73 lines
2.2 KiB
Rust
73 lines
2.2 KiB
Rust
|
// nifty utility borrowed from serde :)
|
||
|
|
// https://github.com/serde-rs/serde/blob/master/serde_derive/src/internals/ctxt.rs
|
||
|
|
|
||
|
|
use proc_macro2::TokenStream;
|
||
|
|
use quote::{quote, ToTokens};
|
||
|
|
use std::cell::RefCell;
|
||
|
|
use std::fmt::Display;
|
||
|
|
use std::thread;
|
||
|
|
use syn;
|
||
|
|
|
||
|
|
/// A type to collect errors together and format them.
|
||
|
|
///
|
||
|
|
/// Dropping this object will cause a panic. It must be consumed using `check`.
|
||
|
|
///
|
||
|
|
/// References can be shared since this type uses run-time exclusive mut checking.
|
||
|
|
#[derive(Default)]
|
||
|
|
pub struct Ctxt {
|
||
|
|
// The contents will be set to `None` during checking. This is so that checking can be
|
||
|
|
// enforced.
|
||
|
|
errors: RefCell<Option<Vec<syn::Error>>>,
|
||
|
|
}
|
||
|
|
|
||
|
|
impl Ctxt {
|
||
|
|
/// Create a new context object.
|
||
|
|
///
|
||
|
|
/// This object contains no errors, but will still trigger a panic if it is not `check`ed.
|
||
|
|
pub fn new() -> Self {
|
||
|
|
Ctxt {
|
||
|
|
errors: RefCell::new(Some(Vec::new())),
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Add an error to the context object with a tokenenizable object.
|
||
|
|
///
|
||
|
|
/// The object is used for spanning in error messages.
|
||
|
|
pub fn error_spanned_by<A: ToTokens, T: Display>(&self, obj: A, msg: T) {
|
||
|
|
self.errors
|
||
|
|
.borrow_mut()
|
||
|
|
.as_mut()
|
||
|
|
.unwrap()
|
||
|
|
// Curb monomorphization from generating too many identical methods.
|
||
|
|
.push(syn::Error::new_spanned(obj.into_token_stream(), msg));
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Add one of Syn's parse errors.
|
||
|
|
#[allow(unused)]
|
||
|
|
pub fn syn_error(&self, err: syn::Error) {
|
||
|
|
self.errors.borrow_mut().as_mut().unwrap().push(err);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Consume this object, producing a formatted error string if there are errors.
|
||
|
|
pub fn check(self) -> Result<(), TokenStream> {
|
||
|
|
let errors = self.errors.borrow_mut().take().unwrap();
|
||
|
|
match errors.len() {
|
||
|
|
0 => Ok(()),
|
||
|
|
_ => Err(to_compile_errors(errors)),
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
fn to_compile_errors(errors: Vec<syn::Error>) -> proc_macro2::TokenStream {
|
||
|
|
let compile_errors = errors.iter().map(syn::Error::to_compile_error);
|
||
|
|
quote!(#(#compile_errors)*)
|
||
|
|
}
|
||
|
|
|
||
|
|
impl Drop for Ctxt {
|
||
|
|
fn drop(&mut self) {
|
||
|
|
if !thread::panicking() && self.errors.borrow().is_some() {
|
||
|
|
panic!("forgot to check for errors");
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|