Add react-native support (#63)

Reviewed-on: https://home.schmelczer.dev/git/git/andras/reconcile/pulls/63

reconcile-js/src/index.rn.ts

@@ -0,0 +1,47 @@
+// React Native entrypoint (resolved via the `react-native` package field).
+//
+// Hermes — the default React Native engine since RN 0.84 / Expo SDK 56 — does
+// not expose a runtime `WebAssembly` global, so the normal `new
+// WebAssembly.Module(...)` path used by `index.ts` throws
+// `ReferenceError: Property 'WebAssembly' doesn't exist`.
+//
+// Instead we link a wasm2js translation of the module: pure JavaScript that
+// needs no `WebAssembly` global and is instantiated synchronously at import
+// time. The public API and its synchronous signatures are unchanged, so
+// callers need no modification. The `pkg-rn` directory is generated by
+// `scripts/build-rn.mjs`.
+
+import {
+  CursorPosition as wasmCursorPosition,
+  TextWithCursors as wasmTextWithCursors,
+  reconcile as wasmReconcile,
+  reconcileWithHistory as wasmReconcileWithHistory,
+  diff as wasmDiff,
+  undiff as wasmUndiff,
+} from '../pkg-rn/reconcile_text.js';
+
+import { makeReconcileApi, type WasmBackend } from './core';
+
+const backend: WasmBackend = {
+  CursorPosition: wasmCursorPosition,
+  TextWithCursors: wasmTextWithCursors,
+  reconcile: wasmReconcile,
+  reconcileWithHistory: wasmReconcileWithHistory,
+  diff: wasmDiff,
+  undiff: wasmUndiff,
+  // The wasm2js module initialises itself at import time, so this is a no-op.
+  ensureReady() {},
+};
+
+export const { reconcile, diff, undiff, reconcileWithHistory } =
+  makeReconcileApi(backend);
+
+export type {
+  BuiltinTokenizer,
+  History,
+  CursorPosition,
+  TextWithCursors,
+  TextWithOptionalCursors,
+  TextWithCursorsAndHistory,
+  SpanWithHistory,
+} from './core';