From e9e2328f03b845c9df1d61e67e91bbe0e551d904 Mon Sep 17 00:00:00 2001
From: Andras Schmelczer <andras@schmelczer.dev>
Date: Tue, 1 Apr 2025 20:10:03 +0100
Subject: [PATCH] Expose merge_text_with_cursors on API

---
 backend/reconcile/src/lib.rs  |  8 +++--
 backend/sync_lib/src/lib.rs   | 18 ++++++++++-
 backend/sync_lib/tests/web.rs | 58 +++++++++++++++++++++++++++++++++--
 3 files changed, 79 insertions(+), 5 deletions(-)

diff --git a/backend/reconcile/src/lib.rs b/backend/reconcile/src/lib.rs
index 9c5bb764..8023cc15 100644
--- a/backend/reconcile/src/lib.rs
+++ b/backend/reconcile/src/lib.rs
@@ -1,7 +1,11 @@
+mod cursor;
 mod diffs;
 mod operation_transformation;
 mod tokenizer;
 mod utils;
 
-pub use operation_transformation::{EditedText, reconcile, reconcile_with_tokenizer};
-pub use tokenizer::token::Token;
+pub use cursor::{CursorPosition, TextWithCursors};
+pub use operation_transformation::{
+    EditedText, reconcile, reconcile_with_cursors, reconcile_with_tokenizer,
+};
+pub use tokenizer::{Tokenizer, token::Token};
diff --git a/backend/sync_lib/src/lib.rs b/backend/sync_lib/src/lib.rs
index 6f27e055..dc35e27f 100644
--- a/backend/sync_lib/src/lib.rs
+++ b/backend/sync_lib/src/lib.rs
@@ -8,12 +8,15 @@
 //! # Modules
 //!
 //! - `errors`: Contains error types used in this crate.
+
 use core::str;
 
 use base64::{Engine as _, engine::general_purpose::STANDARD};
+use cursor::OwnedTextWithCursors;
 use errors::SyncLibError;
 use wasm_bindgen::prelude::*;
 
+pub mod cursor;
 pub mod errors;
 
 /// Encode binary data for easy transport over HTTP. Inverse of
@@ -93,7 +96,7 @@ pub fn merge(parent: &[u8], left: &[u8], right: &[u8]) -> Vec<u8> {
     }
 }
 
-/// WASM wrapper around `reconcile::reconcile` for text merging.
+/// WASM wrapper around `reconcile::reconcile` for merging text.
 #[wasm_bindgen(js_name = mergeText)]
 #[must_use]
 pub fn merge_text(parent: &str, left: &str, right: &str) -> String {
@@ -102,6 +105,19 @@ pub fn merge_text(parent: &str, left: &str, right: &str) -> String {
     reconcile::reconcile(parent, left, right)
 }
 
+/// WASM wrapper around `reconcile::reconcile_with_cursors` for merging text.
+#[wasm_bindgen(js_name = mergeText)]
+#[must_use]
+pub fn merge_text_with_cursors(
+    parent: &str,
+    left: OwnedTextWithCursors,
+    right: OwnedTextWithCursors,
+) -> OwnedTextWithCursors {
+    set_panic_hook();
+
+    reconcile::reconcile_with_cursors(parent, left.into(), right.into()).into()
+}
+
 /// Heuristically determine if the given data is a binary or a text file's
 /// content.
 #[wasm_bindgen(js_name = isBinary)]
diff --git a/backend/sync_lib/tests/web.rs b/backend/sync_lib/tests/web.rs
index e45cbea6..017e2dc2 100644
--- a/backend/sync_lib/tests/web.rs
+++ b/backend/sync_lib/tests/web.rs
@@ -1,5 +1,8 @@
 use insta::assert_debug_snapshot;
-use sync_lib::*;
+use sync_lib::{
+    cursor::{OwnedCursorPosition, OwnedTextWithCursors},
+    *,
+};
 use wasm_bindgen_test::*;
 
 #[wasm_bindgen_test(unsupported = test)]
@@ -23,11 +26,62 @@ fn test_base64_to_bytes_error() {
 }
 
 #[wasm_bindgen_test(unsupported = test)]
-fn merge_text() {
+fn test_merge() {
     let left = b"hello ";
     let right = b"world";
     let result = merge(b"", left, right);
     assert_eq!(result, b"hello world");
+
+    let left = b"\0binary";
+    let right = b"other";
+    let result = merge(b"", left, right);
+    assert_eq!(result, right);
+}
+
+#[wasm_bindgen_test(unsupported = test)]
+fn test_merge_text() {
+    let left = "hello ";
+    let right = "world";
+    let result = merge_text("", left, right);
+    assert_eq!(result, "hello world");
+}
+
+#[wasm_bindgen_test(unsupported = test)]
+fn test_merge_text_with_cursors() {
+    let result = merge_text_with_cursors(
+        "hi",
+        OwnedTextWithCursors::new("hi world", vec![]),
+        OwnedTextWithCursors::new(
+            "hi",
+            vec![
+                OwnedCursorPosition {
+                    id: 0,
+                    char_index: 1,
+                },
+                OwnedCursorPosition {
+                    id: 1,
+                    char_index: 2,
+                },
+            ],
+        ),
+    );
+
+    assert_eq!(
+        result,
+        OwnedTextWithCursors::new(
+            "hi world",
+            vec![
+                OwnedCursorPosition {
+                    id: 0,
+                    char_index: 1,
+                },
+                OwnedCursorPosition {
+                    id: 1,
+                    char_index: 8,
+                }
+            ]
+        ),
+    );
 }
 
 #[wasm_bindgen_test(unsupported = test)]