From 3f6071d196a94b3b434095890b6b004815e98833 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Thu, 16 Apr 2020 14:07:12 -0400
Subject: [PATCH] Add no_std support and testing

---
 Cargo.toml      |  5 +++++
 Jenkinsfile     | 10 ++++++++++
 src/bigint.rs   | 11 +++++++++++
 src/lib.rs      | 14 +++++++++++++-
 src/rational.rs |  4 ++--
 5 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index b9c5bcb..2fa4709 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,11 @@ edition = "2018"
 [dev-dependencies]
 criterion = "0.3"
 
+[features]
+default = ["std"]
+alloc = []
+std = ["alloc"]
+
 [[bench]]
 name = "stock_functions"
 harness = false
diff --git a/Jenkinsfile b/Jenkinsfile
index 28d0739..af90c99 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -16,6 +16,16 @@ pipeline {
              sh "cargo test"
          }
      }
+     stage('Check no_std') {
+         steps {
+             sh "cargo check --no-default-features --features alloc"
+         }
+     }
+     stage('Test no_std') {
+         steps {
+             sh "cargo test --no-default-features --features alloc"
+         }
+     }
      stage('Coverage') {
          steps {
              sh "cargo clean"
diff --git a/src/bigint.rs b/src/bigint.rs
index 5a457d1..cce0172 100644
--- a/src/bigint.rs
+++ b/src/bigint.rs
@@ -2,6 +2,17 @@
 //! \[WIP\] Arbitrarily large integers
 use crate::num::Sign::*;
 use crate::num::*;
+
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+extern crate alloc;
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::vec::*;
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::string::*;
+
+#[cfg(feature = "std")]
+use std::prelude::v1::*;
+
 use core::convert::TryInto;
 use core::mem::replace;
 use core::ops::{
diff --git a/src/lib.rs b/src/lib.rs
index b281c9b..aaa3ccd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,8 +2,18 @@
 //!
 //! Playin' with Numerics in Rust
 #![forbid(unsafe_code)]
+#![no_std]
 
-use std::f64::consts::{E, PI};
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+#[macro_use]
+extern crate alloc;
+
+#[cfg(feature = "std")]
+#[macro_use]
+extern crate std;
+
+#[cfg(feature = "std")]
+use core::f64::consts::{E, PI};
 
 pub mod bigint;
 pub mod num;
@@ -183,6 +193,7 @@ pub fn factorial(n: usize) -> Option<u128> {
 /// let invalid = approx_factorial(171.0); // None
 /// # assert!(invalid.is_none());
 /// ```
+#[cfg(feature = "std")]
 #[inline]
 pub fn approx_factorial(n: f64) -> Option<f64> {
     let power = (n / E).powf(n);
@@ -233,6 +244,7 @@ mod tests {
         assert!(it_factorial(35).is_none());
     }
 
+    #[cfg(feature = "std")]
     #[test]
     fn test_approx_factorial() {
         assert!(approx_factorial(170.624).is_some());
diff --git a/src/rational.rs b/src/rational.rs
index 562ecf1..a64502c 100644
--- a/src/rational.rs
+++ b/src/rational.rs
@@ -2,8 +2,8 @@
 
 use crate::num::Sign::*;
 use crate::num::*;
-use std::cmp::{Ord, Ordering, PartialOrd};
-use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
+use core::cmp::{Ord, Ordering, PartialOrd};
+use core::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign};
 
 /// Type representing a fraction
 ///