From 9538f4bc4655bfc81b9580b5a1592382a48b6fcd Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Thu, 27 Aug 2020 20:17:31 +0100
Subject: [PATCH] take two

---
 src/error.rs | 274 ++++++++++++++-------------------------------------
 src/main.rs  |  22 +----
 2 files changed, 77 insertions(+), 219 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 979cddf..1612ab9 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -4,257 +4,133 @@ use std::{
     fmt,
 };
 
-//TODO:
-// this was a complete failure, look at eyre instead or something
-
-/// Context for an error
-#[derive(Debug, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
-pub struct Context
-{
-    line: Option<u32>,
-    column: Option<u32>,
-    file: &'static str,
-}
-
-impl Context
-{
-    pub fn new(line: Option<u32>, column: Option<u32>, file: &'static str) -> Self
-    {
-	Self {
-	    line,column,file
-	}
-    }
-}
-
-impl fmt::Display for Context
+pub trait Context
 {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
-    {
-	write!(f, "{} ", self.file)?;
-	if let Some(line) = self.line {
-	    write!(f, "{}:", line)?;
-	} else {
-	    write!(f, "?:")?;
-	}
-	if let Some(column) = self.column {
-	    write!(f, "{}", column)?;
-	} else {
-	    write!(f, "?")?;
-	}
-	Ok(())
-    }
+    fn line(&self) -> Option<u32>;
+    fn column(&self) -> Option<u32>;
+    fn file(&self) -> Option<&str>;
 }
 
-/// A wrapper over an error with a nicer error message
-///
-/// Like doushio's `Muggle`.
-pub struct Wrap<E,D>(E, D);
-
-pub trait WrappedError
+pub trait Reporter
 {
-    fn long_msg(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
-    fn short_msg(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
-}
+    type Error: error::Error + ?Sized;
 
-impl<E,D> WrappedError for Wrap<E,D>
-where D: fmt::Display,
-      E: error::Error + 'static
-{
-    fn long_msg(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    #[inline] fn context(&self) -> Option<&dyn Context>
     {
-	write!(f, "{}", self.long_message())
+	None
     }
-    fn short_msg(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    fn source(&self) -> &Self::Error;
+    
+    fn short_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result;
+    #[inline] fn long_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	write!(f, "{}", self)
+	self.short_message(f)
     }
 }
 
-impl<E,D> Wrap<E,D>
-where D: fmt::Display,
-      E: error::Error + 'static
-{
-    /// Get all sources of the error
-    pub fn all_sources(&self) -> Vec<&(dyn error::Error + 'static)>
-    {
-	use std::error::Error;
-	std::iter::successors(self.source(), |x| x.source()).collect()
-    }
-
-    /// Into the inner error
-    pub fn into_inner(self) -> E
-    {
-	self.0
-    }
+pub struct ShortMessage<R>(R)
+where R: Reporter;
 
-    /// Get the full and long error message
-    pub fn long_message(&self) -> impl fmt::Display + '_
+impl<R> fmt::Display for ShortMessage<R>
+where R: Reporter
+{
+    #[inline] fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	struct LongOutput<'a, E,D>(&'a Wrap<E,D>);
-	impl<'a, E,D> fmt::Display for LongOutput<'a, E,D>
-	where Wrap<E,D>: error::Error
-	{
-	    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
-	    {
-		writeln!(f, "{}", self.0)?;
-		use std::error::Error;
-		for (i, spec) in (1..).zip(std::iter::successors(self.0.source(), |x| x.source()))
-		{
-		    writeln!(f, " [{}] -> {}", i, spec)?;
-		}
-
-		Ok(())
-	    }
-	}
-
-	LongOutput(&self)
+	self.0.short_message(f)
     }
 }
 
-pub trait WrapExt: Sized
-{
-    /// Wrap this error in another
-    fn wrap<T>(self, msg: T) -> Wrap<Self, T>
-    where T: fmt::Display;
-}
+pub struct LongMessage<R>(R)
+where R: Reporter;
 
-impl<E> WrapExt for E where E: error::Error
+impl<R> fmt::Display for LongMessage<R>
+where R: Reporter
 {
-    fn wrap<T>(self, msg: T) -> Wrap<Self, T>
-    where T: fmt::Display
+    #[inline] fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	Wrap(self, msg)
+	self.0.long_message(f)
     }
 }
 
-pub trait WrapErrExt<T,E>: Sized
+impl<E> Reporter for Box<E>
+where E: error::Error + ?Sized
 {
-    /// Wrap the error from this result with a nicer error message
-    fn wrap_err<U>(self, msg: U) -> Result<T,Wrap<E, U>>
-    where U: fmt::Display;
-}
+    type Error = E;
 
-impl<T,E> WrapErrExt<T,E> for Result<T,E>
-{
-    fn wrap_err<U>(self, msg: U) -> Result<T,Wrap<E, U>>
-    where U: fmt::Display
+    fn source(&self) -> &Self::Error
     {
-	self.map_err(|e| Wrap(e, msg))
+	&self
     }
-}
-
-
-impl<E,D> fmt::Debug for Wrap<E,D>
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    
+    fn short_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	write!(f, "{}", std::any::type_name::<Self>())
+	write!(f, "{}", &self)
     }
 }
 
