handle escaping and honor root pointer (#52)

* handle escaping and honor root pointer

* Update client/lib/json-patch-lib.ts

* Update client/lib/json-patch-lib.ts

Co-authored-by: Lucy C <12953208+elvece@users.noreply.github.com>

client/lib/json-patch-lib.ts

@@ -25,12 +25,12 @@ export type Operation<T> =
 
 export function getValueByPointer<T extends Record<string, T>>(
   data: T,
-  pointer: string,
+  path: string,
 ): any {
-  if (pointer === '/') return data
+  if (!path) return data
 
   try {
-    return jsonPathToKeyArray(pointer).reduce((acc, next) => acc[next], data)
+    return arrayFromPath(path).reduce((acc, next) => acc[next], data)
   } catch (e) {
     return undefined
   }
@@ -40,11 +40,33 @@ export function applyOperation<T>(
   doc: DBCache<Record<string, any>>,
   { path, op, value }: Operation<T> & { value?: T },
 ) {
-  doc.data = recursiveApply(doc.data, jsonPathToKeyArray(path), op, value)
+  doc.data = recursiveApply(doc.data, arrayFromPath(path), op, value)
 }
 
-export function jsonPathToKeyArray(path: string): string[] {
-  return path.split('/').slice(1)
+export function arrayFromPath(path: string): string[] {
+  return path
+    .split('/')
+    .slice(1)
+    .map(p =>
+      // order matters, always replace "~1" first
+      p.replace(new RegExp('~1', 'g'), '/').replace(new RegExp('~0', 'g'), '~'),
+    )
+}
+
+export function pathFromArray(args: Array<string | number>): string {
+  if (!args.length) return ''
+
+  return (
+    '/' +
+    args
+      .map(a =>
+        String(a)
+           // do not change order, "~" needs to be replaced first
+          .replace(new RegExp('~', 'g'), '~0')
+          .replace(new RegExp('/', 'g'), '~1'),
+      )
+      .join('/')
+  )
 }
 
 function recursiveApply<T extends Record<string, any> | any[]>(

client/lib/patch-db.ts

@@ -10,8 +10,9 @@ import {
 } from 'rxjs'
 import {
   applyOperation,
+  arrayFromPath,
   getValueByPointer,
-  jsonPathToKeyArray,
+  pathFromArray,
 } from './json-patch-lib'
 
 export class PatchDB<T extends { [key: string]: any }> {
@@ -133,12 +134,12 @@ export class PatchDB<T extends { [key: string]: any }> {
       filter(({ sequence }) => !!sequence),
       take(1),
       switchMap(({ data }) => {
-        const path = args.length ? `/${args.join('/')}` : ''
+        const path = pathFromArray(args)
         if (!this.watchedNodes[path]) {
           const value = getValueByPointer(data, path)
           this.watchedNodes[path] = {
             subject: new BehaviorSubject(value),
-            pathArr: jsonPathToKeyArray(path),
+            pathArr: arrayFromPath(path),
           }
         }
         return this.watchedNodes[path].subject
@@ -183,7 +184,7 @@ export class PatchDB<T extends { [key: string]: any }> {
   }
 
   private updateWatchedNodes(revisionPath: string, data: T): void {
-    const r = jsonPathToKeyArray(revisionPath)
+    const r = arrayFromPath(revisionPath)
     Object.entries(this.watchedNodes).forEach(([path, { pathArr }]) => {
       if (startsWith(pathArr, r) || startsWith(r, pathArr)) {
         this.updateWatchedNode(path, data)