feat: Add a fromJSON static method

README.md

@@ -159,6 +159,9 @@ export class LRUMap<K,V> {
   // Returns an object suitable for JSON encoding
   toJSON() : Array<{key :K, value :V}>;
 
+  // Returns an LRU Map from JSON encoding
+  fromJSON(json :Array<{key :K, value :V}>) : LRUMap<K,V>;
+
   // Returns a human-readable text representation
   toString() : string;
 }

lru.d.ts

@@ -72,6 +72,9 @@ export class LRUMap<K,V> {
   // Returns an object suitable for JSON encoding
   toJSON() : Array<{key :K, value :V}>;
 
+  // Returns an LRU Map from JSON encoding
+  fromJSON(json :Array<{key :K, value :V}>) : LRUMap<K,V>;
+
   // Returns a human-readable text representation
   toString() : string;
 }

lru.js

@@ -245,6 +245,13 @@ class LRUMap {
     return s;
   }
 
+  /** Static method to create an LRUMap instance from a JSON export of a previous LRUMap */
+  static fromJSON(json) {
+    return new LRUMap(json.map(it => {
+      return [it.key, it.value]
+    }))
+  }
+
   /** Returns a String representation */
   toString() {
     var s = '', entry = this.oldest;

package.json

@@ -1,6 +1,6 @@
 {
   "name": "lru_map",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "description": "Finite key-value map using the Least Recently Used (LRU) algorithm where the most recently used objects are keept in the map while less recently used items are evicted to make room for new ones.",
   "main": "dist/lru.js",
   "types": "lru.d.ts",

test.js

@@ -287,6 +287,19 @@ toJSON() {
   ]);
 },
 
+fromJSON() {
+  let c = new LRUMap(4, [
+    ['adam',   29],
+    ['john',   26],
+    ['angela', 24],
+    ['bob',    48],
+  ]);
+  let json = c.toJSON();
+  let n = LRUMap.fromJSON(json);
+  assert(n.size == 4);
+  assert.deepEqual(n, c);
+  assert.deepEqual(n.entries(), c.entries());
+},
 
 }; // tests