QLocale: Add option to pad numbers with trailing zeroes

EcmaScript mandates that number-to-string functions pad the resulting
strings with zeroes, up to the requested precision. QLocale actually
supports this, under the disguise of the "Alternate" flag, used by
QString::asprintf().

We split this flag into the three options it actually represents and
make IncludeTrailingZeroesAfterDot available as a NumberOption. This
allows us to generate numbers in an EcmaScript compliant way.

In addition, a symmetrical option to reject trailing zeroes when
parsing strings to numbers is added.

[ChangeLog][QtCore][QLocale] Additional flags in QLocale::NumberOption
allow generating strings from doubles in accordance to EcmaScript's
Number.toPrecision(n).

Change-Id: If1090d5a0364a29811011a472afc8b75d0af0a8f
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/src/corelib/io/qtextstream.cpp b/src/corelib/io/qtextstream.cpp
index b8db23329a..80df3a12e1 100644
--- a/src/corelib/io/qtextstream.cpp
+++ b/src/corelib/io/qtextstream.cpp
@@ -2547,6 +2547,7 @@ QTextStream &QTextStream::operator<<(double f)
     }
 
     uint flags = 0;
+    const QLocale::NumberOptions numberOptions = locale().numberOptions();
     if (numberFlags() & ShowBase)
         flags |= QLocaleData::ShowBase;
     if (numberFlags() & ForceSign)
@@ -2555,12 +2556,18 @@ QTextStream &QTextStream::operator<<(double f)
         flags |= QLocaleData::UppercaseBase;
     if (numberFlags() & UppercaseDigits)
         flags |= QLocaleData::CapitalEorX;
-    if (numberFlags() & ForcePoint)
-        flags |= QLocaleData::Alternate;
-    if (locale() != QLocale::c() && !(locale().numberOptions() & QLocale::OmitGroupSeparator))
+    if (numberFlags() & ForcePoint) {
+        flags |= QLocaleData::ForcePoint;
+
+        // Only for backwards compatibility
+        flags |= QLocaleData::AddTrailingZeroes | QLocaleData::ShowBase;
+    }
+    if (locale() != QLocale::c() && !(numberOptions & QLocale::OmitGroupSeparator))
         flags |= QLocaleData::ThousandsGroup;
-    if (!(locale().numberOptions() & QLocale::OmitLeadingZeroInExponent))
+    if (!(numberOptions & QLocale::OmitLeadingZeroInExponent))
         flags |= QLocaleData::ZeroPadExponent;
+    if (numberOptions & QLocale::IncludeTrailingZeroesAfterDot)
+        flags |= QLocaleData::AddTrailingZeroes;
 
     const QLocaleData *dd = d->locale.d->m_data;
     QString num = dd->doubleToString(f, d->params.realNumberPrecision, form, -1, flags);