CodeM8

CodeM8 is a Rust command-line application for deterministic source code reports. It can report functions whose cognitive or cyclomatic complexity exceeds configurable limits:

codem8 --report-complexity

CodeM8 can also detect duplicated line-based code blocks in a repository:

codem8 --report-duplicate

The duplicate report is designed for both human developers and coding agents. It trims source lines, ignores empty lines, hashes normalized lines with XXH3 128-bit, classifies syntax-only lines as block-only, groups repeated blocks, and prints a stable plain-text report sorted by duplicate weight.

Installation

Install codem8 from the GitHub source with Cargo:

cargo install --locked --git https://github.com/b4prog/CodeM8 codem8

Build from a local checkout with Cargo:

cargo build --release

Install from a local checkout:

cargo install --locked --path .

Run from the local checkout without installing:

cargo run -- --report-complexity

Usage

Analyze function complexity for languages supported by rust-code-analysis:

codem8 --report-complexity

Analyze supported source files from the current directory for duplicate code:

codem8 --report-duplicate

Restrict analysis to specific extensions:

codem8 --report-duplicate -file-extension=ts,tsx,js,jsx

Analyze an explicit list of files instead of recursively discovering files:

codem8 --report-duplicate -file-extension=ts,js -files="src/a.ts,src/b.js"

Quoting -files values is recommended in PowerShell when paths contain file extensions.

Analyze files changed on the current local Git branch compared to the origin base branch:

codem8 --report-complexity -git-branch

The complexity and duplicate reports are mutually exclusive; run one report per command.

Reports exit with a non-zero status when they detect issues: functions above the configured limits for --report-complexity, or duplicate blocks for --report-duplicate.

Include analyzed files, report metrics, and timing information:

codem8 --report-complexity -verbose

Set complexity thresholds:

codem8 --report-complexity -max-cognitive-complexity=15 -max-cyclomatic-complexity=10

Complexity Report

The complexity report uses rust-code-analysis and only applies to file extensions supported by that crate. It reports SpaceKind::Function entries whose cognitive complexity exceeds the configured cognitive limit or whose cyclomatic complexity exceeds the configured cyclomatic limit.

The default maximum cognitive complexity is 15, and the default maximum cyclomatic complexity is 10. Use -max-cognitive-complexity=<value> and -max-cyclomatic-complexity=<value> to adjust them.

Use -git-branch to analyze complexity only in supported files changed on the current local branch. The same origin branch resolution and -files exclusion rules used by the duplicate report apply.

Use -verbose to list analyzed files and timing information.

Duplicate Report

By default, CodeM8 analyzes all registered source file extensions. Recursive discovery respects Git ignore rules, works outside Git repositories, and skips common irrelevant directories such as .git, node_modules, target, dist, build, coverage, .next, .nuxt, .svelte-kit, .idea, and .vscode. Symbolic links are not followed.

Every non-empty line is normalized with Rust string trimming, so leading and trailing Unicode whitespace are removed before hashing and comparison. Empty trimmed lines are ignored. CodeM8 currently expects UTF-8 source files; invalid UTF-8 produces a clear error rather than lossy output.

Use -git-branch to search duplicate code only in files changed on the current local branch. CodeM8 resolves that branch set from origin/HEAD with origin/main and origin/master fallbacks. The option requires a Git repository and cannot be combined with -files.

Duplicate block weight is calculated as:

(occurrences - 1) * duplicated_line_count * cumulative_normalized_character_count

Reports are sorted deterministically by descending weight, then by line count, character count, first location, and normalized block text.

By default, each duplicate block prints only the duplicate locations. Use -verbose to also show analyzed files, the duplicated code, weight, line count, occurrence count, and timings for discovery, file processing, and duplicate detection. Character counts are used internally for scoring and sorting, but are not printed.

Development

Run the full local verification set:

cargo test
cargo fmt --all -- --check
cargo clippy --workspace --all-targets --all-features -- -D warnings -W clippy::too_many_lines -W clippy::too_many_arguments -W clippy::type_complexity -W clippy::excessive_nesting -W clippy::cognitive_complexity -W clippy::pedantic -W clippy::nursery -W clippy::cargo
cargo build --locked --all-targets

The repository includes GitHub Actions workflows for Rust CI and a CodeRabbit review gate. CI verifies formatting, build success, and tests on pushes and pull requests. The CodeRabbit gate runs when CodeRabbit submits or edits a pull request review and fails if CodeRabbit requests changes on the current PR head.