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#![cfg_attr(not(any(test, feature = "std")), no_std)]
#![forbid(missing_docs, missing_debug_implementations)]
#![cfg_attr(test, deny(warnings))]
#![feature(never_type)]
#[cfg(any(test, feature = "std"))]
extern crate core;
use core::fmt;
extern crate failure;
use failure::Fail;
pub trait Error: Fail + Copy + Eq {
fn describe(self) -> &'static str;
}
impl Error for ! {
fn describe(self) -> &'static str {
self
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct DivByZero;
impl Fail for DivByZero {}
impl Error for DivByZero {
#[inline]
fn describe(self) -> &'static str {
"division by zero"
}
}
impl fmt::Display for DivByZero {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.describe())
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub enum CannotDiv {
ByZero,
WouldOverflow,
}
impl Fail for CannotDiv {
fn cause(&self) -> Option<&Fail> {
match *self {
CannotDiv::ByZero => Some(&DivByZero),
CannotDiv::WouldOverflow => Some(&WouldOverflow),
}
}
}
impl Error for CannotDiv {
#[inline]
fn describe(self) -> &'static str {
match self {
CannotDiv::ByZero => DivByZero.describe(),
CannotDiv::WouldOverflow => WouldOverflow.describe(),
}
}
}
impl From<DivByZero> for CannotDiv {
#[inline]
fn from(_: DivByZero) -> CannotDiv {
CannotDiv::ByZero
}
}
impl From<WouldOverflow> for CannotDiv {
#[inline]
fn from(_: WouldOverflow) -> CannotDiv {
CannotDiv::WouldOverflow
}
}
impl fmt::Display for CannotDiv {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.describe())
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct Overflowed;
impl Fail for Overflowed {}
impl Error for Overflowed {
#[inline]
fn describe(self) -> &'static str {
"operation overflowed"
}
}
impl fmt::Display for Overflowed {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.describe())
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
pub struct WouldOverflow;
impl Fail for WouldOverflow {}
impl Error for WouldOverflow {
fn describe(self) -> &'static str {
"operation was not performed, as it would overflow"
}
}
impl fmt::Display for WouldOverflow {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(self.describe())
}
}