Feature: Add support for circular references

.npmignore

@@ -1,9 +1,11 @@
 /coverage/
 /typings/
 /src/
-/lib/*.test.*
+/lib/**/*.test.*
 /.editorconfig
 /.gitignore
 /.travis.yml
+/custom.d.ts
+/mocha.opts
 /tsconfig.json
 /tslint.json

README.md

@@ -9,7 +9,8 @@
 [Install](#install) | [Usage](#usage) | [API](#api) | [TypeScript](#typescript) | [License](#license)
 
 **Deep Map Keys** recurses through an object and transforms its keys – and
-the keys of any nested objects – according to some function.
+the keys of any nested objects – according to some function. Circular
+references are supported.
 
 To transform the *values* of an object rather than its keys, use
 [Deep Map][deep-map].
@@ -86,7 +87,8 @@ And the result will look like this:
         a complex object containing other nested objects. This object may be an
         <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array">
         <code>Array</code></a>, in which case the keys of any objects it
-        contains will be transformed.
+        contains will be transformed. The object may contain circular
+        references.
       </td>
     </tr>
     <tr>

custom.d.ts

@@ -0,0 +1,10 @@
+declare module 'es6-weak-map' {
+
+  export = class WeakMap<K, V> {
+    delete(key: K): boolean;
+    get(key: K): V;
+    has(key: K): boolean;
+    set(key: K, value?: V): this;
+  };
+
+}

mocha.opts

@@ -0,0 +1,3 @@
+--compilers ts:ts-node/register
+--recursive
+--reporter dot

package.json

@@ -9,7 +9,7 @@
     "build:remove": "rimraf lib",
     "build": "npm run build:remove && npm run build:compile",
     "test:lint": "tslint 'src/**/*.ts'",
-    "test:unit": "istanbul cover -e .ts -x '*.test.ts' _mocha -- 'src/**/*.test.ts' --compilers ts:ts-node/register",
+    "test:unit": "istanbul cover -e .ts -x '*.test.ts' _mocha -- src --opts mocha.opts",
     "test:report": "npm test && open coverage/lcov-report/index.html",
     "test": "npm run test:lint && npm run test:unit",
     "ci:typings": "typings install",
@@ -26,6 +26,7 @@
     "nested",
     "object",
     "array",
+    "circular",
     "json",
     "typescript",
     "typings"
@@ -45,7 +46,10 @@
     "typescript": "^1.8.10",
     "typings": "^1.1.0"
   },
-  "dependencies": {},
+  "dependencies": {
+    "es6-weak-map": "^2.0.1",
+    "lodash": "^4.13.1"
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/akim-mcmath/deep-map-keys.git"

src/deep-map-keys.ts

@@ -1,53 +1,65 @@
-import {isArray, isFunction, isObject, isVoid} from './lang';
+import WeakMap = require('es6-weak-map');
+import {isArray, isObject} from 'lodash';
+
+interface NonPrimitive extends Object {
+  [key: string]: any;
+  [index: number]: any;
+}
 
 export interface MapFn {
   (key: string, value: any): string;
 }
 
-export interface Options {
+export interface Opts {
   thisArg?: any;
 }
 
-export function deepMapKeys<T>(object: any, mapFn: MapFn, options?: Options): T {
-  options = isVoid(options) ? {} : options;
+export class DeepMapKeys {
+
+  private cache = new WeakMap<NonPrimitive, any>();
 
-  if (!mapFn) {
-    throw new Error('mapFn is required');
-  } else if (!isFunction(mapFn)) {
-    throw new TypeError('mapFn must be a function');
-  } else if (!isObject(options)) {
-    throw new TypeError('options must be an object');
+  constructor(
+    private mapFn: MapFn,
+    private opts: Opts
+  ) { }
+
+  public map(value: any): any {
+    return isArray(value) ? this.mapArray(value) :
+      isObject(value) ? this.mapObject(value) :
+      value;
   }
 
