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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 {
match e {
SubstituteError::FreeParameter { span, .. } => {
Self::new(span.unwrap_or_else(Span::call_site), "unbound parameter")
}
SubstituteError::WrongArgCount { call, expected, span } => {
let msg = if call.args.len() == 1 {
format!("this function takes {} arguments but 1 was supplied", expected)
} else {
format!("this function takes {} arguments but {} were supplied", expected, call.args.len())
};
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 } => {
let start = span.unwrap_or_else(Span::call_site).start();
if let Some(name) = name {
write!(f, "{}:{}: unbound parameter `{}`", start.line, start.column, name)
} else {
write!(f, "{}:{}: unbound parameter '{}", start.line, start.column, param.index)
}
}
Self::WrongArgCount { call, expected, span } => {
let start = span.unwrap_or_else(Span::call_site).start();
if call.args.len() == 1 {
write!(f, "{}:{}: this function takes {} arguments but 1 was supplied", start.line, start.column, expected)
} else {
write!(f, "{}:{}: this function takes {} arguments but {} were supplied", start.line, start.column, expected, call.args.len())
}
}
}
}
}
impl Error for SubstituteError {}
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