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// re2rust $INPUT -o $OUTPUT -fc --no-unsafe
use std::fs::File;
use std::io::{Read, Write};
const BUFSIZE: usize = 10;
/*!conditions:re2c*/
const DEBUG: bool = false;
macro_rules! log {
($($fmt:expr)? $(, $args:expr)*) => { if DEBUG { println!($($fmt)? $(, $args)*) } }
}
struct State {
file: File,
yyinput: [u8; BUFSIZE + 1],
yylimit: usize,
yycursor: usize,
yymarker: usize,
token: usize,
yystate: isize,
}
#[derive(Debug, PartialEq)]
enum Status {End, Ready, Waiting, BadPacket, BigPacket}
fn fill(st: &mut State) -> Status {
let shift = st.token;
let used = st.yylimit - st.token;
let free = BUFSIZE - used;
// Error: no space. In real life can reallocate a larger buffer.
if free < 1 { return Status::BigPacket; }
// Shift buffer contents (discard already processed data).
unsafe {
let p = st.yyinput.as_mut_ptr();
std::ptr::copy(p, p.offset(shift as isize), used);
}
st.yylimit -= shift;
st.yycursor -= shift;
st.yymarker = st.yymarker.overflowing_sub(shift).0; // underflow ok if marker is unused
st.token -= shift;
// Fill free space at the end of buffer with new data.
match st.file.read(&mut st.yyinput[st.yylimit..BUFSIZE]) {
Ok(n) => st.yylimit += n,
Err(why) => panic!("cannot read from file: {}", why)
}
st.yyinput[st.yylimit] = 0; // append sentinel symbol
return Status::Ready;
}
fn lex(yyrecord: &mut State, nc: &mut isize, wc: &mut isize) -> Status {
#[allow(unused_assignments)]
let mut yych: u8 = 0;
'lex: loop {
yyrecord.token = yyrecord.yycursor;
/*!re2c
re2c:api = record;
re2c:eof = 0;
re2c:define:YYCTYPE = "u8";
re2c:define:YYFILL = "return Status::Waiting;";
digit = [0-9];
letter = [a-z];
space = [ \t];
<*> * { return Status::BadPacket; }
<*> $ { return Status::End; }
<INIT> "" / digit :=> NUMBER
<INIT> "" / letter :=> WORD
<INIT> "" / space :=> SPACES
<SPACES> space+ => INIT{ continue 'lex; }
<NUMBER> digit+ => SPACES { *nc += 1; continue 'lex; }
<WORD> letter+ => SPACES { *wc += 1; continue 'lex; }
*/}
}
fn test(packets: Vec<&[u8]>, expect: Status, expect_nc: isize, expect_wc: isize) {
// Create a "socket" (open the same file for reading and writing).
let fname = "pipe";
let mut fw: File = match File::create(fname) {
Err(why) => panic!("cannot open {}: {}", fname, why),
Ok(file) => file,
};
let fr: File = match File::open(fname) {
Err(why) => panic!("cannot read file {}: {}", fname, why),
Ok(file) => file,
};
// Initialize lexer state: `state` value is -1, all offsets are at the end
// of buffer, the character at `yylimit` offset is the sentinel (null).
let mut state = State {
file: fr,
yyinput: [0; BUFSIZE + 1], // sentinel (at `yylimit` offset) is set to null
yylimit: BUFSIZE,
yycursor: BUFSIZE,
yymarker: BUFSIZE,
token: BUFSIZE,
yystate: -1,
};
// Main loop. The buffer contains incomplete data which appears packet by
// packet. When the lexer needs more input it saves its internal state and
// returns to the caller which should provide more input and resume lexing.
let mut status;
let mut send = 0;
let mut nc = 0;
let mut wc = 0;
loop {
status = lex(&mut state, &mut nc, &mut wc);
if status == Status::End {
log!("done: got {} numbers and {} words", nc, wc);
break;
} else if status == Status::Waiting {
log!("waiting...");
if send < packets.len() {
log!("sent packet {}", send);
match fw.write_all(packets[send]) {
Err(why) => panic!("cannot write to {}: {}", fname, why),
Ok(_) => send += 1,
}
}
status = fill(&mut state);
log!("queue: '{}'", String::from_utf8_lossy(&state.yyinput));
if status == Status::BigPacket {
log!("error: packet too big");
break;
}
assert_eq!(status, Status::Ready);
} else {
assert_eq!(status, Status::BadPacket);
log!("error: ill-formed packet");
break;
}
}
// Check results.
assert_eq!(status, expect);
if status == Status::End {
assert_eq!(nc, expect_nc);
assert_eq!(wc, expect_wc);
}
// Cleanup: remove input file.
match std::fs::remove_file(fname) {
Err(why) => panic!("cannot remove {}: {}", fname, why),
Ok(_) => {}
}
}
fn main() {
test(vec![], Status::End, 0, 0);
test(vec![b" zero one", b" ", b"123", b"4 tw", b"o ", b"456789"], Status::End, 2, 3);
test(vec![b"zer0"], Status::BadPacket, -1, -1);
test(vec![b"tooooooloooooong"], Status::BigPacket, -1, -1);
}
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