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/*! [](https://crates.io/crates/embedded-error-chain) [](https://docs.rs/embedded-error-chain/) Easy error handling for embedded devices (`no_alloc` and `no_std`). A rust library implementing easy error handling for embedded devices. An [`Error`] value is only a single [`u32`] in size and supports up to 4 chained error codes. Each error code can have a value from `0` to `15` (4 bits). All error codes come from an enum that implements the [`ErrorCategory`] trait (a derive macro exists). This trait is also used to implement debug printing and equality for each error code. This library was inspired by libraries such as [error-chain](https://crates.io/crates/error-chain) and [anyhow](https://crates.io/crates/anyhow), though its goal is to work in `no_std` and `no_alloc` environments with very little memory overhead. ## Example ```rust use embedded_error_chain::prelude::*; #[derive(Clone, Copy, ErrorCategory)] #[repr(u8)] enum SpiError { BusError, // ... } static LAST_GYRO_ACC_READOUT: usize = 200; #[derive(Clone, Copy, ErrorCategory)] #[error_category(links(SpiError))] #[repr(u8)] enum GyroAccError { InitFailed, #[error("{variant} (readout={})", LAST_GYRO_ACC_READOUT)] ReadoutFailed, /// Value must be in range [0, 256) #[error("{variant}: {summary}")] InvalidValue, } #[derive(Clone, Copy, ErrorCategory)] #[error_category(links(GyroAccError))] #[repr(u8)] enum CalibrationError { Inner, } fn main() { if let Err(err) = calibrate() { // log the error println!("{:?}", err); // ... } let readout = match gyro_acc_readout() { Ok(val) => val, Err(err) => { if let Some(spi_error) = err.code_of_category::<SpiError>() { // try to fix it 0 } else { panic!("unfixable spi error"); } } }; } fn spi_init() -> Result<(), SpiError> { Err(SpiError::BusError) } fn gyro_acc_init() -> Result<(), Error<GyroAccError>> { spi_init().chain_err(GyroAccError::InitFailed)?; Ok(()) } fn gyro_acc_readout() -> Result<u32, Error<GyroAccError>> { Err(SpiError::BusError.chain(GyroAccError::InvalidValue)) } fn calibrate() -> Result<(), Error<CalibrationError>> { gyro_acc_init().chain_err(CalibrationError::Inner)?; Ok(()) } ``` */ #![no_std] #![cfg_attr(feature = "nightly", feature(const_panic, const_fn))] #[cfg(feature = "std")] extern crate std; mod error; mod error_category; mod error_data; #[doc(hidden)] pub mod utils; pub use error::{ChainError, Error, ErrorIter, ResultChainError}; pub use error_category::{ format_chained, ErrorCategory, ErrorCategoryHandle, ErrorCodeFormatter, ErrorCodeFormatterVal, }; pub use error_data::{ErrorData, ERROR_CHAIN_LEN}; /// Everything for easy error handling. pub mod prelude { #[doc(no_inline)] pub use crate::{ChainError, Error, ErrorCategory, ErrorCategoryHandle, ResultChainError}; } /// Marker types. pub mod marker { /// A tag type to disambiguate between trait implementations. pub struct L0; /// A tag type to disambiguate between trait implementations. pub struct L1; /// A tag type to disambiguate between trait implementations. pub struct L2; /// A tag type to disambiguate between trait implementations. pub struct L3; /// A tag type to disambiguate between trait implementations. pub struct L4; /// A tag type to disambiguate between trait implementations. pub struct L5; /// A tag type to disambiguate between `ChainError` trait implementations for /// `Error<T>` and just for `T`. #[allow(non_camel_case_types)] pub struct Error_t; /// A tag type to disambiguate between `ChainError` trait implementations for /// `Error<T>` and just for `T`. #[allow(non_camel_case_types)] pub struct Concrete_t; pub use super::error_category::Unused; } /// An error code. /// /// Must only be 4 bits wide. pub type ErrorCode = u8; /// Derive [`ErrorCategory`](ErrorCategory) for an enum. /// /// This will also try to derive the trait dependencies of /// [`ErrorCategory`](ErrorCategory) with the exception of /// [`Copy`](core::marker::Copy): /// - [`core::fmt::Debug`](core::fmt::Debug) /// - [`Into`](core::convert::Into)`<`[`ErrorCode`](ErrorCode)`>` /// - [`From`](core::convert::From)`<`[`ErrorCode`](ErrorCode)`>` /// /// The traits `Into<ErrorCode>` and `From<ErrorCode>` are only derived if the enum is /// `repr(u8)` (see /// [`Data Layout` in the /// nomicon](https://doc.rust-lang.org/nomicon/other-reprs.html#repru-repri)) or does *not* /// contain any variants. /// /// ## Usage /// /// ```rust /// use embedded_error_chain::prelude::*; /// /// #[derive(Clone, Copy, ErrorCategory)] /// #[repr(u8)] /// enum OtherError { /// ExtremeFailure, /// } /// /// static SOME_GLOBAL_VARIABLE: usize = 200; /// /// #[derive(Clone, Copy, ErrorCategory)] /// #[error_category(name = "optional name", links(OtherError))] /// #[repr(u8)] /// enum TestError { /// #[error("format string {summary}, {details}, {variant}, {category}")] /// Foo = 0, /// /// #[error("custom {}, {:?}", "some_expr", SOME_GLOBAL_VARIABLE)] /// Other, /// /// /// Summary /// /// /// /// Detailed description. /// /// The summary and detailed description are available as placeholders in /// /// the `#[error(...)]` attribute. If no such attribute is put on the variant /// /// or the `...` part is empty, then the summary will be used. If the summary /// /// does not exist (no doc comments on the variant), then the variant name is /// /// used for debug printing. /// Bar, /// } /// /// #[derive(Clone, Copy, ErrorCategory)] /// #[error_category(links(OtherError, TestError))] /// #[repr(u8)] /// enum SeperateError { /// SomethingHappened, /// } /// /// #[derive(Clone, Copy, ErrorCategory)] /// enum YetEmptyError {} /// ``` pub use macros::ErrorCategory;