1 files changed, 56 insertions, 0 deletions
diff --git a/devtools/client/debugger/src/utils/resource/selector.js b/devtools/client/debugger/src/utils/resource/selector.js
new file mode 100644
index 0000000000..df5fae4422
--- /dev/null
+++ b/devtools/client/debugger/src/utils/resource/selector.js
@@ -0,0 +1,56 @@
+/* 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/>. */
+
+// @flow
+
+import {
+  getValidatedResource,
+  getResourceValues,
+  type ResourceState,
+  type Id,
+  type ResourceBound,
+  type ResourceIdentity,
+} from "./core";
+
+export type ResourceMap<R: ResourceBound, Mapped> = (
+  R,
+  ResourceIdentity
+) => Mapped;
+
+export function hasResource<R: ResourceBound>(
+  state: ResourceState<R>,
+  id: Id<R>
+): boolean %checks {
+  return !!getValidatedResource(state, id);
+}
+
+export function getResourceIds<R: ResourceBound>(
+  state: ResourceState<R>
+): Array<Id<R>> {
+  return Object.keys(getResourceValues(state));
+}
+
+export function getResource<R: ResourceBound>(
+  state: ResourceState<R>,
+  id: Id<R>
+): R {
+  const validatedState = getValidatedResource(state, id);
+  if (!validatedState) {
+    throw new Error(`Resource ${id} does not exist`);
+  }
+  return validatedState.values[id];
+}
+
+export function getMappedResource<R: ResourceBound, Mapped>(
+  state: ResourceState<R>,
+  id: Id<R>,
+  map: ResourceMap<R, Mapped>
+): Mapped {
+  const validatedState = getValidatedResource(state, id);
+  if (!validatedState) {
+    throw new Error(`Resource ${id} does not exist`);
+  }
+
+  return map(validatedState.values[id], validatedState.identity[id]);
+}