flag parsing

src/flags.rs

@@ -18,6 +18,21 @@ pub enum Kind<'a>
     Short(&'a [(char, )], bool),
     /// A single `--`.
     Terminator,
+    /// An exact match with no prefix.
+    Exact(&'a str),
+}
+
+impl Kind<'static>
+{
+    pub fn as_ref<'a>(&'a self) -> Kind<'a>
+    {
+	match &self {
+	    Self::Long(strs, bl) => Kind::Long(strs, *bl),
+	    Self::Short(chrs, bl) => Kind::Short(chrs, *bl),
+	    Self::Terminator => Kind::Terminator,
+	    Self::Exact(stri) => Kind::Exact(&stri[..]),
+	}
+    }
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -33,25 +48,25 @@ pub struct ArgState<T=()>
 {
     user: T,
 
-    flags: Vec<(Kind<'static>, Cow<'static, str>, ValueKind, Box<(dyn FlagCallback<T, Box<dyn Any + 'static>, Box<dyn error::Error + 'static>> + 'static)>, bool, bool)>,
+    flags: Vec<(Kind<'static>, Cow<'static, str>, ValueKind, Box<(dyn FlagCallback<T, Box<dyn Any + 'static>, eyre::Report> + 'static)>, bool, bool)>,
 }
 
 pub trait FlagCallback<U, T,E>: FnMut(&mut StateHandle<'_, U>, usize, &str) -> Result<T, E>{}
 impl<U, F, T, E> FlagCallback<U, T,E> for F
 where F: FnMut(&mut StateHandle<'_, U>, usize, &str) -> Result<T, E>,
       T: Any + 'static,
-      E: 'static{}
+      E: Into<eyre::Report> {}
 
 impl<U> ArgState<U>
 {
     /// Push a handle to the state
-    pub fn push<T: Any + 'static,E: error::Error + 'static, F>(&mut self, kind: Kind<'static>, desc: impl Into<Cow<'static, str>>, value: ValueKind, mut handle: F, single: bool) -> usize
+    pub fn push<T: Any + 'static,E: Into<eyre::Report>, F>(&mut self, kind: Kind<'static>, desc: impl Into<Cow<'static, str>>, value: ValueKind, mut handle: F, single: bool) -> usize
     where F: FlagCallback<U, T,E> + 'static
     {
-	let handle: Box<dyn FlagCallback<U, Box<(dyn Any + 'static)>, Box<(dyn error::Error + 'static)>>> =
+	let handle: Box<dyn FlagCallback<U, Box<(dyn Any + 'static)>, eyre::Report>> =
 	    Box::new(move |state, index, value| handle(state, index, value)
 		     .map(|x| -> Box<(dyn Any + 'static)> {Box::new(x)})
-		     .map_err(|x| -> Box<(dyn error::Error +'static)> {Box::new(x)}));
+		     .map_err(Into::into));
 	self.flags.push((kind, desc.into(), value, handle, single, true));
 	self.flags.len()-1
     }
@@ -208,7 +223,7 @@ impl<U> ArgState<U>
     /// # Note
     /// This mutates the argument state container indefinately, and multiple calls to it will keep the mutated state.
     /// So this might not behave as expected (e.g. callbacks marked `single` that were fired in the first call will not be fired in the second, etc.)
-    pub fn parse<I,T: Into<String>>(&mut self, input: I) -> Result<Vec<Box<dyn Any+'static>>, Error>
+    pub fn parse<I,T: Into<String>>(&mut self, input: I) -> Result<Vec<Box<dyn Any+'static>>, CtxError>
     where I: Iterator<Item=T>
     {
 	let mut output = Vec::with_capacity(self.flags.len());
@@ -245,19 +260,78 @@ impl<U> ArgState<U>
     }
 }
 
