Add react-native support (#63)

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

reconcile-js/src/index.ts

@@ -1,8 +1,7 @@
 import {
   CursorPosition as wasmCursorPosition,
-  reconcile as wasmReconcile,
   TextWithCursors as wasmTextWithCursors,
-  SpanWithHistory as wasmSpanWithHistory,
+  reconcile as wasmReconcile,
   reconcileWithHistory as wasmReconcileWithHistory,
   diff as wasmDiff,
   undiff as wasmUndiff,
@@ -11,341 +10,40 @@ import {
 
 import wasmBytes from 'reconcile-text/reconcile_text_bg.wasm';
 
-// Define the enum values as const arrays to avoid duplication
-const BUILTIN_TOKENIZERS = ['Character', 'Line', 'Markdown', 'Word'] as const;
-const HISTORY_VALUES = [
-  'Unchanged',
-  'AddedFromLeft',
-  'AddedFromRight',
-  'RemovedFromLeft',
-  'RemovedFromRight',
-] as const;
-
-/**
- * Tokenisation strategies for text merging.
- *
- * These correspond to the built-in tokenizers available in the underlying WASM module.
- */
-export type BuiltinTokenizer = (typeof BUILTIN_TOKENIZERS)[number];
-
-/**
- * History classification for text spans in merge results.
- *
- * Indicates the origin of each text span in the merged document.
- */
-export type History = (typeof HISTORY_VALUES)[number];
-
-/**
- * Represents a text document with associated cursor positions.
- *
- * This interface is used both as input to reconcile functions (to specify where
- * cursors are positioned in the original documents) and as output (with cursors
- * automatically repositioned after merging).
- */
-export interface TextWithCursors {
-  /** The document's entire content as a string */
-  text: string;
-
-  /**
-   * Array of cursor positions within the text. Can be empty if there are no cursors to track.
-   * Each cursor has a unique ID and position.
-   */
-  cursors: CursorPosition[];
-}
-
-/**
- * Like `TextWithCursors`, but cursors may be null or undefined (treated as empty).
- * Used as input where cursor tracking is optional.
- */
-export interface TextWithOptionalCursors {
-  /** The document's entire content as a string */
-  text: string;
-
-  /**
-   * Array of cursor positions within the text. Can be null, undefined, or empty
-   * if there are no cursors to track. Each cursor has a unique ID and position.
-   */
-  cursors: null | undefined | CursorPosition[];
-}
-
-/**
- * Represents a cursor position within a text document.
- *
- * Cursors are automatically repositioned during text merging to maintain their
- * relative positions as text is inserted, deleted, or modified around them.
- */
-export interface CursorPosition {
-  /** Unique identifier for the cursor (can be any number, must be unique within the document) */
-  id: number;
-
-  /** Character position in the text, 0-based index from the beginning of the document */
-  position: number;
-}
-
-/**
- * Represents a merged text document with cursor positions and detailed change history.
- *
- * This is the return type of `reconcileWithHistory()` and provides complete information
- * about how the merge was performed, including which parts of the final text came from
- * which source documents.
- */
-export interface TextWithCursorsAndHistory {
-  /** The merged document's entire content */
-  text: string;
-
-  /**
-   * Array of cursor positions within the merged text. Can be empty if there are no cursors to track.
-   * All cursors are automatically repositioned from the left and right documents.
-   */
-  cursors: CursorPosition[];
-
-  /**
-   * Detailed provenance information showing the origin of each text span in the result.
-   * Each span indicates whether it was unchanged, added from left, added from right, etc.
-   */
-  history: SpanWithHistory[];
-}
-
-/**
- * Represents a span of text in the merged result with its change history.
- *
- * This shows exactly which source document contributed each piece of text to the
- * final merged result. Useful for understanding merge decisions and creating
- * visualisations of how documents were combined.
- */
-export interface SpanWithHistory {
-  /** The text content of this span */
-  text: string;
-
-  /** The origin of this text span in the merge result */
-  history: History;
-}
-
-const UNSUPPORTED_TOKENIZER_ERROR = `Unsupported tokenizer, only ${BUILTIN_TOKENIZERS.join(
-  ', '
-)} are supported`;
+import { makeReconcileApi, type WasmBackend } from './core';
 
 let isInitialised = false;
 
