Implement `time` module for `wasm-bindgen` backend in `iced_futures`

2 files changed, 45 insertions, 0 deletions

diff --git a/futures/Cargo.toml b/futures/Cargo.toml
index aa55df1e..93c7693d 100644
--- a/futures/Cargo.toml
+++ b/futures/Cargo.toml
@@ -36,6 +36,7 @@ optional = true
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen-futures = "0.4"
+wasm-timer = "0.2"
 
 [package.metadata.docs.rs]
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/futures/src/backend/wasm/wasm_bindgen.rs b/futures/src/backend/wasm/wasm_bindgen.rs
index e914aeba..b726501a 100644
--- a/futures/src/backend/wasm/wasm_bindgen.rs
+++ b/futures/src/backend/wasm/wasm_bindgen.rs
@@ -13,3 +13,47 @@ impl crate::Executor for Executor {
         wasm_bindgen_futures::spawn_local(future);
     }
 }
+
+pub mod time {
+    //! Listen and react to time.
+    use crate::subscription::{self, Subscription};
+    use crate::BoxStream;
+
+    /// Returns a [`Subscription`] that produces messages at a set interval.
+    ///
+    /// The first message is produced after a `duration`, and then continues to
+    /// produce more messages every `duration` after that.
+    pub fn every<H: std::hash::Hasher, E>(
+        duration: std::time::Duration,
+    ) -> Subscription<H, E, wasm_timer::Instant> {
+        Subscription::from_recipe(Every(duration))
+    }
+
+    #[derive(Debug)]
+    struct Every(std::time::Duration);
+
+    impl<H, E> subscription::Recipe<H, E> for Every
+    where
+        H: std::hash::Hasher,
+    {
+        type Output = wasm_timer::Instant;
+
+        fn hash(&self, state: &mut H) {
+            use std::hash::Hash;
+
+            std::any::TypeId::of::<Self>().hash(state);
+            self.0.hash(state);
+        }
+
+        fn stream(
+            self: Box<Self>,
+            _input: BoxStream<E>,
+        ) -> BoxStream<Self::Output> {
+            use futures::stream::StreamExt;
+
+            wasm_timer::Interval::new(self.0)
+                .map(|_| wasm_timer::Instant::now())
+                .boxed_local()
+        }
+    }
+}