Add a basic collection of env locators.

Author: ericsnowcurrently

src/client/pythonEnvironments/base/locators.ts

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+import { chain } from '../../common/utils/async';
+import { PythonEnvInfo } from './info';
+import { ILocator, PythonEnvsIterator, PythonLocatorQuery } from './locator';
+import { PythonEnvsWatchers } from './watchers';
+
+/**
+ * A wrapper around a set of locators.
+ *
+ * Events and iterator results are combined.
+ */
+export class Locators extends PythonEnvsWatchers {
+    constructor(
+        // The locators will be watched as well as iterated.
+        private readonly locators: ReadonlyArray<ILocator>
+    ) {
+        super(locators);
+    }
+
+    public iterEnvs(query?: PythonLocatorQuery): PythonEnvsIterator {
+        const iterators = this.locators.map((loc) => loc.iterEnvs(query));
+        return chain<PythonEnvInfo>(iterators);
+    }
+}