From 200e3568f5b7b5aab5388512ddefceb813168f90 Mon Sep 17 00:00:00 2001
From: Grant Shangreaux <grant@unabridgedsoftware.com>
Date: Fri, 12 Nov 2021 20:20:25 -0600
Subject: Add: phasor iterator implementation

---
 klangfarbrs/src/lib.rs    |  2 ++
 klangfarbrs/src/phasor.rs | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 klangfarbrs/src/phasor.rs

diff --git a/klangfarbrs/src/lib.rs b/klangfarbrs/src/lib.rs
index 1fdc0fb..a118d38 100644
--- a/klangfarbrs/src/lib.rs
+++ b/klangfarbrs/src/lib.rs
@@ -14,6 +14,8 @@ use gdnative::core_types::TypedArray;
 use rand::Rng;
 use std::f32::consts::TAU;
 
+mod phasor;
+
 mod osc;
 use osc::Osc;
 
diff --git a/klangfarbrs/src/phasor.rs b/klangfarbrs/src/phasor.rs
new file mode 100644
index 0000000..00372c0
--- /dev/null
+++ b/klangfarbrs/src/phasor.rs
@@ -0,0 +1,46 @@
+use super::{SamplesPerSecond, Hz};
+
+type Phase = f32; // Phase will always be between 0.0 and 1.0.
+
+pub struct PhasorIter {
+    pub phase: Phase,
+    pub frequency: Hz,
+    sample_rate: SamplesPerSecond,
+}
+
+impl PhasorIter {
+    fn new(frequency: Hz, sample_rate: SamplesPerSecond) -> Self {
+        Self { phase: 0.0, frequency, sample_rate }
+    }
+}
+
+impl Iterator for PhasorIter {
+    type Item = Phase;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.phase += (self.frequency / self.sample_rate);
+
+        if self.phase > 1.0 { self.phase -= 1.0; }
+
+        Some(self.phase)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_produces_expected_next_value() {
+        let mut phasor = PhasorIter::new(10.0, 100.0);
+        assert_eq!(phasor.next(), Some(0.1))
+    }
+
+    #[test]
+    fn it_produces_expected_next_values() {
+        let phasor = PhasorIter::new(10.0, 100.0);
+        let next  = phasor.take(11);
+        assert_eq!(0.1, next.last().unwrap())
+        // assert_eq!([0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 0.1], next)
+    }
+}
-- 
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