cccc - A tool/library for measurement of Cognitive Complexity and Cyclomatic Complexity

A fast CLI — a single cccc binary — that measures Cognitive Complexity (SonarSource / G. Ann Campbell) and Cyclomatic Complexity (McCabe). Written in Rust. It routes each file to the right front-end by its extension, so one run can analyze a mixed-language tree. Various languages ship today, all sharing the same engine, flags, and output format:
- TypeScript / JavaScript (--lang es), via the oxc parser. Analyzes .ts, .tsx, .js, .jsx, .mts, .cts, .mjs, .cjs.
- Rust (--lang rust), via the syn parser. .rs.
- Go (--lang go), via the gosyn parser. .go.
- PHP (--lang php), via the php-rs-parser parser. .php.
- Ruby (--lang ruby), via the ruby-prism parser (Ruby's official Prism parser). .rb.
- Scheme (--lang scheme), R7RS-small, via the lispexp S-expression reader. .scm, .ss, .sld. Its child dialect Racket (--lang racket, .rkt/.rktl/.rktd) rides the same tolerant reader, with match and the for comprehension family scored on top of R7RS.
- Common Lisp (--lang commonlisp), via the lispexp S-expression reader. .lisp, .lsp, .cl.
- Emacs Lisp (--lang emacslisp), via the lispexp S-expression reader. .el.
- Clojure (--lang clojure), via the lispexp S-expression reader. .clj, .cljs, .cljc.
- Kotlin (--lang kotlin), via the exoego/tree-sitter-kotlin grammar (a fork of the fwcd tree-sitter Kotlin grammar with fixes for modern-Kotlin constructs). Analyzes .kt, .kts.
- Python (--lang python), via the official tree-sitter-python grammar. Analyzes .py, .pyi.
- Zig (--lang zig), via the pure-Rust zigsyn parser. Analyzes .zig.
- C (--lang c), via the official tree-sitter-c grammar. Analyzes .c, .h.
- C++ (--lang cpp, aliases c++/cxx), via the official tree-sitter-cpp grammar. Analyzes .cpp, .cc, .cxx, .hpp, .hh, .hxx, .h++, .tpp, .ipp (.h is claimed by C, since extension routing needs disjoint claims — see C++ for routing .h to C++). Shares its lowering for everything C and C++ have in common with cccc-c, via cccc-clike.
- Perl (--lang perl), via the community-maintained tree-sitter-perl grammar. Analyzes .pl, .pm, .t.
- Swift (--lang swift), via the alex-pinkus/tree-sitter-swift grammar. Analyzes .swift.
- Java (--lang java), via the official tree-sitter-java grammar. Analyzes .java.
- Dart (--lang dart), via the nielsenko/tree-sitter-dart grammar. Analyzes .dart.
- Scala (--lang scala), via the official tree-sitter-scala grammar. Analyzes .scala, .sc.
A Rust library for calculating cognitive and cyclomatic complexity in a language-agnostic way

Workspace layout

The complexity engine is split from the language parser so it can be reused as a library and extended to other languages:

