Initial commit: Text encoding component with UTF-8 polyfills

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

TextEncodingFactory.ts

@@ -0,0 +1,132 @@
+/**
+ * Text Encoding Factory
+ *
+ * Creates encoder/decoder instances with automatic polyfill selection
+ *
+ * @module text-encoding@1.0.0
+ */
+
+import { TextDecoderPolyfill } from './TextDecoderPolyfill';
+import { TextEncoderPolyfill } from './TextEncoderPolyfill';
+import type {
+  ITextDecoder,
+  ITextEncoder,
+  ITextEncodingFactory,
+  TextDecoderOptions,
+} from './interfaces';
+
+export class TextEncodingFactory implements ITextEncodingFactory {
+  private static instance: TextEncodingFactory;
+
+  /**
+   * Get factory singleton instance
+   */
+  static getInstance(): TextEncodingFactory {
+    if (!TextEncodingFactory.instance) {
+      TextEncodingFactory.instance = new TextEncodingFactory();
+    }
+    return TextEncodingFactory.instance;
+  }
+
+  /**
+   * Create a new TextEncoder instance
+   * Uses native implementation if available, otherwise polyfill
+   */
+  createEncoder(): ITextEncoder {
+    // @ts-expect-error - Check for native TextEncoder
+    if (typeof TextEncoder !== 'undefined') {
+      try {
+        // @ts-expect-error - Try to use native
+        return new TextEncoder();
+      } catch (e) {
+        // Fall back to polyfill if native fails
+        console.warn('[TextEncodingFactory] Native TextEncoder failed, using polyfill:', e);
+      }
+    }
+
+    return new TextEncoderPolyfill();
+  }
+
+  /**
+   * Create a new TextDecoder instance
+   * Uses native implementation if available, otherwise polyfill
+   */
+  createDecoder(label: string = 'utf-8', options?: TextDecoderOptions): ITextDecoder {
+    // @ts-expect-error - Check for native TextDecoder
+    if (typeof TextDecoder !== 'undefined') {
+      try {
+        // @ts-expect-error - Try to use native
+        return new TextDecoder(label, options);
+      } catch (e) {
+        // Fall back to polyfill if native fails
+        console.warn('[TextEncodingFactory] Native TextDecoder failed, using polyfill:', e);
+      }
+    }
+
+    return new TextDecoderPolyfill(label, options);
+  }
+
+  /**
+   * Check if native TextEncoder/TextDecoder are available
+   */
+  isNativelySupported(): boolean {
+    // @ts-expect-error - Check global scope
+    if (typeof TextEncoder === 'undefined' || typeof TextDecoder === 'undefined') {
+      return false;
+    }
+
+    // Try to instantiate to make sure they work
+    try {
+      // @ts-expect-error
+      const encoder = new TextEncoder();
+      // @ts-expect-error
+      const decoder = new TextDecoder();
+
+      // Basic functionality test
+      const testString = 'test';
+      const encoded = encoder.encode(testString);
+      const decoded = decoder.decode(encoded);
+
+      return decoded === testString;
+    } catch (_e) {
+      return false;
+    }
+  }
+}
+
+/**
+ * Convenience function to create an encoder
+ */
+export function createTextEncoder(): ITextEncoder {
+  return TextEncodingFactory.getInstance().createEncoder();
+}
+
+/**
+ * Convenience function to create a decoder
+ */
+export function createTextDecoder(label?: string, options?: TextDecoderOptions): ITextDecoder {
+  return TextEncodingFactory.getInstance().createDecoder(label, options);
+}
+
+/**
+ * Install polyfills globally if not present
+ * This makes TextEncoder/TextDecoder available everywhere
+ */
+export function installTextEncodingPolyfills(): void {
+  // @ts-expect-error
+  if (typeof global !== 'undefined') {
+    // @ts-expect-error
+    if (typeof global.TextEncoder === 'undefined') {
+      // @ts-expect-error
+      global.TextEncoder = TextEncoderPolyfill;
+      console.info('[TextEncodingFactory] Installed TextEncoder polyfill globally');
+    }
+
+    // @ts-expect-error
+    if (typeof global.TextDecoder === 'undefined') {
+      // @ts-expect-error
+      global.TextDecoder = TextDecoderPolyfill;
+      console.info('[TextEncodingFactory] Installed TextDecoder polyfill globally');
+    }
+  }
+}