1 files changed, 150 insertions, 0 deletions
diff --git a/third_party/rust/uniffi-example-todolist/src/lib.rs b/third_party/rust/uniffi-example-todolist/src/lib.rs
new file mode 100644
index 0000000000..fb2900e615
--- /dev/null
+++ b/third_party/rust/uniffi-example-todolist/src/lib.rs
@@ -0,0 +1,150 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::sync::{Arc, RwLock};
+
+use once_cell::sync::Lazy;
+
+#[derive(Debug, Clone)]
+pub struct TodoEntry {
+    text: String,
+}
+
+// There is a single "default" TodoList that can be shared
+// by all consumers of this component. Depending on requirements,
+// a real app might like to use a `Weak<>` rather than an `Arc<>`
+// here to reduce the risk of circular references.
+static DEFAULT_LIST: Lazy<RwLock<Option<Arc<TodoList>>>> = Lazy::new(|| RwLock::new(None));
+
+#[derive(Debug, thiserror::Error)]
+pub enum TodoError {
+    #[error("The todo does not exist!")]
+    TodoDoesNotExist,
+    #[error("The todolist is empty!")]
+    EmptyTodoList,
+    #[error("That todo already exists!")]
+    DuplicateTodo,
+    #[error("Empty String error!: {0}")]
+    EmptyString(String),
+    #[error("I am a delegated Error: {0}")]
+    DeligatedError(#[from] std::io::Error),
+}
+
+/// Get a reference to the global default TodoList, if set.
+///
+fn get_default_list() -> Option<Arc<TodoList>> {
+    DEFAULT_LIST.read().unwrap().clone()
+}
+
+/// Set the global default TodoList.
+///
+/// This will silently drop any previously set value.
+///
+fn set_default_list(list: Arc<TodoList>) {
+    *DEFAULT_LIST.write().unwrap() = Some(list);
+}
+
+/// Create a new TodoEntry from the given string.
+///
+fn create_entry_with<S: Into<String>>(item: S) -> Result<TodoEntry> {
+    let text = item.into();
+    if text.is_empty() {
+        return Err(TodoError::EmptyString(
+            "Cannot add empty string as entry".to_string(),
+        ));
+    }
+    Ok(TodoEntry { text })
+}
+
+type Result<T, E = TodoError> = std::result::Result<T, E>;
+
+// A simple Todolist.
+// UniFFI requires that we use interior mutability for managing mutable state, so we wrap our `Vec` in a RwLock.
+// (A Mutex would also work, but a RwLock is more appropriate for this use-case, so we use it).
+#[derive(Debug)]
+pub struct TodoList {
+    items: RwLock<Vec<String>>,
+}
+
+impl TodoList {
+    fn new() -> Self {
+        Self {
+            items: RwLock::new(Vec::new()),
+        }
+    }
+
+    fn add_item<S: Into<String>>(&self, item: S) -> Result<()> {
+        let item = item.into();
+        if item.is_empty() {
+            return Err(TodoError::EmptyString(
+                "Cannot add empty string as item".to_string(),
+            ));
+        }
+        let mut items = self.items.write().unwrap();
+        if items.contains(&item) {
+            return Err(TodoError::DuplicateTodo);
+        }
+        items.push(item);
+        Ok(())
+    }
+
+    fn get_last(&self) -> Result<String> {
+        let items = self.items.read().unwrap();
+        items.last().cloned().ok_or(TodoError::EmptyTodoList)
+    }
+
+    fn get_first(&self) -> Result<String> {
+        let items = self.items.read().unwrap();
+        items.first().cloned().ok_or(TodoError::EmptyTodoList)
+    }
+
+    fn add_entries(&self, entries: Vec<TodoEntry>) {
+        let mut items = self.items.write().unwrap();
+        items.extend(entries.into_iter().map(|e| e.text))
+    }
+
+    fn add_entry(&self, entry: TodoEntry) -> Result<()> {
+        self.add_item(entry.text)
+    }
+
+    fn add_items<S: Into<String>>(&self, items: Vec<S>) {
+        let mut my_items = self.items.write().unwrap();
+        my_items.extend(items.into_iter().map(Into::into))
+    }
+
+    fn get_items(&self) -> Vec<String> {
+        let items = self.items.read().unwrap();
+        items.clone()
+    }
+
+    fn get_entries(&self) -> Vec<TodoEntry> {
+        let items = self.items.read().unwrap();
+        items
+            .iter()
+            .map(|text| TodoEntry { text: text.clone() })
+            .collect()
+    }
+
+    fn get_last_entry(&self) -> Result<TodoEntry> {
+        let text = self.get_last()?;
+        Ok(TodoEntry { text })
+    }
+
+    fn clear_item<S: Into<String>>(&self, item: S) -> Result<()> {
+        let item = item.into();
+        let mut items = self.items.write().unwrap();
+        let idx = items
+            .iter()
+            .position(|s| s == &item)
+            .ok_or(TodoError::TodoDoesNotExist)?;
+        items.remove(idx);
+        Ok(())
+    }
+
+    fn make_default(self: Arc<Self>) {
+        set_default_list(self);
+    }
+}
+
+include!(concat!(env!("OUT_DIR"), "/todolist.uniffi.rs"));