Add cursor moving (#19)

backend/sync_lib/src/cursor.rs

@@ -0,0 +1,88 @@
+use wasm_bindgen::prelude::*;
+
+/// Wrapper type to expose `TextWithCursors` to JS.
+#[wasm_bindgen]
+#[derive(Debug, Clone, PartialEq)]
+pub struct TextWithCursors {
+    text: String,
+    cursors: Vec<CursorPosition>,
+}
+
+#[wasm_bindgen]
+impl TextWithCursors {
+    #[wasm_bindgen(constructor)]
+    #[must_use]
+    pub fn new(text: String, cursors: Vec<CursorPosition>) -> Self { Self { text, cursors } }
+
+    #[must_use]
+    pub fn text(&self) -> String { self.text.clone() }
+
+    #[must_use]
+    pub fn cursors(&self) -> Vec<CursorPosition> { self.cursors.clone() }
+}
+
+impl From<TextWithCursors> for reconcile::TextWithCursors<'_> {
+    fn from(owned: TextWithCursors) -> Self {
+        reconcile::TextWithCursors::new_owned(
+            owned.text.to_string(),
+            owned
+                .cursors
+                .into_iter()
+                .map(std::convert::Into::into)
+                .collect(),
+        )
+    }
+}
+
+impl From<reconcile::TextWithCursors<'_>> for TextWithCursors {
+    fn from(text_with_cursors: reconcile::TextWithCursors<'_>) -> Self {
+        TextWithCursors {
+            text: text_with_cursors.text.into_owned(),
+            cursors: text_with_cursors
+                .cursors
+                .into_iter()
+                .map(std::convert::Into::into)
+                .collect(),
+        }
+    }
+}
+
+/// Wrapper type to expose `CursorPosition` to JS.
+#[wasm_bindgen]
+#[derive(Debug, Clone, PartialEq)]
+pub struct CursorPosition {
+    id: usize,
+    char_index: usize,
+}
+
+#[wasm_bindgen]
+impl CursorPosition {
+    #[wasm_bindgen(constructor)]
+    #[must_use]
+    pub fn new(id: usize, char_index: usize) -> Self { Self { id, char_index } }
+
+    #[must_use]
+    pub fn id(&self) -> usize { self.id }
+
+    #[wasm_bindgen(js_name = characterPosition)]
+    #[must_use]
+    pub fn char_index(&self) -> usize { self.char_index }
+}
+
+impl From<CursorPosition> for reconcile::CursorPosition {
+    fn from(owned: CursorPosition) -> Self {
+        reconcile::CursorPosition {
+            id: owned.id,
+            char_index: owned.char_index,
+        }
+    }
+}
+
+impl From<reconcile::CursorPosition> for CursorPosition {
+    fn from(cursor: reconcile::CursorPosition) -> Self {
+        CursorPosition {
+            id: cursor.id,
+            char_index: cursor.char_index,
+        }
+    }
+}

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::TextWithCursors;
 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 = mergeTextWithCursors)]
+#[must_use]
+pub fn merge_text_with_cursors(
+    parent: &str,
+    left: TextWithCursors,
+    right: TextWithCursors,
+) -> TextWithCursors {
+    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)]

backend/sync_lib/tests/web.rs

@@ -1,5 +1,8 @@
 use insta::assert_debug_snapshot;
-use sync_lib::*;
+use sync_lib::{
+    cursor::{CursorPosition, TextWithCursors},
+    *,
+};
 use wasm_bindgen_test::*;
 
 #[wasm_bindgen_test(unsupported = test)]
@@ -23,11 +26,44 @@ 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",
+        TextWithCursors::new("hi world".to_owned(), vec![]),
+        TextWithCursors::new(
+            "hi".to_owned(),
+            vec![CursorPosition::new(0, 1), CursorPosition::new(1, 2)],
+        ),
+    );
+
+    assert_eq!(
+        result,
+        TextWithCursors::new(
+            "hi world".to_owned(),
+            vec![CursorPosition::new(0, 1), CursorPosition::new(1, 2)]
+        ),
+    );
 }
 
 #[wasm_bindgen_test(unsupported = test)]