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|
use std::{
error::Error,
fmt::{self, Display},
};
use proc_macro2::Span;
use crate::chomp::Name;
use super::{Call, Parameter};
#[derive(Debug)]
pub enum SubstituteError {
FreeParameter {
param: Parameter,
span: Option<Span>,
name: Option<Name>,
},
WrongArgCount {
call: Call,
expected: usize,
span: Option<Span>,
},
}
impl From<SubstituteError> for syn::Error {
fn from(e: SubstituteError) -> Self {
let msg = e.to_string();
let span = match e {
SubstituteError::FreeParameter { span, .. } => span,
SubstituteError::WrongArgCount { span, .. } => span,
};
Self::new(span.unwrap_or_else(Span::call_site), msg)
}
}
impl Display for SubstituteError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::FreeParameter { param, span, name } => {
if let Some(name) = name {
write!(f, "unbound parameter: `{}`", name)
} else {
write!(f, "unbound parameter: '{}", param.index)
}
}
Self::WrongArgCount {
call,
expected,
span,
} => {
if call.args.len() == 1 {
write!(
f,
"this function takes {} arguments but 1 was supplied",
expected
)
} else {
write!(
f,
"this function takes {} arguments but {} were supplied",
expected,
call.args.len()
)
}
}
}
}
}
impl Error for SubstituteError {}
|
