This is an improved form of the previous `error::Unexpected` type, now with more capabilities and generally better naming.main
Brian Picciano
11 months ago
parent
42a033a50b
commit
420f1ff42a
@ -1,3 +1 @@ |
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- expect statements (pretend it's "expected", not "expect") |
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- map_unexpected annotation string |
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- clean up main a lot |
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@ -1,56 +1 @@ |
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use std::error; |
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use std::fmt; |
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use std::fmt::Write; |
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#[derive(Debug, Clone)] |
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/// Unexpected is a String which implements the Error trait. It is intended to be used in
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/// situations where the caller is being given an error they can't really handle, except to pass it
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/// along or log it.
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///
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/// The error is intended to also implement Send + Sync + Clone, such that it is easy to use in
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/// async situations.
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pub struct Unexpected(String); |
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impl fmt::Display for Unexpected { |
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
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write!(f, "Unexpected error occurred: {}", self.0) |
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} |
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} |
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impl error::Error for Unexpected {} |
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impl From<&str> for Unexpected { |
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fn from(s: &str) -> Self { |
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Unexpected(s.to_string()) |
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} |
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} |
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pub trait ToUnexpected { |
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fn to_unexpected(&self) -> Unexpected; |
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} |
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impl<E: error::Error> ToUnexpected for E { |
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fn to_unexpected(&self) -> Unexpected { |
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let mut w = String::new(); |
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write!(w, "{}", self.to_string()).expect("underlying error formatted correctly"); |
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if let Some(src) = self.source() { |
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write!(w, " [{src}]").expect("underyling source formatted correctly"); |
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} |
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Unexpected(w.to_string()) |
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} |
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} |
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pub trait MapUnexpected<T> { |
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fn map_unexpected(self) -> Result<T, Unexpected>; |
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} |
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impl<T, E: ToUnexpected> MapUnexpected<T> for Result<T, E> { |
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fn map_unexpected(self) -> Result<T, Unexpected> { |
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match self { |
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Ok(t) => Ok(t), |
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Err(err) => Err(err.to_unexpected()), |
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} |
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} |
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} |
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pub mod unexpected; |
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@ -0,0 +1,128 @@ |
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use std::fmt::Write; |
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use std::{error, fmt}; |
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#[derive(Debug, Clone)] |
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/// Error is a String which implements the Error trait. It is intended to be used in
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/// situations where the caller is being given an error they can't really handle, except to pass it
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/// along or log it.
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///
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/// The error is intended to also implement Send + Sync + Clone, such that it is easy to use in
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/// async situations.
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pub struct Error(String); |
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impl Error { |
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fn from_displays<D1, D2, D3>(prefix: Option<D1>, body: &D2, source: Option<D3>) -> Error |
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where |
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D1: fmt::Display, |
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D2: fmt::Display + ?Sized, |
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D3: fmt::Display, |
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{ |
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let mut w = String::new(); |
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if let Some(prefix) = prefix { |
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write!(w, "{prefix}").expect("error writing prefix"); |
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} |
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write!(w, "{body}").expect("error formatting body"); |
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if let Some(source) = source { |
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write!(w, " [{source}]").expect("error formatting source"); |
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} |
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Error(w.to_string()) |
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} |
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fn from_err<E, D>(prefix: Option<D>, e: E) -> Error |
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where |
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E: error::Error, |
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D: fmt::Display, |
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{ |
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return Error::from_displays(prefix, &e, e.source()); |
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} |
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pub fn from(s: &str) -> Error { |
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Error::from_displays(None::<String>, s, None::<String>) |
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} |
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} |
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impl fmt::Display for Error { |
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
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write!(f, "Unexpected error occurred: {}", self.0) |
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} |
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} |
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impl error::Error for Error {} |
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pub trait Mappable<T> { |
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/// or_unexpected returns an Err(Error) wrapping self's Err, or the Ok value of self.
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fn or_unexpected(self) -> Result<T, Error>; |
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/// or_unexpected_while is like or_unexpected, but will prefix the error message. The prefix
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/// should be worded as if it started with the word "while", e.g.: `opening file {path}`.
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fn or_unexpected_while<D: fmt::Display>(self, prefix: D) -> Result<T, Error>; |
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/// map_unexpected_while is like or_unexpected_while, but uses a closure to produce the error
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/// prefix.
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fn map_unexpected_while<F, D>(self, f: F) -> Result<T, Error> |
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where |
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F: FnOnce() -> D, |
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D: fmt::Display; |
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} |
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fn map_unexpected_maybe_while<T, E, F, D>( |
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res: Result<T, E>, |
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prefix_fn: Option<F>, |
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) -> Result<T, Error> |
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where |
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E: error::Error, |
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F: FnOnce() -> D, |
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D: std::fmt::Display, |
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{ |
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match res { |
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Ok(res) => Ok(res), |
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Err(err) => Err(Error::from_err(prefix_fn.map(|prefix_fn| prefix_fn()), err)), |
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} |
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} |
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impl<T, E: error::Error> Mappable<T> for Result<T, E> { |
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fn or_unexpected(self) -> Result<T, Error> { |
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let no_fn = None::<Box<dyn FnOnce() -> Box<dyn fmt::Display>>>; // lol, good job rust
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map_unexpected_maybe_while(self, no_fn) |
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} |
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fn or_unexpected_while<D: fmt::Display>(self, prefix: D) -> Result<T, Error> { |
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map_unexpected_maybe_while(self, Some(|| prefix)) |
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} |
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fn map_unexpected_while<F, D>(self, f: F) -> Result<T, Error> |
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where |
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F: FnOnce() -> D, |
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D: fmt::Display, |
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{ |
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map_unexpected_maybe_while(self, Some(f)) |
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} |
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} |
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pub trait Intoable { |
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fn into_unexpected(self) -> Error; |
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/// into_unexpected_while is like to_unexpected, but will prefix the Error error. The
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/// prefix should be worded as if it started with the word "while", e.g.: `opening file
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/// {path}`.
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fn into_unexpected_while<D>(self, prefix: D) -> Error |
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where |
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D: fmt::Display; |
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} |
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impl<E: error::Error> Intoable for E { |
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fn into_unexpected(self) -> Error { |
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Error::from_err(None::<String>, self) |
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} |
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fn into_unexpected_while<D>(self, prefix: D) -> Error |
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where |
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D: fmt::Display, |
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{ |
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Error::from_err(Some(prefix), self) |
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} |
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} |
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@ -0,0 +1,11 @@ |
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use std::{fs, io, path}; |
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pub fn open_file(path: &path::Path) -> io::Result<Option<fs::File>> { |
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match fs::File::open(path) { |
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Ok(file) => Ok(Some(file)), |
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Err(err) => match err.kind() { |
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io::ErrorKind::NotFound => Ok(None), |
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_ => Err(err), |
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}, |
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} |
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} |
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