chore(tailwind): split loader in separate file

plugins/tailwind/src/iconify.ts

@@ -1,45 +1,11 @@
-import { readFileSync } from 'fs';
-import type { IconifyJSON } from '@iconify/types';
 import { getIconsCSSData } from '@iconify/utils/lib/css/icons';
 import { matchIconName } from '@iconify/utils/lib/icon/name';
-import type { IconifyPluginFileOptions, IconifyPluginOptions } from './options';
+import { loadIconSet } from './loader';
+import type { IconifyPluginOptions } from './options';
 
 const missingIconsListError =
 	'TailwindCSS cannot dynamically find all used icons. Need to pass list of used icons to Iconify plugin.';
 
-/**
- * Locate icon set
- */
-function locateIconSet(
-	prefix: string,
-	options: IconifyPluginFileOptions
-): string | undefined {
-	if (options.files?.[prefix]) {
-		return options.files?.[prefix];
-	}
-	try {
-		return require.resolve(`@iconify-json/${prefix}/icons.json`);
-	} catch {}
-	try {
-		return require.resolve(`@iconify/json/json/${prefix}.json`);
-	} catch {}
-}
-
-/**
- * Load icon set
- */
-function loadIconSet(
-	prefix: string,
-	options: IconifyPluginFileOptions
-): IconifyJSON | undefined {
-	const filename = locateIconSet(prefix, options);
-	if (filename) {
-		try {
-			return JSON.parse(readFileSync(filename, 'utf8'));
-		} catch {}
-	}
-}
-
 /**
  * Get icon names from list
  */

plugins/tailwind/src/loader.ts

@@ -0,0 +1,82 @@
+import { readFileSync } from 'fs';
+import type { IconifyJSON } from '@iconify/types';
+
+/**
+ * Callback for loading icon set
+ */
+type IconifyJSONLoaderCallback = () => IconifyJSON;
+
+/**
+ * Options for icon set loaders
+ */
+export interface IconifyPluginLoaderOptions {
+	// Location of icon set files. Key is icon set prefix
+	files?: Record<string, string>;
+
+	// Custom icon sets
+	// Value can be loaded icon set or callback that loads icon set
+	iconSets?: Record<string, IconifyJSON | IconifyJSONLoaderCallback>;
+}
+
+/**
+ * Locate icon set
+ */
+export function locateIconSet(
+	prefix: string,
+	options: IconifyPluginLoaderOptions
+): string | undefined {
+	if (options.files?.[prefix]) {
+		return options.files?.[prefix];
+	}
+	try {
+		return require.resolve(`@iconify-json/${prefix}/icons.json`);
+	} catch {}
+	try {
+		return require.resolve(`@iconify/json/json/${prefix}.json`);
+	} catch {}
+}
+
+/**
+ * Cache for loaded icon sets
+ *
+ * Tailwind CSS can send multiple separate requests to plugin, this will
+ * prevent same data from being loaded multiple times.
+ *
+ * Key is filename, not prefix!
+ */
+const cache = Object.create(null) as Record<string, IconifyJSON>;
+
+/**
+ * Load icon set
+ */
+export function loadIconSet(
+	prefix: string,
+	options: IconifyPluginLoaderOptions
+): IconifyJSON | undefined {
+	// Check for custom icon set
+	const customIconSet = options.iconSets?.[prefix];
+	if (customIconSet) {
+		if (typeof customIconSet === 'function') {
+			// Callback. Store result in options to avoid loading it again
+			const result = customIconSet();
+			options.iconSets[prefix] = result;
+			return result;
+		}
+		return customIconSet;
+	}
+
+	const filename = options.files?.[prefix] || locateIconSet(prefix, options);
+	if (filename) {
+		// Check for cache
+		if (cache[filename]) {
+			return cache[filename];
+		}
+
+		// Attempt to load it
+		try {
+			const result = JSON.parse(readFileSync(filename, 'utf8'));
+			cache[filename] = result;
+			return result;
+		} catch {}
+	}
+}