-/**
- * Merges three versions of text using intelligent conflict resolution.
- *
- * This is the primary function for 3-way text merging. Unlike traditional merge tools
- * that produce conflict markers, this function automatically resolves conflicts by
- * applying both sets of changes where possible.
- *
- * @param original - The original/base version of the text that both sides diverged from
- * @param left - The left version of the text (either string or TextWithCursors with cursor positions)
- * @param right - The right version of the text (either string or TextWithCursors with cursor positions)
- * @param tokenizer - The tokenisation strategy: "Word" (default, recommended for prose),
- *                    "Character" (fine-grained), or "Line" (similar to git merge)
- * @returns The reconciled text with automatically repositioned cursor positions
- *
- * @example
- * ```typescript
- * const original = "Hello world";
- * const left = "Hello beautiful world";    // Added "beautiful"
- * const right = "Hi world";                // Changed "Hello" to "Hi"
- *
- * const result = reconcile(original, left, right);
- * console.log(result.text); // "Hi beautiful world"
- * ```
- */
-export function reconcile(
-  original: string,
-  left: string | TextWithOptionalCursors,
-  right: string | TextWithOptionalCursors,
-  tokenizer: BuiltinTokenizer = 'Word'
-): TextWithCursors {
-  init();
+const backend: WasmBackend = {
+  CursorPosition: wasmCursorPosition,
+  TextWithCursors: wasmTextWithCursors,
+  reconcile: wasmReconcile,
+  reconcileWithHistory: wasmReconcileWithHistory,
+  diff: wasmDiff,
+  undiff: wasmUndiff,
+  ensureReady() {
+    if (isInitialised) {
+      return;
+    }
 
-  if (!BUILTIN_TOKENIZERS.includes(tokenizer)) {
-    throw new Error(UNSUPPORTED_TOKENIZER_ERROR);
-  }
+    const wasmBinary = Uint8Array.from(atob(wasmBytes as unknown as string), (c) =>
+      c.charCodeAt(0)
+    );
+    initSync({ module: wasmBinary });
 
-  const leftCursor = toWasmTextWithCursors(left);
-  const rightCursor = toWasmTextWithCursors(right);
+    isInitialised = true;
+  },
+};
 
-  const result = wasmReconcile(original, leftCursor, rightCursor, tokenizer);
+export const { reconcile, diff, undiff, reconcileWithHistory } =
+  makeReconcileApi(backend);
 
