Instead of returning just bool, return a result struct {State,
CharBuff}, a State is useful as it can have an Intermediate state
where the input isn't Acceptable yet, but not Invalid as such. The
example from the linked bug is in tst_QIntValidator::validateFrench(), a
string "1 ", which can be interpretted as a number with a group
separator, but the input shouldn't end with a group separator (changing
the unittest will be done as part of a separate commit).
CharBuff (QVarLengthArray<char, 256>) replaces the QByteArray input
parameter; a QVarLengthArray means no heap allocation in typical
use-cases with input text < 256 characters to validate. This required
minimum changes (QVLA doesn't have startsWith, replaced by comparing
with buff[0]; and for converting to double, wrapped it in a QBAV).
Task-number: QTBUG-111371
Change-Id: I4e0eb612d470ef03faf52031ddfe9c4bdb31e1e1
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
67129ef9cd