mirror of https://github.com/tfussell/xlnt
bug fixes, move the faster serialisation into the numeric header
serialisation ends up roughly 2x improvement going from sstream to snprintf Run on (4 X 3500 MHz CPU s) CPU Caches: L1 Data 32K (x4) L1 Instruction 32K (x4) L2 Unified 262K (x4) L3 Unified 6291K (x1) ------------------------------------------------------------------------------------------------------------- Benchmark Time CPU Iterations ------------------------------------------------------------------------------------------------------------- RandFloatStrs/double_from_string_sstream 968 ns 977 ns 640000 RandFloatStrs/double_from_string_strtod 272 ns 270 ns 2488889 RandFloatStrs/double_from_string_strtod_fixed 272 ns 270 ns 2488889 RandFloatStrs/double_from_string_strtod_fixed_const_ref 273 ns 270 ns 2488889 RandFloatStrs/double_from_string_std_from_chars 193 ns 195 ns 3446154 RandFloatCommaStrs/double_from_string_strtod_fixed_comma_ref 272 ns 273 ns 2635294 RandFloatCommaStrs/double_from_string_strtod_fixed_comma_const_ref 276 ns 273 ns 2635294 RandFloats/string_from_double_sstream 1311 ns 1318 ns 497778 RandFloats/string_from_double_sstream_cached 1076 ns 1050 ns 640000 RandFloats/string_from_double_snprintf 601 ns 600 ns 1120000 RandFloats/string_from_double_snprintf_fixed 600 ns 600 ns 1120000 RandFloats/string_from_double_std_to_chars 117 ns 117 ns 5600000 RandFloatsComma/string_from_double_snprintf_fixed_comma 600 ns 600 ns 1120000pull/447/head
JCrawfy
parent
fbbf7ae767
commit
ee593c2673
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@ -118,7 +118,7 @@ public:
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std::string serialise(double d)
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{
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char buf[Excel_Digit_Precision + 1]; // need space for trailing '\0'
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int len = snprintf(buf, sizeof(buf), "%16f", d);
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int len = snprintf(buf, sizeof(buf), "%.15g", d);
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if (should_convert_comma)
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{
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convert_comma(buf, len);
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@ -158,7 +158,7 @@ BENCHMARK_F(RandFloats, string_from_double_snprintf)
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while (state.KeepRunning())
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{
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char buf[16];
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int len = snprintf(buf, sizeof(buf), "%16f", get_rand());
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int len = snprintf(buf, sizeof(buf), "%.15g", get_rand());
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benchmark::DoNotOptimize(
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std::string(buf, len));
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@ -34,21 +34,6 @@
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namespace xlnt {
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namespace detail {
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/// <summary>
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/// Takes in any number and outputs a string form of that number which will
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/// serialise and deserialise without loss of precision
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/// </summary>
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template <typename Number>
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std::string serialize_number_to_string(Number num)
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{
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// more digits and excel won't match
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constexpr int Excel_Digit_Precision = 15; //sf
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std::stringstream ss;
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ss.precision(Excel_Digit_Precision);
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ss << num;
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return ss.str();
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}
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/// <summary>
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/// constexpr abs
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/// </summary>
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@ -117,45 +102,72 @@ bool float_equals(const LNumber &lhs, const RNumber &rhs,
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return ((lhs + scaled_fuzz) >= rhs) && ((rhs + scaled_fuzz) >= lhs);
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}
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struct number_converter
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class number_serialiser
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{
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explicit number_converter()
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: should_convert_to_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
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static constexpr int Excel_Digit_Precision = 15; //sf
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bool should_convert_comma;
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static void convert_comma_to_pt(char *buf, int len)
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{
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char *buf_end = buf + len;
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char *decimal = std::find(buf, buf_end, ',');
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if (decimal != buf_end)
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{
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*decimal = '.';
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}
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}
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static void convert_pt_to_comma(char *buf, size_t len)
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{
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char *buf_end = buf + len;
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char *decimal = std::find(buf, buf_end, '.');
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if (decimal != buf_end)
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{
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*decimal = ',';
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}
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}
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public:
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explicit number_serialiser()
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: should_convert_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
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{
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}
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double stold(std::string &s) const noexcept
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std::string serialise(double d) const
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{
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char buf[30];
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int len = snprintf(buf, sizeof(buf), "%.15g", d);
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if (should_convert_comma)
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{
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convert_comma_to_pt(buf, len);
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}
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return std::string(buf, len);
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}
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double deserialise(std::string &s) const noexcept
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{
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assert(!s.empty());
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if (should_convert_to_comma)
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if (should_convert_comma)
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{
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auto decimal_pt = std::find(s.begin(), s.end(), '.');
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if (decimal_pt != s.end())
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{
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*decimal_pt = ',';
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}
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// s.data() doesn't have a non-const overload until c++17, hence this little dance
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convert_pt_to_comma(&s[0], s.size());
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}
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return strtod(s.c_str(), nullptr);
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}
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double stold(const std::string &s) const
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double deserialise(const std::string &s) const
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{
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assert(!s.empty());
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if (!should_convert_to_comma)
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if (!should_convert_comma)
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{
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return strtod(s.c_str(), nullptr);
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}
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std::string copy(s);
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auto decimal_pt = std::find(copy.begin(), copy.end(), '.');
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if (decimal_pt != copy.end())
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{
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*decimal_pt = ',';
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}
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return strtod(copy.c_str(), nullptr);
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char buf[30];
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assert(s.size() < std::size(buf));
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auto copy_end = std::copy(s.begin(), s.end(), buf);
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convert_pt_to_comma(buf, static_cast<size_t>(copy_end - buf));
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return strtod(buf, nullptr);
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}
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private:
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bool should_convert_to_comma = false;
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};
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} // namespace detail
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@ -40,17 +40,18 @@ public:
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void test_serialise_number()
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{
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xlnt::detail::number_serialiser serialiser;
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// excel serialises numbers as floating point values with <= 15 digits of precision
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xlnt_assert(xlnt::detail::serialize_number_to_string(1) == "1");
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xlnt_assert(serialiser.serialise(1) == "1");
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// trailing zeroes are ignored
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.0) == "1");
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.0f) == "1");
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xlnt_assert(serialiser.serialise(1.0) == "1");
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xlnt_assert(serialiser.serialise(1.0f) == "1");
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// one to 1 relation
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456) == "1.23456");
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345) == "1.23456789012345");
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xlnt_assert(xlnt::detail::serialize_number_to_string(123456.789012345) == "123456.789012345");
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345e+67) == "1.23456789012345e+67");
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xlnt_assert(xlnt::detail::serialize_number_to_string(1.23456789012345e-67) == "1.23456789012345e-67");
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xlnt_assert(serialiser.serialise(1.23456) == "1.23456");
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xlnt_assert(serialiser.serialise(1.23456789012345) == "1.23456789012345");
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xlnt_assert(serialiser.serialise(123456.789012345) == "123456.789012345");
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xlnt_assert(serialiser.serialise(1.23456789012345e+67) == "1.23456789012345e+67");
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xlnt_assert(serialiser.serialise(1.23456789012345e-67) == "1.23456789012345e-67");
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}
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void test_float_equals_zero()
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