Add Source::from_iter

src/source/from_factory.rs

@@ -1,7 +1,5 @@
-use std::time::Duration;
-
-use Sample;
-use Source;
+use source::from_iter;
+use source::FromIter;
 
 /// Builds a source that chains sources built from a factory.
 ///
@@ -10,138 +8,31 @@ use Source;
 /// played next.
 ///
 /// If the `factory` closure returns `None`, then the sound ends.
-pub fn from_factory<F, S>(mut factory: F) -> FromFactory<F, S>
+pub fn from_factory<F, S>(factory: F) -> FromIter<FromFactoryIter<F>>
     where F: FnMut() -> Option<S>
 {
-    let first_source = factory().expect("The factory returned an empty source");    // TODO: meh
-
-    FromFactory {
+    from_iter(FromFactoryIter {
         factory: factory,
-        current_source: first_source,
-    }
+    })
 }
 
-/// A source that chains sources built from a factory.
-#[derive(Clone)]
-pub struct FromFactory<F, S> {
+/// Internal type used by `from_factory`.
+pub struct FromFactoryIter<F> {
     factory: F,
-    current_source: S,
 }
 
-impl<F, S> Iterator for FromFactory<F, S>
-    where F: FnMut() -> Option<S>,
-          S: Source,
-          S::Item: Sample
+impl<F, S> Iterator for FromFactoryIter<F>
+    where F: FnMut() -> Option<S>
 {
-    type Item = <S as Iterator>::Item;
+    type Item = S;
 
     #[inline]
-    fn next(&mut self) -> Option<<S as Iterator>::Item> {
-        loop {
-            if let Some(value) = self.current_source.next() {
-                return Some(value);
-            }
-
-            if let Some(src) = (self.factory)() {
-                self.current_source = src;
-            } else {
-                return None;
-            }
-        }
+    fn next(&mut self) -> Option<S> {
+        (self.factory)()
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.current_source.size_hint().0, None)
-    }
-}
-
-impl<F, S> Source for FromFactory<F, S>
-    where F: FnMut() -> Option<S>,
-          S: Iterator + Source,
-          S::Item: Sample
-{
-    #[inline]
-    fn current_frame_len(&self) -> Option<usize> {
-        // This function is non-trivial because the boundary between the current source and the
-        // next must be a frame boundary as well.
-        //
-        // The current sound is free to return `None` for `current_frame_len()`, in which case
-        // we *should* return the number of samples remaining the current sound.
-        // This can be estimated with `size_hint()`.
-        //
-        // If the `size_hint` is `None` as well, we are in the worst case scenario. To handle this
-        // situation we force a frame to have a maximum number of samples indicate by this
-        // constant.
-        const THRESHOLD: usize = 10240;
-
-        // Try the current `current_frame_len`.
-        if let Some(val) = self.current_source.current_frame_len() {
-            if val != 0 {
-                return Some(val);
-            }
-        }
-
-        // Try the size hint.
-        if let Some(val) = self.current_source.size_hint().1 {
-            if val < THRESHOLD && val != 0 {
-                return Some(val);
-            }
-        }
-
-        // Otherwise we use the constant value.
-        Some(THRESHOLD)
-    }
-
-    #[inline]
-    fn channels(&self) -> u16 {
-        self.current_source.channels()
-    }
-
-    #[inline]
-    fn samples_rate(&self) -> u32 {
-        self.current_source.samples_rate()
-    }
-
-    #[inline]
-    fn total_duration(&self) -> Option<Duration> {
-        None
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use buffer::SamplesBuffer;
-    use source::from_factory;
-    use source::Source;
-
-    #[test]
-    fn basic() {
-        let mut n = 0;
-        let mut rx = from_factory(move || {
-            if n == 0 {
-                n = 1;
-                Some(SamplesBuffer::new(1, 48000, vec![10i16, -10, 10, -10]))
-            } else if n == 1 {
-                n = 2;
-                Some(SamplesBuffer::new(2, 96000, vec![5i16, 5, 5, 5]))
-            } else {
-                None
-            }
-        });
-
-        assert_eq!(rx.channels(), 1);
-        assert_eq!(rx.samples_rate(), 48000);
-        assert_eq!(rx.next(), Some(10));
-        assert_eq!(rx.next(), Some(-10));
-        assert_eq!(rx.next(), Some(10));
-        assert_eq!(rx.next(), Some(-10));
-        /*assert_eq!(rx.channels(), 2);
-        assert_eq!(rx.samples_rate(), 96000);*/     // FIXME: not working
-        assert_eq!(rx.next(), Some(5));
-        assert_eq!(rx.next(), Some(5));
-        assert_eq!(rx.next(), Some(5));
-        assert_eq!(rx.next(), Some(5));
-        assert_eq!(rx.next(), None);
+        (0, None)
     }
 }

