Add wxString::FromDouble() and FromCDouble().

wxString::FromCDouble() is needed inside wxWidgets itself to format numbers
independently of the current locale. FromDouble() was added for symmetry with
ToDouble/ToCDouble() functions.

Use std::locale for the implementation if available and manual wxLocale-based
fallback otherwise.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64449 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/string.h

@@ -2288,6 +2288,13 @@ public:
       // convert to a double
   bool ToCDouble(double *val) const;
 
+  // create a string representing the given floating point number
+    // in the current locale
+  static wxString FromDouble(double val)
+    { return wxString::Format(wxS("%g"), val); }
+    // in C locale
+  static wxString FromCDouble(double val);
+
 #ifndef wxNEEDS_WXSTRING_PRINTF_MIXIN
   // formatted input/output
     // as sprintf(), returns the number of characters written or < 0 on error

interface/wx/string.h

@@ -1507,6 +1507,36 @@ public:
     static wxString FromAscii(char c);
     //@}
 
+    /**
+        Returns a string with the textual representation of the number in C
+        locale.
+
+        Unlike FromDouble() the string returned by this function always uses
+        the period character as decimal separator, independently of the current
+        locale.
+
+        @since 2.9.1
+
+        @see ToCDouble()
+     */
+    static wxString FromCDouble(double val);
+
+    /**
+        Returns a string with the textual representation of the number.
+
+        This is a simple wrapper for @code wxString::Format("%g", val)
+        @endcode.
+
+        Notice that the string returned by this function uses the decimal
+        separator appropriate for the current locale, e.g. @c "," and not a
+        period in French locale. Use FromCDouble() if this is unwanted.
+
+        @since 2.9.1
+
+        @see ToDouble()
+     */
+    static wxString FromDouble(double val);
+
     //@{
     /**
         Converts C string encoded in UTF-8 to wxString.

src/common/string.cpp

@@ -45,6 +45,10 @@
     #include "wx/msw/wrapwin.h"
 #endif // __WXMSW__
 
+#if wxUSE_STD_IOSTREAM
+    #include <sstream>
+#endif
+
 // string handling functions used by wxString:
 #if wxUSE_UNICODE_UTF8
     #define wxStringMemcpy   memcpy
@@ -1785,6 +1789,37 @@ bool wxString::ToCDouble(double *pVal) const
 
 #endif  // wxUSE_XLOCALE/!wxUSE_XLOCALE
 
+// ----------------------------------------------------------------------------
+// number to string conversion
+// ----------------------------------------------------------------------------
+
+/* static */
+wxString wxString::FromCDouble(double val)
+{
+#if wxUSE_STD_IOSTREAM && wxUSE_STD_STRING
+    // We assume that we can use the ostream and not wstream for numbers.
+    wxSTD ostringstream os;
+    os << val;
+    return os.str();
+#else // wxUSE_STD_IOSTREAM
+    // Can't use iostream locale support, fall back to the manual method
+    // instead.
+    wxString s = FromDouble(val);
+#if wxUSE_INTL
+    wxString sep = wxLocale::GetInfo(wxLOCALE_DECIMAL_POINT,
+                                     wxLOCALE_CAT_NUMBER);
+#else // !wxUSE_INTL
+    // As above, this is the most common alternative value. Notice that here it
+    // doesn't matter if we guess wrongly and the current separator is already
+    // ".": we'll just waste a call to Replace() in this case.
+    wxString sep(",");
+#endif // wxUSE_INTL/!wxUSE_INTL
+
+    s.Replace(sep, ".");
+    return s;
+#endif // wxUSE_STD_IOSTREAM/!wxUSE_STD_IOSTREAM
+}
+
 // ---------------------------------------------------------------------------
 // formatted output
 // ---------------------------------------------------------------------------

tests/strings/strings.cpp

@@ -53,6 +53,7 @@ private:
         CPPUNIT_TEST( ToULongLong );
 #endif // wxLongLong_t
         CPPUNIT_TEST( ToDouble );
+        CPPUNIT_TEST( FromDouble );
         CPPUNIT_TEST( StringBuf );
         CPPUNIT_TEST( UTF8Buf );
         CPPUNIT_TEST( CStrDataTernaryOperator );
@@ -85,6 +86,7 @@ private:
     void ToULongLong();
 #endif // wxLongLong_t
     void ToDouble();
+    void FromDouble();
     void StringBuf();
     void UTF8Buf();
     void CStrDataTernaryOperator();
@@ -747,6 +749,41 @@ void StringTestCase::ToDouble()
     }
 }
 
+void StringTestCase::FromDouble()
+{
+    static const struct FromDoubleTestData
+    {
+        double value;
+        const char *str;
+    } testData[] =
+    {
+        { 1.23,             "1.23" },
+        { -3e-10,           "-3e-10" },
+        { -0.45678,         "-0.45678" },
+    };
+
+    for ( unsigned n = 0; n < WXSIZEOF(testData); n++ )
+    {
+        const FromDoubleTestData& td = testData[n];
+        CPPUNIT_ASSERT_EQUAL( td.str, wxString::FromCDouble(td.value) );
+    }
+
+    if ( !wxLocale::IsAvailable(wxLANGUAGE_FRENCH) )
+        return;
+
+    wxLocale locale;
+    CPPUNIT_ASSERT( locale.Init(wxLANGUAGE_FRENCH, wxLOCALE_DONT_LOAD_DEFAULT) );
+
+    for ( unsigned m = 0; m < WXSIZEOF(testData); m++ )
+    {
+        const FromDoubleTestData& td = testData[m];
+
+        wxString str(td.str);
+        str.Replace(".", ",");
+        CPPUNIT_ASSERT_EQUAL( str, wxString::FromDouble(td.value) );
+    }
+}
+
 void StringTestCase::StringBuf()
 {
     // check that buffer can be used to write into the string