Expose undiff to JS

reconcile-js/src/index.ts

@@ -4,7 +4,8 @@ import {
   TextWithCursors as wasmTextWithCursors,
   SpanWithHistory as wasmSpanWithHistory,
   reconcileWithHistory as wasmReconcileWithHistory,
-  getCompactDiff as wasmGetCompactDiff,
+  diff as wasmDiff,
+  undiff as wasmUndiff,
   initSync,
 } from 'reconcile-text';
 
@@ -182,7 +183,8 @@ export function reconcile(
 /**
  * Generates a compact diff representation between an original and changed text.
  *
- * These can be parsed and unpacked using Rust crate's EditedText::from_changes.
+ * 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.
@@ -192,7 +194,7 @@ export function reconcile(
  * @param tokenizer - The tokenisation strategy, which is the same as used in `reconcile`.
  * @returns An array representing the compact diff, with inserts as strings and deletes as negative integers.
  */
-export function getCompactDiff(
+export function diff(
   original: string,
   changed: string | TextWithOptionalCursors,
   tokenizer: BuiltinTokenizer = 'Word'
@@ -205,13 +207,38 @@ export function getCompactDiff(
 
   const changedWasm = toWasmTextWithCursors(changed);
 
-  const result = wasmGetCompactDiff(original, changedWasm, tokenizer);
+  const result = wasmDiff(original, changedWasm, tokenizer);
 
   changedWasm.free();
 
   return result;
 }
 
+/**
+ * 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 representing changes (inserts as strings, deletes as negative 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 | 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.
  *

src/lib.rs

@@ -172,7 +172,7 @@
 //!     &changes.into()
 //! );
 //!
-//! let serialized = serde_yaml::to_string(&result.to_changes()).unwrap();
+//! let serialized = serde_yaml::to_string(&result.to_diff()).unwrap();
 //! assert_eq!(
 //!     serialized,
 //!     concat!(
@@ -183,7 +183,7 @@
 //! );
 //!
 //! let deserialized = serde_yaml::from_str(&serialized).unwrap();
-//! let reconstructed = EditedText::from_changes(
+//! let reconstructed = EditedText::from_diff(
 //!     original,
 //!     deserialized,
 //!     &*BuiltinTokenizer::Word

src/wasm.rs

@@ -3,7 +3,7 @@ use core::str;
 
 use wasm_bindgen::prelude::*;
 
-use crate::{BuiltinTokenizer, CursorPosition, SpanWithHistory, TextWithCursors};
+use crate::{BuiltinTokenizer, CursorPosition, EditedText, SpanWithHistory, TextWithCursors};
 
 #[global_allocator]
 static ALLOC: wee_alloc::WeeAlloc<'_> = wee_alloc::WeeAlloc::INIT;
@@ -32,6 +32,7 @@ pub fn reconcile_with_history(
     tokenizer: BuiltinTokenizer,
 ) -> TextWithCursorsAndHistory {
     set_panic_hook();
+
     let reconciled = crate::reconcile(parent, left, right, &*tokenizer);
     let text_with_cursors = reconciled.apply();
 
@@ -80,22 +81,37 @@ pub fn generic_reconcile(
 
 /// WASM wrapper around getting a compact diff representation of two texts as a
 /// list of numbers and strings.
-#[wasm_bindgen(js_name = getCompactDiff)]
+#[wasm_bindgen(js_name = diff)]
 #[must_use]
-pub fn get_compact_diff(
-    parent: &str,
-    changed: &TextWithCursors,
-    tokenizer: BuiltinTokenizer,
-) -> Vec<JsValue> {
+pub fn diff(parent: &str, changed: &TextWithCursors, tokenizer: BuiltinTokenizer) -> Vec<JsValue> {
     set_panic_hook();
-    let edited_text = crate::EditedText::from_strings_with_tokenizer(parent, changed, &*tokenizer);
+
+    let edited_text = EditedText::from_strings_with_tokenizer(parent, changed, &*tokenizer);
     edited_text
-        .to_changes()
+        .to_diff()
         .into_iter()
         .map(std::convert::Into::into)
         .collect()
 }
 
+/// Inverse of `diff`, applies a compact diff representation to a parent text
+#[wasm_bindgen(js_name = undiff)]
+#[must_use]
+pub fn undiff(parent: &str, diff: Vec<JsValue>, tokenizer: BuiltinTokenizer) -> String {
+    set_panic_hook();
+
+    EditedText::from_diff(
+        parent,
+        diff.into_iter()
+            .map(|js_value| js_value.try_into())
+            .collect::<Result<_, _>>()
+            .expect("Invalid diff format"),
+        &*tokenizer,
+    )
+    .apply()
+    .text()
+}
+
 fn set_panic_hook() {
     // https://github.com/rustwasm/console_error_panic_hook#readme
     #[cfg(feature = "console_error_panic_hook")]

tests/test.rs

@@ -50,16 +50,16 @@ fn test_document_one_way_with_serialisation() {
         );
 
         let serialised_left =
-            serde_yaml::from_str(&serde_yaml::to_string(&left_operations.to_changes()).unwrap())
+            serde_yaml::from_str(&serde_yaml::to_string(&left_operations.to_diff()).unwrap())
                 .unwrap();
         let serialised_right =
-            serde_yaml::from_str(&serde_yaml::to_string(&right_operations.to_changes()).unwrap())
+            serde_yaml::from_str(&serde_yaml::to_string(&right_operations.to_diff()).unwrap())
                 .unwrap();
 
         let restored_left_operations =
-            EditedText::from_changes(&parent, serialised_left, &*BuiltinTokenizer::Word);
+            EditedText::from_diff(&parent, serialised_left, &*BuiltinTokenizer::Word);
         let restored_right_operations =
-            EditedText::from_changes(&parent, serialised_right, &*BuiltinTokenizer::Word);
+            EditedText::from_diff(&parent, serialised_right, &*BuiltinTokenizer::Word);
 
         doc.assert_eq_without_cursors(
             &restored_left_operations

tests/wasm.rs

@@ -56,11 +56,11 @@ fn test_merge_binary() {
 }
 
 #[wasm_bindgen_test] // JsValue isn't supported outside of wasm
-fn test_get_compact_diff() {
+fn test_diff() {
     let parent = "hello ";
     let changed = "world";
 
-    let result = get_compact_diff(parent, &changed.into(), BuiltinTokenizer::Word);
+    let result = diff(parent, &changed.into(), BuiltinTokenizer::Word);
 
     assert_eq!(result.len(), 2);
     let first: i64 = result[0].clone().try_into().unwrap();