From be1b2a1c3e0418620147b89a69b6d6b610277eb1 Mon Sep 17 00:00:00 2001
From: Alexander Rose <alex.rose@rcsb.org>
Date: Fri, 17 Aug 2018 12:08:32 -0700
Subject: [PATCH] added DefaultMap
---
src/mol-util/map.ts | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
create mode 100644 src/mol-util/map.ts
diff --git a/src/mol-util/map.ts b/src/mol-util/map.ts
new file mode 100644
index 000000000..42c258907
--- /dev/null
+++ b/src/mol-util/map.ts
@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ *
+ * @author Alexander Rose <alexander.rose@weirdbyte.de>
+ */
+
+export interface DefaultMap<K, V> extends Map<K, V> {
+ /** Return the value for `key` when available or the default value otherwise. */
+ getDefault: (key: K) => V
+}
+
+/** A `Map` instance with a `getDefault` method added. */
+export function DefaultMap<K, V>(valueCtor: () => V) {
+ const map = new Map<K, V>() as DefaultMap<K, V>
+ map.getDefault = (key: K) => {
+ if (map.has(key)) return map.get(key)!
+ const value = valueCtor()
+ map.set(key, value)
+ return value
+ }
+ return map
+}
+
+// TODO currently not working, see https://github.com/Microsoft/TypeScript/issues/10853
+// /** A `Map` with a `getDefault` method added. */
+// export class DefaultMap<K, V> extends Map<K, V> {
+// constructor(private valueCtor: () => V, entries?: ReadonlyArray<[K, V]>) {
+// super(entries)
+// }
+// /** Return the value for `key` when available or the default value otherwise. */
+// getDefault(key: K) {
+// if (this.has(key)) return this.get(key)!
+// const value = this.valueCtor()
+// this.set(key, value)
+// return value
+// }
+// }
\ No newline at end of file
--
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