Crate	Role
`cccc-core`	Language-agnostic engine: a normalized IR (`ir::Node`), the scoring rules (`engine::analyze`), and the result/aggregation types. Depends only on `serde`.
`cccc-cli`	The unified `cccc` binary. Owns argument parsing, config-file handling, file walking, parallelism, and output rendering, and holds the registry of bundled languages (`lang::LANGUAGES`) that routes each file to its adapter.
`cccc-es`	ECMAScript/TypeScript adapter library: lowers the oxc AST into `cccc-core`'s IR. Depends only on `cccc-core` + oxc — no CLI dependencies, so embedding it stays lightweight.
`cccc-rs`	Rust adapter library: lowers the syn AST into `cccc-core`'s IR. Depends only on `cccc-core` + syn — no CLI dependencies.
`cccc-go`	Go adapter library: lowers the gosyn AST into `cccc-core`'s IR. Depends only on `cccc-core` + gosyn — no CLI dependencies.
`cccc-php`	PHP adapter library: lowers the php-rs-parser AST into `cccc-core`'s IR. Depends only on `cccc-core` + php-rs-parser / php-ast — no CLI dependencies.
`cccc-rb`	Ruby adapter library: lowers the ruby-prism AST into `cccc-core`'s IR. Depends only on `cccc-core` + ruby-prism — no CLI dependencies. Note: ruby-prism is an FFI binding to the vendored Prism C source, so building this crate (unlike the others) needs a C99 compiler and libclang.
`cccc-scheme`	Scheme (R7RS-small) + Racket adapter library: lowers the lispexp S-expression tree into `cccc-core`'s IR. Depends only on `cccc-core` + lispexp (pure Rust) — no CLI dependencies.
`cccc-lisp-kit`	Shared lowering kit for the Lisp-family adapters: the collector stack, the `walk_regions` code-vs-data traversal, and logical folding. A dialect adapter supplies just a reader preset + a head-symbol dispatch table. Re-exports `cccc-core`'s IR and the pure-Rust lispexp reader.
`cccc-lisp`	Lisp-family adapter library (Common Lisp, Emacs Lisp, …) built on `cccc-lisp-kit`. Its `Dialect` API also analyzes Scheme/Clojure by delegating to `cccc-scheme`/`cccc-clojure` (no duplicated lowering). No CLI dependencies.
`cccc-clojure`	Clojure adapter library: lowers the lispexp S-expression tree into `cccc-core`'s IR. Depends only on `cccc-core` + lispexp (pure Rust) — no CLI dependencies.
`cccc-scheme`	Scheme (R7RS-small) adapter library: lowers the lispexp S-expression tree into `cccc-core`'s IR. Depends only on `cccc-core` + lispexp (pure Rust) — no CLI dependencies.
`cccc-kt`	Kotlin adapter library: lowers the exoego/tree-sitter-kotlin CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Kotlin grammar — no CLI dependencies. Note: the grammar ships C source compiled by `cc`, so building this crate needs a C compiler (but not libclang, unlike `cccc-rb`). Not published to crates.io (the grammar is a git dependency); `cccc-cli` includes it via its default `kotlin` feature.
`cccc-py`	Python adapter library: lowers the official tree-sitter-python CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Python grammar — no CLI dependencies. Like `cccc-kt`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-zig`	Zig adapter library: lowers the pure-Rust zigsyn AST into `cccc-core`'s IR. Depends only on `cccc-core` + zigsyn — no CLI dependencies or C toolchain.
`cccc-c`	C adapter library: lowers the official tree-sitter-c CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the C grammar — no CLI dependencies. Like `cccc-kt`/`cccc-py`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-clike`	Shared lowering for the C-family adapters: `tree-sitter-cpp`'s grammar is a superset of `tree-sitter-c`'s, so `cccc-c` and `cccc-cpp` both construct a `cccc_clike::SharedBuilder` (tagged `Language::C`/`Language::Cpp`) instead of duplicating the lowering for what they share (functions, `if`, loops, `switch`, jumps, logical folding, preprocessor conditionals, calls). C++-only constructs (lambdas, `catch`, range-`for`) are gated on the language tag in the same `visit`. Depends only on `cccc-core` + tree-sitter — no grammar crate, no CLI dependencies.
`cccc-cpp`	C++ adapter library: lowers the official tree-sitter-cpp CST into `cccc-core`'s IR via `cccc-clike`. Depends only on `cccc-core` + `cccc-clike` + tree-sitter + the C++ grammar — no CLI dependencies.
`cccc-pl`	Perl adapter library: lowers the tree-sitter-perl CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Perl grammar — no CLI dependencies. Like `cccc-kt`/`cccc-py`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-swift`	Swift adapter library: lowers the alex-pinkus/tree-sitter-swift CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Swift grammar — no CLI dependencies. Like `cccc-kt`/`cccc-py`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-java`	Java adapter library: lowers the official tree-sitter-java CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Java grammar — no CLI dependencies. Like `cccc-kt`/`cccc-py`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-dart`	Dart adapter library: lowers the nielsenko/tree-sitter-dart CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Dart grammar — no CLI dependencies. The grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).
`cccc-scala`	Scala adapter library: lowers the official tree-sitter-scala CST into `cccc-core`'s IR. Depends only on `cccc-core` + tree-sitter + the Scala grammar — no CLI dependencies. Like `cccc-kt`/`cccc-py`, the grammar's C source is compiled by `cc`, so building needs a C compiler (no libclang).

Each adapter is a standalone library so that a consumer who only wants the metrics pulls in just that adapter (+ cccc-core + its parser), never clap / ignore / rayon. The cccc binary depends on all of them and dispatches by extension.

