From d59603f1bbdc400c2a5194bf4a720b3df17c4304 Mon Sep 17 00:00:00 2001
From: Nick Van Doorn <vandoorn.nick@gmail.com>
Date: Mon, 4 Mar 2019 02:01:03 -0800
Subject: Factor out & test path helpers

---
 lib/path.test.ts | 11 +++++++++++
 lib/path.ts      | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 lib/path.test.ts

diff --git a/lib/path.test.ts b/lib/path.test.ts
new file mode 100644
index 0000000..af987ac
--- /dev/null
+++ b/lib/path.test.ts
@@ -0,0 +1,11 @@
+import { getPathSuperSets } from './path'
+
+describe('path library', () => {
+  test('getPathSuperSets', () => {
+    expect(getPathSuperSets('/my/long/path')).toEqual([
+      '/my',
+      '/my/long',
+      '/my/long/path'
+    ])
+  })
+})
diff --git a/lib/path.ts b/lib/path.ts
index ab2bb1c..df12e01 100644
--- a/lib/path.ts
+++ b/lib/path.ts
@@ -1,3 +1,5 @@
+import { last } from './util'
+
 export const encodePath = (path: string): string =>
   path
     .split('/')
@@ -5,3 +7,34 @@ export const encodePath = (path: string): string =>
     .join('%2F') // encode the '/' char for the url
 
 export const decodePath = (path: string): string => `/${path}`
+
+/**
+ * Split path using "/" as a delimiter
+ */
+export const splitPath = (path: string): string[] =>
+  path.split('/').filter(k => k)
+
+/**
+ * Identify if a path is a root node
+ */
+export const isRootNode = (path: string): boolean => path === '/' || path === ''
+
+/**
+ * Check if path1 matches path2,
+ * if not, check if its a subpath
+ *
+ * https://stackoverflow.com/questions/37521893/determine-if-a-path-is-subdirectory-of-another-in-node-js
+ */
+export const isChildOrMatch = (child: string, parent: string) => {
+  if (child === parent || parent === '/') return true
+  const parentTokens = parent.split('/').filter((i: string) => i.length)
+  return parentTokens.every((t, i) => child.split('/')[i] === t)
+}
+
+export const getPathSuperSets = (path: string): string[] =>
+  splitPath(path).reduce((acc: any[], path: string) => {
+    if (!acc.length) return [`/${path}`]
+    else {
+      return [...acc, [last(acc), path].join('/')]
+    }
+  }, [])
-- 
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