-impl<E,D> fmt::Display for Wrap<E,D>
-where D: fmt::Display
+impl<'a, R> Reporter for &'a R
+where R: Reporter
 {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    type Error = <R as Reporter>::Error;
+    
+    #[inline] fn context(&self) -> Option<&dyn Context>
     {
-	write!(f, "{}", self.1)
+	(*self).context()
     }
-}
-
-impl<E,D> error::Error for Wrap<E,D>
-where E: error::Error + 'static,
-      D: fmt::Display
-{
-    fn source(&self) -> Option<&(dyn error::Error + 'static)>
+    fn source(&self) -> &Self::Error
     {
-	Some(&self.0)
+	(*self).source()
     }
-}
-
-/// An error with a context
-#[derive(Debug)]
-pub struct ContextError<E>(pub E, pub Context)
-where E: fmt::Debug;
-
-impl<E> WrappedError for ContextError<E>
-where E: fmt::Debug + fmt::Display
-{
-    fn long_msg(&self,f: &mut fmt::Formatter<'_>) -> fmt::Result
+    
+    fn short_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	write!(f, "{}", self)
+	(*self).short_message(f)
     }
-    fn short_msg(&self,f: &mut fmt::Formatter<'_>) -> fmt::Result
+    #[inline] fn long_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	write!(f, "{}", self.0)
+	(*self).long_message(f)
     }
 }
 
-impl<E> fmt::Display for ContextError<E>
-where E: fmt::Display + fmt::Debug
+pub struct Wrap<E,M>(E, M);
+
+impl<E,M> Reporter for Wrap<E,M>
+where E: Reporter,
+M: fmt::Display
 {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    type Error = E::Error;
+
+    #[inline] fn context(&self) -> Option<&dyn Context>
     {
-	write!(f, "{}: {}", self.1, self.0)
+	self.0.context()
     }
-}
-
-impl<E> error::Error for ContextError<E>
-where E: fmt::Display + fmt::Debug{}
-
-#[macro_export]
-    macro_rules! context {
-    () => ($crate::error::Context::new(Some(line!()), Some(column!()), file!()));
-}
-
-/// Construct a new error with context
-#[macro_export] macro_rules! error {
-    ($err:expr) => ($crate::error::ContextError($err, $crate::context!()));
-    ($fmt:literal $($tt:tt)*) => ($crate::error!(format!($fmt $($tt)*)));
-}
-
-pub struct ErrorStack(Box<dyn WrappedError>);
-
-impl<T: WrappedError + 'static> From<T> for ErrorStack
-{
-    fn from(from: T) -> Self
+    fn source(&self) -> &Self::Error
     {
-	Self(Box::new(from))
+	self.0.source()
     }
-}
-
-impl fmt::Display for ErrorStack
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    
+    fn short_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	self.0.long_msg(f)
+	write!(f, "{}", self.1)
     }
-}
-
-impl fmt::Debug for ErrorStack
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    #[inline] fn long_message(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	write!(f,"<opaque stack>")
+	write!(f, "{}", self.1)?;
+	self.0.long_message(f) //ehh, also failed
     }
 }
 
-impl error::Error for ErrorStack{}
-
-impl ErrorStack
-{
-    /// Get the short message from this stack
-    pub fn short_message(&self) -> impl fmt::Display + '_
+#[cfg(test)]
+mod tests {
+    use super::*;
+    fn test() -> Box<dyn error::Error>
     {
-	pub struct ShortMessage<'a>(&'a ErrorStack);
-
-	impl<'a> fmt::Display for ShortMessage<'a>
-	{
-	    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
-	    {
-		self.0.0.short_msg(f)
-	    }
-	}
-
-	ShortMessage(self)
+	Box::new(std::io::Error::new(std::io::ErrorKind::UnexpectedEof, "uhhhhh"))
+    }
+    #[test]
+    fn atest()
+    {
+	let bx = test();
+	assert_eq!(format!("{}", LongMessage(&bx)), format!("{}", bx));
     }
 }
diff --git a/src/main.rs b/src/main.rs
index 64def7b..3b5e444 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,10 +7,6 @@ mod ext;
 use ext::*;
 
 mod error;
-use error::{
-    WrapErrExt as _,
-    WrapExt as _,
-};
 mod consts;
 mod util;
 mod hash;
@@ -18,21 +14,8 @@ mod metadata;
 mod resolve;
 mod database;
 
-fn inner() -> Result<(), error::ErrorStack>
+async fn begin() -> Result<i32, Box<dyn std::error::Error>>
 {
-    Err(error!("constructing an error"))?;
-    Ok(())
-}
-
-fn outer() -> Result<(), error::ErrorStack>
-{
-    inner().wrap_err("propagating an error")?;
-    Ok(())
-}
-
-async fn begin() -> Result<i32, error::ErrorStack>
-{
-    outer().wrap_err("outer failed").wrap_err("outer failed twice!")?;
     Ok(0)
 }
 
@@ -41,8 +24,7 @@ async fn main() {
     std::process::exit(match begin().await {
 	Ok(0) => return,
 	Err(err) => {
-	    eprintln!("\nexited with error: {}", err.short_message());
-	    println!("\n{}", err);
+	    eprintln!("\nexited with error: {}", err);
 	    1
 	},
 	Ok(v) => v