unescape.cc

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#include "src/parse/unescape.h"

namespace re2c {

// expected characters: [0-9a-zA-Z]
static inline uint32_t hex_digit (const char c)
{
    switch (c)
    {
        case '0': return 0;
        case '1': return 1;
        case '2': return 2;
        case '3': return 3;
        case '4': return 4;
        case '5': return 5;
        case '6': return 6;
        case '7': return 7;
        case '8': return 8;
        case '9': return 9;
        case 'a':
        case 'A': return 0xA;
        case 'b':
        case 'B': return 0xB;
        case 'c':
        case 'C': return 0xC;
        case 'd':
        case 'D': return 0xD;
        case 'e':
        case 'E': return 0xE;
        case 'f':
        case 'F': return 0xF;
        default:  return ~0u; // unexpected
    }
}

// expected string format: "\" [xXuU] [0-9a-zA-Z]*
uint32_t unesc_hex (const char * s, const char * s_end)
{
    uint32_t n = 0;
    for (s += 2; s != s_end; ++s)
    {
        n <<= 4;
        n += hex_digit (*s);
    }
    return n;
}

// expected string format: "\" [0-7]*
uint32_t unesc_oct (const char * s, const char * s_end)
{
    uint32_t n = 0;
    for (++s; s != s_end; ++s)
    {
        n <<= 3;
        n += static_cast<uint8_t> (*s - '0');
    }
    return n;
}

} // namespace re2c