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// re2rust $INPUT -o $OUTPUT use std::fs::File; use std::io::{Read, Write}; const BUFSIZE: usize = 4096; struct State { file: File, buf: [u8; BUFSIZE], lim: usize, cur: usize, mar: usize, tok: usize, eof: bool, } #[derive(PartialEq)] enum Fill { Ok, Eof, LongLexeme } fn fill(st: &mut State) -> Fill { if st.eof { return Fill::Eof; } // Error: lexeme too long. In real life could reallocate a larger buffer. if st.tok < 1 { return Fill::LongLexeme; } // Shift buffer contents (discard everything up to the current token). st.buf.copy_within(st.tok..st.lim, 0); st.lim -= st.tok; st.cur -= st.tok; st.mar = st.mar.overflowing_sub(st.tok).0; // may underflow if marker is unused st.tok = 0; // Fill free space at the end of buffer with new data from file. match st.file.read(&mut st.buf[st.lim..BUFSIZE - 1]) { // -1 for sentinel Ok(n) => { st.lim += n; st.eof = n == 0; // end of file st.buf[st.lim] = 0; // append sentinel } Err(why) => panic!("cannot read from file: {}", why) } return Fill::Ok; } fn lex(st: &mut State) -> isize { let mut count: isize = 0; 'lex: loop { st.tok = st.cur; /*!re2c re2c:define:YYCTYPE = u8; re2c:define:YYPEEK = "*st.buf.get_unchecked(st.cur)"; re2c:define:YYSKIP = "st.cur += 1;"; re2c:define:YYBACKUP = "st.mar = st.cur;"; re2c:define:YYRESTORE = "st.cur = st.mar;"; re2c:define:YYLESSTHAN = "st.cur >= st.lim"; re2c:define:YYFILL = "fill(st) == Fill::Ok"; re2c:eof = 0; str = ['] ([^'\\] | [\\][^])* [']; * { return -1; } $ { return count; } str { count += 1; continue 'lex; } [ ]+ { continue 'lex; } */} } fn main() { let fname = "input"; let content = b"'qu\0tes' 'are' 'fine: \\'' "; // Prepare input file: a few times the size of the buffer, containing // strings with zeroes and escaped quotes. match File::create(fname) { Err(why) => panic!("cannot open {}: {}", fname, why), Ok(mut file) => match file.write_all(&content.repeat(BUFSIZE)) { Err(why) => panic!("cannot write to {}: {}", fname, why), Ok(_) => {} } }; let count = 3 * BUFSIZE; // number of quoted strings written to file // Reopen input file for reading. let file = match File::open(fname) { Err(why) => panic!("cannot read file {}: {}", fname, why), Ok(file) => file, }; // Initialize lexer state: all offsets are at the end of buffer. let lim = BUFSIZE - 1; let mut st = State { file: file, // Sentinel (at `lim` offset) is set to null, which triggers YYFILL. buf: [0; BUFSIZE], lim: lim, cur: lim, mar: lim, tok: lim, eof: false, }; // Run the lexer. assert_eq!(lex(&mut st), count as isize); // Cleanup: remove input file. match std::fs::remove_file(fname) { Err(why) => panic!("cannot remove {}: {}", fname, why), Ok(_) => {} } }