Plugin: Introduce tools folder with configuration files

.eslintrc.js

@@ -49,7 +49,7 @@ module.exports = {
 		jsdoc: {
 			mode: 'typescript',
 		},
-		'import/resolver': require.resolve( './test/lint/import-resolver' ),
+		'import/resolver': require.resolve( './tools/eslint/import-resolver' ),
 	},
 	rules: {
 		'jest/expect-expect': 'off',

docs/contributors/folder-structure.md

@@ -124,4 +124,10 @@ The following snippet explains how the Gutenberg repository is structured omitti
     │   Configuration for the Gutenberg Mobile unit tests.
     │
     └── test/unit
-        Configuration for the Packages unit tests.
+    │   Configuration for the Packages unit tests.
+    │
+    └── tools/eslint
+    │   Configuration files for the ESLint linter.
+    │
+    └── tools/webpack
+    │   Configuration files for the webpack build.

packages/react-native-editor/.eslintrc.js

@@ -15,7 +15,9 @@ module.exports = {
 			version: 'detect',
 			flowVersion: '0.92.0',
 		},
-		'import/resolver': require.resolve( '../../test/lint/import-resolver' ),
+		'import/resolver': require.resolve(
+			'../../tools/eslint/import-resolver'
+		),
 	},
 	rules: {
 		'no-restricted-syntax': [

