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Current File : //usr/share/doc/re2c/examples/c/conditions/parse_u32_blocks.re

// re2c $INPUT -o $OUTPUT -i
#include <stdint.h>
#include <limits.h>
#include <assert.h>

static const uint64_t ERROR = UINT64_MAX;

template<int BASE> static void add(uint64_t &u, char d) {
    u = u * BASE + d;
    if (u > UINT32_MAX) u = ERROR;
}

static uint64_t parse_u32(const char *s) {
    const char *YYCURSOR = s, *YYMARKER;
    uint64_t u = 0;

    /*!re2c
        re2c:yyfill:enable = 0;
        re2c:define:YYCTYPE = char;

        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]  { add<2>(u, YYCURSOR[-1] - '0'); goto bin; }
        *     { return ERROR; }
    */
oct:
    /*!re2c
        end   { return u; }
        [0-7] { add<8>(u, YYCURSOR[-1] - '0'); goto oct; }
        *     { return ERROR; }
    */
dec:
    /*!re2c
        end   { return u; }
        [0-9] { add<10>(u, YYCURSOR[-1] - '0'); goto dec; }
        *     { return ERROR; }
    */
hex:
    /*!re2c
        end   { return u; }
        [0-9] { add<16>(u, YYCURSOR[-1] - '0');      goto hex; }
        [a-f] { add<16>(u, YYCURSOR[-1] - 'a' + 10); goto hex; }
        [A-F] { add<16>(u, YYCURSOR[-1] - 'A' + 10); goto hex; }
        *     { return ERROR; }
    */
}

int main() {
    assert(parse_u32("") == ERROR);
    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);
    return 0;
}

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