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i2c: enforce all traits have the same Error type. #336

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Jan 12, 2022
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i2c: enforce all traits have the same Error type. #336

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3 changes: 3 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
### Fixed
- Fixed blanket impl of `DelayUs` not covering the `delay_ms` method.

### Changed
- `i2c`: traits now enforce all impls on the same struct have the same `Error` type.

## [v1.0.0-alpha.6] - 2021-11-19

*** This is (also) an alpha release with breaking changes (sorry) ***
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70 changes: 22 additions & 48 deletions src/i2c.rs
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Expand Up @@ -22,14 +22,13 @@
//! Here is an example of an embedded-hal implementation of the `Write` trait
//! for both modes:
//! ```
//! # use embedded_hal::i2c::{ErrorKind, SevenBitAddress, TenBitAddress, blocking::Write};
//! # use embedded_hal::i2c::{ErrorKind, ErrorType, SevenBitAddress, TenBitAddress, blocking::Write};
//! /// I2C0 hardware peripheral which supports both 7-bit and 10-bit addressing.
//! pub struct I2c0;
//!
//! # impl ErrorType for I2c0 { type Error = ErrorKind; }
//! impl Write<SevenBitAddress> for I2c0
//! {
//! # type Error = ErrorKind;
//! #
//! fn write(&mut self, addr: u8, output: &[u8]) -> Result<(), Self::Error> {
//! // ...
//! # Ok(())
Expand All @@ -38,8 +37,6 @@
//!
//! impl Write<TenBitAddress> for I2c0
//! {
//! # type Error = ErrorKind;
//! #
//! fn write(&mut self, addr: u16, output: &[u8]) -> Result<(), Self::Error> {
//! // ...
//! # Ok(())
Expand Down Expand Up @@ -184,6 +181,18 @@ impl core::fmt::Display for NoAcknowledgeSource {
}
}

/// I2C error type trait
///
/// This just defines the error type, to be used by the other traits.
pub trait ErrorType {
/// Error type
type Error: Error;
}

impl<T: ErrorType> ErrorType for &mut T {
type Error = T::Error;
}

/// Address mode (7-bit / 10-bit)
///
/// Note: This trait is sealed and should not be implemented outside of this crate.
Expand All @@ -202,13 +211,10 @@ impl AddressMode for TenBitAddress {}
/// Blocking I2C traits
pub mod blocking {

use super::{AddressMode, Error, SevenBitAddress};
use super::{AddressMode, ErrorType, SevenBitAddress};

/// Blocking read
pub trait Read<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait Read<A: AddressMode = SevenBitAddress>: ErrorType {
/// Reads enough bytes from slave with `address` to fill `buffer`
///
/// # I2C Events (contract)
Expand All @@ -231,18 +237,13 @@ pub mod blocking {
}

impl<A: AddressMode, T: Read<A>> Read<A> for &mut T {
type Error = T::Error;

fn read(&mut self, address: A, buffer: &mut [u8]) -> Result<(), Self::Error> {
T::read(self, address, buffer)
}
}

/// Blocking write
pub trait Write<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait Write<A: AddressMode = SevenBitAddress>: ErrorType {
/// Writes bytes to slave with address `address`
///
/// # I2C Events (contract)
Expand All @@ -263,18 +264,13 @@ pub mod blocking {
}

impl<A: AddressMode, T: Write<A>> Write<A> for &mut T {
type Error = T::Error;

fn write(&mut self, address: A, bytes: &[u8]) -> Result<(), Self::Error> {
T::write(self, address, bytes)
}
}

/// Blocking write (iterator version)
pub trait WriteIter<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait WriteIter<A: AddressMode = SevenBitAddress>: ErrorType {
/// Writes bytes to slave with address `address`
///
/// # I2C Events (contract)
Expand All @@ -286,8 +282,6 @@ pub mod blocking {
}

impl<A: AddressMode, T: WriteIter<A>> WriteIter<A> for &mut T {
type Error = T::Error;

fn write_iter<B>(&mut self, address: A, bytes: B) -> Result<(), Self::Error>
where
B: IntoIterator<Item = u8>,
Expand All @@ -297,10 +291,7 @@ pub mod blocking {
}

/// Blocking write + read
pub trait WriteRead<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait WriteRead<A: AddressMode = SevenBitAddress>: ErrorType {
/// Writes bytes to slave with address `address` and then reads enough bytes to fill `buffer` *in a
/// single transaction*
///
Expand Down Expand Up @@ -332,8 +323,6 @@ pub mod blocking {
}

impl<A: AddressMode, T: WriteRead<A>> WriteRead<A> for &mut T {
type Error = T::Error;

fn write_read(
&mut self,
address: A,
Expand All @@ -345,10 +334,7 @@ pub mod blocking {
}

/// Blocking write (iterator version) + read
pub trait WriteIterRead<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait WriteIterRead<A: AddressMode = SevenBitAddress>: ErrorType {
/// Writes bytes to slave with address `address` and then reads enough bytes to fill `buffer` *in a
/// single transaction*
///
Expand All @@ -366,8 +352,6 @@ pub mod blocking {
}

impl<A: AddressMode, T: WriteIterRead<A>> WriteIterRead<A> for &mut T {
type Error = T::Error;

fn write_iter_read<B>(
&mut self,
address: A,
Expand Down Expand Up @@ -395,10 +379,7 @@ pub mod blocking {
/// Transactional I2C interface.
///
/// This allows combining operations within an I2C transaction.
pub trait Transactional<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait Transactional<A: AddressMode = SevenBitAddress>: ErrorType {
/// Execute the provided operations on the I2C bus.
///
/// Transaction contract:
Expand All @@ -420,8 +401,6 @@ pub mod blocking {
}

impl<A: AddressMode, T: Transactional<A>> Transactional<A> for &mut T {
type Error = T::Error;

fn exec<'a>(
&mut self,
address: A,
Expand All @@ -434,10 +413,7 @@ pub mod blocking {
/// Transactional I2C interface (iterator version).
///
/// This allows combining operation within an I2C transaction.
pub trait TransactionalIter<A: AddressMode = SevenBitAddress> {
/// Error type
type Error: Error;

pub trait TransactionalIter<A: AddressMode = SevenBitAddress>: ErrorType {
/// Execute the provided operations on the I2C bus (iterator version).
///
/// Transaction contract:
Expand All @@ -457,8 +433,6 @@ pub mod blocking {
}

impl<A: AddressMode, T: TransactionalIter<A>> TransactionalIter<A> for &mut T {
type Error = T::Error;

fn exec_iter<'a, O>(&mut self, address: A, operations: O) -> Result<(), Self::Error>
where
O: IntoIterator<Item = Operation<'a>>,
Expand Down