Merge pull request #48 from tweedegolf/dyn-len-key

Make keys dynamic length

Author: diondokter

.github/workflows/ci.yaml

@@ -20,7 +20,7 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - uses: dtolnay/rust-toolchain@stable
-    - run: cargo test
+    - run: cargo test --features arrayvec
 
   clippy:
     runs-on: ubuntu-latest

.vscode/settings.json

@@ -1,4 +1,5 @@
 {
+    "rust-analyzer.cargo.allTargets": false,
     "rust-analyzer.linkedProjects": [
         "Cargo.toml",
         "fuzz/Cargo.toml",

CHANGELOG.md

@@ -12,6 +12,7 @@
   and carries a predefined error subtype.
 - Added `erase_all` function as a helper to erase the flash in a region.
 - *Breaking:* Changed the way that queue iteration works. Now there's an `iter` function instead of two separate `peek_many` and `pop_many` functions. The new iter returns an entry from which you can get the data that was just peeked. If you want to pop it, then call the pop function on the entry.
+- Added `arrayvec` feature that when activated impls the `Key` trait for `ArrayVec` and `ArrayString`.
 
 ## 1.0.0 01-03-24
 

Cargo.toml

@@ -16,6 +16,7 @@ embedded-storage-async = "0.4.1"
 defmt = { version = "0.3", optional = true }
 futures = { version = "0.3.30", features = ["executor"], optional = true }
 approx = { version = "0.5.1", optional = true }
+arrayvec = { version = "0.7.4", default-features = false, optional = true }
 
 [dev-dependencies]
 approx = "0.5.1"
@@ -25,4 +26,6 @@ futures-test = "0.3.30"
 [features]
 defmt-03 = ["dep:defmt"]
 std = []
-_test = ["dep:futures", "dep:approx", "std"]
+# Enable the implementation of the map Key trait for ArrayVec and ArrayString
+arrayvec = ["dep:arrayvec"]
+_test = ["dep:futures", "dep:approx", "std", "arrayvec"]

src/arrayvec_impl.rs

@@ -0,0 +1,123 @@
+use arrayvec::{ArrayString, ArrayVec};
+
+use crate::map::{Key, SerializationError};
+
+impl<const CAP: usize> Key for ArrayVec<u8, CAP> {
+    fn serialize_into(&self, buffer: &mut [u8]) -> Result<usize, SerializationError> {
+        if buffer.len() < self.len() + 2 {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        if self.len() > u16::MAX as usize {
+            return Err(SerializationError::InvalidData);
+        }
+
+        buffer[..2].copy_from_slice(&(self.len() as u16).to_le_bytes());
+        buffer[2..][..self.len()].copy_from_slice(self);
+
+        Ok(self.len() + 2)
+    }
+
+    fn deserialize_from(buffer: &[u8]) -> Result<(Self, usize), SerializationError> {
+        let total_len = Self::get_len(buffer)?;
+
+        if buffer.len() < total_len {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        let data_len = total_len - 2;
+
+        let mut output = ArrayVec::new();
+        output
+            .try_extend_from_slice(&buffer[2..][..data_len])
+            .map_err(|_| SerializationError::InvalidFormat)?;
+
+        Ok((output, total_len))
+    }
+
+    fn get_len(buffer: &[u8]) -> Result<usize, SerializationError> {
+        if buffer.len() < 2 {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        let len = u16::from_le_bytes(buffer[..2].try_into().unwrap());
+
+        Ok(len as usize + 2)
+    }
+}
+
+impl<const CAP: usize> Key for ArrayString<CAP> {
+    fn serialize_into(&self, buffer: &mut [u8]) -> Result<usize, SerializationError> {
+        if buffer.len() < self.len() + 2 {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        if self.len() > u16::MAX as usize {
+            return Err(SerializationError::InvalidData);
+        }
+
+        buffer[..2].copy_from_slice(&(self.len() as u16).to_le_bytes());
+        buffer[2..][..self.len()].copy_from_slice(self.as_bytes());
+
+        Ok(self.len() + 2)
+    }
+
+    fn deserialize_from(buffer: &[u8]) -> Result<(Self, usize), SerializationError> {
+        let total_len = Self::get_len(buffer)?;
+
+        if buffer.len() < total_len {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        let data_len = total_len - 2;
+
+        let mut output = ArrayString::new();
+        output
+            .try_push_str(
+                core::str::from_utf8(&buffer[2..][..data_len])
+                    .map_err(|_| SerializationError::InvalidFormat)?,
+            )
+            .map_err(|_| SerializationError::InvalidFormat)?;
+
+        Ok((output, total_len))
+    }
+
+    fn get_len(buffer: &[u8]) -> Result<usize, SerializationError> {
+        if buffer.len() < 2 {
+            return Err(SerializationError::BufferTooSmall);
+        }
+
+        let len = u16::from_le_bytes(buffer[..2].try_into().unwrap());
+
+        Ok(len as usize + 2)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use core::str::FromStr;
+
+    use super::*;
+
+    #[test]
+    fn serde_arrayvec() {
+        let mut buffer = [0; 128];
+
+        let val = ArrayVec::<u8, 12>::from_iter([0xAA; 12]);
+        val.serialize_into(&mut buffer).unwrap();
+        let new_val = ArrayVec::<u8, 12>::deserialize_from(&buffer).unwrap();
+
+        assert_eq!((val, 14), new_val);
+    }
+
+    #[test]
+    fn serde_arraystring() {
+        let mut buffer = [0; 128];
+
+        let val = ArrayString::<45>::from_str("Hello world!").unwrap();
+        val.serialize_into(&mut buffer).unwrap();
+        let new_val = ArrayString::<45>::deserialize_from(&buffer).unwrap();
+
+        assert_eq!((val, 14), new_val);
+    }
+}

src/lib.rs

@@ -13,8 +13,10 @@ use core::{
     ops::{Deref, DerefMut, Range},
 };
 use embedded_storage_async::nor_flash::NorFlash;
-use map::MapValueError;
+use map::SerializationError;
 
+#[cfg(feature = "arrayvec")]
+mod arrayvec_impl;
 pub mod cache;
 mod item;
 pub mod map;
@@ -377,8 +379,14 @@ pub enum Error<S> {
     BufferTooBig,
     /// A provided buffer was to small to be used (usize is size needed)
     BufferTooSmall(usize),
-    /// A map value error
-    MapValueError(MapValueError),
+    /// A serialization error (from the key or value)
+    SerializationError(SerializationError),
+}
+
+impl<S> From<SerializationError> for Error<S> {
+    fn from(v: SerializationError) -> Self {
+        Self::SerializationError(v)
+    }
 }
 
 impl<S: PartialEq> PartialEq for Error<S> {
@@ -407,7 +415,7 @@ where
                 f,
                 "A provided buffer was to small to be used. Needed was {needed}"
             ),
-            Error::MapValueError(value) => write!(f, "Map value error: {value}"),
+            Error::SerializationError(value) => write!(f, "Map value error: {value}"),
         }
     }
 }