tools/webpack/packages.js

@@ -0,0 +1,321 @@
+/**
+ * External dependencies
+ */
+const { BundleAnalyzerPlugin } = require( 'webpack-bundle-analyzer' );
+const { DefinePlugin } = require( 'webpack' );
+const CopyWebpackPlugin = require( 'copy-webpack-plugin' );
+const TerserPlugin = require( 'terser-webpack-plugin' );
+const postcss = require( 'postcss' );
+const { escapeRegExp, compact } = require( 'lodash' );
+const { join, sep } = require( 'path' );
+const fastGlob = require( 'fast-glob' );
+
+/**
+ * WordPress dependencies
+ */
+const CustomTemplatedPathPlugin = require( '@wordpress/custom-templated-path-webpack-plugin' );
+const LibraryExportDefaultPlugin = require( '@wordpress/library-export-default-webpack-plugin' );
+const DependencyExtractionWebpackPlugin = require( '@wordpress/dependency-extraction-webpack-plugin' );
+const ReadableJsAssetsWebpackPlugin = require( '@wordpress/readable-js-assets-webpack-plugin' );
+const {
+	camelCaseDash,
+} = require( '@wordpress/dependency-extraction-webpack-plugin/lib/util' );
+
+/**
+ * Internal dependencies
+ */
+const { dependencies } = require( '../../package' );
+
+const {
+	NODE_ENV: mode = 'development',
+	WP_DEVTOOL: devtool = mode === 'production' ? false : 'source-map',
+} = process.env;
+
+const WORDPRESS_NAMESPACE = '@wordpress/';
+const BUNDLED_PACKAGES = [ '@wordpress/icons', '@wordpress/interface' ];
+
+const gutenbergPackages = Object.keys( dependencies )
+	.filter(
+		( packageName ) =>
+			! BUNDLED_PACKAGES.includes( packageName ) &&
+			packageName.startsWith( WORDPRESS_NAMESPACE ) &&
+			! packageName.startsWith( WORDPRESS_NAMESPACE + 'react-native' )
+	)
+	.map( ( packageName ) => packageName.replace( WORDPRESS_NAMESPACE, '' ) );
+
+const stylesTransform = ( content ) => {
+	if ( mode === 'production' ) {
+		return postcss( [
+			require( 'cssnano' )( {
+				preset: [
+					'default',
+					{
+						discardComments: {
+							removeAll: true,
+						},
+					},
+				],
+			} ),
+		] )
+			.process( content, {
+				from: 'src/app.css',
+				to: 'dest/app.css',
+			} )
+			.then( ( result ) => result.css );
+	}
+	return content;
+};
+
+/*
+ * Matches a block's name in paths in the form
+ * build-module/<blockName>/view.js
+ */
+const blockNameRegex = new RegExp( /(?<=build-module\/).*(?=(\/view))/g );
+
+const createEntrypoints = () => {
+	/*
+	 * Returns an array of paths to view.js files within the `@wordpress/block-library` package.
+	 * These paths can be matched by the regex `blockNameRegex` in order to extract
+	 * the block's name.
+	 *
+	 * Returns an empty array if no files were found.
+	 */
+	const blockViewScriptPaths = fastGlob.sync(
+		'./packages/block-library/build-module/**/view.js'
+	);
+
+	/*
+	 * Go through the paths found above, in order to define webpack entry points for
+	 * each block's view.js file.
+	 */
+	const blockViewScriptEntries = blockViewScriptPaths.reduce(
+		( entries, scriptPath ) => {
+			const [ blockName ] = scriptPath.match( blockNameRegex );
+
+			return {
+				...entries,
+				[ 'blocks/' + blockName ]: scriptPath,
+			};
+		},
+		{}
+	);
+
+	const packageEntries = gutenbergPackages.reduce( ( memo, packageName ) => {
+		return {
+			...memo,
+			[ packageName ]: `./packages/${ packageName }`,
+		};
+	}, {} );
+
+	return { ...packageEntries, ...blockViewScriptEntries };
+};
+
+module.exports = {
+	optimization: {
+		// Only concatenate modules in production, when not analyzing bundles.
+		concatenateModules:
+			mode === 'production' && ! process.env.WP_BUNDLE_ANALYZER,
+		minimizer: [
+			new TerserPlugin( {
+				cache: true,
+				parallel: true,
+				sourceMap: mode !== 'production',
+				terserOptions: {
+					output: {
+						comments: /translators:/i,
+					},
+					compress: {
+						passes: 2,
+					},
+					mangle: {
+						reserved: [ '__', '_n', '_nx', '_x' ],
+					},
+				},
+				extractComments: false,
+			} ),
+		],
+	},
+	mode,
+	entry: createEntrypoints(),
+	output: {
+		devtoolNamespace: 'wp',
+		filename: ( pathData ) => {
+			const { chunk } = pathData;
+			const { entryModule } = chunk;
+			const { rawRequest, rootModule } = entryModule;
+
+			// When processing ESM files, the requested path
+			// is defined in `entryModule.rootModule.rawRequest`, instead of
+			// being present in `entryModule.rawRequest`.
+			// In the context of frontend view files, they would be processed
+			// as ESM if they use `import` or `export` within it.
+			const request = rootModule?.rawRequest || rawRequest;
+
+			if ( request.includes( '/view.js' ) ) {
+				return `./build/block-library/[name]/view.min.js`;
+			}
+
+			return `./build/[name]/index.min.js`;
+		},
+		path: join( __dirname, '..', '..' ),
