Merge pull request #215 from bheisler/iterate_units

Generate an enum with one variant for each unit, use that for iteration.

src/quantity.rs

@@ -284,6 +284,46 @@ macro_rules! quantity {
             $description
         }
 
+        /// Unit enum.
+        #[allow(non_camel_case_types)]
+        #[non_exhaustive]
+        #[derive(Debug, Clone, Copy)]
+        pub enum Units {
+            $(#[doc=$plural] $unit($unit),)+
+        }
+
+        impl Units {
+            /// Unit abbreviation.
+            pub fn abbreviation(&self) -> &'static str {
+                match self {
+                    $(Units::$unit(_) => <$unit as super::Unit>::abbreviation(),)+
+                }
+            }
+
+            /// Unit singular description.
+            pub fn singular(&self) -> &'static str {
+                match self {
+                    $(Units::$unit(_) => <$unit as super::Unit>::singular(),)+
+                }
+            }
+
+            /// Unit plural description.
+            pub fn plural(&self) -> &'static str {
+                match self {
+                    $(Units::$unit(_) => <$unit as super::Unit>::plural(),)+
+                }
+            }
+        }
+
+        static ALL_UNITS: &[Units] = &[
+            $(Units::$unit($unit),)+
+        ];
+
+        /// Iterate over all defined units for this quantity.
+        pub fn units() -> impl Iterator<Item = Units> {
+            ALL_UNITS.iter().copied()
+        }
+
         impl<U, V> $quantity<U, V>
         where
             U: super::Units<V> + ?Sized,

src/tests/quantity.rs

@@ -182,6 +182,19 @@ storage_types! {
             a == b && a == c
         }
     }
+
+    #[test]
+    fn test_units_iterator() {
+        let mut units_iter = crate::si::volume::units();
+
+        // Specifically check the first few units. Doubles as a test of abbreviation() and others
+        assert_eq!("Ym³", units_iter.next().unwrap().abbreviation());
+        assert_eq!("cubic zettameter", units_iter.next().unwrap().singular());
+        assert_eq!("cubic exameters", units_iter.next().unwrap().plural());
+
+        // And there should be 63 remaining units.
+        assert_eq!(63, units_iter.count());
+    }
 }
 
 #[cfg(feature = "std")]