must 0.2.0

assertion library for rust
Documentation 
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use errors::Error;
use std::env::current_dir;
use std::fmt::{self, Display, Formatter};
use std::fs::File;
use std::io::{BufRead, BufReader};

#[derive(Debug,Clone,Copy,PartialEq)]
pub struct Source {
	pub filename: &'static str,
	pub line: u32,
	pub column: u32,
}

pub struct ErrRenderer<'a> {
	pub err: &'a Error,
	pub src: Option<Source>,
	pub msg: Option<String>,
}

impl Display for Error {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
		let renderer = ErrRenderer {
			err: self,
			src: None,
			msg: None,
		};
		Display::fmt(&renderer, f)
	}
}


impl<'a> Display for ErrRenderer<'a> {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
		let &Error { ref got, ref kind } = self.err;

		writeln!(f, "")?;
		writeln!(f, "error[]: assertion failed")?;





		if let Some(Source { filename, line, column }) = self.src {
			writeln!(f, "   --> {}:{}:{}", filename, line, column)?;

			let file_path = current_dir().unwrap().join(filename);

			// skip lines
			if let Ok(buf) = BufReader::new(File::open(&file_path).unwrap())
				.lines()
				.skip(line as usize - 1)
				.next()
				.unwrap() {
				writeln!(f, "   |")?;
				writeln!(f, "{line:<width$}| {}", buf, line = line, width = 3)?;
				writeln!(f, "   | {:<column$}  ^^^^", ' ', column = column as usize)?;
			}
		}


		if let Some(ref msg) = self.msg {
			writeln!(f, "{}", msg)?;
		}
		writeln!(f, "")?;
		writeln!(f, "Got: {:?}", got)?;
		write!(f, "\n{:?} {}\n\n", got, kind)
	}
}