Move custom Object.keys() overload to util (#2020)

Closes #2018

## Checklist

- [x] I have not broken the cheatsheet

Author: auscompgeek

packages/cursorless-engine/src/languages/getNodeMatcher.ts

@@ -52,7 +52,7 @@ export function getNodeMatcher(
 
 export const languageMatchers: Record<
   LegacyLanguageId,
-  Record<SimpleScopeTypeType, NodeMatcher>
+  Partial<Record<SimpleScopeTypeType, NodeMatcher>>
 > = {
   c: cpp,
   cpp,

packages/cursorless-engine/src/processTargets/modifiers/surroundingPair/delimiterMaps.ts

@@ -2,13 +2,14 @@ import {
   ComplexSurroundingPairName,
   SimpleSurroundingPairName,
 } from "@cursorless/common";
+import { unsafeKeys } from "../../../util/object";
 
 type IndividualDelimiterText = string | string[];
 
 export const delimiterToText: Record<
   SimpleSurroundingPairName,
   [IndividualDelimiterText, IndividualDelimiterText]
-> = {
+> = Object.freeze({
   angleBrackets: [
     ["</", "<"],
     [">", "/>"],
@@ -23,7 +24,7 @@ export const delimiterToText: Record<
   parentheses: [["(", "$("], ")"],
   singleQuotes: ["'", "'"],
   squareBrackets: ["[", "]"],
-};
+});
 
 export const leftToRightMap: Record<string, string> = Object.fromEntries(
   Object.values(delimiterToText),
@@ -37,7 +38,7 @@ export const complexDelimiterMap: Record<
   ComplexSurroundingPairName,
   SimpleSurroundingPairName[]
 > = {
-  any: Object.keys(delimiterToText),
+  any: unsafeKeys(delimiterToText),
   string: ["singleQuotes", "doubleQuotes", "backtickQuotes"],
   collectionBoundary: [
     "parentheses",

packages/cursorless-engine/src/runIntegrationTests.ts

@@ -3,6 +3,7 @@ import { languageMatchers } from "./languages/getNodeMatcher";
 import { TreeSitter } from "./typings/TreeSitter";
 import { legacyLanguageIds } from "./languages/LegacyLanguageId";
 import { LanguageDefinitions } from "./languages/LanguageDefinitions";
+import { unsafeKeys } from "./util/object";
 
 /**
  * Run tests that require multiple components to be instantiated, as well as a
@@ -27,7 +28,7 @@ async function assertNoScopesBothLegacyAndNew(
   for (const languageId of legacyLanguageIds) {
     await treeSitter.loadLanguage(languageId);
 
-    Object.keys(languageMatchers[languageId]).map((scopeTypeType) => {
+    unsafeKeys(languageMatchers[languageId]).map((scopeTypeType) => {
       if (
         languageDefinitions.get(languageId)?.getScopeHandler({
           type: scopeTypeType,

packages/cursorless-engine/src/scripts/transformRecordedTests/checkMarks.ts

@@ -27,9 +27,7 @@ export function checkMarks(originalFixture: TestCaseFixtureLegacy): undefined {
     ...(originalFixture.marksToCheck ?? []),
   ];
 
-  const actualMarks = Object.keys(
-    originalFixture.initialState.marks ?? {},
-  ) as string[];
+  const actualMarks = Object.keys(originalFixture.initialState.marks ?? {});
 
   assert.deepStrictEqual(
     uniq(actualMarks.map(normalizeGraphemes)).sort(),

packages/cursorless-engine/src/testCaseRecorder/TestCase.ts

@@ -23,6 +23,7 @@ import { ide } from "../singletons/ide.singleton";
 import { extractTargetKeys } from "../testUtil/extractTargetKeys";
 import { takeSnapshot } from "../testUtil/takeSnapshot";
 import { getPartialTargetDescriptors } from "../util/getPartialTargetDescriptors";
+import { unsafeKeys } from "../util/object";
 
 export class TestCase {
   private languageId: string;
@@ -122,7 +123,7 @@ export class TestCase {
       visibleRanges: !visibleRangeActions.includes(this.command.action.name),
     };
 
