public static bool parse_string_sse41(uint8_t *buf, size_t len, ParsedJson pj, uint32_t depth, uint32_t offset)
{
#if SIMDJSON_SKIPSTRINGPARSING // for performance analysis, it is sometimes useful to skip parsing
pj.write_tape(0, '"'); // don't bother with the string parsing at all
return(true); // always succeeds
#else
uint8_t *src = &buf[offset + 1]; // we know that buf at offset is a "
uint8_t *dst = pj.current_string_buf_loc;
#if JSON_TEST_STRINGS // for unit testing
uint8_t *const start_of_string = dst;
#endif
Vector128 <byte> slashVec = Vector128.Create((byte)'\\');
Vector128 <byte> quoteVec = Vector128.Create((byte)'"');
Vector128 <byte> unitsep = Vector128.Create((byte)0x1F);
while (true)
{
Vector128 <byte> v = Sse2.LoadVector128((src));
uint32_t bs_bits = (uint32_t)Sse2.MoveMask(Sse2.CompareEqual(v, slashVec));
uint32_t quote_bits = (uint32_t)Sse2.MoveMask(Sse2.CompareEqual(v, quoteVec));
// All Unicode characters may be placed within the
// quotation marks, except for the characters that MUST be escaped:
// quotation mark, reverse solidus, and the control characters (U+0000
//through U+001F).
// https://tools.ietf.org/html/rfc8259
#if CHECKUNESCAPED
Vector128 <byte> unescaped_vec =
Sse2.CompareEqual(Sse2.Max(unitsep, v), unitsep); // could do it with saturated subtraction
#endif // CHECKUNESCAPED
uint32_t quote_dist = (uint32_t)trailingzeroes(quote_bits);
uint32_t bs_dist = (uint32_t)trailingzeroes(bs_bits);
// store to dest unconditionally - we can overwrite the bits we don't like
// later
memcpy(dst, src, (size_t)Vector128 <byte> .Count);
if (quote_dist < bs_dist)
{
// we encountered quotes first. Move dst to point to quotes and exit
dst[quote_dist] = 0; // null terminate and get out
pj.WriteTape((size_t)pj.current_string_buf_loc - (size_t)pj.string_buf, (uint8_t)'"');
pj.current_string_buf_loc = dst + quote_dist + 1; // the +1 is due to the 0 value
#if CHECKUNESCAPED
// check that there is no unescaped char before the quote
uint32_t unescaped_bits = (uint32_t)Sse2.MoveMask(unescaped_vec);
bool is_ok = ((quote_bits - 1) & (~quote_bits) & unescaped_bits) == 0;
#if JSON_TEST_STRINGS // for unit testing
if (is_ok)
{
foundString(buf + offset, start_of_string, pj.current_string_buf_loc - 1);
}
else
{
foundBadString(buf + offset);
}
#endif // JSON_TEST_STRINGS
return(is_ok);
#else //CHECKUNESCAPED
#if JSON_TEST_STRINGS // for unit testing
foundString(buf + offset, start_of_string, pj.current_string_buf_loc - 1);
#endif // JSON_TEST_STRINGS
return(true);
#endif //CHECKUNESCAPED
}
else if (quote_dist > bs_dist)
{
uint8_t escape_char = src[bs_dist + 1];
#if CHECKUNESCAPED
// we are going to need the unescaped_bits to check for unescaped chars
uint32_t unescaped_bits = (uint32_t)Sse2.MoveMask(unescaped_vec);
if (((bs_bits - 1) & (~bs_bits) & unescaped_bits) != 0)
{
#if JSON_TEST_STRINGS // for unit testing
foundBadString(buf + offset);
#endif // JSON_TEST_STRINGS
return(false);
}
#endif //CHECKUNESCAPED
// we encountered backslash first. Handle backslash
if (escape_char == 'u')
{
// move src/dst up to the start; they will be further adjusted
// within the unicode codepoint handling code.
src += bs_dist;
dst += bs_dist;
if (!handle_unicode_codepoint(&src, &dst))
{
#if JSON_TEST_STRINGS // for unit testing
foundBadString(buf + offset);
#endif // JSON_TEST_STRINGS
return(false);
}
}
else
{
// simple 1:1 conversion. Will eat bs_dist+2 characters in input and
// write bs_dist+1 characters to output
// note this may reach beyond the part of the buffer we've actually
// seen. I think this is ok
uint8_t escape_result = escape(escape_char);
if (escape_result == 0)
{
#if JSON_TEST_STRINGS // for unit testing
foundBadString(buf + offset);
#endif // JSON_TEST_STRINGS
return(false); // bogus escape value is an error
}
dst[bs_dist] = escape_result;
src += bs_dist + 2;
dst += bs_dist + 1;
}
}
else
{
// they are the same. Since they can't co-occur, it means we encountered
// neither.
src += Vector128 <byte> .Count;
dst += Vector128 <byte> .Count;
#if CHECKUNESCAPED
// check for unescaped chars
if (Sse2.MoveMask(unescaped_vec) != 0)
{
#if JSON_TEST_STRINGS // for unit testing
foundBadString(buf + offset);
#endif // JSON_TEST_STRINGS
return(false);
}
#endif // CHECKUNESCAPED
}
}
// can't be reached
return(true);
#endif // SIMDJSON_SKIPSTRINGPARSING
}