support no_std mode

Cargo.toml

@@ -10,12 +10,14 @@ description = "Tools for convenient comparison of matrices"
 readme = "README.md"
 
 [features]
+default = ["std"]
+std = []
 proptest-support = [ "proptest"]
 
 [dependencies]
 num-traits = { version = "0.2", default-features = false }
 matrixcompare-core = { path = "matrixcompare-core", version="0.1"}
-proptest = { version = "1.0", optional = true }
+proptest = { version = "1.0", optional = true, default-features = false }
 
 [dev-dependencies]
 quickcheck = "0.9"

matrixcompare-core/src/lib.rs

@@ -1,3 +1,7 @@
+#![no_std]
+extern crate alloc;
+use alloc::vec::Vec;
+
 /// Defines how the elements of a matrix may be accessed.
 pub enum Access<'a, T> {
     Dense(&'a dyn DenseAccess<T>),
@@ -28,8 +32,8 @@ pub trait SparseAccess<T>: Matrix<T> {
 }
 
 impl<T, X> Matrix<T> for &X
-    where
-        X: Matrix<T>,
+where
+    X: Matrix<T>,
 {
     fn rows(&self) -> usize {
         X::rows(*self)
@@ -45,17 +49,17 @@ impl<T, X> Matrix<T> for &X
 }
 
 impl<T, X> DenseAccess<T> for &X
-    where
-        X: DenseAccess<T>,
+where
+    X: DenseAccess<T>,
 {
     fn fetch_single(&self, row: usize, col: usize) -> T {
         X::fetch_single(*self, row, col)
     }
 }
 
 impl<T, X> SparseAccess<T> for &X
-    where
-        X: SparseAccess<T>,
+where
+    X: SparseAccess<T>,
 {
     fn nnz(&self) -> usize {
         X::nnz(*self)
@@ -64,4 +68,4 @@ impl<T, X> SparseAccess<T> for &X
     fn fetch_triplets(&self) -> Vec<(usize, usize, T)> {
         X::fetch_triplets(&self)
     }
-}
+}

src/comparators.rs

@@ -1,11 +1,14 @@
 //! Comparators used for element-wise comparison of matrix entries.
 
+use crate::alloc::string::ToString;
 use crate::ulp::{Ulp, UlpComparisonResult};
+use core::fmt::Write;
 
 use num_traits::{float::FloatCore, Num};
 
-use std::fmt;
-use std::fmt::{Display, Formatter};
+use alloc::string::String;
+use core::fmt;
+use core::fmt::{Display, Formatter};
 
 /// Trait that describes elementwise comparators for [assert_matrix_eq!](../macro.assert_matrix_eq!.html).
 ///
@@ -72,7 +75,14 @@ where
     }
 
     fn description(&self) -> String {
-        format!("absolute difference, |x - y| <= {tol}.", tol = self.tol)
+        let mut out = String::new();
+        write!(
+            out,
+            "absolute difference, |x - y| <= {tol}.",
+            tol = self.tol
+        )
+        .unwrap();
+        out
     }
 }
 
@@ -147,10 +157,14 @@ where
     }
 
     fn description(&self) -> String {
-        format!(
+        let mut out = String::new();
+        write!(
+            out,
             "ULP difference less than or equal to {tol}. See documentation for details.",
             tol = self.tol
         )
+        .unwrap();
+        out
     }
 }
 
@@ -208,14 +222,18 @@ where
     }
 
     fn description(&self) -> String {
-        format!(
+        let mut out = String::new();
+        write!(
+            out,
             "Epsilon-sized absolute comparison, followed by an ULP-based comparison.
 Please see the documentation for details.
 Epsilon:       {eps}
 ULP tolerance: {ulp}",
             eps = self.abs.tol,
             ulp = self.ulp.tol
         )
+        .unwrap();
+        out
     }
 }
 
@@ -227,12 +245,12 @@ mod tests {
         UlpElementwiseComparator, UlpError,
     };
     use crate::ulp::{Ulp, UlpComparisonResult};
+    use core::f64;
     use quickcheck::TestResult;
-    use std::f64;
 
     /// Returns the next adjacent floating point number (in the direction of positive infinity)
     fn next_f64(x: f64) -> f64 {
-        use std::mem;
+        use core::mem;
         let as_int = unsafe { mem::transmute::<f64, i64>(x) };
         unsafe { mem::transmute::<i64, f64>(as_int + 1) }
     }

src/comparison_failure.rs

@@ -1,5 +1,9 @@
+use crate::alloc::string::ToString;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::fmt;
-use std::fmt::{Display, Formatter};
+use core::fmt::Write;
+use core::fmt::{Display, Formatter};
 
 const MAX_MISMATCH_REPORTS: usize = 12;
 
