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

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