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// re2c $INPUT -o $OUTPUT -i --loop-switch
#include <stdint.h>
#include <limits.h>
#include <assert.h>
static const uint64_t ERROR = ~0lu;
template<int BASE> static void adddgt(uint64_t &u, unsigned int d)
{
u = u * BASE + d;
if (u > UINT32_MAX) u = ERROR;
}
static uint64_t parse_u32(const char *s)
{
const char *YYMARKER;
uint64_t u = 0;
/*!re2c
re2c:yyfill:enable = 0;
re2c:define:YYCTYPE = char;
re2c:define:YYCURSOR = s;
end = "\x00";
'0b' / [01] { goto bin; }
"0" { goto oct; }
"" / [1-9] { goto dec; }
'0x' / [0-9a-fA-F] { goto hex; }
* { return ERROR; }
*/
bin:
/*!re2c
end { return u; }
[01] { adddgt<2>(u, s[-1] - '0'); goto bin; }
* { return ERROR; }
*/
oct:
/*!re2c
end { return u; }
[0-7] { adddgt<8>(u, s[-1] - '0'); goto oct; }
* { return ERROR; }
*/
dec:
/*!re2c
end { return u; }
[0-9] { adddgt<10>(u, s[-1] - '0'); goto dec; }
* { return ERROR; }
*/
hex:
/*!re2c
end { return u; }
[0-9] { adddgt<16>(u, s[-1] - '0'); goto hex; }
[a-f] { adddgt<16>(u, s[-1] - 'a' + 10); goto hex; }
[A-F] { adddgt<16>(u, s[-1] - 'A' + 10); goto hex; }
* { return ERROR; }
*/
}
int main()
{
assert(parse_u32("1234567890") == 1234567890);
assert(parse_u32("0b1101") == 13);
assert(parse_u32("0x7Fe") == 2046);
assert(parse_u32("0644") == 420);
assert(parse_u32("9999999999") == ERROR);
assert(parse_u32("") == ERROR);
return 0;
}
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