-  return map(object, mapFn, options);
-}
+  private mapArray(arr: any[]): any[] {
+    if (this.cache.has(arr)) {
+      return this.cache.get(arr);
+    }
 
-function map(value: any, fn: MapFn, opts: Options): any {
-  return isArray(value) ? mapArray(value, fn, opts) :
-    isObject(value) ? mapObject(value, fn, opts) :
-    value;
-}
+    let length = arr.length;
+    let result: any[] = [];
+    this.cache.set(arr, result);
 
-function mapArray(arr: any[], fn: MapFn, opts: Options): any[] {
-  let result: any[] = [];
-  let len = arr.length;
+    for (let i = 0; i < length; i++) {
+      result.push(this.map(arr[i]));
+    }
 
-  for (let i = 0; i < len; i++) {
-    result.push(map(arr[i], fn, opts));
+    return result;
   }
 
-  return result;
-}
+  private mapObject(obj: NonPrimitive): NonPrimitive {
+    if (this.cache.has(obj)) {
+      return this.cache.get(obj);
+    }
 
-function mapObject(obj: {[key: string]: any}, fn: MapFn, opts: Options): {[key: string]: any} {
-  let result: {[key: string]: any} = {};
+    let {mapFn, opts: {thisArg}} = this;
+    let result: NonPrimitive = {};
+    this.cache.set(obj, result);
 
-  for (let key in obj) {
-    if (obj.hasOwnProperty(key)) {
-      let value = obj[key];
-      result[fn.call(opts.thisArg, key, value)] = map(value, fn, opts);
+    for (let key in obj) {
+      if (obj.hasOwnProperty(key)) {
+        result[mapFn.call(thisArg, key, obj[key])] = this.map(obj[key]);
+      }
     }
-  }
 
-  return result;
+    return result;
+  }
 }

src/index.test.ts

@@ -35,6 +35,18 @@ describe('deepMapKeys(object, mapFn, [options])', () => {
         .should.deep.equal([1, {TWO: 2, THREE: 3, ARR: [4, {FIVE: 5}]}]);
     });
 
+    it('transforms an object with circular references', () => {
+      let obj = {one: 1, arr: [2, 3], self: null as any, arr2: null as any[]};
+      obj.self = obj;
+      obj.arr2 = obj.arr;
+
+      let exp = {ONE: 1, ARR: [2, 3], SELF: null as any, ARR2: null as any[]};
+      exp.SELF = exp;
+      exp.ARR2 = exp.ARR;
+
+      deepMapKeys(obj, caps).should.deep.equal(exp);
+    });
+
   });
 
   describe('@mapFn(key: string, value: any): string', () => {

src/index.ts

@@ -1,3 +1,18 @@
-import {deepMapKeys} from './deep-map-keys';
+import {isFunction, isNil, isObject} from 'lodash';
+import {DeepMapKeys, MapFn, Opts} from './deep-map-keys';
+
+function deepMapKeys<T>(object: any, mapFn: MapFn, options?: Opts): T {
+  options = isNil(options) ? {} : options;
+
+  if (!mapFn) {
+    throw new Error('mapFn is required');
+  } else if (!isFunction(mapFn)) {
+    throw new TypeError('mapFn must be a function');
+  } else if (!isObject(options)) {
+    throw new TypeError('options must be an object');
+  }
+
+  return new DeepMapKeys(mapFn, options).map(object);
+}
 
 export = deepMapKeys;

typings.json

@@ -6,6 +6,7 @@
   "devDependencies": {
     "chai": "registry:npm/chai#3.5.0+20160415060238",
     "sinon": "registry:npm/sinon#1.16.0+20160427193336",
-    "sinon-chai": "registry:npm/sinon-chai#2.8.0+20160310030142"
+    "sinon-chai": "registry:npm/sinon-chai#2.8.0+20160310030142",
+    "lodash": "registry:npm/lodash#4.0.0+20160416211519"
   }
 }