feat(v2): generalize usage of _ prefix convention to exclude content files/folders (#5173)

* create a swizzleWarning partial for shared text

* Generalize usage of _ prefix convention to exclude content files/folders

* add api doc

* MDX loader should not expect metadata/frontmatter on MDX partial files

packages/docusaurus-utils/src/globUtils.ts

@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// Globby/Micromatch are the 2 libs we use in Docusaurus consistently
+
+export {default as Globby} from 'globby';
+
+import Micromatch from 'micromatch'; // Note: Micromatch is used by Globby
+
+// The default patterns we ignore when globbing
+// using _ prefix for exclusion by convention
+export const GlobExcludeDefault = [
+  // Ignore files starting with _
+  '**/_*.{js,jsx,ts,tsx,md,mdx}',
+
+  // Ignore folders starting with _ (including folder content)
+  '**/_*/**',
+
+  // Ignore tests
+  '**/*.test.{js,jsx,ts,tsx}',
+  '**/__tests__/**',
+];
+
+type Matcher = (str: string) => boolean;
+
+export function createMatcher(patterns: string[]): Matcher {
+  const regexp = new RegExp(
+    patterns.map((pattern) => Micromatch.makeRe(pattern).source).join('|'),
+  );
+  return (str) => regexp.test(str);
+}

packages/docusaurus-utils/src/index.ts

@@ -31,6 +31,7 @@ export * from './markdownParser';
 export * from './markdownLinks';
 export * from './escapePath';
 export {md5Hash, simpleHash, docuHash} from './hashUtils';
+export {Globby, GlobExcludeDefault, createMatcher} from './globUtils';
 
 const fileHash = new Map();
 export async function generate(