To support another language: (1) add an adapter crate that lowers its AST into cccc_core::ir::Node and calls cccc_core::engine::analyze, then (2) register it with one entry in cccc-cli's lang::LANGUAGES (and add the dependency) — no new binary, and no reimplementing the metrics or the CLI. cccc-es (oxc), cccc-rs (syn), cccc-go (gosyn), cccc-php (php-rs-parser), cccc-rb (ruby-prism), cccc-kt / cccc-py / cccc-pl (tree-sitter), cccc-swift (tree-sitter), cccc-c / cccc-cpp (tree-sitter), cccc-java (tree-sitter), cccc-dart (tree-sitter), cccc-scala (tree-sitter), cccc-scheme (lispexp), cccc-clojure (lispexp), cccc-lisp (lispexp, Common Lisp / Emacs Lisp / …), and cccc-zig (zigsyn) are the reference adapters: same shape, different parser. The Lisp-family adapters share their lowering skeleton via cccc-lisp-kit; cccc-c and cccc-cpp share theirs via cccc-clike.

See docs/ADDING_A_LANGUAGE.md for the full step-by-step guide, including the IR-node reference table, the logical-operator folding rule, and how to test the adapter.

use cccc_core::{engine::analyze, ir::Node};

let f = Node::Function {
    name: "f".into(), kind: "function".into(), line: 1,
    body: vec![Node::Branch { test: vec![], then: vec![], alternate: None }],
};
let report = analyze("example", &[f], vec![]);
assert_eq!(report.functions[0].cognitive, 1);  // one `if`

Install / build

Prebuilt binaries for Linux, macOS, and Windows are attached to each GitHub Release. To build from source:

cargo build --release
# single binary at ./target/release/cccc

Or install from crates.io:

cargo install cccc-cli

Note

The crates.io build does not support Kotlin. cccc-kt depends on a Kotlin grammar that is only available from git, and crates.io rejects git dependencies, so cccc-kt is not published and cccc-cli is published without its (default) kotlin feature. Use a GitHub Release binary or build from this repository to analyze Kotlin.

Usage

cccc <paths...> [options]

One binary handles every language. Pass one or more files or directories; directories are walked recursively (respecting .gitignore, always skipping node_modules). Each file is dispatched to the right front-end by its extension, so a directory mixing .ts, .rs, .go, and .php is analyzed in a single run. Restrict the languages with --lang (e.g. --lang go,rust).

Output is JSON by default — compact, on one line, ready to pipe into jq or an artifact store; --pretty prints the same document indented.

Options

Flag	Description
`--lang LIST`	Restrict analysis to these languages (comma-separated; canonical names or aliases, e.g. `es`,`rust`/`rs`,`go`,`php`). Default: all
`--exclude-lang LIST`	Exclude these languages (comma-separated). The inverse of `--lang`; applied to all languages, or to `--lang`'s set when both are given
`--config PATH`	Use this config file instead of discovering one (must exist)
`--no-config`	Do not look for or load a `cccc.toml` config file
`--table`	Human-readable table instead of JSON
`--ext EXTS \| LANG=EXTS`	Extensions to analyze. Global form `--ext ts,tsx` filters across all languages; per-language form `--ext es=ts,tsx` overrides that language's extensions and routes them to it. Repeatable
`--exclude GLOB`	Exclude files matching a glob (repeatable)
`--max-cognitive N`	Exit non-zero if any function's cognitive complexity exceeds N
`--max-cyclomatic N`	Exit non-zero if any function's cyclomatic complexity exceeds N
`--min N`	Only report functions with complexity >= N
`--top-cognitive N`	Show only the N most cognitively-complex functions, as a flat cross-file ranking
`--top-cyclomatic N`	Show only the N most cyclomatically-complex functions, as a flat cross-file ranking
`--no-ignore`	Do not respect `.gitignore` when walking directories
`--cache`	Cache results and reuse them for files unchanged since the last run
`--cache-file PATH`	Where to keep the results cache (implies `--cache`). Default: `.cccc.cache` next to the config file, or in the current directory
`--no-cache`	Do not use the results cache, even if the config file enables it
`--print-cache-file`	Print the resolved cache path (nothing when disabled) and exit; for tooling
`--pretty`	Pretty-print the JSON output (default is compact, one line)
`-j, --jobs N`	Number of files to analyze in parallel (default: logical CPU count)

Configuration file

Recurring options can be stored in a cccc.toml file so they don't have to be repeated on every run. By default cccc discovers one by walking up from the current directory, looking for cccc.toml (then .cccc.toml) in each ancestor; --config PATH selects an explicit file and --no-config disables discovery.

