Hide implementation details of `Command` in `iced_futures`

2 files changed, 71 insertions, 0 deletions

diff --git a/futures/src/command.rs b/futures/src/command.rs
new file mode 100644
index 00000000..d8adfe49
--- /dev/null
+++ b/futures/src/command.rs
@@ -0,0 +1,69 @@
+/// A set of asynchronous actions to be performed by some runtime.
+#[derive(Debug)]
+pub struct Command<T>(Internal<T>);
+
+#[derive(Debug)]
+enum Internal<T> {
+    None,
+    Single(T),
+    Batch(Vec<T>),
+}
+
+impl<T> Command<T> {
+    /// Creates an empty [`Command`].
+    ///
+    /// In other words, a [`Command`] that does nothing.
+    pub const fn none() -> Self {
+        Self(Internal::None)
+    }
+
+    /// Creates a [`Command`] that performs a single [`Action`].
+    pub const fn single(action: T) -> Self {
+        Self(Internal::Single(action))
+    }
+
+    /// Creates a [`Command`] that performs the actions of all the given
+    /// commands.
+    ///
+    /// Once this command is run, all the commands will be executed at once.
+    pub fn batch(commands: impl IntoIterator<Item = Command<T>>) -> Self {
+        let mut batch = Vec::new();
+
+        for Command(command) in commands {
+            match command {
+                Internal::None => {}
+                Internal::Single(command) => batch.push(command),
+                Internal::Batch(commands) => batch.extend(commands),
+            }
+        }
+
+        Self(Internal::Batch(batch))
+    }
+
+    /// Applies a transformation to the result of a [`Command`].
+    pub fn map<A>(self, f: impl Fn(T) -> A) -> Command<A>
+    where
+        T: 'static,
+    {
+        let Command(command) = self;
+
+        match command {
+            Internal::None => Command::none(),
+            Internal::Single(action) => Command::single(f(action)),
+            Internal::Batch(batch) => {
+                Command(Internal::Batch(batch.into_iter().map(f).collect()))
+            }
+        }
+    }
+
+    /// Returns all of the actions of the [`Command`].
+    pub fn actions(self) -> Vec<T> {
+        let Command(command) = self;
+
+        match command {
+            Internal::None => Vec::new(),
+            Internal::Single(action) => vec![action],
+            Internal::Batch(batch) => batch,
+        }
+    }
+}
diff --git a/futures/src/lib.rs b/futures/src/lib.rs
index 657aab37..01cf5c89 100644
--- a/futures/src/lib.rs
+++ b/futures/src/lib.rs
@@ -10,6 +10,7 @@
 
 pub use futures;
 
+mod command;
 mod runtime;
 
 pub mod executor;
@@ -34,6 +35,7 @@ pub mod subscription;
 )]
 pub mod time;
 
+pub use command::Command;
 pub use executor::Executor;
 pub use runtime::Runtime;
 pub use subscription::Subscription;