Current File : //proc/thread-self/root/usr/share/doc/re2c/examples/go/fill/02_fill.re
//go:generate re2go $INPUT -o $OUTPUT
package main
import (
"os"
"strings"
)
/*!max:re2c*/
const BUFSIZE int = 4096
type Input struct {
file *os.File
buf []byte
cur int
tok int
lim int
eof bool
}
func fill(in *Input, need int) int {
if in.eof { return -1 } // unexpected EOF
// Error: lexeme too long. In real life can reallocate a larger buffer.
if in.tok < need { return -2 }
// Shift buffer contents (discard everything up to the current token).
copy(in.buf[0:], in.buf[in.tok:in.lim])
in.cur -= in.tok
in.lim -= in.tok
in.tok = 0
// Fill free space at the end of buffer with new data from file.
n, _ := in.file.Read(in.buf[in.lim:BUFSIZE])
in.lim += n
// If read less than expected, this is end of input => add zero padding
// so that the lexer can access characters at the end of buffer.
if in.lim < BUFSIZE {
in.eof = true
for i := 0; i < YYMAXFILL; i += 1 { in.buf[in.lim+i] = 0 }
in.lim += YYMAXFILL
}
return 0
}
func lex(in *Input) int {
count := 0
for {
in.tok = in.cur
/*!re2c
re2c:define:YYCTYPE = byte;
re2c:define:YYPEEK = "in.buf[in.cur]";
re2c:define:YYSKIP = "in.cur += 1";
re2c:define:YYLESSTHAN = "in.lim-in.cur < @@";
re2c:define:YYFILL = "if r := fill(in, @@); r != 0 { return r }";
str = ['] ([^'\\] | [\\][^])* ['];
[\x00] {
// Check that it is the sentinel, not some unexpected null.
if in.tok == in.lim - YYMAXFILL { return count } else { return -1 }
}
str { count += 1; continue }
[ ]+ { continue }
* { return -1 }
*/
}
}
func main() () {
fname := "input"
content := "'qu\000tes' 'are' 'fine: \\'' ";
// Prepare input file: a few times the size of the buffer, containing
// strings with zeroes and escaped quotes.
f, _ := os.Create(fname)
f.WriteString(strings.Repeat(content, BUFSIZE))
f.Seek(0, 0)
count := 3 * BUFSIZE // number of quoted strings written to file
// Prepare lexer state: all offsets are at the end of buffer.
// This immediately triggers YYFILL, as the YYLESSTHAN condition is true.
in := &Input{
file: f,
buf: make([]byte, BUFSIZE+YYMAXFILL),
cur: BUFSIZE,
tok: BUFSIZE,
lim: BUFSIZE,
eof: false,
}
// Run the lexer.
if lex(in) != count { panic("error"); }
// Cleanup: remove input file.
f.Close();
os.Remove(fname);
}
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