Resolution precedence is CLI flag > config file > built-in default: anything passed on the command line always wins. Supported keys (all optional):

# cccc.toml
languages         = ["es", "go"]        # same as --lang
exclude-languages = ["php"]             # same as --exclude-lang
exclude           = ["dist/**", "**/*.test.ts"]
table         = false
max-cognitive = 15
max-cyclomatic = 10
min           = 1
no-ignore     = false
jobs          = 8
pretty        = false               # indented JSON instead of the compact default
cache         = false               # reuse results for unchanged files
cache-file    = ".cccc.cache"       # cache location (does not enable by itself)

# Per-language extension overrides. Each entry replaces that language's default
# extensions (and routes those extensions to it). Keyed by a language's name or
# alias; languages without an entry keep their defaults.
[ext]
es = ["ts", "tsx"]      # analyze only .ts/.tsx as ECMAScript (not .js, .mjs, …)
go = ["go", "tmpl"]     # also route a custom .tmpl extension to the Go front-end

The config-file ext is a per-language table: it both narrows/extends which extensions a language claims and determines how a custom extension is routed. The same per-language form is available on the command line as --ext LANG=ext,ext (which overrides the config's entry for that language), alongside the global filter form --ext ext,ext.

(--top-cognitive/--top-cyclomatic and the input paths are command-line only.)

--top-cognitive and --top-cyclomatic are mutually exclusive. In top mode the output is a ranking ({ "metric", "top": [...], "summary" }) instead of the per-file files array; each entry carries its own path and line. The summary still reflects the full population.

--exclude takes a glob pattern and may be given multiple times. Each pattern is matched both against a file's path relative to the directory you passed (so dist/** is anchored at that root) and against its file name alone (so *.test.ts matches at any depth without a **/ prefix). * does not cross /; use ** to span directories. Brace alternation is supported, e.g. **/*.{test,spec}.ts. Excluded files are dropped whether found by walking a directory or named explicitly on the command line. An invalid pattern is an error (exit code 2). This is independent of --no-ignore and .gitignore handling.

Results cache

--cache (or cache = true in cccc.toml) makes repeat runs reuse the previous results for files that haven't changed, re-analyzing only what did. The output is byte-for-byte identical to an uncached run: the cache is an accelerator, never a source of errors — anything unexpected (a missing, corrupt, or version-mismatched cache file) just degrades to a full run. It pays off wherever cccc runs repeatedly over a mostly-unchanged tree: watch loops, pre-commit hooks, editor integrations, and CI. On large monorepos, warm runs measure ~3× (TS/JS via oxc) to ~17× (tree-sitter languages such as C) faster than cold ones — numbers and method in BENCHMARK.md.

An entry is reused only when it provably still describes the file's current content, checked cheapest-first:

stat — size and mtime unchanged: trusted without reading the file. The steady local path; a fully warm run does nothing but stat.
git's index — the mtime moved, but git calls the file clean and the index's blob SHA matches the one recorded at analysis time: still no read. One git ls-files/git status pair answers for the whole tree, which is what keeps fresh CI checkouts (every mtime reset) warm. git is consulted only after a stat check has failed, and never trusted beyond content: dirty or untracked files, non-git trees, and any git failure at all fall through to step 3.
content re-hash — the file is read and its blob SHA re-derived from the bytes; the final authority, and the same value step 2 compares without reading. A mismatch means the content really changed, and only then is the file re-analyzed. (The blob SHA is SHA-1 — the same non-adversarial, per-path content comparison git itself rests on, not a cryptographic boundary.)

A hit that needed step 2 or 3 gets its refreshed mtime written back, so the next run takes the stat path again. Entries are also keyed to the analyzing language (--ext re-routing must not resurface another language's scores), and the whole cache to the cccc version that wrote it.

The cache lives in .cccc.cache next to the config file (so runs from any subdirectory share it), or where --cache-file points; add it to .gitignore. It needs no maintenance beyond that: every run rewrites it to match exactly the current tree — deleted files' entries are pruned, and its size stays proportional to the project, not its history — and deleting the file at any time is always safe (the next run is simply cold).

