no_std support

Cargo.toml

@@ -3,5 +3,10 @@ name = "libshire"
 version = "0.1.0"
 edition = "2021"
 
+[features]
+default = ["std", "serde"]
+alloc = ["serde?/alloc"]
+std = ["serde?/std"]
+
 [dependencies]
 serde = { version = "1", default-features = false, optional = true }

src/convert.rs

@@ -1,4 +1,4 @@
-use std::convert::Infallible;
+use core::convert::Infallible;
 
 /// Consumes an element of type `Infallible` and produces an element of any type `T`. This is
 /// possible because `Infallible` has no elements and thus this function can never be called, so

src/either.rs

@@ -1,9 +1,8 @@
-use std::{
+use core::{
     convert::identity,
     fmt,
     hint,
     ops::{Deref, DerefMut},
-    process::{ExitCode, Termination},
 };
 
 use crate::convert::{clone, clone_mut, copy, copy_mut, Empty};
@@ -586,14 +585,15 @@ where
     }
 }
 
-impl<L, R> Termination for Either<L, R>
+#[cfg(feature = "std")]
+impl<L, R> std::process::Termination for Either<L, R>
 where
-    L: Termination,
-    R: Termination,
+    L: std::process::Termination,
+    R: std::process::Termination,
 {
     #[inline]
-    fn report(self) -> ExitCode {
-        self.fold(<L as Termination>::report, <R as Termination>::report)
+    fn report(self) -> std::process::ExitCode {
+        self.fold(<L as std::process::Termination>::report, <R as std::process::Termination>::report)
     }
 }
 

src/hex.rs

@@ -1,5 +1,4 @@
-use std::{
-    error,
+use core::{
     fmt::{self, Write},
     marker::PhantomData,
 };
@@ -215,7 +214,8 @@ impl fmt::Display for ParseError {
     }
 }
 
-impl error::Error for ParseError {}
+#[cfg(feature = "std")]
+impl std::error::Error for ParseError {}
 
 #[derive(Debug)]
 pub enum ArrayParseError {
@@ -232,7 +232,8 @@ impl fmt::Display for ArrayParseError {
     }
 }
 
-impl error::Error for ArrayParseError {}
+#[cfg(feature = "std")]
+impl std::error::Error for ArrayParseError {}
 
 impl From<ParseError> for ArrayParseError {
     fn from(err: ParseError) -> Self {
@@ -244,8 +245,12 @@ impl From<ParseError> for ArrayParseError {
 mod tests {
     use super::*;
 
+    #[cfg(any(feature = "alloc", feature = "std"))]
     #[test]
     fn test_hex_bytes_debug() {
+        #[cfg(not(feature = "std"))]
+        use alloc::format;
+
         assert_eq!(
             format!("{:?}", HexBytes::<Lowercase>::new(&[0x87, 0xe1, 0x8f, 0xaa, 0x88, 0x8d, 0x43, 0x4e, 0xf2, 0xb2, 0x5d, 0xe1, 0xa5, 0x1b, 0xa0, 0x94])),
             "[0x87, 0xe1, 0x8f, 0xaa, 0x88, 0x8d, 0x43, 0x4e, 0xf2, 0xb2, 0x5d, 0xe1, 0xa5, 0x1b, 0xa0, 0x94]"
@@ -257,8 +262,12 @@ mod tests {
         );
     }
 
+    #[cfg(any(feature = "alloc", feature = "std"))]
     #[test]
     fn test_hex_bytes_display() {
+        #[cfg(not(feature = "std"))]
+        use alloc::string::ToString;
+
         assert_eq!(
             HexBytes::<Lowercase>::new(&[0x87, 0xe1, 0x8f, 0xaa, 0x88, 0x8d, 0x43, 0x4e, 0xf2, 0xb2, 0x5d, 0xe1, 0xa5, 0x1b, 0xa0, 0x94]).to_string(),
             "87e18faa888d434ef2b25de1a51ba094"

src/lib.rs

@@ -1,3 +1,8 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
+#[cfg(feature = "alloc")]
+extern crate alloc;
+
 pub mod convert;
 pub mod either;
 pub mod hex;

src/strings/capped.rs

@@ -1,13 +1,25 @@
-use std::{
-    borrow::{self, Cow},
+use core::{
+    borrow,
     cmp::Ordering,
-    error,
     fmt,
     hash::{Hash, Hasher},
     ops,
     str,
 };
 
+#[cfg(not(feature = "std"))]
+use core::convert::TryFrom;
+
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::{
+    borrow::{Cow, ToOwned},
+    boxed::Box,
+    string::String,
+};
+
+#[cfg(feature = "std")]
+use std::borrow::Cow;
+
 #[derive(Clone)]
 pub struct CappedString<const N: usize> {
     buf: [u8; N],
@@ -97,10 +109,6 @@ impl<const N: usize> CappedString<N> {
         unsafe { str::from_utf8_unchecked_mut(slice) }
     }
 
