mirror of https://github.com/tfussell/xlnt
195 lines
6.7 KiB
C++
195 lines
6.7 KiB
C++
// Copyright (c) 2014-2021 Thomas Fussell
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE
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//
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// @license: http://www.opensource.org/licenses/mit-license.php
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// @author: see AUTHORS file
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#pragma once
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#include <xlnt/xlnt_config.hpp>
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#include <algorithm>
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#include <cassert>
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#include <cmath>
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#include <cstddef>
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#include <limits>
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#include <sstream>
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#include <type_traits>
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#undef min
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#undef max
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namespace xlnt {
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namespace detail {
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/// <summary>
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/// constexpr abs
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/// </summary>
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template <typename Number>
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constexpr Number abs(Number val)
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{
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return (val < Number{0}) ? -val : val;
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}
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/// <summary>
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/// constexpr max
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/// </summary>
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template <typename NumberL, typename NumberR>
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constexpr typename std::common_type<NumberL, NumberR>::type max(NumberL lval, NumberR rval)
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{
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return (lval < rval) ? rval : lval;
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}
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/// <summary>
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/// constexpr min
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/// </summary>
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template <typename NumberL, typename NumberR>
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constexpr typename std::common_type<NumberL, NumberR>::type min(NumberL lval, NumberR rval)
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{
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return (lval < rval) ? lval : rval;
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}
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/// <summary>
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/// Floating point equality requires a bit of fuzzing due to the imprecise nature of fp calculation
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/// References:
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/// - Several blogs/articles were referenced with the following being the most useful
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/// -- https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
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/// -- http://realtimecollisiondetection.net/blog/?p=89
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/// - Testing Frameworks {Catch2, Boost, Google}, primarily for selecting the default scale factor
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/// -- None of these even remotely agree
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/// </summary>
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template <typename EpsilonType = float, // the type to extract epsilon from
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typename LNumber, typename RNumber> // parameter types (deduced)
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bool float_equals(const LNumber &lhs, const RNumber &rhs,
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int epsilon_scale = 20) // scale the "fuzzy" equality. Higher value gives a more tolerant comparison
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{
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// a type that lhs and rhs can agree on
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using common_t = typename std::common_type<LNumber, RNumber>::type;
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// asserts for sane usage
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static_assert(std::is_floating_point<LNumber>::value || std::is_floating_point<RNumber>::value,
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"Using this function with two integers is just wasting time. Use ==");
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static_assert(std::numeric_limits<EpsilonType>::epsilon() < EpsilonType{1},
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"epsilon >= 1.0 will cause all comparisons to return true");
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// NANs always compare false with themselves
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if (std::isnan(lhs) || std::isnan(rhs))
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{
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return false;
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}
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// epsilon type defaults to float because even if both args are a higher precision type
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// either or both could have been promoted by prior operations
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// if a higher precision is required, the template type can be changed
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constexpr common_t epsilon = static_cast<common_t>(std::numeric_limits<EpsilonType>::epsilon());
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// the "epsilon" then needs to be scaled into the comparison range
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// epsilon for numeric_limits is valid when abs(x) <1.0, scaling only needs to be upwards
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// in particular, this prevents a lhs of 0 from requiring an exact comparison
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// additionally, a scale factor is applied.
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common_t scaled_fuzz = epsilon_scale * epsilon * max(max(xlnt::detail::abs<common_t>(lhs),
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xlnt::detail::abs<common_t>(rhs)), // |max| of parameters.
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common_t{1}); // clamp
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return ((lhs + scaled_fuzz) >= rhs) && ((rhs + scaled_fuzz) >= lhs);
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}
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class number_serialiser
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{
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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(localeconv()->decimal_point[0] == ',')
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{
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}
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// for printing to file.
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// This matches the output format of excel irrespective of current locale
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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, static_cast<size_t>(len));
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}
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// replacement for std::to_string / s*printf("%f", ...)
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// behaves same irrespective of locale
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std::string serialise_short(double d) const
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{
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char buf[30];
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int len = snprintf(buf, sizeof(buf), "%f", 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, static_cast<size_t>(len));
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}
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double deserialise(const std::string &s, ptrdiff_t *len_converted) const
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{
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assert(!s.empty());
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assert(len_converted != nullptr);
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char *end_of_convert;
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if (!should_convert_comma)
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{
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double d = strtod(s.c_str(), &end_of_convert);
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*len_converted = end_of_convert - s.c_str();
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return d;
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}
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char buf[30];
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assert(s.size() < sizeof(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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double d = strtod(buf, &end_of_convert);
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*len_converted = end_of_convert - buf;
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return d;
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}
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double deserialise(const std::string &s) const
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{
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ptrdiff_t ignore;
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return deserialise(s, &ignore);
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}
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};
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} // namespace detail
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} // namespace xlnt
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