In CI

The git-index check is what makes the cache effective in CI, where every checkout resets every mtime: persist the cache file across runs and each run validates unchanged files off git's index instead of re-parsing them — measured 1.6–9.6× faster than a cold run (see BENCHMARK.md). Correctness never depends on which commit (or how stale a run) the restored cache came from: every entry is checked content-to-content. Under CI=… (GitHub Actions sets it) the git subprocesses start early so their latency hides behind file discovery.

On GitHub Actions, cccc-action wires the persistence up for you when the config sets cache = true. Wiring it by hand looks like:

- uses: actions/cache@v4
  with:
    path: .cccc.cache
    key: cccc-${{ github.sha }}
    restore-keys: cccc-
- run: cccc --cache --max-cognitive 15 src/

Tooling that needs the resolved cache location up front (the way cccc-action does) can ask cccc --print-cache-file, which prints the path the current config resolves to — or nothing when caching is disabled — and exits.

Examples

# JSON for one file
cccc src/app.ts

# Pretty table for a directory (any mix of supported languages)
cccc --table src/

# Only Go and Rust files under a mixed tree
cccc --lang go,rust .

# Everything except PHP
cccc --exclude-lang php .

# Analyze only .ts/.tsx as ECMAScript (not .js, .mjs, …)
cccc --ext es=ts,tsx src/

# CI gate: fail if any function exceeds cognitive complexity 15
cccc --max-cognitive 15 src/

# The 10 most cognitively-complex functions across the project
cccc --top-cognitive 10 src/

# Skip build output and test files
cccc --exclude 'dist/**' --exclude '**/*.{test,spec}.ts' src/

# Limit parallelism to 4 workers (default is the logical CPU count)
cccc -j 4 src/

# Recurring runs: reuse results for files unchanged since the last run
cccc --cache src/

Files are analyzed in parallel. The worker count defaults to the number of logical CPUs and can be capped with -j/--jobs; the output is identical regardless of the worker count.

GitHub Action

A composite action to install and run cccc in CI lives in its own repository: moznion/cccc-action.

- uses: moznion/cccc-action@v1
  with:
    path: src/           # analyze this; thresholds come from cccc.toml

Like thresholds, caching is driven by the config: when cccc.toml sets cache = true, the action persists the results cache across runs on its own (via actions/cache — no workflow wiring needed).

An example GitHub Actions workflow for continuously measuring complexity with k1LoW/octocov is available at .github/workflows/complexity.yml.

Output shape (JSON)

An object with files (per-file reports) and summary (a whole-project rollup). Each function is measured independently and nested functions appear under children. A file's totals sum every function at every depth plus module-level code.

The summary is computed over every function in every file (all nesting depths). Because complexity is right-skewed, it reports the distribution (sum/max/median/p90/p95) rather than a mean — the percentiles describe the tail where refactoring candidates live. It is unaffected by --min.

{
  "files": [
    {
      "path": "src/app.ts",
      "cognitive": 10,
      "cyclomatic": 10,
      "functions": [
        {
          "name": "handleRequest",
          "kind": "function",
          "line": 10,
          "cognitive": 7,
          "cyclomatic": 4,
          "children": []
        }
      ]
    }
  ],
  "summary": {
    "file_count": 1,
    "function_count": 3,
    "parse_error_count": 0,
    "parse_error_file_count": 0,
    "cognitive":  { "sum": 10, "max": 7, "median": 2, "p90": 7, "p95": 7 },
    "cyclomatic": { "sum": 10, "max": 4, "median": 3, "p90": 4, "p95": 4 }
  }
}

Parse errors

A file that fails to parse cleanly is still measured from whatever the parser recovered, and its parse_errors (an array of messages, omitted when empty) appears on that file's entry. The summary aggregates them — parse_error_count (total errors), parse_error_file_count (affected files), and parse_error_files (the affected paths, omitted when empty) — so a partial parse can't go unnoticed without inspecting every file entry, even in --top-* mode where per-file entries aren't emitted at all:

{
  "files": [
    {
      "path": "src/broken.py",
      "parse_errors": ["syntax error at line 6"],
      ...
    }
  ],
  "summary": {
    "parse_error_count": 1,
    "parse_error_file_count": 1,
    "parse_error_files": ["src/broken.py"],
    ...
  }
}

In --table mode the aggregate count is printed in the summary block, and a warning listing each affected file (with its error count) goes to stderr so it isn't lost in a long table:

$ cccc --table src/ >/dev/null
cccc: warning: 1 parse error(s) in 1 file(s); results for those files may be incomplete:
cccc:   src/broken.py (1)

Note: the top level is an object ({ files, summary }), so to post-process the per-file array with jq, start from .files — e.g. cccc src/ | jq '.files | sort_by(-.cognitive)'.