-    pub fn into_string(self) -> String {
-        self.as_str().to_owned()
-    }
-
     pub fn len(&self) -> usize {
         usize::from(self.len)
     }
@@ -110,6 +118,17 @@ impl<const N: usize> CappedString<N> {
     }
 }
 
+#[cfg(any(feature = "alloc", feature = "std"))]
+impl<const N: usize> CappedString<N> {
+    pub fn into_boxed_str(self) -> Box<str> {
+        self.as_str().into()
+    }
+
+    pub fn into_string(self) -> String {
+        self.as_str().to_owned()
+    }
+}
+
 impl<const N: usize> Default for CappedString<N> {
     #[inline]
     fn default() -> Self {
@@ -170,6 +189,7 @@ impl<'a, const N: usize> TryFrom<&'a str> for CappedString<N> {
     }
 }
 
+#[cfg(any(feature = "alloc", feature = "std"))]
 impl<const N: usize> TryFrom<String> for CappedString<N> {
     type Error = Error;
 
@@ -179,6 +199,7 @@ impl<const N: usize> TryFrom<String> for CappedString<N> {
     }
 }
 
+#[cfg(any(feature = "alloc", feature = "std"))]
 impl<'a, const N: usize> TryFrom<Cow<'a, str>> for CappedString<N> {
     type Error = Error;
 
@@ -188,6 +209,7 @@ impl<'a, const N: usize> TryFrom<Cow<'a, str>> for CappedString<N> {
     }
 }
 
+#[cfg(any(feature = "alloc", feature = "std"))]
 impl<const N: usize> From<CappedString<N>> for String {
     #[inline]
     fn from(s: CappedString<N>) -> Self {
@@ -275,4 +297,5 @@ impl fmt::Display for Error {
     }
 }
 
-impl error::Error for Error {}
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}

src/strings/experimental.rs

@@ -1,5 +1,5 @@
-use std::{
-    borrow::{self, Cow},
+use core::{
+    borrow,
     cmp::Ordering,
     convert::Infallible,
     fmt,
@@ -12,6 +12,16 @@ use std::{
     str,
 };
 
+#[cfg(not(feature = "std"))]
+use alloc::{
+    borrow::Cow,
+    boxed::Box,
+    string::String,
+};
+
+#[cfg(feature = "std")]
+use std::borrow::Cow;
+
 /// A non-growable string where strings 23 bytes or shorter are stored inline and longer strings
 /// use a separate heap allocation. If maximum inline lengths other than 23 are desired, see the
 /// more general [InliningString].
@@ -274,7 +284,7 @@ impl<const N: usize> InliningString<N> {
 
     #[inline]
     #[must_use]
-    pub fn into_string(self) -> String {
+    pub fn into_boxed_str(self) -> Box<str> {
         match self.inline_string_len() {
             Some(len) => {
                 // Get a pointer to the `inline` field of the union.
@@ -296,7 +306,7 @@ impl<const N: usize> InliningString<N> {
                 // of `InliningString`.
                 let str_slice = unsafe { str::from_utf8_unchecked(bytes) };
 
-                str_slice.to_owned()
+                Box::from(str_slice)
             },
 
             None => {
@@ -328,13 +338,18 @@ impl<const N: usize> InliningString<N> {
                 // The boxed string is initialised, as we obtained it by moving `repr.boxed`, and
                 // the only time `repr.boxed` is uninitialised is when it is briefly replaced with
                 // a temporary value in the block above.
-                let box_str = unsafe { maybe_box_str.assume_init() };
-                
-                box_str.into_string()
+                unsafe { maybe_box_str.assume_init() }
             },
         }
     }
 
+    #[inline]
+    #[must_use]
+    pub fn into_string(self) -> String {
+        self.into_boxed_str()
+            .into_string()
+    }
+
     #[inline]
     #[must_use]
     pub fn heap_allocated(&self) -> bool {
@@ -519,19 +534,26 @@ impl<'de, const N: usize> serde::Deserialize<'de> for InliningString<N> {
 
 #[cfg(test)]
 mod tests {
+    #[cfg(not(feature = "std"))]
+    use alloc::{
+        borrow::{Cow, ToOwned},
+        vec::Vec,
+    };
+
+    #[cfg(feature = "std")]
     use std::borrow::Cow;
 
     use super::*;
 
     #[test]
     fn test_align() {
-        use std::mem::align_of;
+        use core::mem::align_of;
         assert_eq!(align_of::<InliningString23>(), align_of::<Box<str>>());
     }
 
     #[test]
     fn test_niche() {
-        use std::mem::size_of;
+        use core::mem::size_of;
         assert_eq!(size_of::<InliningString23>(), size_of::<Option<InliningString23>>());
     }
 

src/strings/fixed.rs

@@ -1,7 +1,6 @@
-use std::{
+use core::{
     borrow,
     cmp::Ordering,
-    error,
     fmt,
     hash::{Hash, Hasher},
     ops,
@@ -191,7 +190,8 @@ impl fmt::Display for Error {
     }
 }
 
