int lre_parse_escape()

in src/couch_quickjs/quickjs/libregexp.c [415:524]

• 103 lines of code
• 40 McCabe index (conditional complexity)

int lre_parse_escape(const uint8_t **pp, int allow_utf16)
{
    const uint8_t *p;
    uint32_t c;

    p = *pp;
    c = *p++;
    switch(c) {
    case 'b':
        c = '\b';
        break;
    case 'f':
        c = '\f';
        break;
    case 'n':
        c = '\n';
        break;
    case 'r':
        c = '\r';
        break;
    case 't':
        c = '\t';
        break;
    case 'v':
        c = '\v';
        break;
    case 'x':
    case 'u':
        {
            int h, n, i;
            uint32_t c1;

            if (*p == '{' && allow_utf16) {
                p++;
                c = 0;
                for(;;) {
                    h = from_hex(*p++);
                    if (h < 0)
                        return -1;
                    c = (c << 4) | h;
                    if (c > 0x10FFFF)
                        return -1;
                    if (*p == '}')
                        break;
                }
                p++;
            } else {
                if (c == 'x') {
                    n = 2;
                } else {
                    n = 4;
                }

                c = 0;
                for(i = 0; i < n; i++) {
                    h = from_hex(*p++);
                    if (h < 0) {
                        return -1;
                    }
                    c = (c << 4) | h;
                }
                if (is_hi_surrogate(c) &&
                    allow_utf16 == 2 && p[0] == '\\' && p[1] == 'u') {
                    /* convert an escaped surrogate pair into a
                       unicode char */
                    c1 = 0;
                    for(i = 0; i < 4; i++) {
                        h = from_hex(p[2 + i]);
                        if (h < 0)
                            break;
                        c1 = (c1 << 4) | h;
                    }
                    if (i == 4 && is_lo_surrogate(c1)) {
                        p += 6;
                        c = from_surrogate(c, c1);
                    }
                }
            }
        }
        break;
    case '0': case '1': case '2': case '3':
    case '4': case '5': case '6': case '7':
        c -= '0';
        if (allow_utf16 == 2) {
            /* only accept \0 not followed by digit */
            if (c != 0 || is_digit(*p))
                return -1;
        } else {
            /* parse a legacy octal sequence */
            uint32_t v;
            v = *p - '0';
            if (v > 7)
                break;
            c = (c << 3) | v;
            p++;
            if (c >= 32)
                break;
            v = *p - '0';
            if (v > 7)
                break;
            c = (c << 3) | v;
            p++;
        }
        break;
    default:
        return -2;
    }
    *pp = p;
    return c;
}