Benchmark

On zod's packages/zod/src (286 .ts files, 68,357 LOC), median wall-clock and peak memory over 5 runs on an Apple M4 Pro:

Tool	Metrics	Time	Peak RSS
cccc (ECMAScript)	cognitive + cyclomatic, per-function, full AST	15.5 ms	12.5 MB
ESLint + SonarJS	cognitive + cyclomatic, per-function, full AST	1,807 ms (117× slower)	604 MB (48× more)
lizard	cyclomatic only, heuristic parser	1,413 ms (91× slower)	45.7 MB
scc	coarse per-file keyword count, no AST	8.3 ms (1.9× faster)	13.9 MB

Among tools that do the same job — both metrics, per-function, over a real AST — cccc is ~117× faster than ESLint+SonarJS (the only other tool that computes cognitive complexity) and uses ~48× less memory. scc is faster only because it never parses: it counts keywords per file, with no AST, no per-function data, and no cognitive complexity.

See BENCHMARK.md for the full methodology, the verify-then-time harness, per-run numbers, function-count sanity checks, and caveats.

Metric rules

Cyclomatic (McCabe): base 1 per function; +1 for each if/else if, ternary, for/for-in/for-of/while/do-while, case (excluding default), catch, each &&/||/??, and each explicit null guard such as an optional-chain segment. Null guards do not add cognitive complexity or nesting.

Cognitive (SonarSource):

+1 plus a nesting bonus for if, ternary, switch, loops, catch.
+1 flat (no bonus) for else/else if, labelled break/continue, each run of like logical operators, and recursion (call to the enclosing function's own name).
Nesting increases inside control-flow bodies and nested function bodies.

Each function-like unit is scored independently (nesting resets to 0 at the function boundary); nested functions are reported as children rather than inflating the parent's own score.

The rules above are stated in TypeScript/JavaScript terms; each adapter maps its language onto the same IR, with the per-language differences below.

Rust (`--lang rust`)

Function-like units: fn / impl methods / trait default methods / closures.
Maps to the shared nodes: if/else if/else, match (a _ or bare-binding arm is the non-decision default), for/while/loop, labelled break/continue, and &&/||.
No ternary (if is an expression) and no try/catch (errors flow through ?) — those constructs simply don't occur.

Go (`--lang go`)

Function-like units: top-level functions / methods / function literals (closures).
Maps to the shared nodes: if/else if/else, for (including for-range), switch/type-switch/select (a default clause is the non-decision arm), labelled break/continue/goto, and &&/||.
No ternary and no try/catch (errors are returned values) — those constructs simply don't occur.

PHP (`--lang php`)

Function-like units: functions / methods / closures / fn arrow functions / property hooks.
Maps to the shared nodes: if/elseif/else, while/do-while/ for/foreach, switch and the match expression (a default arm is the non-decision case), catch clauses, multi-level break N/continue N and goto, the ternary ?:, and &&/and/||/or/??.
&&/and (likewise ||/or) are the same normalized operator. ?? folds as a coalescing run.
Each null-safe property or method access (?->) adds one cyclomatic path.

Ruby (`--lang ruby`)

Function-like units: methods, blocks, and lambdas.
Maps to the shared nodes: branches, loops, case/when and case/in, rescue clauses, ternary expressions, logical operators.
Each safe navigation operator (&.) adds one cyclomatic path.

Kotlin (`--lang kotlin`)

Function-like units: fun declarations / methods / local functions / fun anonymous functions / lambdas / property get/set accessors.
Maps to the shared nodes: the if expression (else if — an if nested in the else body — chains flat), the when expression with or without a subject (its else entry is the non-decision default arm), for/while/do-while, catch clauses, labelled break@/continue@, and &&/||.
The elvis operator ?: folds as a coalescing run (like PHP's ??). Kotlin has no C-style ternary — if is already an expression.
Each safe-navigation operator (?.) adds one cyclomatic path.

