Implement serde::ser::Serialize and serde::de::Deserialize.

Fixes iliekturtles#37.

Cargo.toml

@@ -22,6 +22,7 @@ maintenance = { status = "actively-developed" }
 
 [dependencies]
 num = "0.1"
+serde = { version = "1.0", optional = true }
 typenum = "1.9.0"
 
 [dev-dependencies]

README.md

@@ -63,10 +63,10 @@ See the [examples](examples) directory for more advanced usage:
 
 ## Features
 `uom` has multiple `Cargo` features for controlling available underlying storage types, the
-inclusion of the pre-built [International System of Units][si] (SI), and `no_std` functionality. The
-features are described below. `f32`, `f64`, `std`, and `si` are enabled by default. Features can be
-cherry-picked by using the `--no-default-features` and `--features "..."` flags when compiling `uom`
-or specifying features in Cargo.toml:
+inclusion of the pre-built [International System of Units][si] (SI), support for [Serde][serde], and
+`no_std` functionality. The features are described below. `f32`, `f64`, `std`, and `si` are enabled
+by default. Features can be cherry-picked by using the `--no-default-features` and
+`--features "..."` flags when compiling `uom` or specifying features in Cargo.toml:
 
 ```toml
 [dependencies]
@@ -88,12 +88,15 @@ uom = {
    `rational`, `rational32`, `rational64`, `bigrational`, `f32`, `f64` -- Features to enable
    underlying storage types. At least one of these features must be enabled. `f32` and `f64` are
    enabled by default.
+ * `serde` -- Feature to enable support for serialization and deserialization of quantities with
+   the [serde][serde] crate.
  * `si` -- Feature to include the pre-built [International System of Units][si] (SI). Enabled by
    default.
  * `std` -- Feature to compile with standard library support. Disabling this feature compiles `uom`
    with `no_std`. Enabled by default.
 
 [si]: http://jcgm.bipm.org/vim/en/1.16.html
+[serde]: https://serde.rs/
 
 ## Design
 Rather than working with [measurement units](http://jcgm.bipm.org/vim/en/1.9.html) (meter,

src/lib.rs

@@ -52,10 +52,10 @@
 //!
 //! ## Features
 //! `uom` has multiple `Cargo` features for controlling available underlying storage types, the
-//! inclusion of the pre-built [International System of Units][si] (SI), and `no_std` functionality.
-//! The features are described below. `f32`, `f64`, `std`, and `si` are enabled by default. Features
-//! can be cherry-picked by using the `--no-default-features` and `--features "..."` flags when
-//! compiling `uom` or specifying features in Cargo.toml:
+//! inclusion of the pre-built [International System of Units][si] (SI), support for [Serde][serde],
+//! and `no_std` functionality. The features are described below. `f32`, `f64`, `std`, and `si` are
+//! enabled by default. Features can be cherry-picked by using the `--no-default-features` and
+//! `--features "..."` flags when compiling `uom` or specifying features in Cargo.toml:
 //!
 //! ```toml
 //! [dependencies]
@@ -77,12 +77,15 @@
 //!    `rational`, `rational32`, `rational64`, `bigrational`, `f32`, `f64` -- Features to enable
 //!    underlying storage types. At least one of these features must be enabled. `f32` and `f64` are
 //!    enabled by default.
+//!  * `serde` -- Feature to enable support for serialization and deserialization of quantities with
+//!    the [serde][serde] crate.
 //!  * `si` -- Feature to include the pre-built [International System of Units][si] (SI). Enabled by
 //!    default.
 //!  * `std` -- Feature to compile with standard library support. Disabling this feature compiles
 //!    `uom` with `no_std`. Enabled by default.
 //!
 //! [si]: http://jcgm.bipm.org/vim/en/1.16.html
+//! [serde]: https://serde.rs/
 //!
 //! ## Design
 //! Rather than working with [measurement units](http://jcgm.bipm.org/vim/en/1.9.html) (meter,
@@ -156,6 +159,10 @@ compile_error!("A least one underlying storage type must be enabled. See the fea
 #[doc(hidden)]
 pub extern crate num;
 
+#[doc(hidden)]
+#[cfg(feature = "serde")]
+pub extern crate serde;
+
 #[doc(hidden)]
 pub extern crate typenum;
 

src/system.rs

@@ -858,6 +858,42 @@ macro_rules! system {
             }
         }
 
+        #[cfg(feature = "serde")]
+        impl<D, U, V> $crate::serde::ser::Serialize for Quantity<D, U, V>
+        where
+            D: Dimension + ?Sized,
+            U: Units<V> + ?Sized,
+            V: $crate::num::Num + $crate::Conversion<V> + $crate::serde::ser::Serialize,
+        {
+            fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+            where
+                S: $crate::serde::ser::Serializer
+            {
+                self.value.serialize(serializer)
+            }
+        }
+
+        #[cfg(feature = "serde")]
+        impl<'de, D, U, V> $crate::serde::de::Deserialize<'de> for Quantity<D, U, V>
+        where
+            D: Dimension + ?Sized,
+            U: Units<V> + ?Sized,
+            V: $crate::num::Num + $crate::Conversion<V> + $crate::serde::de::Deserialize<'de>,
+        {
+            fn deserialize<De>(deserializer: De) -> Result<Self, De::Error>
+            where
+                De: $crate::serde::de::Deserializer<'de>,
+            {
+                let value: V = $crate::serde::de::Deserialize::deserialize(deserializer)?;
+
+                Ok(Quantity {
+                    dimension: $crate::lib::marker::PhantomData,
+                    units: $crate::lib::marker::PhantomData,
+                    value,
+                })
+            }
+        }
+
         /// Macro to implement [`quantity`](si/struct.Quantity.html) type aliases for a specific
         /// [system of units][units] and value storage type.
         ///