-impl error::Error for Error {}
+#[cfg(feature = "std")]
+impl std::error::Error for Error {}
 
 #[cfg(test)]
 mod tests {

src/strings/inlining.rs

@@ -1,5 +1,5 @@
-use std::{
-    borrow::{self, Cow},
+use core::{
+    borrow,
     cmp::Ordering,
     convert::Infallible,
     fmt,
@@ -8,6 +8,12 @@ use std::{
     str::FromStr,
 };
 
+#[cfg(not(feature = "std"))]
+use alloc::{borrow::Cow, boxed::Box, string::String};
+
+#[cfg(feature = "std")]
+use std::borrow::Cow;
+
 use super::CappedString;
 
 /// A non-growable string where strings 22 bytes or shorter are stored inline and longer strings
@@ -103,6 +109,15 @@ impl<const N: usize> InliningString<N> {
         }
     }
 
+    #[inline]
+    #[must_use]
+    pub fn into_boxed_str(self) -> Box<str> {
+        match self {
+            Self(Repr::Inline(buf)) => buf.into_boxed_str(),
+            Self(Repr::Boxed(buf)) => buf,
+        }
+    }
+
     /// Consumes the `InliningString` and converts it to a heap-allocated `String`.
     #[inline]
     #[must_use]
@@ -304,7 +319,7 @@ impl<const N: usize> fmt::Display for InliningString<N> {
 impl<const N: usize> serde::Serialize for InliningString<N> {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where
-        S: serde::Serializer
+        S: serde::Serializer,
     {
         serde::Serialize::serialize(&**self, serializer)
     }
@@ -314,10 +329,9 @@ impl<const N: usize> serde::Serialize for InliningString<N> {
 impl<'de, const N: usize> serde::Deserialize<'de> for InliningString<N> {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
-        D: serde::Deserializer<'de>
+        D: serde::Deserializer<'de>,
     {
-        serde::Deserialize::deserialize(deserializer)
-            .map(Self::new::<&'de str>)
+        serde::Deserialize::deserialize(deserializer).map(Self::new::<Cow<'de, str>>)
     }
 }
 
@@ -329,6 +343,10 @@ enum Repr<const N: usize> {
 
 #[cfg(test)]
 mod tests {
+    #[cfg(not(feature = "std"))]
+    use alloc::borrow::{Cow, ToOwned};
+
+    #[cfg(feature = "std")]
     use std::borrow::Cow;
 
     use super::{InliningString, InliningString22};
@@ -341,7 +359,7 @@ mod tests {
             "Somethingfortheweekend",
             "Dichlorodifluoromethane",
             "こんにちは",
-            "❤️🧡💛💚💙💜"
+            "❤️🧡💛💚💙💜",
         ];
 
         for s in test_strings {

src/strings/mod.rs

@@ -1,8 +1,11 @@
+#[cfg(any(feature = "alloc", feature = "std"))]
 pub mod experimental;
 pub mod fixed;
 pub mod capped;
+#[cfg(any(feature = "alloc", feature = "std"))]
 pub mod inlining;
 
 pub use fixed::{FixedString, Error as FixedStringError};
 pub use capped::{CappedString, Error as CappedStringError};
+#[cfg(any(feature = "alloc", feature = "std"))]
 pub use inlining::{InliningString, InliningString22};

src/uuid.rs

@@ -1,4 +1,4 @@
-use std::{error, fmt, str};
+use core::{fmt, str};
 
 use crate::{hex, strings::FixedString};
 
@@ -222,7 +222,8 @@ impl fmt::Display for ParseError {
     }
 }
 
-impl error::Error for ParseError {}
+#[cfg(feature = "std")]
+impl std::error::Error for ParseError {}
 
 #[derive(Debug)]
 pub enum UuidV5Error {
@@ -237,7 +238,8 @@ impl fmt::Display for UuidV5Error {
     }
 }
 
-impl error::Error for UuidV5Error {}
+#[cfg(feature = "std")]
+impl std::error::Error for UuidV5Error {}
 
 fn sha1(namespace: [u8; 16], name: &[u8]) -> Result<[u8; 20], UuidV5Error> {
     let (mut h0, mut h1, mut h2, mut h3, mut h4) = (
@@ -410,8 +412,12 @@ impl<'a> Iterator for Sha1ChunkIter<'a> {
 mod tests {
     use super::Uuid;
 
+    #[cfg(any(feature = "alloc", feature = "std"))]
     #[test]
     fn test_uuid_display() {
+        #[cfg(not(feature = "std"))]
+        use alloc::string::ToString;
+
         assert_eq!(
             Uuid::from_bytes([
                 0x12, 0x3e, 0x45, 0x67, 0xe8, 0x9b, 0x12, 0xd3, 0xa4, 0x56, 0x42, 0x66, 0x14, 0x17,

test.sh

@@ -1,5 +1,9 @@
 #!/bin/bash
 
+cargo miri test --no-default-features --features serde
+
+cargo miri test --no-default-features --features alloc,serde
+
 cargo miri test
 
 # 32-bit target