Summary

Makes CPAN's Switch module (and any other module that uses method-style source filters via Filter::Util::Call) work on PerlOnJava.

./jcpan -t Switch before: all 3 test files fail with syntax error ... near "" (0/3).
./jcpan -t Switch after: Files=3, Tests=590, Result: PASS.

Root cause

Switch.pm is a source filter. In its import() it calls filter_add({}) (a hashref), which Filter::Util::Call blesses into the caller's package — a method filter. Its filter() method does filter_read(1_000_000) to slurp the whole source, then rewrites switch/case blocks via Text::Balanced.

Two bugs in FilterUtilCall.java broke this:

1. Method filters were unimplemented. applyFilters() had an explicit // TODO: Implement method filter calling branch that just returned the source unchanged, so switch (...) { case ... } was passed verbatim to the parser.
2. filter_read($blocksize) was broken in block mode. The read loop broke out on the first "\n", turning block reads into line reads. Switch::filter asked for 1,000,000 bytes but got only "\n" then "switch (1) {\n", so Text::Balanced::_match_codeblock failed with Bad switch statement (problem in the code block?).

Fix

In src/main/java/org/perlonjava/runtime/perlmodule/FilterUtilCall.java:

• Method-filter support: resolve ${pkg}::filter via InheritanceResolver.findMethodInHierarchy, call it with the blessed filter object as $self, accumulate $_, and loop until status ≤ 0 — matching the closure-filter loop that was already there.
• Block-mode fix: remove the erroneous if (line.endsWith("\n")) break; so filter_read($n) reads up to $n bytes instead of up to one line.

Test plan

• make — BUILD SUCCESSFUL, all unit tests pass, no regressions
• ./jcpan -t Switch — Files=3, Tests=590, Result: PASS
  • t/given.t — 293/293
  • t/nested.t — 4/4
  • t/switch.t — 293/293

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