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,
+        }
+    }
+}