Python (`--lang python`)

Function-like units: def (incl. async def and decorated definitions) / methods / lambda.
Maps to the shared nodes: if/elif/else (elif chains flat), the conditional expression a if b else c (a ternary — its else arm is not a second increment), for/while (incl. async for; a loop's else clause runs at the surrounding level), match (a bare case _: is the non-decision default arm), except/except* clauses, and and/or.
Comprehensions and generator expressions score like the written-out loop: each for clause is a loop and each if clause a branch, nested left-to-right.
No labelled break/continue and no ??. not adds nothing.

Zig (`--lang zig`)

Function-like units: named fn declarations and test blocks.
Maps to the shared nodes: if/else if/else, while/for (a loop's else branch runs at the surrounding level), switch (an else prong is the non-decision default arm), catch handlers, labelled break/continue, and and/or.
orelse folds as a coalescing run. Zig has no ternary expression — if is already an expression.

C (`--lang c`)

Function-like units: function definitions, including K&R-style definitions and GNU nested functions.
Maps to the shared nodes: if/else if/else, the ternary ?: (GNU's elided-middle a ?: b included), for/while/do-while, switch (the default: label is the non-decision arm; each fall-through case label is its own cyclomatic point), goto (one flat cognitive point — like a labelled jump), and &&/||.
Preprocessor conditionals (#if/#ifdef/#ifndef, chained via #elif/#else) score as branches, mirroring the SonarSource C/C++ analyzers.
No exceptions and no ??. #define bodies are opaque to the grammar, so code inside a macro body is not scored.
Known wart of preprocessor-unaware parsing: the standard extern "C" { guard splits its braces across two #ifdef __cplusplus blocks, which surfaces as a parse warning — the rest of the header still parses and scores.
Another wart: the <cinttypes> printf-width macros ("..." PRIu32 "..." and friends) only become adjacent string literals after macro expansion, which the grammar never performs, so they also surface as a parse warning local to that expression.

C++ (`--lang cpp`)

Everything above for C applies unchanged (tree-sitter-cpp's grammar is a superset of tree-sitter-c's, sharing the same node kinds/fields for what the two languages have in common).
Function-like units: additionally, a [...](...){...} lambda is its own unit (like a closure elsewhere).
Maps to the shared nodes: additionally, catch clauses (the try body runs at the surrounding level, same as Kotlin/Python's catch/except) and range-for (for (auto &x : xs)), which is a loop like any other.
Constructor/destructor/operator-overload names, including out-of-line qualified definitions (Foo::bar), are dug out of the declarator chain, as are functions returning a reference (int &get()), conversion operators (named e.g. operator bool), and explicit specializations (spec<int> is named spec). A qualified definition and a qualified or unqualified self-call both resolve to the same trailing simple name, and template arguments are dropped on both sides (fact<N - 1>() inside fact), so recursion is still detected.
C++20 module units (.cppm/.ixx) aren't claimed: the grammar can't parse export module/import declarations.
C++ headers in .h files. .h is routed to C by default, and when two languages claim the same extension the one registered first (C) wins — so to analyze .h as C++, add h to cpp and drop it from c:
```
[ext]
c = ["c"]
cpp = ["cpp", "cc", "cxx", "hpp", "hh", "hxx", "h++", "tpp", "ipp", "h"]
```
or on the command line, --ext c=c --ext cpp=cpp,cc,cxx,hpp,hh,hxx,h++,tpp,ipp,h. In a C++-only project, --exclude-lang c plus the cpp override works too.
Extension matching is case-insensitive, so .C (a traditional C++ extension on case-sensitive filesystems) is analyzed as C.

Perl (`--lang perl`)

Function-like units: named subs / method declarations (feature class, Perl 5.38+) / anonymous subs. A block callback passed to grep/map/sort is its own anonymous unit (like a Ruby block).
Maps to the shared nodes: if/elsif/else (elsif chains flat) and unless, the statement modifiers EXPR if/unless COND (a branch) and EXPR while/until/for COND (a loop — incl. do { } while), the ternary ?:, while/until/C-style for/foreach, try/catch (Perl 5.34+'s try feature — finally runs at the surrounding level), labelled next/last/redo, and &&/and/||/or///.
&&/and (likewise ||/or) are the same normalized operator. // folds as a coalescing run.
A classic eval { } is transparent (the if ($@) after it is the decision point). xor/not/! add nothing. given/when (long deprecated) is not scored.

