Current File : //usr/share/doc/re2c/examples/c/fill/02_fill.re
// re2c $INPUT -o $OUTPUT
#include <assert.h>
#include <stdio.h>
#include <string.h>
/*!max:re2c*/
#define BUFSIZE (4096 - YYMAXFILL)
struct Input {
FILE *file;
char buf[BUFSIZE + YYMAXFILL], *lim, *cur, *tok;
bool eof;
};
static int fill(Input &in, size_t need) {
if (in.eof) return 1;
const size_t shift = in.tok - in.buf;
const size_t used = in.lim - in.tok;
// Error: lexeme too long. In real life could reallocate a larger buffer.
if (shift < need) return 2;
// Shift buffer contents (discard everything up to the current token).
memmove(in.buf, in.tok, used);
in.lim -= shift;
in.cur -= shift;
in.tok -= shift;
// Fill free space at the end of buffer with new data from file.
in.lim += fread(in.lim, 1, BUFSIZE - used, in.file);
// 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 < in.buf + BUFSIZE) {
in.eof = true;
memset(in.lim, 0, YYMAXFILL);
in.lim += YYMAXFILL;
}
return 0;
}
static int lex(Input &in) {
int count = 0;
for (;;) {
in.tok = in.cur;
/*!re2c
re2c:api:style = free-form;
re2c:define:YYCTYPE = char;
re2c:define:YYCURSOR = in.cur;
re2c:define:YYLIMIT = in.lim;
re2c:define:YYFILL = "if (fill(in, @@) != 0) return -1;";
str = ['] ([^'\\] | [\\][^])* ['];
[\x00] {
// Check that it is the sentinel, not some unexpected null.
return in.tok == in.lim - YYMAXFILL ? count : -1;
}
str { ++count; continue; }
[ ]+ { continue; }
* { return -1; }
*/
}
}
int main() {
const char *fname = "input";
const char content[] = "'qu\0tes' 'are' 'fine: \\'' ";
// Prepare input file: a few times the size of the buffer, containing
// strings with zeroes and escaped quotes.
FILE *f = fopen(fname, "w");
for (int i = 0; i < BUFSIZE; ++i) {
fwrite(content, 1, sizeof(content) - 1, f);
}
fclose(f);
int count = 3 * BUFSIZE; // number of quoted strings written to file
// Initialize lexer state: all pointers are at the end of buffer.
// This immediately triggers YYFILL, as the check `in.cur < in.lim` fails.
Input in;
in.file = fopen(fname, "r");
in.cur = in.tok = in.lim = in.buf + BUFSIZE;
in.eof = 0;
// Run the lexer.
assert(lex(in) == count);
// Cleanup: remove input file.
fclose(in.file);
remove(fname);
return 0;
}
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