Add the std / no_std feature.

.travis.yml

@@ -19,3 +19,6 @@ script:
   - echo "Testing feature serialization"
   - cargo build --verbose --features serialization
   - cargo test --verbose --features serialization
+  - echo "Testing without std"
+  - cargo build --verbose --no-default-features
+  - cargo test --verbose --no-default-features

Cargo.toml

@@ -18,8 +18,9 @@ is-it-maintained-open-issues = { repository = "phaazon/splines" }
 maintenance = { status = "actively-developed" }
 
 [features]
-default = []
+default = ["std"]
 serialization = ["serde", "serde_derive"]
+std = []
 
 [dependencies]
 cgmath = "0.16"

README.md

@@ -9,6 +9,11 @@ Feel free to dig in the [online documentation](https://docs.rs/splines) for furt
 
 This crate has features! Here’s a comprehensive list of what you can enable:
 
-  - **Serialization / deserialization**
+  - **Serialization / deserialization.**
     + This feature implements both the `Serialize` and `Deserialize` traits from `serde`.
-    + Enable with the feature `"serialization"`.
+    + Enable with the `"serialization"` feature.
+  - **Standard library / no stdandard library**
+    + It’s possible to compile against the standard library or go on your own without it.
+    + Compiling with the standard library is enabled by default.
+    + Use `defaut-features = []` in your `Cargo.toml` to disable.
+    + Enable explicitly with the `"std"` feataure.

src/lib.rs

@@ -76,9 +76,20 @@
 //!
 //! So here’s a list of currently supported features and how to enable them:
 //!
-//!   - **Serialization / deserialization**
+//!   - **Serialization / deserialization.**
 //!     + This feature implements both the `Serialize` and `Deserialize` traits from `serde`.
-//!     + Enable with the feature `"serialization"`.
+//!     + Enable with the `"serialization"` feature.
+//!   - **Standard library / no stdandard library**
+//!     + It’s possible to compile against the standard library or go on your own without it.
+//!     + Compiling with the standard library is enabled by default.
+//!     + Use `defaut-features = []` in your `Cargo.toml` to disable.
+//!     + Enable explicitly with the `"std"` feataure.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(not(feature = "std"), feature(alloc))]
+
+// on no_std, we also need the alloc crate for Vec
+#[cfg(not(feature = "std"))] extern crate alloc;
 
 extern crate cgmath;
 
@@ -86,9 +97,15 @@ extern crate cgmath;
 #[cfg(feature = "serialization")] #[macro_use] extern crate serde_derive;
 
 use cgmath::{InnerSpace, Quaternion, Vector2, Vector3, Vector4};
-use std::cmp::Ordering;
+
-use std::f32::consts;
+#[cfg(feature = "std")] use std::cmp::Ordering;
-use std::ops::{Add, Div, Mul, Sub};
+#[cfg(feature = "std")] use std::f32::consts;
+#[cfg(feature = "std")] use std::ops::{Add, Div, Mul, Sub};
+
+#[cfg(not(feature = "std"))] use alloc::vec::Vec;
+#[cfg(not(feature = "std"))] use core::cmp::Ordering;
+#[cfg(not(feature = "std"))] use core::f32::consts;
+#[cfg(not(feature = "std"))] use core::ops::{Add, Div, Mul, Sub};
 
 /// A spline control point.
 ///