add SummaryStats util type to tidepool

tidepool/src/output.rs

@@ -34,6 +34,95 @@ pub struct Profile {
     // TODO: histograms about selected nodes
 }
 
+#[derive(Copy, Clone, Debug)]
+pub struct SummaryStats<T: Copy> {
+    count: usize,
+    min: Option<T>,
+    max: Option<T>,
+    sum: Option<T>,
+}
+
+impl<T: Copy> Default for SummaryStats<T> {
+    fn default() -> Self {
+        SummaryStats {
+            count: 0,
+            min: None,
+            max: None,
+            sum: None,
+        }
+    }
+}
+
+impl<T: Copy> SummaryStats<T> {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn count(&self) -> usize {
+        self.count
+    }
+
+    pub fn min(&self) -> Option<T> {
+        self.min
+    }
+
+    pub fn max(&self) -> Option<T> {
+        self.max
+    }
+}
+
+impl<T> SummaryStats<T>
+where
+    T: Ord + Copy + std::ops::Add<T, Output = T>,
+{
+    pub fn insert(&mut self, x: T) {
+        self.count += 1;
+        self.min = Some(self.min.map_or(x, |y| x.min(y)));
+        self.max = Some(self.max.map_or(x, |y| x.max(y)));
+        self.sum = Some(self.sum.map_or(x, |y| x + y));
+    }
+}
+
+impl SummaryStats<f64> {
+    pub fn insert_f64(&mut self, x: f64) {
+        self.count += 1;
+        self.min = Some(self.min.map_or(x, |y| x.min(y)));
+        self.max = Some(self.max.map_or(x, |y| x.max(y)));
+        self.sum = Some(self.sum.map_or(x, |y| x + y));
+    }
+}
+
+impl<T> SummaryStats<T>
+where
+    T: Copy + std::ops::Div<usize, Output = T>,
+{
+    pub fn avg(&self) -> Option<T> {
+        self.sum.map(|x| x / self.count)
+    }
+}
+
+impl<T> SummaryStats<T>
+where
+    T: Copy,
+    f64: From<T>,
+{
+    pub fn avg_f64(&self) -> Option<f64> {
+        self.sum.map(|x| f64::from(x) / self.count as f64)
+    }
+}
+
+impl<T> Serialize for SummaryStats<T>
+where
+    T: Serialize + Copy + std::ops::Div<usize, Output = T>,
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        ser::summary_stats(self, serializer)
+    }
+}
+
 mod ser {
     use super::*;
 
@@ -78,4 +167,27 @@ mod ser {
     {
         dur.as_secs_f64().serialize(serializer)
     }
+
+    pub fn summary_stats<S, T>(stats: &SummaryStats<T>, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        T: Serialize + Copy + std::ops::Div<usize, Output = T>,
+        S: serde::Serializer,
+    {
+        #[derive(Serialize)]
+        struct Stats<T> {
+            #[serde(skip_serializing_if = "Option::is_none")]
+            min: Option<T>,
+            #[serde(skip_serializing_if = "Option::is_none")]
+            max: Option<T>,
+            #[serde(skip_serializing_if = "Option::is_none")]
+            avg: Option<T>,
+        }
+
+        Stats {
+            min: stats.min,
+            max: stats.max,
+            avg: stats.avg(),
+        }
+        .serialize(serializer)
+    }
 }