@@ -29,7 +33,8 @@ where
 
         // Write the error into a string first, so that we can add a space between
         // the element output and the error output only if there is something to report.
-        let error = format!("{}", self.error);
+        let mut error = String::new();
+        write!(error, "{}", self.error)?;
         if !error.is_empty() {
             write!(f, " {}", self.error)?;
         }
@@ -96,10 +101,13 @@ where
         // TODO: Write directly to formatter
         let overflow_msg = if mismatches_overflow {
             let num_hidden_entries = self.mismatches.len() - MAX_MISMATCH_REPORTS;
-            format!(
+            let mut msg = String::new();
+            write!(
+                msg,
                 " ... ({} mismatching elements not shown)\n",
                 num_hidden_entries
-            )
+            )?;
+            msg
         } else {
             String::new()
         };
@@ -139,6 +147,7 @@ pub enum MatrixComparisonFailure<T, Error> {
     DuplicateSparseEntry(Entry),
 }
 
+#[cfg(feature = "std")]
 impl<T, E> std::error::Error for MatrixComparisonFailure<T, E>
 where
     T: fmt::Debug + Display,

src/lib.rs

@@ -71,6 +71,7 @@ example in the repository.
 */
 
 #![allow(clippy::float_cmp)]
+#![no_std]
 
 #[macro_use]
 mod matrix_comparison;
@@ -83,6 +84,7 @@ mod comparison_failure;
 #[cfg(test)]
 #[macro_use]
 extern crate quickcheck;
+extern crate alloc;
 
 pub mod comparators;
 mod macros;

src/macros.rs

@@ -272,7 +272,7 @@ macro_rules! base_scalar_eq {
         {
             use $crate::{compare_scalars};
             use $crate::comparators::ExactElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = ExactElementwiseComparator;
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {
@@ -287,7 +287,7 @@ Please see the documentation for ways to compare scalars approximately.\n",
         {
             use $crate::{compare_scalars};
             use $crate::comparators::ExactElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = ExactElementwiseComparator;
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {
@@ -300,7 +300,7 @@ Please see the documentation for ways to compare scalars approximately.\n",
         {
             use $crate::{compare_scalars};
             use $crate::comparators::AbsoluteElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = AbsoluteElementwiseComparator { tol: $tol.clone() };
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {
@@ -313,7 +313,7 @@ Please see the documentation for ways to compare scalars approximately.\n",
         {
             use $crate::{compare_scalars};
             use $crate::comparators::UlpElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = UlpElementwiseComparator { tol: $tol.clone() };
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {
@@ -326,7 +326,7 @@ Please see the documentation for ways to compare scalars approximately.\n",
         {
             use $crate::{compare_scalars};
             use $crate::comparators::FloatElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = FloatElementwiseComparator::default();
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {
@@ -341,7 +341,7 @@ Please see the documentation for ways to compare scalars approximately.\n",
         {
             use $crate::{compare_scalars};
             use $crate::comparators::FloatElementwiseComparator;
-            use std::borrow::Borrow;
+            use core::borrow::Borrow;
             let comp = FloatElementwiseComparator::default()$(.$key($val))+;
             let result = compare_scalars($x.borrow(), $y.borrow(), comp);
             if let Err(error) = result {

src/matrix_comparison.rs

@@ -3,8 +3,9 @@ use crate::{
     Access, Coordinate, DenseAccess, DimensionMismatch, ElementsMismatch, Matrix,
     MatrixComparisonFailure, MatrixElementComparisonFailure, SparseAccess,
 };
+use alloc::vec::Vec;
+use hashbrown::{HashMap, HashSet};
 use num_traits::Zero;
-use std::collections::{HashMap, HashSet};
 
 use crate::Entry;
 
@@ -26,7 +27,8 @@ where
     for (i, j, v) in triplets.iter().cloned() {
         if i >= rows || j >= cols {
             return Err(HashMapBuildError::OutOfBoundsCoord((i, j)));
-        } else if matrix.insert((i, j), v).is_some() {
+        }
+        if matrix.insert((i, j), v).is_some() {
             return Err(HashMapBuildError::DuplicateCoord((i, j)));
         }
     }
@@ -71,7 +73,7 @@ where
     let right_keys: HashSet<_> = right_hash.keys().collect();
     let zero = T::zero();
 
-    for coord in left_keys.union(&right_keys) {
+    for &coord in left_keys.union(&right_keys) {
         let a = left_hash.get(coord).unwrap_or(&zero);
         let b = right_hash.get(coord).unwrap_or(&zero);
         if let Err(error) = comparator.compare(&a, &b) {

src/scalar_comparison.rs

@@ -1,4 +1,5 @@
-use std::fmt;
+use alloc::string::String;
+use core::fmt;
 
 use crate::comparators::ElementwiseComparator;
 

src/ulp.rs

@@ -1,5 +1,6 @@
 //! Tools for ULP-based comparison of floating point numbers.
-use std::mem;
+use crate::alloc::borrow::ToOwned;
+use core::mem;
 
 /// Represents the result of an ULP-based comparison between two floating point numbers.
 #[derive(Debug, Copy, Clone, PartialEq)]
@@ -67,9 +68,9 @@ impl_float_ulp!(f64, i64);
 mod tests {
     use super::Ulp;
     use super::UlpComparisonResult;
+    use core::mem;
+    use core::{f32, f64};
     use quickcheck::TestResult;
-    use std::mem;
-    use std::{f32, f64};
 
     #[test]
     fn plus_minus_zero_is_exact_match_f32() {