mailbox 0.2.0

MBOX reader.
Documentation 
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//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//                    Version 2, December 2004
//
// Copyleft (ↄ) meh. <meh@schizofreni.co> | http://meh.schizofreni.co
//
// Everyone is permitted to copy and distribute verbatim or modified
// copies of this license document, and changing it is allowed as long
// as the name is changed.
//
//            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
//   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
//
//  0. You just DO WHAT THE FUCK YOU WANT TO.

use std::ops::Range;
use std::io;
use nom::IResult;

/// The beginning of a new email.
#[derive(Eq, PartialEq, Clone, Debug)]
pub struct Begin {
	inner: String,

	address:   Range<usize>,
	timestamp: Range<usize>,
}

impl Begin {
	#[inline]
	pub(crate) fn ranges<T: AsRef<[u8]>>(string: T) -> io::Result<(Range<usize>, Range<usize>)> {
		let string = string.as_ref();

		if let IResult::Done(_, (address, timestamp)) = parser::parse(string) {
			if timestamp.len() == 24 {
				let a = address.as_ptr() as usize - string.as_ptr() as usize;
				let t = timestamp.as_ptr() as usize - string.as_ptr() as usize;

				return Ok((
					Range { start: a, end: a + address.len() },
					Range { start: t, end: t + timestamp.len() },
				));
			}
		}

		Err(io::Error::new(io::ErrorKind::InvalidInput, "invalid beginning"))
	}

	/// Create a new `Begin` from the given `String`.
	#[inline]
	pub fn new<T: Into<Vec<u8>>>(string: T) -> io::Result<Self> {
		let string               = string.into();
		let (address, timestamp) = try!(Begin::ranges(&string));

		Ok(Begin {
			// The parser verifies the content is US-ASCII, so it's safe.
			inner: unsafe { String::from_utf8_unchecked(string) },

			address:   address,
			timestamp: timestamp,
		})
	}

	/// The origin address, by RFC this can be any address ever used in any
	/// system at any time.
	#[inline]
	pub fn address(&self) -> &str {
		&self.inner[Range { start: self.address.start, end: self.address.end }]
	}

	/// The timestamp.
	#[inline]
	pub fn timestamp(&self) -> &str {
		&self.inner[Range { start: self.timestamp.start, end: self.timestamp.end }]
	}
}

mod parser {
	use util::parser::{is_ws, is_printable, is_printable_or_ws};

	named!(pub parse(&[u8]) -> (&[u8], &[u8]),
		do_parse!(
			tag!("From ") >>
			take_while!(is_ws) >>
			addr: address >>
			take_while!(is_ws) >>
			time: timestamp >>
			eof!() >>

			(addr, time)));

	named!(address(&[u8]) -> &[u8],
		take_while!(is_printable));

	named!(timestamp(&[u8]) -> &[u8],
		take_while_n!(24, is_printable_or_ws));
}

#[cfg(test)]
mod test {
	use super::*;

	#[test]
	fn ok() {
		let v = Begin::new("From foo@example.com Wed Nov 17 14:35:53 2010").unwrap();
		assert_eq!(v.address(), "foo@example.com");
		assert_eq!(v.timestamp(), "Wed Nov 17 14:35:53 2010");
	}

	#[test]
	fn fail() {
		assert!(Begin::new("From foo@example.com").is_err());
		assert!(Begin::new("From foo@example.com Wed Nov 17 14:35:53 20109").is_err());
	}
}