allow for no_std (#14)

Co-authored-by: bwty <whalelephant@users.noreply.github.com>

Cargo.toml

@@ -18,3 +18,7 @@ rand = "0.3"
 [[bench]]
 name = "base"
 harness = false
+
+[features]
+default = ["std"]
+std = []

src/alphabet.rs

@@ -1,3 +1,5 @@
+#[cfg(not(feature = "std"))]
+use alloc::{string::String, vec::Vec};
 use DecodeError;
 
 use decoder::*;

src/bigint.rs

@@ -1,3 +1,9 @@
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
+
+#[cfg(not(feature = "std"))]
+use core as std;
+
 use std::{ptr, u32};
 
 /// This is a pretty naive implementation of a BigUint abstracting all

src/decoder.rs

@@ -1,3 +1,9 @@
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
+
+#[cfg(not(feature = "std"))]
+use core as std;
+
 use bigint::BigUint;
 use DecodeError;
 
@@ -43,7 +49,6 @@ where
     }
 }
 
-
 pub(crate) struct U8Decoder<'b> {
     alphabet: &'b [u8],
     lookup: [u8; 256],
@@ -60,7 +65,6 @@ impl<'a> U8Decoder<'a> {
         }
         U8Decoder { alphabet, lookup }
     }
-
 }
 
 impl<'a, 'b> Decoder<'a, 'b> for U8Decoder<'b> {
@@ -109,4 +113,4 @@ impl<'a, 'b> Decoder<'a, 'b> for CharDecoder<'b> {
     {
         self.0
     }
-}
+}

src/encoder.rs

@@ -1,3 +1,5 @@
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
 use bigint::BigUint;
 
 pub(crate) fn encode<T>(alpha: &[T], input: &[u8]) -> Vec<T>

src/lib.rs

@@ -23,14 +23,24 @@
 //! }
 //! ```
 
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(not(feature = "std"))]
+extern crate alloc;
+
 pub mod alphabet;
 mod bigint;
 pub mod decoder;
 pub mod encoder;
 
 pub use alphabet::Alphabet;
 
-use std::error::Error;
+#[cfg(not(feature = "std"))]
+use alloc::{string::String, vec::Vec};
+
+#[cfg(not(feature = "std"))]
+use core as std;
+
 use std::fmt;
 
 #[derive(Debug)]
@@ -42,7 +52,8 @@ impl fmt::Display for DecodeError {
     }
 }
 
-impl Error for DecodeError {
+#[cfg(features = "std")]
+impl std::error::Error for DecodeError {
     fn description(&self) -> &str {
         "Can not decode the provided data"
     }