Initial menu implementation

native/src/lib.rs

@@ -37,6 +37,7 @@ pub mod clipboard;
 pub mod event;
 pub mod keyboard;
 pub mod layout;
+pub mod menu;
 pub mod mouse;
 pub mod overlay;
 pub mod program;
@@ -75,6 +76,7 @@ pub use element::Element;
 pub use event::Event;
 pub use hasher::Hasher;
 pub use layout::Layout;
+pub use menu::{Menu, MenuEntry};
 pub use overlay::Overlay;
 pub use program::Program;
 pub use renderer::Renderer;

native/src/menu.rs

@@ -0,0 +1,81 @@
+//! Build menus for your application.
+use crate::keyboard::Hotkey;
+
+/// Menu representation.
+///
+/// This can be used by `shell` implementations to create a menu.
+#[derive(Debug, Clone, PartialEq)]
+pub struct Menu<Message> {
+    items: Vec<MenuEntry<Message>>,
+}
+
+impl<Message> Menu<Message> {
+    /// Creates an empty [`Menu`].
+    pub fn new() -> Self {
+        Menu { items: Vec::new() }
+    }
+
+    /// Adds an item to the [`Menu`].
+    pub fn item<S: Into<String>>(
+        mut self,
+        content: S,
+        hotkey: impl Into<Option<Hotkey>>,
+        on_activation: Message,
+    ) -> Self {
+        let content = content.into();
+        let hotkey = hotkey.into();
+
+        self.items.push(MenuEntry::Item {
+            on_activation,
+            content,
+            hotkey,
+        });
+        self
+    }
+
+    /// Adds a separator to the [`Menu`].
+    pub fn separator(mut self) -> Self {
+        self.items.push(MenuEntry::Separator);
+        self
+    }
+
+    /// Adds a dropdown to the [`Menu`].
+    pub fn dropdown<S: Into<String>>(
+        mut self,
+        content: S,
+        submenu: Menu<Message>,
+    ) -> Self {
+        let content = content.into();
+
+        self.items.push(MenuEntry::Dropdown { content, submenu });
+        self
+    }
+
+    /// Returns a [`MenuEntry`] iterator.
+    pub fn iter(self) -> std::vec::IntoIter<MenuEntry<Message>> {
+        self.items.into_iter()
+    }
+}
+
+/// Represents one of the possible entries used to build a [`Menu`].
+#[derive(Debug, Clone, PartialEq)]
+pub enum MenuEntry<Message> {
+    /// Item for a [`Menu`]
+    Item {
+        /// The title of the item
+        content: String,
+        /// The [`Hotkey`] to activate the item, if any
+        hotkey: Option<Hotkey>,
+        /// The message generated when the item is activated
+        on_activation: Message,
+    },
+    /// Dropdown for a [`Menu`]
+    Dropdown {
+        /// Title of the dropdown
+        content: String,
+        /// The submenu of the dropdown
+        submenu: Menu<Message>,
+    },
+    /// Separator for a [`Menu`]
+    Separator,
+}