update

package/node_modules/treeverse/lib/breadth.js

@@ -0,0 +1,67 @@
+// Perform a breadth-first walk of a tree, either logical or physical
+// This one only visits, it doesn't leave.  That's because
+// in a breadth-first traversal, children may be visited long
+// after their parent, so the "exit" pass ends up being just
+// another breadth-first walk.
+//
+// Breadth-first traversals are good for either creating a tree (ie,
+// reifying a dep graph based on a package.json without a node_modules
+// or package-lock), or mutating it in-place.  For a map-reduce type of
+// walk, it doesn't make a lot of sense, and is very expensive.
+const breadth = ({
+  visit,
+  filter = () => true,
+  getChildren,
+  tree,
+}) => {
+  const queue = []
+  const seen = new Map()
+
+  const next = () => {
+    while (queue.length) {
+      const node = queue.shift()
+      const res = visitNode(node)
+      if (isPromise(res)) {
+        return res.then(() => next())
+      }
+    }
+    return seen.get(tree)
+  }
+
+  const visitNode = (visitTree) => {
+    if (seen.has(visitTree)) {
+      return seen.get(visitTree)
+    }
+
+    seen.set(visitTree, null)
+    const res = visit ? visit(visitTree) : visitTree
+    if (isPromise(res)) {
+      const fullResult = res.then(resThen => {
+        seen.set(visitTree, resThen)
+        return kidNodes(visitTree)
+      })
+      seen.set(visitTree, fullResult)
+      return fullResult
+    } else {
+      seen.set(visitTree, res)
+      return kidNodes(visitTree)
+    }
+  }
+
+  const kidNodes = (kidTree) => {
+    const kids = getChildren(kidTree, seen.get(kidTree))
+    return isPromise(kids) ? kids.then(processKids) : processKids(kids)
+  }
+
+  const processKids = (kids) => {
+    kids = (kids || []).filter(filter)
+    queue.push(...kids)
+  }
+
+  queue.push(tree)
+  return next()
+}
+
+const isPromise = p => p && typeof p.then === 'function'
+
+module.exports = breadth

package/node_modules/treeverse/lib/depth-descent.js

@@ -0,0 +1,88 @@
+// Perform a depth-first walk of a tree, ONLY doing the descent (visit)
+//
+// This uses a stack rather than recursion, so that it can handle deeply
+// nested trees without call stack overflows.  (My kingdom for proper TCO!)
+//
+// This is only used for cases where leave() is not specified.
+//
+// a
+// +-- b
+// |   +-- 1
+// |   +-- 2
+// +-- c
+//     +-- 3
+//     +-- 4
+//
+// Expect:
+// visit a
+// visit b
+// visit 1
+// visit 2
+// visit c
+// visit 3
+// visit 4
+//
+// stack.push(tree)
+// while stack not empty
+//   pop T from stack
+//   VISIT(T)
+//   get children C of T
+//   push each C onto stack
+
+const depth = ({
+  visit,
+  filter,
+  getChildren,
+  tree,
+}) => {
+  const stack = []
+  const seen = new Map()
+
+  const next = () => {
+    while (stack.length) {
+      const node = stack.pop()
+      const res = visitNode(node)
+      if (isPromise(res)) {
+        return res.then(() => next())
+      }
+    }
+    return seen.get(tree)
+  }
+
+  const visitNode = (visitTree) => {
+    if (seen.has(visitTree)) {
+      return seen.get(visitTree)
+    }
+
+    seen.set(visitTree, null)
+    const res = visit ? visit(visitTree) : visitTree
+    if (isPromise(res)) {
+      const fullResult = res.then(resThen => {
+        seen.set(visitTree, resThen)
+        return kidNodes(visitTree)
+      })
+      seen.set(visitTree, fullResult)
+      return fullResult
+    } else {
+      seen.set(visitTree, res)
+      return kidNodes(visitTree)
+    }
+  }
+
+  const kidNodes = (kidTree) => {
+    const kids = getChildren(kidTree, seen.get(kidTree))
+    return isPromise(kids) ? kids.then(processKids) : processKids(kids)
+  }
+
+  const processKids = (kids) => {
+    kids = (kids || []).filter(filter)
+    stack.push(...kids)
+  }
+
+  stack.push(tree)
+  return next()
+}
+
+const isPromise = p => p && typeof p.then === 'function'
+
+module.exports = depth

package/node_modules/treeverse/lib/depth.js

@@ -0,0 +1,76 @@
+// Perform a depth-first walk of a tree.
+//
+// `visit(node)` is called when the node is first encountered.
+// `leave(node, children)` is called when all of the node's children
+// have been left or (in the case of cyclic graphs) visited.
+//
+// Only one of visit or leave is required.  (Technically both are optional,
+// but if you don't provide at least one, the tree is just walked without
+// doing anything, which is a bit pointless.)  If visit is provided, and
+// leave is not, then this is a root->leaf traversal.  If leave is provided,
+// and visit is not, then it's leaf->root.  Both can be provided for a
+// map-reduce operation.
+//
+// If either visit or leave return a Promise for any node, then the
+// walk returns a Promise.
+
+const depthDescent = require('./depth-descent.js')
+const depth = ({
+  visit,
+  leave,
+  filter = () => true,
+  seen = new Map(),
+  getChildren,
+  tree,
+}) => {
+  if (!leave) {
+    return depthDescent({ visit, filter, getChildren, tree })
+  }
+
+  if (seen.has(tree)) {
+    return seen.get(tree)
+  }
+
+  seen.set(tree, null)
+
+  const visitNode = () => {
+    const res = visit ? visit(tree) : tree
+    if (isPromise(res)) {
+      const fullResult = res.then(resThen => {
+        seen.set(tree, resThen)
+        return kidNodes()
+      })
+      seen.set(tree, fullResult)
+      return fullResult
+    } else {
+      seen.set(tree, res)
+      return kidNodes()
+    }
+  }
+
+  const kidNodes = () => {
+    const kids = getChildren(tree, seen.get(tree))
+    return isPromise(kids) ? kids.then(processKids) : processKids(kids)
+  }
+
+  const processKids = nodes => {
+    const kids = (nodes || []).filter(filter).map(kid =>
+      depth({ visit, leave, filter, seen, getChildren, tree: kid }))
+    return kids.some(isPromise)
+      ? Promise.all(kids).then(leaveNode)
+      : leaveNode(kids)
+  }
+
+  const leaveNode = kids => {
+    const res = leave(seen.get(tree), kids)
+    seen.set(tree, res)
+    // if it's a promise at this point, the caller deals with it
+    return res
+  }
+
+  return visitNode()
+}
+
+const isPromise = p => p && typeof p.then === 'function'
+
+module.exports = depth

package/node_modules/treeverse/lib/index.js

@@ -0,0 +1,4 @@
+module.exports = {
+  breadth: require('./breadth.js'),
+  depth: require('./depth.js'),
+}