Fix interpreter package scoping, array interpolation, and scalar context

[fglock]

Summary

This PR fixes three critical bugs in the interpreter that were preventing proper package scoping, array interpolation in strings, and scalar context handling.

1. Package Scoping for our Variables (a9edd88)

Problem: our @ISA = (...) in non-main packages created @main::ISA instead of @Obj2::ISA, breaking method inheritance.

Solution: Updated the "package" operator handler to extract the package name from the AST and update the currentPackage field, mirroring how the compiled backend uses the symbol table.

Impact:

• ✅ Method inheritance via @ISA now works in all packages
• ✅ Qualified access @Obj2::X now sees values from unqualified @X
• ✅ Object tests fully pass (10/10 including inheritance tests)

2. Array Interpolation in Strings (47c4901)

Problem: Array interpolation like "@array" was converting arrays to scalar count instead of space-separated elements.

• Example: my @x=(1,2,3); "@x" produced "3" instead of "1 2 3"

Root Cause: The parser converts "@array" into BinaryOperatorNode(join, $", @array). The interpreter compiled both operands in the current context (SCALAR), causing the array to be converted to its size instead of being expanded.

Solution: Added special handling for the "join" operator before general operand compilation, explicitly setting contexts:

• Left operand (separator $"): SCALAR context
• Right operand (array): LIST context

Impact:

• ✅ Array interpolation in strings works correctly
• ✅ Sort tests fully pass (5/5) - were failing because Test::More uses "@sorted"

3. Scalar Context Handling (29189e1)

Problem: scalar(@array) and keys %hash returned joined strings instead of counts.

• Example: scalar(@x) where @x=(1,2,3) returned "123" instead of 3
• Test::More is(keys %h, 0, "msg") received wrong argument types

Root Causes:

1. scalar() operator set context but didn't emit ARRAY_SIZE opcode
2. ListNode always created RuntimeList regardless of context
3. Parser generates scalar(@x) as OperatorNode(scalar, ListNode(@x))
4. ListNode wrapped array in list, then scalar() got size of wrapper (1) not array (3)

Solution:

1. scalar() operator: Explicitly emit ARRAY_SIZE after evaluating operand
2. ListNode in SCALAR context: Match compiled backend behavior
   • Evaluate all elements except last for side effects (discard results)
   • Return only the last element's value (not wrapped in RuntimeList)

Impact:

• ✅ scalar(@array) returns array count
• ✅ keys %hash in scalar context returns correct count
• ✅ Test::More argument handling works correctly
• ✅ All demo.t tests now pass (9/9)

Changes

• BytecodeCompiler.java: Package operator now updates currentPackage
• BytecodeCompiler.java: Special handling for "join" operator contexts
• BytecodeCompiler.java: Fixed scalar() operator to emit ARRAY_SIZE
• BytecodeCompiler.java: Fixed ListNode to handle scalar context properly
• BytecodeInterpreter.java: Added CALL_METHOD opcode support
• InterpretedCode.java: Added disassembler entries for global arrays/hashes

Testing

make test-unit          # All pass ✅
./jperl --interpreter src/test/resources/unit/demo.t
  ok 1 - Variable assignment and modification
  ok 2 - List assignment in scalar context
  ok 3 - List assignment with lvalue array and hash
  ok 4 - Basic syntax tests
  ok 5 - Splice tests
  ok 6 - Map tests
  ok 7 - Grep tests
  ok 8 - Sort tests
  ok 9 - Object tests
  1..9                  # All tests pass ✅

Specific test cases verified:

• our @ISA = ("Parent") in non-main packages ✅
• Method inheritance via @ISA ✅
• Array interpolation: "@array" ✅
• scalar(@array) returns count ✅
• keys %hash in scalar context ✅
• Test::More is() with array/hash operations ✅

🤖 Generated with Claude Code