You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: request.rs
    path of file: ./repos/sipcore/crates/sipmsg/src
    
    the code of the file until where you have to start completion: use crate::common::{errorparse::SipParseError, sip_method::*};
use crate::{headers::*, message::*};
use nom::{
    bytes::complete::{tag, take_while1},
    character::{complete, is_alphabetic},
    sequence::tuple,
};

use core::{str, u8};

/// [rfc3261 section-7.1](https://tools.ietf.org/html/rfc3261#section-7.1)
pub struct Request<'a> {
    /// The request line. Example: `OPTIONS sip:user@example.com SIP/2.0`
    pub rl: RequestLine<'a>,
    /// The request headers.
    pub headers: SipHeaders<'a>,
    /// The body of message
    pub body: Option<&'a [u8]>,
}

impl<'a> Request<'a> {
    fn new(rl: RequestLine<'a>, headers: SipHeaders<'a>, body
    
    pub fn parse(source_input: &[u8]) -> nom::IResult<&[u8], RequestLine, SipParseError> {
        let method = take_while1(is_alphabetic);
        let uri = take_while1(|c| c != b' ' as u8);
        let (input, (method, _, uri, _, _, major_version, _, minor_version, _)) =
            tuple((
                method,
                complete::space1,
                uri,
                complete::space1,
                tag("SIP/"),
                complete::digit1,
                complete::char('.'),
                complete::digit1,
                complete::crlf,
            ))(source_input)?;

        let (_, sip_uri) = SipUri::parse(uri)?;

        let sip_version = SipVersion(
            u8::from_str_radix(str::from_utf8(major_version).unwrap(), 10).unwrap(),
            u8::from_str_radix(str::from_utf8(minor_version).unwrap(), 10).unwrap(),
        );

        match RequestLine::parse_method(method) {
            Some(m) => Ok((
                input,
                RequestLine {
                    method: m,
                    uri: sip_uri,
                    sip_version: sip_version,
                    raw: &source_input[..source_input.len() - input.len()],
                },
            )),
            None => return sip_parse_error!(1, "Error cast from_utf8"),
        }
    }