On Sat, 27 Mar 2021 15:19:37 GMT, Attila Szegedi <att...@openjdk.org> wrote:
> I noticed that `javax.script.ScriptEngineManager` `getEngineByXxx` methods
> had a lot of code duplication among themselves, and even within each method.
> I refactored them into a modern unified implementation. While there I also
> took the opportunity to introduce `Objects.requireNonNull` in place of null
> checks followed by NPE throws, mark private fields final where possible, use
> lambdas for `doPrivileged` block, use `List.of` and `List.copyOf` where
> possible, and generally sanitize/deduplicate.
src/java.scripting/share/classes/javax/script/ScriptEngineManager.java line 224:
> 222: try {
> 223: List<String> matches = valuesFn.apply(spi);
> 224: return matches != null && matches.contains(selector);
Note this under anomalous conditions, calling `List.contains` here can result
in somewhat different behavior than [what was here
before](https://github.com/openjdk/jdk/blob/master/src/java.scripting/share/classes/javax/script/ScriptEngineManager.java#L238).
Notably:
* if `spi` returns a list that contains the selector value _at least twice_, and
* it throws an exception while creating the engine for the first time, then
* the previous implementation will invoke `getScriptEngine` for the second time
too.
My modified implementation will ignore multiple occurrences of the selector
value in the returned list. I believe that behavior is correct, especially
since the list of values for engine names, extensions, and mime types is
expected to contain unique entries (too bad the interface didn't define these
methods to return a `Set<String>`…)
-------------
PR: https://git.openjdk.java.net/jdk/pull/3229
