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%PDF-
Mini Shell
Mini Shell
/* Generated by re2c */
// re2rust $INPUT -o $OUTPUT
// Store u32 number in u64 during parsing to simplify overflow hadling.
struct State<'a> {
str: &'a [u8],
cur: usize,
mar: usize,
num: u64,
}
const ERROR: u64 = std::u32::MAX as u64 + 1; // overflow
macro_rules! maybe { // Convert the number from u64 to optional u32.
($n:expr) => { if $n < ERROR { Some($n as u32) } else { None } }
}
// Add digit with the given base, checking for overflow.
fn add(st: &mut State, offs: u8, base: u64) {
let digit = unsafe { st.str.get_unchecked(st.cur - 1) } - offs;
st.num = std::cmp::min(st.num * base + digit as u64, ERROR);
}
fn parse_u32(s: & [u8]) -> Option<u32> {
let mut st = State {str: s, cur: 0, mar: 0, num: 0};
{
#[allow(unused_assignments)]
let mut yych : u8 = 0;
let mut yystate : usize = 0;
'yyl: loop {
match yystate {
0 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
st.cur += 1;
match yych {
0x30 => {
yystate = 2;
continue 'yyl;
}
0x31 ..= 0x39 => {
yystate = 4;
continue 'yyl;
}
_ => {
yystate = 1;
continue 'yyl;
}
}
}
1 => { return None; }
2 => {
st.mar = st.cur;
yych = unsafe {*st.str.get_unchecked(st.cur)};
match yych {
0x42 |
0x62 => {
st.cur += 1;
yystate = 5;
continue 'yyl;
}
0x58 |
0x78 => {
st.cur += 1;
yystate = 7;
continue 'yyl;
}
_ => {
yystate = 3;
continue 'yyl;
}
}
}
3 => { return parse_oct(&mut st); }
4 => {
st.cur = (st.cur as isize + -1) as usize;
{ return parse_dec(&mut st); }
}
5 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
match yych {
0x30 ..= 0x31 => {
st.cur += 1;
yystate = 8;
continue 'yyl;
}
_ => {
yystate = 6;
continue 'yyl;
}
}
}
6 => {
st.cur = st.mar;
yystate = 3;
continue 'yyl;
}
7 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
match yych {
0x30 ..= 0x39 |
0x41 ..= 0x46 |
0x61 ..= 0x66 => {
st.cur += 1;
yystate = 9;
continue 'yyl;
}
_ => {
yystate = 6;
continue 'yyl;
}
}
}
8 => {
st.cur = (st.cur as isize + -1) as usize;
{ return parse_bin(&mut st); }
}
9 => {
st.cur = (st.cur as isize + -1) as usize;
{ return parse_hex(&mut st); }
}
_ => {
panic!("internal lexer error")
}
}
}
}
}
fn parse_bin(st: &mut State) -> Option<u32> {
'bin: loop {
{
#[allow(unused_assignments)]
let mut yych : u8 = 0;
let mut yystate : usize = 0;
'yyl: loop {
match yystate {
0 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
st.cur += 1;
match yych {
0x30 ..= 0x31 => {
yystate = 2;
continue 'yyl;
}
_ => {
yystate = 1;
continue 'yyl;
}
}
}
1 => { return maybe!(st.num); }
2 => { add(st, 48, 2); continue 'bin; }
_ => {
panic!("internal lexer error")
}
}
}
}
}
}
fn parse_oct(st: &mut State) -> Option<u32> {
'oct: loop {
{
#[allow(unused_assignments)]
let mut yych : u8 = 0;
let mut yystate : usize = 0;
'yyl: loop {
match yystate {
0 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
st.cur += 1;
match yych {
0x30 ..= 0x37 => {
yystate = 2;
continue 'yyl;
}
_ => {
yystate = 1;
continue 'yyl;
}
}
}
1 => { return maybe!(st.num); }
2 => { add(st, 48, 8); continue 'oct; }
_ => {
panic!("internal lexer error")
}
}
}
}
}
}
fn parse_dec(st: &mut State) -> Option<u32> {
'dec: loop {
{
#[allow(unused_assignments)]
let mut yych : u8 = 0;
let mut yystate : usize = 0;
'yyl: loop {
match yystate {
0 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
st.cur += 1;
match yych {
0x30 ..= 0x39 => {
yystate = 2;
continue 'yyl;
}
_ => {
yystate = 1;
continue 'yyl;
}
}
}
1 => { return maybe!(st.num); }
2 => { add(st, 48, 10); continue 'dec; }
_ => {
panic!("internal lexer error")
}
}
}
}
}
}
fn parse_hex(st: &mut State) -> Option<u32> {
'hex: loop {
{
#[allow(unused_assignments)]
let mut yych : u8 = 0;
let mut yystate : usize = 0;
'yyl: loop {
match yystate {
0 => {
yych = unsafe {*st.str.get_unchecked(st.cur)};
st.cur += 1;
match yych {
0x30 ..= 0x39 => {
yystate = 2;
continue 'yyl;
}
0x41 ..= 0x46 => {
yystate = 3;
continue 'yyl;
}
0x61 ..= 0x66 => {
yystate = 4;
continue 'yyl;
}
_ => {
yystate = 1;
continue 'yyl;
}
}
}
1 => { return maybe!(st.num); }
2 => { add(st, 48, 16); continue 'hex; }
3 => { add(st, 55, 16); continue 'hex; }
4 => { add(st, 87, 16); continue 'hex; }
_ => {
panic!("internal lexer error")
}
}
}
}
}
}
fn main() {
assert_eq!(parse_u32(b"\0"), None);
assert_eq!(parse_u32(b"1234567890\0"), Some(1234567890));
assert_eq!(parse_u32(b"0b1101\0"), Some(13));
assert_eq!(parse_u32(b"0x7Fe\0"), Some(2046));
assert_eq!(parse_u32(b"0644\0"), Some(420));
assert_eq!(parse_u32(b"9999999999\0"), None);
}
Zerion Mini Shell 1.0