<i18n dev> Integrated: 8159337: Introduce a method in Locale class to return the language tags as per RFC 5646 convention

[Justin Lu]

On Wed, 26 Apr 2023 22:20:37 GMT, Justin Lu <jlu at openjdk.org> wrote:

> Please review this PR which adds the method `caseFoldLanguageTag(String languageTag)` to java.util.Locale.
> 
> This method case folds a language tag to adhere to _[section 2.1.1. Formatting of Language Tags of RFC5646](https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1)_. This format is defined as _"All subtags, including extension and private use subtags, use lowercase letters with two exceptions: two-letter and four-letter subtags that neither appear at the start of the tag nor occur after singletons.  Such two-letter subtags are all uppercase ... and four-letter subtags are titlecase."_.
> 
> 
> In order to match the behavior of existing language tag related Locale methods, this method matches the 2.1.1 RFC5646 specification with the following **exceptions**:
> - Will not case fold variant subtags
> - Will not case fold private use subtags prefixed by "lvariant"
> 
> As an example, `caseFoldLanguageTag("ja-kana-jp-x-lvariant-Oracle-JDK-Standard-Edition")` returns _"ja-Kana-JP-x-lvariant-Oracle-JDK-Standard-Edition"_. Further examples can be seen in the test file.

This pull request has now been integrated.

Changeset: 82bcee76
Author:    Justin Lu <jlu at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/82bcee76ea6f5a0624c3ed1d7e4a262d59bfbe37
Stats:     279 lines in 3 files changed: 274 ins; 3 del; 2 mod

8159337: Introduce a method in Locale class to return the language tags as per RFC 5646 convention

Reviewed-by: naoto, rriggs

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PR: https://git.openjdk.org/jdk/pull/13679