Draw historic CPU usage.

Version spark library and extend.

src/spark.rs

@@ -12,33 +12,40 @@ use std::f32::MAX as f32_max;
 /// let sparkline = spark::graph(&[1.0, 5.0, 22.0, 13.0, 53.0]);
 /// assert_eq!(sparkline, "▁▁▃▂█");
 /// ```
-pub fn graph(values: &[f32]) -> String {
-    let ticks = "▁▂▃▄▅▆▇█";
-
-    /* XXX: This doesn't feel like idiomatic Rust */
-    let mut min: f32 = f32_max;
-    let mut max: f32 = 0.0;
-
-    for &i in values.iter() {
-        if i > max {
-            max = i;
-        }
-        if i < min {
-            min = i;
-        }
-    }
-
-    let ratio = if max == min {
-        1.0
-    } else {
-        (ticks.chars().count() - 1) as f32 / (max - min)
-    };
-
-    values
-        .iter()
-        .cloned()
-        .map(|n| (n - min) * ratio)
-        .map(|n| n.floor() as usize)
-        .filter_map(|n| ticks.chars().nth(n))
-        .collect()
+pub struct Graph {
+    pub min: Option<f32>,
+    pub max: Option<f32>,
+}
+
+impl Graph {
+    pub fn render(&self, values: &[f32]) -> String {
+        let ticks = "▁▂▃▄▅▆▇█";
+
+        /* XXX: This doesn't feel like idiomatic Rust */
+        let mut min: f32 = self.min.unwrap_or(f32_max);
+        let mut max: f32 = self.max.unwrap_or(0.);
+
+        for &i in values.iter() {
+            if i > max {
+                max = i;
+            }
+            if i < min {
+                min = i;
+            }
+        }
+
+        let ratio = if max == min {
+            1.0
+        } else {
+            (ticks.chars().count() - 1) as f32 / (max - min)
+        };
+
+        values
+            .iter()
+            .cloned()
+            .map(|n| (n - min) * ratio)
+            .map(|n| n.floor() as usize)
+            .filter_map(|n| ticks.chars().nth(n))
+            .collect()
+    }
 }