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// Copyright 2017 Serde Developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::cell::RefCell;
use std::fmt::Display;
use std::thread;
/// 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<String>>>,
}
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.
pub fn error<T: Display>(&self, msg: T) {
self.errors
.borrow_mut()
.as_mut()
.unwrap()
.push(msg.to_string());
}
/// Consume this object, producing a formatted error string if there are errors.
pub fn check(self) -> Result<(), String> {
let mut errors = self.errors.borrow_mut().take().unwrap();
match errors.len() {
0 => Ok(()),
1 => Err(errors.pop().unwrap()),
n => {
let mut msg = format!("{} errors:", n);
for err in errors {
msg.push_str("\n\t# ");
msg.push_str(&err);
}
Err(msg)
}
}
}
}
impl Drop for Ctxt {
fn drop(&mut self) {
if !thread::panicking() && self.errors.borrow().is_some() {
panic!("forgot to check for errors");
}
}
}