add tail-efficient logic extension

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/future/bool_ext.rs

@@ -0,0 +1,82 @@
+//! Extended external extensions to futures::FutureExt
+
+use std::marker::Unpin;
+
+use futures::{
+	future::{select_ok, try_join, try_join_all, try_select},
+	Future, FutureExt,
+};
+
+pub trait BoolExt
+where
+	Self: Future<Output = bool> + Send,
+{
+	fn and<B>(self, b: B) -> impl Future<Output = bool> + Send
+	where
+		B: Future<Output = bool> + Send,
+		Self: Sized;
+
+	fn or<B>(self, b: B) -> impl Future<Output = bool> + Send
+	where
+		B: Future<Output = bool> + Send + Unpin,
+		Self: Sized + Unpin;
+}
+
+pub async fn and<I, F>(args: I) -> impl Future<Output = bool> + Send
+where
+	I: Iterator<Item = F> + Send,
+	F: Future<Output = bool> + Send,
+{
+	type Result = crate::Result<(), ()>;
+
+	let args = args.map(|a| a.map(|a| a.then_some(()).ok_or(Result::Err(()))));
+
+	try_join_all(args).map(|result| result.is_ok())
+}
+
+pub async fn or<I, F>(args: I) -> impl Future<Output = bool> + Send
+where
+	I: Iterator<Item = F> + Send,
+	F: Future<Output = bool> + Send + Unpin,
+{
+	type Result = crate::Result<(), ()>;
+
+	let args = args.map(|a| a.map(|a| a.then_some(()).ok_or(Result::Err(()))));
+
+	select_ok(args).map(|result| result.is_ok())
+}
+
+impl<Fut> BoolExt for Fut
+where
+	Fut: Future<Output = bool> + Send,
+{
+	#[inline]
+	fn and<B>(self, b: B) -> impl Future<Output = bool> + Send
+	where
+		B: Future<Output = bool> + Send,
+		Self: Sized,
+	{
+		type Result = crate::Result<(), ()>;
+
+		let a = self.map(|a| a.then_some(()).ok_or(Result::Err(())));
+
+		let b = b.map(|b| b.then_some(()).ok_or(Result::Err(())));
+
+		try_join(a, b).map(|result| result.is_ok())
+	}
+
+	#[inline]
+	fn or<B>(self, b: B) -> impl Future<Output = bool> + Send
+	where
+		B: Future<Output = bool> + Send + Unpin,
+		Self: Sized + Unpin,
+	{
+		type Result = crate::Result<(), ()>;
+
+		let a = self.map(|a| a.then_some(()).ok_or(Result::Err(())));
+
+		let b = b.map(|b| b.then_some(()).ok_or(Result::Err(())));
+
+		try_select(a, b).map(|result| result.is_ok())
+	}
+}

src/core/utils/future/mod.rs

@@ -1,7 +1,9 @@
+mod bool_ext;
 mod ext_ext;
 mod option_ext;
 mod try_ext_ext;
 
+pub use bool_ext::{and, or, BoolExt};
 pub use ext_ext::ExtExt;
 pub use option_ext::OptionExt;
 pub use try_ext_ext::TryExtExt;