convert ena to no-std

Cargo.toml

@@ -10,9 +10,10 @@ readme = "README.md"
 keywords = ["unification", "union-find"]
 
 [features]
+std = [ ]
 bench = [ ]
-persistent = [ "dogged" ]
+persistent = [ "std", "dogged" ]
 
 [dependencies]
 dogged = { version = "0.2.0", optional = true }
-log = "0.4"
+log = { version = "0.4", optional = true }

src/lib.rs

@@ -10,15 +10,26 @@
 
 //! An implementation of union-find. See the `unify` module for more
 //! details.
-
 #![cfg_attr(feature = "bench", feature(test))]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(feature = "std")]
+extern crate core;
+extern crate alloc;
 
-#[macro_use]
+#[cfg(feature = "log")]
 extern crate log;
 
 #[cfg(feature = "persistent")]
 extern crate dogged;
 
+macro_rules! debug {
+  ($($tt:tt)*) => {
+    #[cfg(feature = "log")]
+    log::debug!($($tt)*);
+  };
+}
+
 pub mod snapshot_vec;
 pub mod undo_log;
 pub mod unify;

src/snapshot_vec.rs

@@ -21,10 +21,11 @@
 
 use self::UndoLog::*;
 
-use std::fmt;
-use std::marker::PhantomData;
-use std::mem;
-use std::ops;
+use core::fmt;
+use core::marker::PhantomData;
+use core::mem;
+use core::ops;
+use alloc::vec::Vec;
 
 use undo_log::{Rollback, Snapshots, UndoLogs, VecLog};
 

src/undo_log.rs

@@ -8,6 +8,9 @@
 //! Since the `*Storage` variants do not have an undo log `with_log` must be called with the
 //! unified log before any mutating actions.
 
+use core::ops;
+use alloc::vec::Vec;
+
 /// A trait which allows undo actions (`T`) to be pushed which can be used to rollback actio at a
 /// later time if needed.
 ///
@@ -220,7 +223,7 @@ impl<T> VecLog<T> {
     }
 }
 
-impl<T> std::ops::Index<usize> for VecLog<T> {
+impl<T> ops::Index<usize> for VecLog<T> {
     type Output = T;
     fn index(&self, key: usize) -> &T {
         &self.log[key]

src/unify/backing_vec.rs

@@ -1,8 +1,9 @@
 #[cfg(feature = "persistent")]
 use dogged::DVec;
 use snapshot_vec as sv;
-use std::marker::PhantomData;
-use std::ops::{self, Range};
+use core::marker::PhantomData;
+use core::ops::{self, Range};
+use alloc::vec::Vec;
 
 use undo_log::{Rollback, Snapshots, UndoLogs, VecLog};