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backend/node_modules/mnemonist/default-weak-map.js

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+/**
+ * Mnemonist DefaultWeakMap
+ * =========================
+ *
+ * JavaScript implementation of a default weak map that will return a constructed
+ * value any time one tries to access an non-existing key. It is similar to
+ * DefaultMap but uses ES6 WeakMap that only holds weak reference to keys.
+ */
+
+/**
+ * DefaultWeakMap.
+ *
+ * @constructor
+ */
+function DefaultWeakMap(factory) {
+  if (typeof factory !== 'function')
+    throw new Error('mnemonist/DefaultWeakMap.constructor: expecting a function.');
+
+  this.items = new WeakMap();
+  this.factory = factory;
+}
+
+/**
+ * Method used to clear the structure.
+ *
+ * @return {undefined}
+ */
+DefaultWeakMap.prototype.clear = function() {
+
+  // Properties
+  this.items = new WeakMap();
+};
+
+/**
+ * Method used to get the value set for given key. If the key does not exist,
+ * the value will be created using the provided factory.
+ *
+ * @param  {any} key - Target key.
+ * @return {any}
+ */
+DefaultWeakMap.prototype.get = function(key) {
+  var value = this.items.get(key);
+
+  if (typeof value === 'undefined') {
+    value = this.factory(key);
+    this.items.set(key, value);
+  }
+
+  return value;
+};
+
+/**
+ * Method used to get the value set for given key. If the key does not exist,
+ * a value won't be created.
+ *
+ * @param  {any} key - Target key.
+ * @return {any}
+ */
+DefaultWeakMap.prototype.peek = function(key) {
+  return this.items.get(key);
+};
+
+/**
+ * Method used to set a value for given key.
+ *
+ * @param  {any} key   - Target key.
+ * @param  {any} value - Value.
+ * @return {DefaultMap}
+ */
+DefaultWeakMap.prototype.set = function(key, value) {
+  this.items.set(key, value);
+  return this;
+};
+
+/**
+ * Method used to test the existence of a key in the map.
+ *
+ * @param  {any} key   - Target key.
+ * @return {boolean}
+ */
+DefaultWeakMap.prototype.has = function(key) {
+  return this.items.has(key);
+};
+
+/**
+ * Method used to delete target key.
+ *
+ * @param  {any} key   - Target key.
+ * @return {boolean}
+ */
+DefaultWeakMap.prototype.delete = function(key) {
+  return this.items.delete(key);
+};
+
+/**
+ * Convenience known methods.
+ */
+DefaultWeakMap.prototype.inspect = function() {
+  return this.items;
+};
+
+if (typeof Symbol !== 'undefined')
+  DefaultWeakMap.prototype[Symbol.for('nodejs.util.inspect.custom')] = DefaultWeakMap.prototype.inspect;
+
+/**
+ * Exporting.
+ */
+module.exports = DefaultWeakMap;