryEdge) {
continue
}
// First, see if it's ok to just replace the peerSet entirely.
// we do this by walking out from the entryEdge, because in a case like
// this:
//
// v -> PEER(a@1||2)
// a@1 -> PEER(b@1)
// a@2 -> PEER(b@2)
// b@1 -> PEER(a@1)
// b@2 -> PEER(a@2)
//
// root
// +-- v
// +-- a@2
// +-- b@2
//
// Trying to place a peer group of (a@1, b@1) would fail to note that
// they can be replaced, if we did it by looping 1 by 1. If we are
// replacing something, we don't have to check its peer deps, because
// the peerDeps in the placed peerSet will presumably satisfy.
const entryNode = entryEdge.to
const entryRep = dep.parent.children.get(entryNode.name)
if (entryRep) {
if (entryRep.canReplace(entryNode, dep.parent.children.keys())) {
continue
}
}
let canClobber = !entryRep
if (!entryRep) {
const peerReplacementWalk = new Set([entryNode])
OUTER: for (const currentPeer of peerReplacementWalk) {
for (const edge of currentPeer.edgesOut.values()) {
if (!edge.peer || !edge.valid) {
continue
}
const rep = dep.parent.children.get(edge.name)
if (!rep) {
if (edge.to) {
peerReplacementWalk.add(edge.to)
}
continue
}
if (!rep.satisfies(edge)) {
canClobber = false
break OUTER
}
}
}
}
if (canClobber) {
continue
}
// ok, we can't replace, but maybe we can nest the current set deeper?
let canNestCurrent = true
for (const currentPeer of currentPeers) {
if (!canNestCurrent) {
break
}
// still possible to nest this peerSet
const curDeep = deepestNestingTarget(entryEdge.from, currentPeer.name)
if (curDeep === target || target.isDescendantOf(curDeep)) {
canNestCurrent = false
canReplace = false
}
if (canNestCurrent) {
continue
}
}
}
// if we can nest or replace all the current peer groups, we can replace.
if (canReplace) {
return this.canPlacePeers(REPLACE)
}
return CONFLICT
}
checkCanPlaceNoCurrent () {
const { target, peerEntryEdge, dep, name } = this
// check to see what that name resolves to here, and who may depend on
// being able to reach it by crawling up past the parent. we know
// that it's not the target's direct child node, and if it was a direct
// dep of the target, we would have conflicted earlier.
const current = target !== peerEntryEdge.from && target.resolve(name)
if (current) {
for (const edge of current.edgesIn.values()) {
if (edge.from.isDescendantOf(target) && edge.valid) {
if (!dep.satisfies(edge)) {
return CONFLICT
}
}
}
}
// no objections, so this is fine as long as peers are ok here.
return this.canPlacePeers(OK)
}
get deepestNestingTarget () {
const start = this.parent ? this.parent.deepestNestingTarget
: this.edge.from
return deepestNestingTarget(start, this.name)
}
get conflictChildren () {
return this.allChildren.filter(c => c.canPlace === CONFLICT)
}
get allChildren () {
const set = new Set(this.children)
for (const child of set) {
for (const grandchild of child.children) {
set.add(grandchild)
}
}
return [...set]
}
get top () {
return this.parent ? this.parent.top : this
}
// check if peers can go here. returns state or CONFLICT
canPlacePeers (state) {
this.canPlaceSelf = state
if (this._canPlacePeers) {
return this._canPlacePeers
}
// TODO: represent peerPath in ERESOLVE error somehow?
const peerPath = [...this.peerPath, this.dep]
let sawConflict = false
for (const peerEdge of this.dep.edgesOut.values()) {
if (!peerEdge.peer || !peerEdge.to || peerPath.includes(peerEdge.to)) {
continue
}
const peer = peerEdge.to
// it may be the case that the *initial* dep can be nested, but a peer
// of that dep needs to be placed shallower, because the target has
// a peer dep on the peer as well.
const target = deepestNestingTarget(this.target, peer.name)
const cpp = new CanPlaceDep({
dep: peer,
target,
parent: this,
edge: peerEdge,
peerPath,
// always place peers in preferDedupe mode
preferDedupe: true,
})
/* istanbul ignore next */
debug(() => {
if (this.children.some(c => c.dep === cpp.dep)) {
throw new Error('checking same dep repeatedly')
}
})
this.children.push(cpp)
if (cpp.canPlace === CONFLICT) {
sawConflict = true
}
}
this._canPlacePeers = sawConflict ? CONFLICT : state
return this._canPlacePeers
}
// what is the node that is causing this peerSet to be placed?
get peerSetSource () {
return this.parent ? this.parent.peerSetSource : this.edge.from
}
get peerEntryEdge () {
return this.top.edge
}
static get CONFLICT () {
return CONFLICT
}
static get OK () {
return OK
}
static get REPLACE () {
return REPLACE
}
static get KEEP () {
return KEEP
}
get description () {
const { canPlace } = this
return canPlace && canPlace.description ||
/* istanbul ignore next - old node affordance */ canPlace
}
}
module.exports = CanPlaceDep