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|
use super::{Expression, Lambda, NamedExpression};
use proc_macro2::Span;
use std::{
error::Error,
fmt::{self, Display},
};
#[derive(Debug)]
pub enum ReductionError {
CallNotAFunction {
on: Expression,
span: Span,
},
WrongArgCount {
lambda: Lambda,
args: Vec<NamedExpression>,
span: Span,
},
}
impl From<ReductionError> for syn::Error {
fn from(e: ReductionError) -> Self {
let msg = e.to_string();
let span = match e {
ReductionError::CallNotAFunction { span, .. }
| ReductionError::WrongArgCount { span, .. } => span,
};
Self::new(span, msg)
}
}
impl Display for ReductionError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::CallNotAFunction { .. } => {
write!(f, "call expected a function")
}
Self::WrongArgCount { lambda, args, .. } => match (lambda.args.len(), args.len()) {
(1, n) => write!(f, "this function takes 1 argument but {} were supplied", n),
(m, 1) => write!(f, "this function takes {} arguments but 1 was supplied", m),
(m, n) => write!(
f,
"this function takes {} arguments but {} were supplied",
m, n
),
},
}
}
}
impl Error for ReductionError {}
|
