⏪ "⚡ micro-optimizations for dump()"
This reverts commit 909b439b03.
For some strange reason, the test suite crashes when compiled
with GCC.
This commit is contained in:
Niels Lohmann
parent
909b439b03
commit
9c4919ff34
2 changed files with 92 additions and 52 deletions
72
src/json.hpp
72
src/json.hpp
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@ -8252,9 +8252,14 @@ class basic_json
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{
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public:
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template<typename NumberType>
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numtostr(NumberType value, std::ostream& o)
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numtostr(NumberType value)
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{
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x_write(value, std::is_integral<NumberType>(), o);
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x_write(value, std::is_integral<NumberType>());
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}
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const char* c_str() const
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{
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return m_buf.data();
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}
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private:
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@ -8262,12 +8267,12 @@ class basic_json
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std::array < char, 64 > m_buf{{}};
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template<typename NumberType>
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void x_write(NumberType x, /*is_integral=*/std::true_type, std::ostream& o)
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void x_write(NumberType x, /*is_integral=*/std::true_type)
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{
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// special case for "0"
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if (x == 0)
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{
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o.put('0');
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m_buf[0] = '0';
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return;
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}
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@ -8293,31 +8298,30 @@ class basic_json
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}
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std::reverse(m_buf.begin(), m_buf.begin() + i);
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o.write(m_buf.data(), static_cast<std::streamsize>(i));
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}
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template<typename NumberType>
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void x_write(NumberType x, /*is_integral=*/std::false_type, std::ostream& o)
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void x_write(NumberType x, /*is_integral=*/std::false_type)
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{
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// special case for 0.0 and -0.0
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if (x == 0)
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{
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size_t i = 0;
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if (std::signbit(x))
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{
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o.write("-0.0", 4);
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}
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else
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{
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o.write("0.0", 3);
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m_buf[i++] = '-';
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}
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m_buf[i++] = '0';
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m_buf[i++] = '.';
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m_buf[i] = '0';
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return;
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}
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// get number of digits for a text -> float -> text round-trip
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static constexpr auto d = std::numeric_limits<NumberType>::digits10;
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// the actual conversion; store how many bytes have been written
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auto written_bytes = snprintf(m_buf.data(), m_buf.size(), "%.*g", d, x);
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// the actual conversion
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const auto written_bytes = snprintf(m_buf.data(), m_buf.size(), "%.*g", d, x);
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// negative value indicates an error
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assert(written_bytes > 0);
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@ -8338,7 +8342,6 @@ class basic_json
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{
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const auto end = std::remove(m_buf.begin(), m_buf.begin() + written_bytes, thousands_sep);
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std::fill(end, m_buf.end(), '\0');
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written_bytes -= m_buf.end() - end;
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}
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// convert decimal point to '.'
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@ -8354,19 +8357,36 @@ class basic_json
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}
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}
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o.write(m_buf.data(), static_cast<std::streamsize>(written_bytes));
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// determine if need to append ".0"
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const bool value_is_int_like = std::all_of(m_buf.begin(),
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m_buf.begin() + written_bytes + 1,
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[](char c)
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size_t i = 0;
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bool value_is_int_like = true;
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for (i = 0; i < m_buf.size(); ++i)
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{
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// we use %g above, so there cannot be an 'E' character
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return c != '.' and c != 'e';
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});
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// break when end of number is reached
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if (m_buf[i] == '\0')
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{
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break;
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}
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// check if we find non-int character
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value_is_int_like = value_is_int_like and m_buf[i] != '.' and
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m_buf[i] != 'e' and m_buf[i] != 'E';
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}
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if (value_is_int_like)
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{
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o.write(".0", 2);
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// there must be 2 bytes left for ".0"
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assert((i + 2) < m_buf.size());
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// we write to the end of the number
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assert(m_buf[i] == '\0');
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assert(m_buf[i - 1] != '\0');
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// add ".0"
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m_buf[i] = '.';
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m_buf[i + 1] = '0';
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// the resulting string is properly terminated
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assert(m_buf[i + 2] == '\0');
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}
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}
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};
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@ -8546,19 +8566,19 @@ class basic_json
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case value_t::number_integer:
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{
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numtostr(m_value.number_integer, o);
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o << numtostr(m_value.number_integer).c_str();
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return;
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}
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case value_t::number_unsigned:
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{
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numtostr(m_value.number_unsigned, o);
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o << numtostr(m_value.number_unsigned).c_str();
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return;
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}
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case value_t::number_float:
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{
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numtostr(m_value.number_float, o);
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o << numtostr(m_value.number_float).c_str();