-    return Object.keys(excludedFields).filter((field) => excludedFields[field]);
+    return unsafeKeys(excludedFields).filter((field) => excludedFields[field]);
   }
 
   toYaml() {

packages/cursorless-engine/src/util/nodeMatchers.ts

@@ -21,6 +21,7 @@ import {
   simpleSelectionExtractor,
   unwrapSelectionExtractor,
 } from "./nodeSelectors";
+import { unsafeKeys } from "./object";
 
 export function matcher(
   finder: NodeFinder,
@@ -177,14 +178,19 @@ export const notSupported: NodeMatcher = (
 
 export function createPatternMatchers(
   nodeMatchers: Partial<Record<SimpleScopeTypeType, NodeMatcherAlternative>>,
-): Record<SimpleScopeTypeType, NodeMatcher> {
-  Object.keys(nodeMatchers).forEach((scopeType: SimpleScopeTypeType) => {
-    const matcher = nodeMatchers[scopeType];
-    if (Array.isArray(matcher)) {
-      nodeMatchers[scopeType] = patternMatcher(...matcher);
-    } else if (typeof matcher === "string") {
-      nodeMatchers[scopeType] = patternMatcher(matcher);
-    }
-  });
-  return nodeMatchers as Record<SimpleScopeTypeType, NodeMatcher>;
+): Partial<Record<SimpleScopeTypeType, NodeMatcher>> {
+  return Object.freeze(
+    Object.fromEntries(
+      unsafeKeys(nodeMatchers).map((scopeType: SimpleScopeTypeType) => {
+        const matcher = nodeMatchers[scopeType];
+        if (Array.isArray(matcher)) {
+          return [scopeType, patternMatcher(...matcher)];
+        } else if (typeof matcher === "string") {
+          return [scopeType, patternMatcher(matcher)];
+        } else {
+          return [scopeType, matcher];
+        }
+      }),
+    ),
+  );
 }

packages/cursorless-engine/src/util/object.ts

@@ -20,3 +20,27 @@ export function mergeStrict<Value>(
 
   return returnValue;
 }
+
+/**
+ * `Object.keys` but returns an array of the keys TypeScript knows about.
+ *
+ * Note that this is technically unsound, as TypeScript is a structural type system.
+ * Consider the following example (from ts-reset's docs):
+ * ```
+ * type Func = () => { id: string };
+ *
+ * const func: Func = () => {
+ *   return {
+ *     id: "123",
+ *     // No error on an excess property!
+ *     name: "Hello!",
+ *   }
+ * };
+ * ```
+ *
+ * Consider only using this on objects frozen at construction time
+ * or locals that don't escape the calling scope.
+ */
+export function unsafeKeys<T extends object>(o: T): (keyof T)[] {
+  return Object.keys(o) as (keyof T)[];
+}

packages/cursorless-vscode-e2e/src/suite/recorded.vscode.test.ts

@@ -159,7 +159,7 @@ async function runTest(file: string, spyIde: SpyIDE) {
       ? undefined
       : marksToPlainObject(
           extractTargetedMarks(
-            Object.keys(fixture.finalState.marks) as string[],
+            Object.keys(fixture.finalState.marks),
             readableHatMap,
           ),
         );

typings/object.d.ts

@@ -1,15 +1,4 @@
-// From https://fettblog.eu/typescript-better-object-keys/
-type ObjectKeys<T> = T extends object
-  ? (keyof T)[]
-  : T extends number
-  ? []
-  : T extends Array<any> | string
-  ? string[]
-  : never;
-
 interface ObjectConstructor {
-  keys<T>(o: T): ObjectKeys<T>;
-
   fromEntries<
     V extends PropertyKey,
     T extends [readonly [V, any]] | Array<readonly [V, any]>,