1 files changed, 40 insertions, 0 deletions
diff --git a/deps/npm/lib/prune.js b/deps/npm/lib/prune.js
new file mode 100644
index 0000000000..4a02dc1f8a
--- /dev/null
+++ b/deps/npm/lib/prune.js
@@ -0,0 +1,40 @@
+// prune extraneous packages.
+
+module.exports = prune
+
+prune.usage = "npm prune"
+
+var readInstalled = require("./utils/read-installed.js")
+  , npm = require("./npm.js")
+
+prune.completion = require("./utils/completion/installed-deep.js")
+
+function prune (args, cb) {
+  readInstalled(npm.prefix, function (er, data) {
+    if (er) return cb(er)
+    prune_(args, data, cb)
+  })
+}
+
+function prune_ (args, data, cb) {
+  npm.commands.unbuild(prunables(args, data, []), cb)
+}
+
+function prunables (args, data, seen) {
+  var deps = data.dependencies || {}
+  return Object.keys(deps).map(function (d) {
+    if (typeof deps[d] !== "object"
+        || seen.indexOf(deps[d]) !== -1) return null
+    seen.push(deps[d])
+    if (deps[d].extraneous
+        && (args.length === 0 || args.indexOf(d) !== -1)) {
+      var extra = deps[d]
+      delete deps[d]
+      return extra.path
+    }
+    return prunables(args, deps[d], seen)
+  }).filter(function (d) { return d !== null })
+  .reduce(function FLAT (l, r) {
+    return l.concat(Array.isArray(r) ? r.reduce(FLAT,[]) : r)
+  }, [])
+}