[yew-devel] [PATCH yew-comp 02/20] rrd: refactor code for compute_min_max

[Dominik Csapak]

using some simple combinators makes the code a bit shorter and more
readable. Using +/- INFINITY as marker for having no values, reduces the
code further since we don't have to handle the options in the loop.

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
 src/rrd_graph_new.rs | 35 ++++++++++-------------------------
 1 file changed, 10 insertions(+), 25 deletions(-)

diff --git a/src/rrd_graph_new.rs b/src/rrd_graph_new.rs
index 2c77a38..bfa7d1e 100644
--- a/src/rrd_graph_new.rs
+++ b/src/rrd_graph_new.rs
@@ -311,34 +311,19 @@ fn render_value(props: &RRDGraph, v: f64) -> String {
 }
 
 fn compute_min_max(props: &RRDGraph, data1: &[f64], data2: &[f64]) -> (f64, f64, f64) {
-    let mut min_data: Option<f64> = None;
-    let mut max_data: Option<f64> = None;
+    let mut min_data: f64 = f64::INFINITY;
+    let mut max_data: f64 = -f64::INFINITY;
 
-    for data in [data1, data2] {
-        for v in data.iter() {
-            if !v.is_finite() {
-                continue; // NaN, INFINITY
-            }
-            if let Some(min) = min_data {
-                if *v < min {
-                    min_data = Some(*v);
-                }
-            } else {
-                min_data = Some(*v);
-            }
-
-            if let Some(max) = max_data {
-                if *v > max {
-                    max_data = Some(*v);
-                }
-            } else {
-                max_data = Some(*v);
-            }
-        }
+    for v in data1.iter().chain(data2).filter(|v| v.is_finite()) {
+        min_data = min_data.min(*v);
+        max_data = max_data.max(*v);
     }
 
-    let mut max_data = max_data.unwrap_or(1.0);
-    let mut min_data = min_data.unwrap_or(0.0);
+    // if one is infinite, the other must be too
+    if min_data.is_infinite() || max_data.is_infinite() {
+        min_data = 0.0;
+        max_data = 1.0;
+    }
 
     if props.include_zero {
         max_data = max_data.max(0.0);
-- 
2.39.5