From d4b7c427c90e59aea46a8f914e0895249183afc5 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Sat, 13 Aug 2016 00:07:08 +0000
Subject: [PATCH] impl Iterator for Generator<Input=()>.

---
 src/generator.rs  | 23 +++++++++++++++++++++++
 tests/iterator.rs | 18 ++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 tests/iterator.rs

diff --git a/src/generator.rs b/src/generator.rs
index 4ddcbff..c181df0 100644
--- a/src/generator.rs
+++ b/src/generator.rs
@@ -42,6 +42,8 @@ pub enum State {
 /// the state is `State::Runnable` after creation and suspension, and `State::Unavailable`
 /// once the generator function returns or panics.
 ///
+/// When the input type is `()`, a generator implements the Iterator trait.
+///
 /// # Example
 ///
 /// ```
@@ -58,6 +60,20 @@ pub enum State {
 /// println!("{:?}", add_one.resume(3)); // prints Some(4)
 /// println!("{:?}", add_one.resume(0)); // prints None
 /// ```
+///
+/// # Iterator example
+///
+/// ```
+/// use fringe::{OsStack, Generator};
+///
+/// let stack = OsStack::new(0).unwrap();
+/// let mut nat = Generator::new(stack, move |yielder, ()| {
+///   for i in 1.. { yielder.generate(i) }
+/// });
+/// println!("{:?}", nat.next()); // prints Some(0)
+/// println!("{:?}", nat.next()); // prints Some(1)
+/// println!("{:?}", nat.next()); // prints Some(2)
+/// ```
 #[derive(Debug)]
 pub struct Generator<Input: Send, Output: Send, Stack: stack::Stack> {
   state:   State,
@@ -199,3 +215,10 @@ impl<Input, Output, Stack> Yielder<Input, Output, Stack>
     self.generate_bare(Some(item))
   }
 }
+
+impl<Output, Stack> Iterator for Generator<(), Output, Stack>
+    where Output: Send, Stack: stack::Stack {
+  type Item = Output;
+
+  fn next(&mut self) -> Option<Self::Item> { self.resume(()) }
+}
diff --git a/tests/iterator.rs b/tests/iterator.rs
new file mode 100644
index 0000000..53620d4
--- /dev/null
+++ b/tests/iterator.rs
@@ -0,0 +1,18 @@
+// This file is part of libfringe, a low-level green threading library.
+// Copyright (c) whitequark <whitequark@whitequark.org>
+// See the LICENSE file included in this distribution.
+extern crate fringe;
+
+use fringe::OsStack;
+use fringe::generator::Generator;
+
+#[test]
+fn producer() {
+  let stack = OsStack::new(0).unwrap();
+  let mut gen = Generator::new(stack, move |yielder, ()| {
+    for i in 0.. { yielder.generate(i) }
+  });
+  assert_eq!(gen.next(), Some(0));
+  assert_eq!(gen.next(), Some(1));
+  assert_eq!(gen.next(), Some(2));
+}