src/westmere/dom_parser_implementation.cpp

#include "simdjson/westmere/begin.h"

//
// Stage 1
//

namespace simdjson {
namespace SIMDJSON_IMPLEMENTATION {
namespace {

using namespace simd;

struct json_character_block {
  static simdjson_really_inline json_character_block classify(const simd::simd8x64<uint8_t>& in);

  simdjson_really_inline uint64_t whitespace() const noexcept { return _whitespace; }
  simdjson_really_inline uint64_t op() const noexcept { return _op; }
  simdjson_really_inline uint64_t scalar() const noexcept { return ~(op() | whitespace()); }

  uint64_t _whitespace;
  uint64_t _op;
};

simdjson_really_inline json_character_block json_character_block::classify(const simd::simd8x64<uint8_t>& in) {
  // These lookups rely on the fact that anything < 127 will match the lower 4 bits, which is why
  // we can't use the generic lookup_16.
  auto whitespace_table = simd8<uint8_t>::repeat_16(' ', 100, 100, 100, 17, 100, 113, 2, 100, '\t', '\n', 112, 100, '\r', 100, 100);

  // The 6 operators (:,[]{}) have these values:
  //
  // , 2C
  // : 3A
  // [ 5B
  // { 7B
  // ] 5D
  // } 7D
  //
  // If you use | 0x20 to turn [ and ] into { and }, the lower 4 bits of each character is unique.
  // We exploit this, using a simd 4-bit lookup to tell us which character match against, and then
  // match it (against | 0x20).
  //
  // To prevent recognizing other characters, everything else gets compared with 0, which cannot
  // match due to the | 0x20.
  //
  // NOTE: Due to the | 0x20, this ALSO treats <FF> and <SUB> (control characters 0C and 1A) like ,
  // and :. This gets caught in stage 2, which checks the actual character to ensure the right
  // operators are in the right places.
  const auto op_table = simd8<uint8_t>::repeat_16(
    0, 0, 0, 0,
    0, 0, 0, 0,
    0, 0, ':', '{', // : = 3A, [ = 5B, { = 7B
    ',', '}', 0, 0  // , = 2C, ] = 5D, } = 7D
  );

  // We compute whitespace and op separately. If the code later only use one or the
  // other, given the fact that all functions are aggressively inlined, we can
  // hope that useless computations will be omitted. This is namely case when
  // minifying (we only need whitespace).


  const uint64_t whitespace = in.eq({
    _mm_shuffle_epi8(whitespace_table, in.chunks[0]),
    _mm_shuffle_epi8(whitespace_table, in.chunks[1]),
    _mm_shuffle_epi8(whitespace_table, in.chunks[2]),
    _mm_shuffle_epi8(whitespace_table, in.chunks[3])
  });
  // Turn [ and ] into { and }
  const simd8x64<uint8_t> curlified{
    in.chunks[0] | 0x20,
    in.chunks[1] | 0x20,
    in.chunks[2] | 0x20,
    in.chunks[3] | 0x20
  };
  const uint64_t op = curlified.eq({
    _mm_shuffle_epi8(op_table, in.chunks[0]),
    _mm_shuffle_epi8(op_table, in.chunks[1]),
    _mm_shuffle_epi8(op_table, in.chunks[2]),
    _mm_shuffle_epi8(op_table, in.chunks[3])
  });
    return { whitespace, op };
}

simdjson_really_inline bool is_ascii(const simd8x64<uint8_t>& input) {
  return input.reduce_or().is_ascii();
}

simdjson_unused simdjson_really_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
  simd8<uint8_t> is_second_byte = prev1.saturating_sub(0b11000000u-1); // Only 11______ will be > 0
  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
  return simd8<int8_t>(is_second_byte | is_third_byte | is_fourth_byte) > int8_t(0);
}

simdjson_really_inline simd8<bool> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
  return simd8<int8_t>(is_third_byte | is_fourth_byte) > int8_t(0);
}

} // unnamed namespace
} // namespace SIMDJSON_IMPLEMENTATION
} // namespace simdjson

#include "generic/stage1/utf8_lookup4_algorithm.h"
#include "generic/stage1/json_structural_indexer.h"
#include "generic/stage1/utf8_validator.h"

//
// Stage 2
//
#include "generic/stage2/tape_builder.h"

//
// Implementation-specific overrides
//

namespace simdjson {
namespace SIMDJSON_IMPLEMENTATION {
namespace {
namespace stage1 {

simdjson_really_inline uint64_t json_string_scanner::find_escaped(uint64_t backslash) {
  if (!backslash) { uint64_t escaped = prev_escaped; prev_escaped = 0; return escaped; }
  return find_escaped_branchless(backslash);
}

} // namespace stage1
} // unnamed namespace

simdjson_warn_unused error_code implementation::minify(const uint8_t *buf, size_t len, uint8_t *dst, size_t &dst_len) const noexcept {
  return westmere::stage1::json_minifier::minify<64>(buf, len, dst, dst_len);
}

simdjson_warn_unused error_code dom_parser_implementation::stage1(const uint8_t *_buf, size_t _len, bool streaming) noexcept {
  this->buf = _buf;
  this->len = _len;
  return westmere::stage1::json_structural_indexer::index<64>(_buf, _len, *this, streaming);
}

simdjson_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
  return westmere::stage1::generic_validate_utf8(buf,len);
}

simdjson_warn_unused error_code dom_parser_implementation::stage2(dom::document &_doc) noexcept {
  return stage2::tape_builder::parse_document<false>(*this, _doc);
}

simdjson_warn_unused error_code dom_parser_implementation::stage2_next(dom::document &_doc) noexcept {
  return stage2::tape_builder::parse_document<true>(*this, _doc);
}

simdjson_warn_unused error_code dom_parser_implementation::parse(const uint8_t *_buf, size_t _len, dom::document &_doc) noexcept {
  auto error = stage1(_buf, _len, false);
  if (error) { return error; }
  return stage2(_doc);
}

} // namespace SIMDJSON_IMPLEMENTATION
} // namespace simdjson

#include "simdjson/westmere/end.h"