-  leftCursor.free();
-  rightCursor.free();
-
-  const jsResult = toTextWithCursors(result);
-  result.free();
-
-  return jsResult;
-}
-
-/**
- * Generates a compact diff representation between an original and changed text.
- *
- * These can be parsed and unpacked using the `undiff` function or the Rust crate's EditedText::from_diff.
- * Cursor positions are omitted from the diff result.
- *
- * This function computes the differences between two versions of text and returns
- * a compact representation of those changes.
- *
- * @param original - The original/base version of the text
- * @param changed - The modified version of the text (either string or TextWithCursors with cursor positions)
- * @param tokenizer - The tokenisation strategy, which is the same as used in `reconcile`.
- * @returns An array of inserts (strings), deletes (negative integers), and retained spans (positive integers).
- */
-export function diff(
-  original: string,
-  changed: string | TextWithOptionalCursors,
-  tokenizer: BuiltinTokenizer = 'Word'
-): Array<number | string> {
-  init();
-
-  if (!BUILTIN_TOKENIZERS.includes(tokenizer)) {
-    throw new Error(UNSUPPORTED_TOKENIZER_ERROR);
-  }
-
-  const changedWasm = toWasmTextWithCursors(changed);
-
-  const result = wasmDiff(original, changedWasm, tokenizer);
-
-  changedWasm.free();
-
-  return result.map((item) => (typeof item === 'bigint' ? Number(item) : item));
-}
-
-/**
- * Applies a compact diff to an original text to reconstruct the changed version.
- *
- * This function takes an original text and a compact diff representation (as produced
- * by the `diff` function) and reconstructs the modified text.
- *
- * @param original - The original/base version of the text
- * @param diff - The compact diff array (inserts as strings, deletes as negative integers, retained spans as positive integers)
- * @param tokenizer - The tokenisation strategy, which is the same as used in `reconcile`.
- * @returns The reconstructed changed text as a string.
- */
-export function undiff(
-  original: string,
-  diff: Array<number | bigint | string>,
-  tokenizer: BuiltinTokenizer = 'Word'
-): string {
-  init();
-
-  if (!BUILTIN_TOKENIZERS.includes(tokenizer)) {
-    throw new Error(UNSUPPORTED_TOKENIZER_ERROR);
-  }
-
-  return wasmUndiff(original, diff, tokenizer);
-}
-
-/**
- * Merges three versions of text and returns detailed provenance information.
- *
- * This function behaves like `reconcile()` but also provides
- * detailed historical information about the origin of each text span in the result.
- * This is valuable for understanding how the merge was performed and which changes
- * came from which source.
- *
- * Note: Computing the history is computationally more expensive than the basic merge.
- *
- * @param original - The original/base version of the text that both sides diverged from
- * @param left - The left version of the text (either string or TextWithCursors with cursor positions)
- * @param right - The right version of the text (either string or TextWithCursors with cursor positions)
- * @param tokenizer - The tokenisation strategy: "Word" (default, recommended for prose),
- *                    "Character" (fine-grained), or "Line" (similar to git merge)
- * @returns The reconciled text with cursor positions and detailed change history
- *
- * @example
- * ```typescript
- * const original = "Hello world";
- * const left = "Hello beautiful world";
- * const right = "Hi world";
- *
- * const result = reconcileWithHistory(original, left, right);
- * console.log(result.text); // "Hi beautiful world"
- * console.log(result.history); // Array of SpanWithHistory objects showing change origins
- * ```
- */
-export function reconcileWithHistory(
-  original: string,
-  left: string | TextWithOptionalCursors,
-  right: string | TextWithOptionalCursors,
-  tokenizer: BuiltinTokenizer = 'Word'
-): TextWithCursorsAndHistory {
-  init();
-
-  if (!BUILTIN_TOKENIZERS.includes(tokenizer)) {
-    throw new Error(UNSUPPORTED_TOKENIZER_ERROR);
-  }
-
-  const leftCursor = toWasmTextWithCursors(left);
-  const rightCursor = toWasmTextWithCursors(right);
-
-  const result = wasmReconcileWithHistory(original, leftCursor, rightCursor, tokenizer);
-
-  leftCursor.free();
-  rightCursor.free();
-
-  const jsResult = toTextWithCursors(result);
-  const history = result.history().map(toSpanWithHistory);
-  result.free();
-
-  return {
-    ...jsResult,
-    history,
-  };
-}
-
-function init() {
-  if (isInitialised) {
-    return;
-  }
-
-  const wasmBinary = Uint8Array.from(atob(wasmBytes as unknown as string), (c) =>
-    c.charCodeAt(0)
-  );
-  initSync({ module: wasmBinary });
-
-  isInitialised = true;
-}
-
-function toWasmTextWithCursors(
-  text: string | TextWithOptionalCursors
-): wasmTextWithCursors {
-  const isInputString = typeof text === 'string';
-  const leftText = isInputString ? text : text.text;
-  const leftCursors = isInputString ? [] : (text.cursors ?? []);
-
-  return new wasmTextWithCursors(leftText, leftCursors.map(toWasmCursorPosition));
-}
-
-function toWasmCursorPosition({ id, position }: CursorPosition): wasmCursorPosition {
-  return new wasmCursorPosition(id, position);
-}
-
-function toTextWithCursors(textWithCursor: wasmTextWithCursors): TextWithCursors {
-  const wasmCursors = textWithCursor.cursors();
-  const cursors = wasmCursors.map(toCursorPosition);
-  for (const cursor of wasmCursors) {
-    cursor.free();
-  }
-
-  return {
-    text: textWithCursor.text(),
-    cursors,
-  };
-}
-
-function toCursorPosition(cursor: wasmCursorPosition): CursorPosition {
-  return {
-    id: cursor.id(),
-    position: cursor.characterIndex(),
-  };
-}
-
-function toSpanWithHistory(span: wasmSpanWithHistory): SpanWithHistory {
-  const result = {
-    text: span.text(),
-    history: span.history(),
-  };
-  span.free();
-  return result;
-}
+export type {
+  BuiltinTokenizer,
+  History,
+  CursorPosition,
+  TextWithCursors,
+  TextWithOptionalCursors,
+  TextWithCursorsAndHistory,
+  SpanWithHistory,
+} from './core';