[loc-en-dev] About Locale#toString()

[Yoshito Umaoka]

In the bi-weekly project call, we agreed not to change the behavior of 
toString().  This implies that you won't get any new field information 
(such as script and extensions) returned by toString().

In the current proposed API set, we have toLanguageTag(), which returns 
syntactically valid BCP47 language tag string.  However, subtags in a 
BCP47 language tag is delimited by hyphen('-') instead of 
underscore('_').  One of the goals in this project is to include script 
field value involved in the resource bundle lookup inheritance. 
Therefore, I would like to have a method creating a locale string 
delimited by underscore, which can be used for resource bundle suffix. 
(Technically, this can be achieved by composing the string by appending 
getLanguage(), getScript()...)  This is a common operation and I think 
it is worth having such API.

I'm considering following three APIs for the purpose.

String toFullString()
Locale getBaseLocale()
Locale getParent()


toFullString() is a variant of toString() to generate a string 
representation of Locale, but also include script and extensions if they 
are available.

getBaseLocale() returns a Locale (proposed implementation is to return a 
singleton) without locale extensions.  Locale extensions is not used for 
resource bundle lookup.

getParent() returns a parent Locale (proposed implementation is to 
return a singleton).  A parent locale represent a locale omitting the 
most right field of its child locale.  For example, Locale("en") is a 
parent locale of Locale("en", "US").  If a locale has a variant field 
and the variant field contains one or more underscore characters, then 
its parent still have variant field, but excluding the substring after 
the last underscore.  For example, Locale("en", "US", "NYC") is a parent 
locale of Locale("en", "US", "NYC_JFK")

With these 3 APIs, the resource bundle is collecting key-value pairs 
with the pseudo code below -

Locale target; // the resolved Locale
Locale loc = target;
ResourceBundleImpl child = null;
while (true) {
     ResourceBundleImpl aBundle = loadFrom(bundleBaseName + "_" +
         loc.getBaseLocale().toFullString());
     if (child != null) {
         child.parent = aBundle;
     }
     loc = loc.getParent();
     if (loc == null) {
         // Locale.ROOT.getParent() returns null
         break;
     }
     child = aBundle;
}

Do you think we should have such APIs?  Also, if you do, do you want to 
make them public or keep them package local/private?

-Yoshito