runtime(java): Provide support for syntax preview features
Introduce a new API variable "g:java_syntax_previews" whose
value must be a list of syntax preview feature numbers.
Enumerate the currently supported numbers in a table at the
end of the documentation entry for "ft-java-syntax".
Also, disable the recognition of String Templates. Despite
the withdrawal of this preview feature in its proposed form
from the upcoming JDK 23 release and the fact that the JDK
22 release is coming to EOL this September, an earlier
iteration of this preview feature was included in JDK 21
(LTS) whose EOL is projected to fall due in late 2028 and,
therefore, retain the current implementation.
Define "g:java_syntax_previews" and include number 430 in
its list to enable the recognition of String Templates:
------------------------------------------------------------
let g:java_syntax_previews = [430]
------------------------------------------------------------
References:
https://openjdk.org/jeps/430 (Preview)
https://openjdk.org/jeps/459 (Second Preview)
https://openjdk.org/jeps/465 (Third Preview)
https://mail.openjdk.org/pipermail/amber-spec-experts/2024-April/004106.html
closes: #15579
Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 736e664..5d67ba6 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt* For Vim version 9.1. Last change: 2024 Aug 22
+*syntax.txt* For Vim version 9.1. Last change: 2024 Aug 26
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -2164,6 +2164,22 @@
displayed line. The default value is 10. The disadvantage of using a larger
number is that redrawing can become slow.
+Significant changes to the Java platform are gradually introduced in the form
+of JDK Enhancement Proposals (JEPs) that can be implemented for a release and
+offered as its preview features. It may take several JEPs and a few release
+cycles for such a feature to become either integrated into the platform or
+withdrawn from this effort. To cater for early adopters, there is optional
+support in Vim for syntax related preview features that are implemented. You
+can request it by specifying a list of preview feature numbers as follows: >
+ :let g:java_syntax_previews = [430]
+
+The supported JEP numbers are to be drawn from this table:
+ `430`: String Templates [JDK 21]
+
+Note that as soon as the particular preview feature will have been integrated
+into the Java platform, its entry will be removed from the table and related
+optionality will be discontinued.
+
JSON *json.vim* *ft-json-syntax* *g:vim_json_conceal*
*g:vim_json_warnings*