src/source/from_iter.rs

@@ -0,0 +1,167 @@
+use std::time::Duration;
+
+use Sample;
+use Source;
+
+/// Builds a source that chains sources provided by an iterator.
+///
+/// The `iterator` parameter is an iterator that produces a source. The source is then played.
+/// Whenever the source ends, the `iterator` is used again in order to produce the source that is
+/// played next.
+///
+/// If the `iterator` produces `None`, then the sound ends.
+pub fn from_iter<I>(iterator: I) -> FromIter<I::IntoIter>
+    where I: IntoIterator
+{
+    let mut iterator = iterator.into_iter();
+    let first_source = iterator.next();
+
+    FromIter {
+        iterator: iterator,
+        current_source: first_source,
+    }
+}
+
+/// A source that chains sources provided by an iterator.
+#[derive(Clone)]
+pub struct FromIter<I> where I: Iterator {
+    // The iterator that provides sources.
+    iterator: I,
+    // Is only ever `None` if the first element of the iterator is `None`.
+    current_source: Option<I::Item>,
+}
+
+impl<I> Iterator for FromIter<I>
+    where I: Iterator,
+          I::Item: Iterator + Source,
+          <I::Item as Iterator>::Item: Sample
+{
+    type Item = <I::Item as Iterator>::Item;
+
+    #[inline]
+    fn next(&mut self) -> Option<<I::Item as Iterator>::Item> {
+        loop {
+            if let Some(ref mut src) = self.current_source {
+                if let Some(value) = src.next() {
+                    return Some(value);
+                }
+            }
+
+            if let Some(src) = self.iterator.next() {
+                self.current_source = Some(src);
+            } else {
+                return None;
+            }
+        }
+    }
+
+    #[inline]
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        if let Some(ref cur) = self.current_source {
+            (cur.size_hint().0, None)
+        } else {
+            (0, None)
+        }
+    }
+}
+
+impl<I> Source for FromIter<I>
+    where I: Iterator,
+          I::Item: Iterator + Source,
+          <I::Item as Iterator>::Item: Sample
+{
+    #[inline]
+    fn current_frame_len(&self) -> Option<usize> {
+        // This function is non-trivial because the boundary between the current source and the
+        // next must be a frame boundary as well.
+        //
+        // The current sound is free to return `None` for `current_frame_len()`, in which case
+        // we *should* return the number of samples remaining the current sound.
+        // This can be estimated with `size_hint()`.
+        //
+        // If the `size_hint` is `None` as well, we are in the worst case scenario. To handle this
+        // situation we force a frame to have a maximum number of samples indicate by this
+        // constant.
+        const THRESHOLD: usize = 10240;
+
+        // Try the current `current_frame_len`.
+        if let Some(ref src) = self.current_source {
+            if let Some(val) = src.current_frame_len() {
+                if val != 0 {
+                    return Some(val);
+                }
+            }
+        }
+
+        // Try the size hint.
+        if let Some(ref src) = self.current_source {
+            if let Some(val) = src.size_hint().1 {
+                if val < THRESHOLD && val != 0 {
+                    return Some(val);
+                }
+            }
+        }
+
+        // Otherwise we use the constant value.
+        Some(THRESHOLD)
+    }
+
+    #[inline]
+    fn channels(&self) -> u16 {
+        if let Some(ref src) = self.current_source {
+            src.channels()
+        } else {
+            // Dummy value that only happens if the iterator was empty.
+            2
+        }
+    }
+
+    #[inline]
+    fn samples_rate(&self) -> u32 {
+        if let Some(ref src) = self.current_source {
+            src.samples_rate()
+        } else {
+            // Dummy value that only happens if the iterator was empty.
+            44100
+        }
+    }
+
+    #[inline]
+    fn total_duration(&self) -> Option<Duration> {
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use buffer::SamplesBuffer;
+    use source::from_iter;
+    use source::Source;
+
+    #[test]
+    fn basic() {
+        let mut rx = from_iter((0..2).map(|n| {
+            if n == 0 {
+                SamplesBuffer::new(1, 48000, vec![10i16, -10, 10, -10])
+            } else if n == 1 {
+                SamplesBuffer::new(2, 96000, vec![5i16, 5, 5, 5])
+            } else {
+                unreachable!()
+            }
+        }));
+
+        assert_eq!(rx.channels(), 1);
+        assert_eq!(rx.samples_rate(), 48000);
+        assert_eq!(rx.next(), Some(10));
+        assert_eq!(rx.next(), Some(-10));
+        assert_eq!(rx.next(), Some(10));
+        assert_eq!(rx.next(), Some(-10));
+        /*assert_eq!(rx.channels(), 2);
+        assert_eq!(rx.samples_rate(), 96000);*/     // FIXME: not working
+        assert_eq!(rx.next(), Some(5));
+        assert_eq!(rx.next(), Some(5));
+        assert_eq!(rx.next(), Some(5));
+        assert_eq!(rx.next(), Some(5));
+        assert_eq!(rx.next(), None);
+    }
+}

src/source/mod.rs

@@ -9,7 +9,8 @@ pub use self::buffered::Buffered;
 pub use self::delay::Delay;
 pub use self::empty::Empty;
 pub use self::fadein::FadeIn;
-pub use self::from_factory::{from_factory, FromFactory};
+pub use self::from_factory::{from_factory, FromFactoryIter};
+pub use self::from_iter::{from_iter, FromIter};
 pub use self::mix::Mix;
 pub use self::pausable::Pausable;
 pub use self::periodic::PeriodicAccess;
@@ -28,6 +29,7 @@ mod delay;
 mod empty;
 mod fadein;
 mod from_factory;
+mod from_iter;
 mod mix;
 mod pausable;
 mod periodic;