+		library: [ 'wp', '[camelName]' ],
+		libraryTarget: 'window',
+	},
+	module: {
+		rules: compact( [
+			mode !== 'production' && {
+				test: /\.js$/,
+				use: require.resolve( 'source-map-loader' ),
+				enforce: 'pre',
+			},
+		] ),
+	},
+	plugins: [
+		// The WP_BUNDLE_ANALYZER global variable enables a utility that represents bundle
+		// content as a convenient interactive zoomable treemap.
+		process.env.WP_BUNDLE_ANALYZER && new BundleAnalyzerPlugin(),
+		new DefinePlugin( {
+			// Inject the `GUTENBERG_PHASE` global, used for feature flagging.
+			'process.env.GUTENBERG_PHASE': JSON.stringify(
+				parseInt(
+					process.env.npm_package_config_GUTENBERG_PHASE,
+					10
+				) || 1
+			),
+			'process.env.FORCE_REDUCED_MOTION': JSON.stringify(
+				process.env.FORCE_REDUCED_MOTION
+			),
+		} ),
+		new CustomTemplatedPathPlugin( {
+			camelName( path, data ) {
+				return camelCaseDash( data.chunk.name );
+			},
+		} ),
+		new LibraryExportDefaultPlugin( [
+			'api-fetch',
+			'deprecated',
+			'dom-ready',
+			'redux-routine',
+			'token-list',
+			'server-side-render',
+			'shortcode',
+			'warning',
+		] ),
+		new CopyWebpackPlugin( {
+			patterns: [].concat(
+				gutenbergPackages.map( ( packageName ) => ( {
+					from: `./packages/${ packageName }/build-style/*.css`,
+					to: `./build/${ packageName }/`,
+					flatten: true,
+					transform: stylesTransform,
+					noErrorOnMissing: true,
+				} ) ),
+				[
+					'style',
+					'style-rtl',
+					'editor',
+					'editor-rtl',
+					'theme',
+					'theme-rtl',
+				].map( ( filename ) => ( {
+					from: `./packages/block-library/build-style/*/${ filename }.css`,
+					to( { absoluteFilename } ) {
+						const [ , dirname ] = absoluteFilename.match(
+							new RegExp(
+								`([\\w-]+)${ escapeRegExp(
+									sep
+								) }${ filename }\\.css$`
+							)
+						);
+
+						return join(
+							'build/block-library/blocks',
+							dirname,
+							filename + '.css'
+						);
+					},
+					transform: stylesTransform,
+				} ) ),
+				Object.entries( {
+					'./packages/block-library/src/':
+						'build/block-library/blocks/',
+					'./packages/edit-widgets/src/blocks/':
+						'build/edit-widgets/blocks/',
+					'./packages/widgets/src/blocks/': 'build/widgets/blocks/',
+				} ).flatMap( ( [ from, to ] ) => [
+					{
+						from: `${ from }/**/index.php`,
+						to( { absoluteFilename } ) {
+							const [ , dirname ] = absoluteFilename.match(
+								new RegExp(
+									`([\\w-]+)${ escapeRegExp(
+										sep
+									) }index\\.php$`
+								)
+							);
+
+							return join( to, `${ dirname }.php` );
+						},
+						transform: ( content ) => {
+							content = content.toString();
+
+							// Within content, search for any function definitions. For
+							// each, replace every other reference to it in the file.
+							return (
+								content
+									.match( /^function [^\(]+/gm )
+									.reduce( ( result, functionName ) => {
+										// Trim leading "function " prefix from match.
+										functionName = functionName.slice( 9 );
+
+										// Prepend the Gutenberg prefix, substituting any
+										// other core prefix (e.g. "wp_").
+										return result.replace(
+											new RegExp( functionName, 'g' ),
+											( match ) =>
+												'gutenberg_' +
+												match.replace( /^wp_/, '' )
+										);
+									}, content )
+									// The core blocks override procedure takes place in
+									// the init action default priority to ensure that core
+									// blocks would have been registered already. Since the
+									// blocks implementations occur at the default priority
+									// and due to WordPress hooks behavior not considering
+									// mutations to the same priority during another's
+									// callback, the Gutenberg build blocks are modified
+									// to occur at a later priority.
+									.replace(
+										/(add_action\(\s*'init',\s*'gutenberg_register_block_[^']+'(?!,))/,
+										'$1, 20'
+									)
+							);
+						},
+						noErrorOnMissing: true,
+					},
+					{
+						from: `${ from }/*/block.json`,
+						to( { absoluteFilename } ) {
+							const [ , dirname ] = absoluteFilename.match(
+								new RegExp(
+									`([\\w-]+)${ escapeRegExp(
+										sep
+									) }block\\.json$`
+								)
+							);
+
+							return join( to, dirname, 'block.json' );
+						},
+					},
+				] )
+			),
+		} ),
+		new DependencyExtractionWebpackPlugin( { injectPolyfill: true } ),
+		mode === 'production' && new ReadableJsAssetsWebpackPlugin(),
+	].filter( Boolean ),
+	watchOptions: {
+		ignored: [ '**/node_modules', '**/packages/*/src' ],
+		aggregateTimeout: 500,
+	},
+	devtool,
+};