locale aware double->string conversions

include/xlnt/utils/numeric.hpp

@@ -129,10 +129,12 @@ class number_serialiser
 
 public:
     explicit number_serialiser()
-        : should_convert_comma(std::use_facet<std::numpunct<char>>(std::locale{}).decimal_point() == ',')
+        : should_convert_comma(localeconv()->decimal_point[0] == ',')
     {
     }
 
+    // for printing to file.
+    // This matches the output format of excel irrespective of current locale
     std::string serialise(double d) const
     {
         char buf[30];
@@ -144,29 +146,43 @@ class number_serialiser
         return std::string(buf, static_cast<size_t>(len));
     }
 
-    double deserialise(std::string &s) const noexcept
+    // replacement for std::to_string / s*printf("%f", ...)
+    // behaves same irrespective of locale
+    std::string serialise_short(double d) const
     {
-        assert(!s.empty());
+        char buf[30];
+        int len = snprintf(buf, sizeof(buf), "%f", d);
         if (should_convert_comma)
         {
-            // s.data() doesn't have a non-const overload until c++17, hence this little dance
-            convert_pt_to_comma(&s[0], s.size());
+            convert_comma_to_pt(buf, len);
         }
-        return strtod(s.c_str(), nullptr);
+        return std::string(buf, static_cast<size_t>(len));
     }
 
-    double deserialise(const std::string &s) const
+    double deserialise(const std::string &s, ptrdiff_t *len_converted) const
     {
         assert(!s.empty());
+        assert(len_converted != nullptr);
+        char *end_of_convert;
         if (!should_convert_comma)
         {
-            return strtod(s.c_str(), nullptr);
+            double d = strtod(s.c_str(), &end_of_convert);
+            *len_converted = end_of_convert - s.c_str();
+            return d;
         }
         char buf[30];
         assert(s.size() < sizeof(buf));
         auto copy_end = std::copy(s.begin(), s.end(), buf);
         convert_pt_to_comma(buf, static_cast<size_t>(copy_end - buf));
-        return strtod(buf, nullptr);
+        double d = strtod(buf, &end_of_convert);
+        *len_converted = end_of_convert - buf;
+        return d;
+    }
+
+    double deserialise(const std::string &s) const
+    {
+        ptrdiff_t ignore;
+        return deserialise(s, &ignore);
     }
 };
 

source/cell/cell.cpp

@@ -57,15 +57,16 @@
 #include <detail/implementations/hyperlink_impl.hpp>
 #include <detail/implementations/stylesheet.hpp>
 #include <detail/implementations/worksheet_impl.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace {
 
 std::pair<bool, double> cast_numeric(const std::string &s)
 {
-    auto str_end = static_cast<char *>(nullptr);
-    auto result = std::strtod(s.c_str(), &str_end);
-
-    return (str_end != s.c_str() + s.size())
+    xlnt::detail::number_serialiser ser;
+    ptrdiff_t len_convert;
+    double result = ser.deserialise(s, &len_convert);
+    return (len_convert != static_cast<ptrdiff_t>(s.size()))
         ? std::make_pair(false, 0.0)
         : std::make_pair(true, result);
 }
@@ -108,7 +109,7 @@ std::pair<bool, xlnt::time> cast_time(const std::string &s)
     }
 
     std::vector<double> numeric_components;
-
+    xlnt::detail::number_serialiser ser;
     for (auto component : time_components)
     {
         if (component.empty() || (component.substr(0, component.find('.')).size() > 2))
@@ -123,9 +124,7 @@ std::pair<bool, xlnt::time> cast_time(const std::string &s)
                 return {false, result};
             }
         }
-
-        auto without_leading_zero = component.front() == '0' ? component.substr(1) : component;
-        auto numeric = std::stod(without_leading_zero);
+        auto numeric = ser.deserialise(component);
 
         numeric_components.push_back(numeric);
     }

source/detail/number_format/number_formatter.cpp

@@ -26,6 +26,7 @@
 #include <cmath>
 
 #include <xlnt/utils/exceptions.hpp>
+#include <xlnt/utils/numeric.hpp>
 #include <detail/default_case.hpp>
 #include <detail/number_format/number_formatter.hpp>
 
@@ -622,7 +623,8 @@ void number_format_parser::parse()
                 value = token.string.substr(1);
             }
 
-            section.condition.value = std::stod(value);
+            detail::number_serialiser ser;
+            section.condition.value = ser.deserialise(value);
             break;
         }
 
@@ -1565,19 +1567,16 @@ std::string number_formatter::fill_placeholders(const format_placeholders &p, do
     if (p.type == format_placeholders::placeholders_type::general
         || p.type == format_placeholders::placeholders_type::text)
     {
-        result = std::to_string(number);
-
-        while (result.back() == '0')
+        auto s = serialiser_.serialise_short(number);
+        while (s.size() > 1 && s.back() == '0')
         {
-            result.pop_back();
+            s.pop_back();
         }
-
-        if (result.back() == '.')
+        if (s.back() == '.')
         {
-            result.pop_back();
+            s.pop_back();
         }
-
-        return result;
+        return s;
     }
 
     if (p.percentage)
@@ -1636,21 +1635,22 @@ std::string number_formatter::fill_placeholders(const format_placeholders &p, do
         auto fractional_part = number - integer_part;
         result = std::fabs(fractional_part) < std::numeric_limits<double>::min()
             ? std::string(".")
-            : std::to_string(fractional_part).substr(1);
+            : serialiser_.serialise_short(fractional_part).substr(1);
 
         while (result.back() == '0' || result.size() > (p.num_zeros + p.num_optionals + p.num_spaces + 1))
         {
             result.pop_back();
         }
 