+/// Error without context
 #[derive(Debug)]
 pub struct Error
 {
     flag: Kind<'static>,
     arg: (usize, String),
     desc: Option<String>,
-    from: Box<dyn error::Error + 'static>,
+    from: eyre::Report,
+}
+
+/// An argument parsing error with context
+#[repr(transparent)]
+#[derive(Debug)]
+pub struct CtxError(Error);
+
+#[derive(Debug, Clone, Copy)]
+pub struct ErrorContext<'a>
+{
+    pub flag: &'a Kind<'static>,
+    pub arg: &'a String,
+    pub arg_idx: &'a usize,
+    pub desc: Option<&'a String>,
+    pub from: &'a eyre::Report,
+}
+
+impl CtxError
+{
+    /// The inner error
+    #[inline] pub fn inner(&self) -> &Error
+    {
+	&self.0
+    }
+    /// Strips the context and returns the inner error
+    #[inline] fn into_inner(self) -> Error
+    {
+	self.0
+    }
+    /// The context of this error
+    pub fn context(&self) -> ErrorContext<'_>
+    {
+	ErrorContext {
+	    flag: &self.0.flag,
+	    arg: &self.0.arg.1,
+	    arg_idx: &self.0.arg.0,
+	    desc: self.0.desc.as_ref(),
+	    from: &self.0.from
+	}
+    }
+
+    /// Which argument was the error thrown for
+    pub fn what(&self) -> (usize, &str)
+    {
+	(self.0.arg.0, &self.0.arg.1[..])
+    }
+
+    /// Where did the parsing fail?
+    pub fn which(&self) -> Kind<'_>
+    {
+	self.0.flag.as_ref()
+    }
+
+    /// The message reported by the failing callback, if any
+    pub fn message(&self) -> Option<&str>
+    {
+	self.0.desc.as_ref().map(|x| &x[..])
+    }
 }
 
 impl error::Error for Error
 {
     fn source(&self) -> Option<&(dyn error::Error + 'static)> {
-	Some(self.from.as_ref())
+	self.from.source()
     }
 }
 
@@ -265,12 +339,86 @@ impl fmt::Display for Error
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
     {
-	writeln!(f, "Failed to parse args: {}", self.from)?;
-	writeln!(f, "\tArg {} which was {:?} failed on parsing for `{:?}`", self.arg.0, self.arg.1, self.flag)?;
-	if let Some(desc) = &self.desc {
-	    writeln!(f, "\n\tUsage of {:?}: {}", self.flag, desc)
+	writeln!(f, "Failed to parse args")
+    }
+}
+
+impl fmt::Display for CtxError
+{
+    #[inline] fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	self.0.fmt(f)
+    }
+}
+
+
+impl Error
+{
+    /// Consume into an `eyre::Report`.
+    fn into_report(self) -> eyre::Report
+    {
+	let Error {flag, desc, from ,arg: (idx, arg)} = self;
+	let  err = Err::<!, _>(from)
+	//.wrap_err(eyre!("Failed to parse args"))
+	    .with_section(move || format!("{:?}", flag).header("While attempting to parse for"))
+	    .with_note(move || idx.to_string().header("Argument index was"))
+	    .with_note(move || format!("{:?}", arg).header("Argument was"));
+	if let Some(desc) = desc {
+	    err.with_suggestion(move || desc)
 	} else {
-	    Ok(())
-	}
+	    err
+	}.unwrap_err()
+    }
+
+    /// Add context to this error
+    pub fn with_context(self) -> CtxError
+    {
+	CtxError(Self {
+	    flag: self.flag.clone(),
+	    arg: self.arg.clone(),
+	    desc: self.desc.clone(),
+	    from: self.into_report(),
+	})
+    }
+}
+
+impl From<Error> for CtxError
+{
+    fn from(from: Error) -> Self
+    {
+	from.with_context()
+    }
+}
+
+impl From<CtxError> for eyre::Report
+{
+    fn from(from: CtxError) -> Self
+    {
+	from.0.from
+    }
+}
+
+
+#[cfg(test)]
+mod tests
+{
+    use super::*;
+    #[test]
+    fn errors() -> Result<(), eyre::Report>
+    {
+	//color_eyre::install()?;
+	
+	let err= Error {
+	    flag: Kind::Long(&["test"], false),
+	    arg: (0, "owo".to_owned()),
+	    desc: Some("expected between 1-10".to_string()),
+	    from: eyre!("Invalid number").wrap_err("Parsing failure"),
+	};
+	println!("No ctx: `{} {:?}`\n", err, err);
+	let err = err.with_context();
+	println!("With ctx: `{} {:?}`\n", err, err);
+
+	//return Err(err)?;
+	Ok(())
     }
 }