crap4swift

Compute CRAP (Change Risk Anti-Pattern) scores for Swift code. Inspired by Uncle Bob's crap4clj.

CRAP(fn) = CC² × (1 - coverage)³ + CC

Uses SwiftSyntax for accurate AST-based cyclomatic complexity analysis — no regex, no string matching, no false positives from keywords in strings or comments.

Install

brew install pproenca/tap/crap4swift

Or build from source:

git clone https://github.com/pproenca/crap4swift.git
cd crap4swift
swift build -c release

Usage

# Analyze current directory (whole codebase)
crap4swift

# With xcresult coverage
crap4swift . --xcresult .build/tests.xcresult

# With llvm-cov coverage
crap4swift . --profdata default.profdata --binary .build/debug/MyApp

# JSON output
crap4swift . --json

# Filter by threshold
crap4swift . --threshold 30

# Filter by function name
crap4swift . --filter "viewDidLoad"

# Exclude generated paths
crap4swift . --exclude-generated

# Exclude custom path patterns (repeatable)
crap4swift . --exclude-path "/GeneratedSources/" --exclude-path "GeneratedTypes.swift"

# Analyze multiple directories
crap4swift Sources Tests

Example Output

CRAP Report
===========

Function                       File                          CC   Cov%     CRAP
--------------------------------------------------------------------------------
complexFunction(_:)            Sources/Logic.swift:42        12   45.0%    130.2
init(value:)                   Sources/Model.swift:8          5    0.0%     30.0
simpleFunction()               Sources/Utils.swift:10         1  100.0%      1.0

What It Counts

Cyclomatic complexity (decision points):

Construct	Example
if / else if	if condition { }
guard	guard x else { }
for	for x in y { }
while	while condition { }
repeat-while	repeat { } while condition
switch case	Each case in a switch
catch	catch Pattern { }
??	x ?? default
&&	a && b
||	a || b
Ternary	condition ? a : b

Functions extracted: func, init, deinit, computed property accessors (get/set/willSet/didSet), subscript.

Formula Verification

CC	Coverage	CRAP
1	100%	1.0
5	100%	5.0
5	0%	30.0
8	45%	~18.65

Credits

Based on the CRAP metric concept by Alberto Savoia and directly inspired by Robert C. Martin (Uncle Bob)'s crap4clj — a Clojure implementation of the same metric.

License

MIT