-        while (result.size() < p.num_zeros + 1)
+
+        if (result.size() < p.num_zeros + 1)
         {
-            result.push_back('0');
+            result.resize(p.num_zeros + 1, '0');
         }
 
-        while (result.size() < p.num_zeros + p.num_optionals + p.num_spaces + 1)
+        if (result.size() < p.num_zeros + p.num_optionals + p.num_spaces + 1)
         {
-            result.push_back(' ');
+            result.resize(p.num_zeros + p.num_optionals + p.num_spaces + 1, ' ');
         }
 
         if (p.percentage)
@@ -1689,13 +1689,7 @@ std::string number_formatter::fill_scientific_placeholders(const format_placehol
         integer_string = std::string(integer_part.num_zeros + integer_part.num_optionals, '0');
     }
 
-    std::string fractional_string = std::to_string(fraction).substr(1);
-
-    while (fractional_string.size() > fractional_part.num_zeros + fractional_part.num_optionals + 1)
-    {
-        fractional_string.pop_back();
-    }
-
+    std::string fractional_string = serialiser_.serialise_short(fraction).substr(1, fractional_part.num_zeros + fractional_part.num_optionals + 1);
     std::string exponent_string = std::to_string(logarithm);
 
     while (exponent_string.size() < fractional_part.num_zeros)

source/detail/number_format/number_formatter.hpp

@@ -28,6 +28,7 @@
 #include <vector>
 
 #include <xlnt/utils/datetime.hpp>
+#include <xlnt/utils/numeric.hpp>
 
 namespace xlnt {
 namespace detail {
@@ -691,6 +692,7 @@ class XLNT_API number_formatter
     number_format_parser parser_;
     std::vector<format_code> format_;
     xlnt::calendar calendar_;
+    xlnt::detail::number_serialiser serialiser_;
 };
 
 } // namespace detail

source/detail/serialization/serialisation_helpers.hpp

@@ -0,0 +1,96 @@
+#ifndef XLNT_DETAIL_SERIALISATION_HELPERS_HPP
+#define XLNT_DETAIL_SERIALISATION_HELPERS_HPP
+
+#include <xlnt/cell/cell_type.hpp>
+#include <xlnt/cell/index_types.hpp>
+#include <string>
+
+namespace xlnt {
+namespace detail {
+
+/// parsing assumptions used by the following functions
+/// - on entry, the start element for the element has been consumed by parser->next
+/// - on exit, the closing element has been consumed by parser->next
+/// using these assumptions, the following functions DO NOT use parser->peek (SLOW!!!)
+/// probable further gains from not building an attribute map and using the attribute events instead as the impl just iterates the map
+
+/// 'r' == cell reference e.g. 'A1'
+/// https://docs.microsoft.com/en-us/openspecs/office_standards/ms-oe376/db11a912-b1cb-4dff-b46d-9bedfd10cef0
+///
+/// a lightweight version of xlnt::cell_reference with no extre functionality (absolute/relative, ...)
+/// many thousands are created during (de)serialisation, so even minor overhead is noticable
+struct Cell_Reference
+{
+    // the obvious ctor
+    explicit Cell_Reference(xlnt::row_t row_arg, xlnt::column_t::index_t column_arg) noexcept
+        : row(row_arg), column(column_arg)
+    {
+    }
+
+    // the common case. row # is already known during parsing (from parent <row> element)
+    // just need to evaluate the column
+    explicit Cell_Reference(xlnt::row_t row_arg, const std::string &reference) noexcept
+        : row(row_arg)
+    {
+        // only three characters allowed for the column
+        // assumption:
+        // - regex pattern match: [A-Z]{1,3}\d{1,7}
+        const char *iter = reference.c_str();
+        int temp = *iter - 'A' + 1; // 'A' == 1
+        ++iter;
+        if (*iter >= 'A') // second char
+        {
+            temp *= 26; // LHS values are more significant
+            temp += *iter - 'A' + 1; // 'A' == 1
+            ++iter;
+            if (*iter >= 'A') // third char
+            {
+                temp *= 26; // LHS values are more significant
+                temp += *iter - 'A' + 1; // 'A' == 1
+            }
+        }
+        column = static_cast<xlnt::column_t::index_t>(temp);
+    }
+
+    // for sorting purposes
+    bool operator<(const Cell_Reference &rhs)
+    {
+        // row first, serialisation is done by row then column
+        if (row < rhs.row)
+        {
+            return true;
+        }
+        else if (rhs.row < row)
+        {
+            return false;
+        }
+        // same row, column comparison
+        return column < rhs.column;
+    }
+
+    xlnt::row_t row; // range:[1, 1048576]
+    xlnt::column_t::index_t column; // range:["A", "ZZZ"] -> [1, 26^3] -> [1, 17576]
+};
+
+// <c> inside <row> element
+// https://docs.microsoft.com/en-us/dotnet/api/documentformat.openxml.spreadsheet.cell?view=openxml-2.8.1
+struct Cell
+{
+    // sort cells by location, row first
+    bool operator<(const Cell &rhs)
+    {
+        return ref < rhs.ref;
+    }
+
+    bool is_phonetic = false; // 'ph'
+    xlnt::cell_type type = xlnt::cell_type::number; // 't'
+    int cell_metatdata_idx = -1; // 'cm'
+    int style_index = -1; // 's'
+    Cell_Reference ref{0, 0}; // 'r'
+    std::string value; // <v> OR <is>
+    std::string formula_string; // <f>
+};
+
+} // namespace detail
+} // namespace xlnt
+#endif