[foreign-jextract] RFR: 8253725: Jextract fails to extract big monolithic headers [v2]

[Maurizio Cimadamore]

> This patch adds support for splitting the symbols in the main header class into multiple classes; the header class is
> then rewrited to extend all these additional classes, so that all symbols would be exposed to users in the classic way.
> I've toyed with some ways to split on a by-header basis, but found that in certain cases we would generate near-empty
> classes - and that would still not prevent issues from occurring in the corner case a single very big header file
> contained so many symbols.  I've reorganized the code a bit - I noted that we were generating several nested classes,
> but in some cases (structs) we were using a builder, in other cases (functional interfaces, typedef) we weren't. Now we
> use builders for classes, and I've added an intermediate nested builder abstraction which does the right thing for all
> nested cases.  I've also converted the source constant generator to be a JavaSourceBuilder too - since it too is a
> class, after all, with a classBegin/End and build methods.  Finally, I moved the string builder/indentation logic out
> to a different class (StringSourceBuilder); since some builders want to have their own string buffer, while others (the
> nested ones) don't.  The organization of the builder code is still far from optimal, but I think that, moving forward,
> this consolidation should make it easier to make changes.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Remove redundant import generation

-------------

Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/357/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/357/files/f36d7651..03048f74

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=357&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=357&range=00-01

  Stats: 11 lines in 1 file changed: 0 ins; 11 del; 0 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/357.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/357/head:pull/357

PR: https://git.openjdk.java.net/panama-foreign/pull/357