Merge pull request #62 from hecrj/feature/async-actions

Async actions

Cargo.toml

@@ -36,6 +36,9 @@ iced_web = { version = "0.1.0-alpha", path = "web" }
 
 [dev-dependencies]
 env_logger = "0.7"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+directories = "2.0"
 
 [target.'cfg(target_arch = "wasm32")'.dev-dependencies]
 wasm-bindgen = "0.2.51"

core/Cargo.toml

@@ -6,3 +6,10 @@ edition = "2018"
 description = "The essential concepts of Iced"
 license = "MIT"
 repository = "https://github.com/hecrj/iced"
+
+[features]
+# Exposes a future-based `Command` type
+command = ["futures"]
+
+[dependencies]
+futures = { version = "0.3", optional = true }

core/src/command.rs

@@ -0,0 +1,49 @@
+use futures::future::{BoxFuture, Future, FutureExt};
+
+pub struct Command<T> {
+    futures: Vec<BoxFuture<'static, T>>,
+}
+
+impl<T> Command<T> {
+    pub fn none() -> Self {
+        Self {
+            futures: Vec::new(),
+        }
+    }
+
+    pub fn perform<A>(
+        future: impl Future<Output = T> + 'static + Send,
+        f: impl Fn(T) -> A + 'static + Send,
+    ) -> Command<A> {
+        Command {
+            futures: vec![future.map(f).boxed()],
+        }
+    }
+
+    pub fn batch(commands: impl Iterator<Item = Command<T>>) -> Self {
+        Self {
+            futures: commands.flat_map(|command| command.futures).collect(),
+        }
+    }
+
+    pub fn futures(self) -> Vec<BoxFuture<'static, T>> {
+        self.futures
+    }
+}
+
+impl<T, A> From<A> for Command<T>
+where
+    A: Future<Output = T> + 'static + Send,
+{
+    fn from(future: A) -> Self {
+        Self {
+            futures: vec![future.boxed()],
+        }
+    }
+}
+
+impl<T> std::fmt::Debug for Command<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Command").finish()
+    }
+}

core/src/lib.rs

@@ -3,6 +3,8 @@ pub mod widget;
 mod align;
 mod background;
 mod color;
+#[cfg(feature = "command")]
+mod command;
 mod font;
 mod length;
 mod point;
@@ -12,6 +14,8 @@ mod vector;
 pub use align::Align;
 pub use background::Background;
 pub use color::Color;
+#[cfg(feature = "command")]
+pub use command::Command;
 pub use font::Font;
 pub use length::Length;
 pub use point::Point;

core/src/widget/text_input.rs

@@ -80,7 +80,7 @@ where
     }
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug, Default, Clone)]
 pub struct State {
     pub is_focused: bool,
     cursor_position: usize,

examples/scroll.rs

@@ -1,12 +1,12 @@
 use iced::{
-    button, scrollable, Align, Application, Button, Container, Element, Image,
-    Length, Scrollable, Text,
+    button, scrollable, Align, Application, Button, Command, Container,
+    Element, Image, Length, Scrollable, Text,
 };
 
 pub fn main() {
     env_logger::init();
 
-    Example::default().run()
+    Example::run()
 }
 
 #[derive(Default)]
@@ -25,16 +25,22 @@ pub enum Message {
 impl Application for Example {
     type Message = Message;
 
+    fn new() -> (Example, Command<Message>) {
+        (Example::default(), Command::none())
+    }
+
     fn title(&self) -> String {
         String::from("Scroll - Iced")
     }
 
-    fn update(&mut self, message: Message) {
+    fn update(&mut self, message: Message) -> Command<Message> {
         match message {
             Message::AddItem => {
                 self.item_count += 1;
             }
         }
+
+        Command::none()
     }
 
     fn view(&mut self) -> Element<Message> {