58 lines
2.0 KiB
Rust
58 lines
2.0 KiB
Rust
//! Converting custom error codes to enums.
|
|
|
|
use num_traits::FromPrimitive;
|
|
|
|
/// Allows custom errors to be decoded back to their original enum.
|
|
///
|
|
/// Some Solana error enums, like [`ProgramError`], include a `Custom` variant,
|
|
/// like [`ProgramError::Custom`], that contains a `u32` error code. This code
|
|
/// may represent any error that is not covered by the error enum's named
|
|
/// variants. It is common for programs to convert their own error enums to an
|
|
/// error code and store it in the `Custom` variant, possibly with the help of
|
|
/// the [`ToPrimitive`] trait.
|
|
///
|
|
/// This trait builds on the [`FromPrimitive`] trait to help convert those error
|
|
/// codes to the original error enum they represent.
|
|
///
|
|
/// As this allows freely converting `u32` to any type that implements
|
|
/// `FromPrimitive`, it is only used correctly when the caller is certain of the
|
|
/// original error type.
|
|
///
|
|
/// [`ProgramError`]: crate::program_error::ProgramError
|
|
/// [`ProgramError::Custom`]: crate::program_error::ProgramError::Custom
|
|
/// [`ToPrimitive`]: num_traits::ToPrimitive
|
|
pub trait DecodeError<E> {
|
|
fn decode_custom_error_to_enum(custom: u32) -> Option<E>
|
|
where
|
|
E: FromPrimitive,
|
|
{
|
|
E::from_u32(custom)
|
|
}
|
|
fn type_of() -> &'static str;
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use {super::*, num_derive::FromPrimitive};
|
|
|
|
#[test]
|
|
fn test_decode_custom_error_to_enum() {
|
|
#[derive(Debug, FromPrimitive, PartialEq, Eq)]
|
|
enum TestEnum {
|
|
A,
|
|
B,
|
|
C,
|
|
}
|
|
impl<T> DecodeError<T> for TestEnum {
|
|
fn type_of() -> &'static str {
|
|
"TestEnum"
|
|
}
|
|
}
|
|
assert_eq!(TestEnum::decode_custom_error_to_enum(0), Some(TestEnum::A));
|
|
assert_eq!(TestEnum::decode_custom_error_to_enum(1), Some(TestEnum::B));
|
|
assert_eq!(TestEnum::decode_custom_error_to_enum(2), Some(TestEnum::C));
|
|
let option: Option<TestEnum> = TestEnum::decode_custom_error_to_enum(3);
|
|
assert_eq!(option, None);
|
|
}
|
|
}
|