68 lines
2 KiB
Rust
68 lines
2 KiB
Rust
use quote::ToTokens;
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use std::cell::RefCell;
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use std::fmt::Display;
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use std::thread;
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/// A type to collect errors together and format them.
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///
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/// Dropping this object will cause a panic. It must be consumed using `check`.
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///
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/// References can be shared since this type uses run-time exclusive mut checking.
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#[derive(Default)]
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pub struct Ctxt {
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// The contents will be set to `None` during checking. This is so that checking can be
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// enforced.
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errors: RefCell<Option<Vec<syn::Error>>>,
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}
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impl Ctxt {
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/// Create a new context object.
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///
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/// This object contains no errors, but will still trigger a panic if it is not `check`ed.
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pub fn new() -> Self {
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Ctxt {
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errors: RefCell::new(Some(Vec::new())),
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}
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}
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/// Add an error to the context object with a tokenenizable object.
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///
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/// The object is used for spanning in error messages.
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pub fn error_spanned_by<A: ToTokens, T: Display>(&self, obj: A, msg: T) {
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self.errors
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.borrow_mut()
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.as_mut()
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.unwrap()
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// Curb monomorphization from generating too many identical methods.
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.push(syn::Error::new_spanned(obj.into_token_stream(), msg));
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}
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/// Add one of Syn's parse errors.
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pub fn syn_error(&self, err: syn::Error) {
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self.errors.borrow_mut().as_mut().unwrap().push(err);
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}
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/// Consume this object, producing a formatted error string if there are errors.
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pub fn check(self) -> syn::Result<()> {
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let mut errors = self.errors.borrow_mut().take().unwrap().into_iter();
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let mut combined = match errors.next() {
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Some(first) => first,
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None => return Ok(()),
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};
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for rest in errors {
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combined.combine(rest);
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}
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Err(combined)
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}
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}
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impl Drop for Ctxt {
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fn drop(&mut self) {
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if !thread::panicking() && self.errors.borrow().is_some() {
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panic!("forgot to check for errors");
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}
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}
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}
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