Swift (`--lang swift`)

Function-like units: func declarations / methods / local functions / closures / init / deinit / subscript / computed-property get/set accessors (including the implicit getter-only form) / willSet/didSet observers.
Maps to the shared nodes: if/else if/else (with if let / if case variants), guard … else (scored exactly like an if), switch (its default entry is the non-decision arm; case a, b: is one arm), for-in (its where clause adds nothing by itself), while/ repeat-while, catch blocks, labelled break/continue, the ternary a ? b : c, and &&/||.
Nil-coalescing ?? folds as a coalescing run (like PHP's ??).
#if compilation directives are transparent — every branch's code scores where it stands. try/try?/await add nothing.
Each optional-chaining guard on a member access, subscript, or call adds one cyclomatic path.

Java (`--lang java`)

Function-like units: methods (incl. ones in anonymous classes and interface default methods) / constructors / record compact constructors / lambdas. Static and instance initializer blocks run at the surrounding level.
Maps to the shared nodes: if/else if/else (else if chains flat), the ternary ?:, switch statements and expressions alike — both colon-style case: groups and arrow-style case -> rules with pattern matching and guards supported (a default or case null, default arm is the non-decision case), for/enhanced for/while/do-while, catch clauses (a multi-catch catch (A | B e) is one clause; try-with-resources bodies are transparent), labelled break L/continue L, and &&/||.
No ??-style coalescing operator.

Dart (`--lang dart`)

Function-like units: top-level and local functions, methods, getters, setters, constructors, factory constructors, operators, and anonymous function expressions.
Maps to the shared nodes: if/else if/else, the ternary ?:, for (including await for)/while/do-while, switch statements and switch expressions (a default or wildcard arm is the non-decision case), catch and on handlers, labelled break/continue, and &&/||.
Pattern &&/|| use the same logical-sequence rules. Collection if/for lower to nested branches/loops. ??/??= map to coalescing logical nodes.
Null-aware access (?., ?[], ?..), null-aware spread (...?), collection elements (?value), and map keys/values each add one cyclomatic path without adding cognitive complexity.
External, native, and otherwise bodyless declarations are not reported as functions.

Scala (`--lang scala`)

Function-like units: def definitions (and bodyless abstract def declarations), anonymous functions (x => …), and partial-function literals (xs.collect { case … }, def receive = { case … } — an anonymous unit whose body is the pattern match). A secondary constructor (def this(…)) is reported as a constructor unit (like the Kotlin/Swift adapters), and its mandatory this(…) self-delegation is not counted as recursion.
Maps to the shared nodes: if/else if/else, match (a bare case _ =>, or a lowercase variable pattern like case other =>, is the non-decision default arm; an uppercase stable-id like case None => stays a decision), for/while/do-while, each catch clause (the try body and finally run at the surrounding level; the case handlers inside a catch score within that one node), and &&/||.
A pattern guard (case x if a && b =>) is transparent: its operators still contribute, but the guard itself is not a separate decision.
A lone unguarded arm that only destructures — { case (k, v) => … } or t match { case (a, b) => … } (tuples of variables / _, nested or bound with @) — is not a decision: it is Scala's idiom for unpacking a tuple, so it adds no match increment and its body scores directly. With more than one arm, a tuple pattern is an ordinary refutable case.
No break/continue statements (nor labelled loops) and no ??-style coalescing operator. The library-based escapes — scala.util.control.Breaks (breakable {} / break()) and Scala 3's scala.util.boundary — are ordinary method calls, so they are not treated as jumps and add nothing to the score.

Name		Name	Last commit message	Last commit date
.github		.github
benchmark		benchmark
crates		crates
docs		docs
.gitignore		.gitignore
.octocov.complexity.yml		.octocov.complexity.yml
.octocov.yml		.octocov.yml
.tagpr		.tagpr
BENCHMARK.md		BENCHMARK.md
CHANGELOG.md		CHANGELOG.md
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
LICENSE		LICENSE
README.md		README.md
cccc.toml		cccc.toml
rust-toolchain.toml		rust-toolchain.toml

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cccc - A tool/library for measurement of Cognitive Complexity and Cyclomatic Complexity

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Usage

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Rust (--lang rust)

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