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: / usr / share / doc / re2c / examples / rust / submatch /
Filename : 03_posix.rs
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/* Generated by re2c */
// re2rust $INPUT -o $OUTPUT

// Maximum number of capturing groups among all rules.
const YYMAXNMATCH: usize = 4;


#[derive(Debug, PartialEq)]
struct SemVer(u32, u32, u32); // version: (major, minor, patch)

fn s2n(str: &[u8]) -> u32 { // convert a pre-parsed string to a number
    let mut n = 0;
    for i in str { n = n * 10 + *i as u32 - 48; }
    return n;
}

fn parse(str: &[u8]) -> Option<SemVer> {
    let (mut cur, mut mar) = (0, 0);

    // Allocate memory for capturing parentheses (twice the number of groups).
    let yynmatch: usize;
    let mut yypmatch = [0; YYMAXNMATCH*2];

    // Autogenerated tag variables used by the lexer to track tag values.
    const NONE: usize = std::usize::MAX;
    let mut yyt1 = NONE;let mut yyt2 = NONE;let mut yyt3 = NONE;let mut yyt4 = NONE;let mut yyt5 = NONE;

    
{
	#[allow(unused_assignments)]
	let mut yych : u8 = 0;
	let mut yystate : usize = 0;
	'yyl: loop {
		match yystate {
			0 => {
				yych = unsafe {*str.get_unchecked(cur)};
				match yych {
					0x30 ..= 0x39 => {
						yyt1 = cur;
						cur += 1;
						yystate = 3;
						continue 'yyl;
					}
					_ => {
						cur += 1;
						yystate = 1;
						continue 'yyl;
					}
				}
			}
			1 => {
				yystate = 2;
				continue 'yyl;
			}
			2 => { return None; }
			3 => {
				mar = cur;
				yych = unsafe {*str.get_unchecked(cur)};
				match yych {
					0x2E => {
						cur += 1;
						yystate = 4;
						continue 'yyl;
					}
					0x30 ..= 0x39 => {
						cur += 1;
						yystate = 6;
						continue 'yyl;
					}
					_ => {
						yystate = 2;
						continue 'yyl;
					}
				}
			}
			4 => {
				yych = unsafe {*str.get_unchecked(cur)};
				match yych {
					0x30 ..= 0x39 => {
						yyt2 = cur;
						cur += 1;
						yystate = 7;
						continue 'yyl;
					}
					_ => {
						yystate = 5;
						continue 'yyl;
					}
				}
			}
			5 => {
				cur = mar;
				yystate = 2;
				continue 'yyl;
			}
			6 => {
				yych = unsafe {*str.get_unchecked(cur)};
				match yych {
					0x2E => {
						cur += 1;
						yystate = 4;
						continue 'yyl;
					}
					0x30 ..= 0x39 => {
						cur += 1;
						yystate = 6;
						continue 'yyl;
					}
					_ => {
						yystate = 5;
						continue 'yyl;
					}
				}
			}
			7 => {
				yych = unsafe {*str.get_unchecked(cur)};
				match yych {
					0x00 => {
						yyt3 = cur;
						yyt4 = NONE;
						yyt5 = NONE;
						cur += 1;
						yystate = 8;
						continue 'yyl;
					}
					0x2E => {
						yyt3 = cur;
						yyt5 = cur;
						cur += 1;
						yystate = 9;
						continue 'yyl;
					}
					0x30 ..= 0x39 => {
						cur += 1;
						yystate = 7;
						continue 'yyl;
					}
					_ => {
						yystate = 5;
						continue 'yyl;
					}
				}
			}
			8 => {
				yynmatch = 4;
				yypmatch[2] = yyt1;
				yypmatch[4] = yyt2;
				yypmatch[5] = yyt3;
				yypmatch[6] = yyt5;
				yypmatch[7] = yyt4;
				yypmatch[0] = yyt1;
				yypmatch[1] = cur;
				yypmatch[3] = yyt2;
				yypmatch[3] -= --1isize as usize;
				{
            // `yynmatch` is the number of capturing groups
            assert_eq!(yynmatch, 4);

            // Even `yypmatch` values are for opening parentheses, odd values
            // are for closing parentheses, the first group is the whole match.
            let major = s2n(&str[yypmatch[2]..yypmatch[3]]);
            let minor = s2n(&str[yypmatch[4]..yypmatch[5]]);
            let patch = if yypmatch[6] == NONE {0}
                else {s2n(&str[yypmatch[6] + 1..yypmatch[7]])};

            return Some(SemVer(major, minor, patch));
        }
			}
			9 => {
				yych = unsafe {*str.get_unchecked(cur)};
				if yych <= 0x00 {
					yystate = 5;
					continue 'yyl;
				}
				yystate = 11;
				continue 'yyl;
			}
			10 => {
				yych = unsafe {*str.get_unchecked(cur)};
				yystate = 11;
				continue 'yyl;
			}
			11 => {
				match yych {
					0x00 => {
						yyt4 = cur;
						cur += 1;
						yystate = 8;
						continue 'yyl;
					}
					0x30 ..= 0x39 => {
						cur += 1;
						yystate = 10;
						continue 'yyl;
					}
					_ => {
						yystate = 5;
						continue 'yyl;
					}
				}
			}
			_ => {
				panic!("internal lexer error")
			}
		}
	}
}

}

fn main() {
    assert_eq!(parse(b"23.34\0"), Some(SemVer(23, 34, 0)));
    assert_eq!(parse(b"1.2.99999\0"), Some(SemVer(1, 2, 99999)));
    assert_eq!(parse(b"1.a\0"), None);
}