refactor: Create patterns package for pattern detection (PR #6)

[shivasurya]

Summary

Creates dedicated patterns package for security pattern detection and framework identification. This PR isolates pattern matching logic into a clean, testable package structure.

Changes

New Package Structure

graph/callgraph/patterns/
├── detector.go        # Pattern matching & vulnerability detection (475 LOC)
├── frameworks.go      # Framework detection helpers (52 LOC)
├── helpers.go         # AST traversal helpers (34 LOC)
├── doc.go            # Package documentation (32 LOC)
└── detector_test.go   # Comprehensive tests (15 tests)

Files Modified

• patterns.go - Backward compatibility wrappers with type aliases

Key Features

• PatternRegistry for managing security patterns
• 3 Pattern Types: SourceSink, MissingSanitizer, DangerousFunction
• Framework Detection: Django, Flask, FastAPI, Tornado, etc.
• Taint Analysis Integration: Intra-procedural vulnerability detection
• Full Backward Compatibility: All existing code continues to work

Pattern Matching

registry := patterns.NewPatternRegistry()
registry.AddPattern(&patterns.Pattern{
    ID: "SQL-INJECTION-001",
    Type: patterns.PatternTypeMissingSanitizer,
    Sources: []string{"request.GET", "request.POST"},
    Sinks: []string{"execute", "executemany"},
    Sanitizers: []string{"escape_sql"},
})

match := registry.MatchPattern(pattern, callGraph)
if match.Matched {
    fmt.Printf("Vulnerability: %s -> %s\n", match.SourceFQN, match.SinkFQN)
}

Framework Detection

framework := patterns.DetectFramework(importMap)
if framework != nil {
    fmt.Printf("Using %s (%s)\n", framework.Name, framework.Category)
}

Test Coverage

• Coverage: 77.8% of statements
• Tests: 15 tests, all passing
• Test file: Moved from patterns_test.go to patterns/detector_test.go

Build Verification

✅ gradle buildGo - SUCCESS
✅ go test ./graph/callgraph/... - ALL PASS
✅ All existing tests pass - NO BREAKING CHANGES

Dependencies

• Imports from core/, extraction/, analysis/taint/
• Uses core.CallGraph for pattern matching
• Integrates with taint analysis for vulnerability detection

Graphite Stack

main
 └─ refactor/05-advanced-resolution (#376)
     └─ refactor/06-patterns (#XXX) ← THIS PR

Related PRs

• Depends on: refactor(callgraph): Move advanced resolution to resolution package (PR #5) #376 (PR Created automated Github Action for building binary #5: Advanced Resolution)
• Blocks: PR Update build.yml #7 (Builder Refactor)

🤖 Generated with Claude Code

[safedep]

SafeDep Report Summary

No dependency changes detected. Nothing to scan.

_{This report is generated by SafeDep Github App}

[codecov]

Codecov Report

❌ Patch coverage is 82.44898% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.71%. Comparing base (d33c02b) to head (6f06e94).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...cecode-parser/graph/callgraph/patterns/detector.go	81.22%	26 Missing and 14 partials ⚠️
sourcecode-parser/graph/callgraph/patterns.go	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #377      +/-   ##
==========================================
- Coverage   79.74%   79.71%   -0.04%     
==========================================
  Files          86       89       +3     
  Lines        6938     6971      +33     
==========================================
+ Hits         5533     5557      +24     
- Misses       1175     1183       +8     
- Partials      230      231       +1     

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[shivasurya]

• refactor: Extract builder logic to builder/ package (#7) #378
• refactor: Create patterns package for pattern detection (PR #6) #377 👈 (View in Graphite)
• refactor(callgraph): Move advanced resolution to resolution package (PR #5) #376
• refactor(callgraph): Create resolution package and complete extraction package (PR #4) #375
• refactor(callgraph): Create analysis/taint, extraction packages and complete registry #374
• refactor: create registry, cfg, and resolution packages #373
• refactor: create core package with foundation types #372
• main

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[shivasurya]

Merge activity

• Nov 16, 12:00 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Nov 16, 12:10 AM UTC: Graphite rebased this pull request as part of a merge.
• Nov 16, 12:10 AM UTC: @shivasurya merged this pull request with Graphite.