switchable pressure unit

1 files changed, 28 insertions, 8 deletions

diff --git a/src/unit_of_measurement.rs b/src/unit_of_measurement.rs
index a3b4b77..ce459bf 100644
--- a/src/unit_of_measurement.rs
+++ b/src/unit_of_measurement.rs
@@ -8,27 +8,47 @@ pub trait UnitOfMeasurement {
 pub mod pressure {
     use super::UnitOfMeasurement;
 
-    #[derive(Default)]
-    pub struct Pressure {
-        val: i32,
-    }
+    #[derive(Default, Clone)]
+    pub struct Pressure(i32);
 
+    #[derive(Copy, Clone)]
     pub enum Unit {
         Pascal = 1,
         KiloPascal = 1000,
     }
 
+    impl Unit {
+        // Pseudo iter::Cycle behavior.
+        pub fn next(&mut self) {
+            match self {
+                Unit::Pascal => {
+                    *self = Unit::KiloPascal;
+                }
+                Unit::KiloPascal => {
+                    *self = Unit::Pascal;
+                }
+            }
+        }
+    }
+
+    impl ToString for Unit {
+        fn to_string(&self) -> String {
+            match self {
+                Self::Pascal => String::from("Pa"),
+                Self::KiloPascal => String::from("kPa"),
+            }
+        }
+    }
+
     impl UnitOfMeasurement for Pressure {
         type Unit = Unit;
 
         fn from_unit(unit: Self::Unit, n: i32) -> Self {
-            Self {
-                val: n * unit as i32,
-            }
+            Self(n * unit as i32)
         }
 
         fn as_unit(&self, unit: Self::Unit) -> i32 {
-            self.val / unit as i32
+            self.0 / unit as i32
         }
     }
 }