Created a RAII class to switch LC_NUMERIC to "C" and back

src/libslic3r/CMakeLists.txt

@@ -126,6 +126,8 @@ add_library(libslic3r STATIC
     Line.hpp
     LibraryCheck.cpp
     LibraryCheck.hpp
+    LocalesUtils.cpp
+    LocalesUtils.hpp
     Model.cpp
     Model.hpp
     ModelArrange.hpp

src/libslic3r/LocalesUtils.cpp

@@ -0,0 +1,59 @@
+#include "LocalesUtils.hpp"
+
+
+namespace Slic3r {
+
+
+CNumericLocalesSetter::CNumericLocalesSetter()
+{
+#ifdef _WIN32
+    _configthreadlocale(_ENABLE_PER_THREAD_LOCALE);
+    m_orig_numeric_locale = std::setlocale(LC_NUMERIC, nullptr);
+    std::setlocale(LC_NUMERIC, "C");
+#else
+    m_original_locale = uselocale((locale_t)0);
+    m_new_locale = duplocale(m_original_locale);
+    m_new_locale = newlocale(LC_NUMERIC_MASK, "C", m_new_locale);
+    uselocale(m_new_locale);
+#endif
+}
+
+
+
+CNumericLocalesSetter::~CNumericLocalesSetter()
+{
+#ifdef _WIN32
+    std::setlocale(LC_NUMERIC, m_orig_numeric_locale)
+#else
+    uselocale(m_original_locale);
+    freelocale(m_new_locale);
+#endif
+}
+
+
+
+bool is_decimal_separator_point()
+{
+    char str[5] = "";
+    sprintf(str, "%.1f", 0.5f);
+    return str[1] == '.';
+}
+
+std::string float_to_string_decimal_point(double value, int precision/* = -1*/)
+{
+    assert(is_decimal_separator_point());
+    std::stringstream buf;
+    if (precision >= 0)
+        buf << std::fixed << std::setprecision(precision);
+    buf << value;
+    return buf.str();
+}
+
+std::string float_to_string_decimal_point(float value, int precision/* = -1*/)
+{
+    return float_to_string_decimal_point(double(value), precision);
+}
+
+
+} // namespace Slic3r
+

src/libslic3r/LocalesUtils.hpp

@@ -0,0 +1,47 @@
+#ifndef slic3r_LocalesUtils_hpp_
+#define slic3r_LocalesUtils_hpp_
+
+#include <string>
+#include <clocale>
+#include <iomanip>
+#include <cassert>
+
+#ifdef __APPLE__
+#include <xlocale.h>
+#endif
+
+namespace Slic3r {
+
+// RAII wrapper that sets LC_NUMERIC to "C" on construction
+// and restores the old value on destruction.
+class CNumericLocalesSetter {
+public:
+    CNumericLocalesSetter();
+    ~CNumericLocalesSetter();
+
+private:
+#ifdef _WIN32
+    std::string m_orig_numeric_locale;
+#else
+    locale_t m_original_locale;
+    locale_t m_new_locale;
+#endif
+
+};
+
+// A function to check that current C locale uses decimal point as a separator.
+// Intended mostly for asserts.
+bool is_decimal_separator_point();
+
+
+// A substitute for std::to_string that works according to
+// C++ locales, not C locale. Meant to be used when we need
+// to be sure that decimal point is used as a separator.
+// (We use user C locales and "C" C++ locales in most of the code.)
+std::string float_to_string_decimal_point(double value, int precision = -1);
+std::string float_to_string_decimal_point(float value,  int precision = -1);
+
+
+} // namespace Slic3r
+
+#endif // slic3r_LocalesUtils_hpp_