update

package/node_modules/@npmcli/arborist/lib/gather-dep-set.js

@@ -0,0 +1,43 @@
+// Given a set of nodes in a tree, and a filter function to test
+// incoming edges to the dep set that should be ignored otherwise.
+//
+// find the set of deps that are only depended upon by nodes in the set, or
+// their dependencies, or edges that are ignored.
+//
+// Used when figuring out what to prune when replacing a node with a newer
+// version, or when an optional dep fails to install.
+
+const gatherDepSet = (set, edgeFilter) => {
+  const deps = new Set(set)
+
+  // add the full set of dependencies.  note that this loop will continue
+  // as the deps set increases in size.
+  for (const node of deps) {
+    for (const edge of node.edgesOut.values()) {
+      if (edge.to && edgeFilter(edge)) {
+        deps.add(edge.to)
+      }
+    }
+  }
+
+  // now remove all nodes in the set that have a dependant outside the set
+  // if any change is made, then re-check
+  // continue until no changes made, or deps set evaporates fully.
+  let changed = true
+  while (changed === true && deps.size > 0) {
+    changed = false
+    for (const dep of deps) {
+      for (const edge of dep.edgesIn) {
+        if (!deps.has(edge.from) && edgeFilter(edge)) {
+          changed = true
+          deps.delete(dep)
+          break
+        }
+      }
+    }
+  }
+
+  return deps
+}
+
+module.exports = gatherDepSet