fix(extraction): detect export-macro-annotated class in .h language check

[luoyxy]

Summary

A .h file defaults to C and is only reclassified as C++ when looksLikeCpp finds a C++-specific construct. Its class branch (\bclass\s+\w+\s*[:{]) could not see through an export/visibility macro: in class ENGINE_API UFoo : public UObject the macro sits between class and the type name, so \w+ consumed the macro and the trailing [:{] guard failed to match.

A lean Unreal-Engine header carrying only that macro-annotated class plus GENERATED_BODY() — with no public: / virtual / namespace / template to fall back on — was therefore parsed as C. The C extractor has classTypes: [] and no export-macro pre-parse, so the class definition and its inheritance edge silently vanished from the graph, quietly undoing the macro-class recovery from #1061.

This is a language-detection gap, distinct from #1061 (which correctly blanks the macro after the file is already routed as C++) — the file never reached the C++ path in the first place.

Fix

Add a detection branch to looksLikeCpp for a macro-annotated class/struct declaration, mirroring the exact shape blankCppExportMacros already recovers before parsing:

\b(?:class|struct)\s+[A-Z][A-Z0-9_]+\s+\w+\s*(?:final\s*)?[:{]

The two-token <keyword> <MACRO> <Name> before a [:{] never occurs in valid C, so genuine C headers are unaffected.

Repro (verified)

Header	Before	After
class ENGINE_API UFoo : public UObject (no other C++ signal)	detected c, 0 class nodes	detected cpp, 1 class node
Same header with public: present	cpp (already worked)	cpp

Test plan

• New regression test in __tests__/extraction.test.ts (macro-class header detects as cpp; macro-struct with inheritance; plain C header still detects as c)
• npm run build succeeds
• No new failures vs. baseline in extraction.test.ts

Thanks for CodeGraph! Follow-up to #1061.

Made with Cursor

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Fixes #1159.