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return;
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}
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@ -8252,9 +8252,14 @@ class basic_json
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{
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public:
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template<typename NumberType>
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numtostr(NumberType value, std::ostream& o)
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numtostr(NumberType value)
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{
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x_write(value, std::is_integral<NumberType>(), o);
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x_write(value, std::is_integral<NumberType>());
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}
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const char* c_str() const
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{
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return m_buf.data();
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}
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private:
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@ -8262,12 +8267,12 @@ class basic_json
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std::array < char, 64 > m_buf{{}};
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template<typename NumberType>
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void x_write(NumberType x, /*is_integral=*/std::true_type, std::ostream& o)
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void x_write(NumberType x, /*is_integral=*/std::true_type)
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{
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// special case for "0"
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if (x == 0)
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{
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o.put('0');
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m_buf[0] = '0';
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return;
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}
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@ -8293,31 +8298,30 @@ class basic_json
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}
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std::reverse(m_buf.begin(), m_buf.begin() + i);
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o.write(m_buf.data(), static_cast<std::streamsize>(i));
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}
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template<typename NumberType>
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void x_write(NumberType x, /*is_integral=*/std::false_type, std::ostream& o)
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void x_write(NumberType x, /*is_integral=*/std::false_type)
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{
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// special case for 0.0 and -0.0
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if (x == 0)
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{
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size_t i = 0;
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if (std::signbit(x))
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{
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o.write("-0.0", 4);
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}
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else
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{
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o.write("0.0", 3);
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m_buf[i++] = '-';
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}
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m_buf[i++] = '0';
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m_buf[i++] = '.';
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m_buf[i] = '0';
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return;
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}
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// get number of digits for a text -> float -> text round-trip
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static constexpr auto d = std::numeric_limits<NumberType>::digits10;
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// the actual conversion; store how many bytes have been written
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auto written_bytes = snprintf(m_buf.data(), m_buf.size(), "%.*g", d, x);
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// the actual conversion
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const auto written_bytes = snprintf(m_buf.data(), m_buf.size(), "%.*g", d, x);
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// negative value indicates an error
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assert(written_bytes > 0);
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@ -8338,7 +8342,6 @@ class basic_json
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{
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const auto end = std::remove(m_buf.begin(), m_buf.begin() + written_bytes, thousands_sep);
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std::fill(end, m_buf.end(), '\0');
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written_bytes -= m_buf.end() - end;
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}
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// convert decimal point to '.'
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@ -8354,19 +8357,36 @@ class basic_json
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}
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}
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o.write(m_buf.data(), static_cast<std::streamsize>(written_bytes));
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// determine if need to append ".0"
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const bool value_is_int_like = std::all_of(m_buf.begin(),
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m_buf.begin() + written_bytes + 1,
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[](char c)
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size_t i = 0;
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bool value_is_int_like = true;
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for (i = 0; i < m_buf.size(); ++i)
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{
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// we use %g above, so there cannot be an 'E' character
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return c != '.' and c != 'e';
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});
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// break when end of number is reached
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if (m_buf[i] == '\0')
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{
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break;
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}
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// check if we find non-int character
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value_is_int_like = value_is_int_like and m_buf[i] != '.' and
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m_buf[i] != 'e' and m_buf[i] != 'E';
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}
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if (value_is_int_like)
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{
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o.write(".0", 2);
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// there must be 2 bytes left for ".0"
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assert((i + 2) < m_buf.size());
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// we write to the end of the number
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assert(m_buf[i] == '\0');
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assert(m_buf[i - 1] != '\0');
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// add ".0"
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m_buf[i] = '.';
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m_buf[i + 1] = '0';
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// the resulting string is properly terminated
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assert(m_buf[i + 2] == '\0');
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}
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}
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};
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@ -8546,19 +8566,19 @@ class basic_json
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case value_t::number_integer:
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{
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numtostr(m_value.number_integer, o);
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o << numtostr(m_value.number_integer).c_str();
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return;
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}
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case value_t::number_unsigned:
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{
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numtostr(m_value.number_unsigned, o);
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o << numtostr(m_value.number_unsigned).c_str();
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return;
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}
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case value_t::number_float:
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{
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numtostr(m_value.number_float, o);
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o << numtostr(m_value.number_float).c_str();
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return;
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}
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