1 files changed, 63 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/utils/memoize.js b/devtools/client/debugger/src/utils/memoize.js
new file mode 100644
index 0000000000..3f634b326d
--- /dev/null
+++ b/devtools/client/debugger/src/utils/memoize.js
@@ -0,0 +1,63 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */
+
+function hasValue(keys, store) {
+  let currentStore = store;
+  for (const key of keys) {
+    if (!currentStore || !currentStore.has(key)) {
+      return false;
+    }
+
+    currentStore = currentStore.get(key);
+  }
+  return true;
+}
+
+function getValue(keys, store) {
+  let currentStore = store;
+  for (const key of keys) {
+    if (!currentStore) {
+      return null;
+    }
+    currentStore = currentStore.get(key);
+  }
+
+  return currentStore;
+}
+
+function setValue(keys, store, value) {
+  const keysExceptLast = keys.slice(0, -1);
+  const lastKey = keys[keys.length - 1];
+
+  let currentStore = store;
+  for (const key of keysExceptLast) {
+    if (!currentStore) {
+      return;
+    }
+
+    if (!currentStore.has(key)) {
+      currentStore.set(key, new WeakMap());
+    }
+    currentStore = currentStore.get(key);
+  }
+
+  if (currentStore) {
+    currentStore.set(lastKey, value);
+  }
+}
+
+// memoize with n arguments
+export default function memoize(func) {
+  const store = new WeakMap();
+
+  return function (...keys) {
+    if (hasValue(keys, store)) {
+      return getValue(keys, store);
+    }
+
+    const newValue = func.apply(null, keys);
+    setValue(keys, store, newValue);
+    return newValue;
+  };
+}