feat: expose trapAccess (#40)

* feat: expose trapAccess

* Update src/__tests__/trapAccess.spec.ts

src/__tests__/trapAccess.spec.ts

@@ -0,0 +1,13 @@
+import { KEYS, trapAccess } from '../trapAccess';
+
+describe('trapAccess', () => {
+  test('given no KEYS, should use own keys in ownKeys trap', () => {
+    const obj = trapAccess({ '404': null, '200': null });
+    expect(Reflect.ownKeys(obj)).toEqual(['200', '404']);
+  });
+
+  test('given KEYS, should use KEYS in ownKeys trap', () => {
+    const obj = trapAccess({ '404': null, '200': null, [KEYS]: ['404', '200'] });
+    expect(Reflect.ownKeys(obj)).toEqual(['404', '200']);
+  });
+});

src/index.ts

@@ -7,3 +7,4 @@ export * from './parse';
 export * from './parseWithPointers';
 export * from './safeStringify';
 export * from './types';
+export * from './trapAccess';

src/parseWithPointers.ts

@@ -11,6 +11,7 @@ import { buildJsonPath } from './buildJsonPath';
 import { SpecialMappingKeys } from './consts';
 import { dereferenceAnchor } from './dereferenceAnchor';
 import { lineForPosition } from './lineForPosition';
+import { KEYS, trapAccess } from './trapAccess';
 import { IParseOptions, Kind, ScalarType, YAMLMapping, YAMLNode, YamlParserResult, YAMLScalar } from './types';
 import { isObject } from './utils';
 
@@ -48,8 +49,6 @@ export const parseWithPointers = <T>(value: string, options?: IParseOptions): Ya
   return parsed;
 };
 
-const KEYS = Symbol('object_keys');
-
 export const walkAST = (
   node: YAMLNode | null,
   options: Optional<IParseOptions>,
@@ -221,15 +220,9 @@ const reduceMergeKeys = (items: unknown, preserveKeyOrder: boolean): object | nu
   return typeof items !== 'object' || items === null ? null : Object(items);
 };
 
-const traps = {
-  ownKeys(target: object) {
-    return target[KEYS];
-  },
-};
-
 function createMapContainer(preserveKeyOrder: boolean): { [key in PropertyKey]: unknown } {
   if (preserveKeyOrder) {
-    const container = new Proxy({}, traps);
+    const container = trapAccess({});
     Reflect.defineProperty(container, KEYS, {
       value: [],
     });

src/trapAccess.ts

@@ -0,0 +1,9 @@
+export const KEYS = Symbol('object_keys');
+
+const traps = {
+  ownKeys(target: object) {
+    return KEYS in target ? target[KEYS] : Reflect.ownKeys(target);
+  },
+};
+
+export const trapAccess = <T extends object = object>(target: T): T => new Proxy<T>(target, traps);