Add optional ufmt impls

Cargo.toml

@@ -22,6 +22,7 @@ version = "0.5.4"
 [features]
 default = ["cas"]
 cas = []
+ufmt-impl = ["ufmt-write"]
 # only for tests
 __trybuild = []
 
@@ -41,3 +42,10 @@ default-features = false
 [dependencies.stable_deref_trait]
 version = "1"
 default-features = false
+
+[dependencies.ufmt-write]
+version = "0.1"
+optional = true
+
+[dev-dependencies.ufmt]
+version = "0.1"

src/lib.rs

@@ -56,6 +56,14 @@
 //! - [`mpmc::Q*`](mpmc/index.html) -- multiple producer multiple consumer lock-free queue
 //! - [`spsc::Queue`](spsc/struct.Queue.html) -- single producer single consumer lock-free queue
 //!
+//! # Optional Features
+//!
+//! The `heapless` crate provides the following optional Cargo features:
+//!
+//! - `ufmt-impl`: Implement [`ufmt_write::uWrite`] for `String<N>` and `Vec<u8, N>`
+//!
+//! [`ufmt_write::uWrite`]: https://docs.rs/ufmt-write/
+//!
 //! # Minimum Supported Rust Version (MSRV)
 //!
 //! This crate is guaranteed to compile on stable Rust 1.36 and up with its default set of features.
@@ -99,4 +107,7 @@ pub mod pool;
 #[cfg(has_atomics)]
 pub mod spsc;
 
+#[cfg(feature = "ufmt-impl")]
+mod ufmt;
+
 mod sealed;

src/ufmt.rs

@@ -0,0 +1,71 @@
+use ufmt_write::uWrite;
+
+use crate::{
+    ArrayLength,
+    string::String,
+    vec::Vec,
+};
+
+impl<N> uWrite for String<N>
+where
+    N: ArrayLength<u8>,
+{
+    type Error = ();
+    fn write_str(&mut self, s: &str) -> Result<(), Self::Error> {
+        self.push_str(s)
+    }
+}
+
+impl<N> uWrite for Vec<u8, N>
+where
+    N: ArrayLength<u8>,
+{
+    type Error = ();
+    fn write_str(&mut self, s: &str) -> Result<(), Self::Error> {
+        self.extend_from_slice(s.as_bytes())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use ufmt::{derive::uDebug, uwrite};
+
+    use crate::consts::*;
+
+    #[derive(uDebug)]
+    struct Pair {
+        x: u32,
+        y: u32,
+    }
+
+    #[test]
+    fn test_string() {
+        let a = 123;
+        let b = Pair { x: 0, y: 1234 };
+
+        let mut s = String::<U32>::new();
+        uwrite!(s, "{} -> {:?}", a, b).unwrap();
+
+        assert_eq!(s, "123 -> Pair { x: 0, y: 1234 }");
+    }
+
+    #[test]
+    fn test_string_err() {
+        let p = Pair { x: 0, y: 1234 };
+        let mut s = String::<U4>::new();
+        assert!(uwrite!(s, "{:?}", p).is_err());
+    }
+
+    #[test]
+    fn test_vec() {
+        let a = 123;
+        let b = Pair { x: 0, y: 1234 };
+
+        let mut v = Vec::<u8, U32>::new();
+        uwrite!(v, "{} -> {:?}", a, b).unwrap();
+
+        assert_eq!(v, b"123 -> Pair { x: 0, y: 1234 }");
+    }
+}