licenses

Go library for matching license text against ScanCode's license rule corpus.

The corpus is embedded in the package. Matching needs no network access, cgo, or Python.

Installation

go get github.com/git-pkgs/licenses

Usage

matcher, err := licenses.New()
if err != nil {
	return err
}

result, err := matcher.Match(ctx, text)
if err != nil {
	return err
}

for _, detection := range result.Detections {
	fmt.Println(detection.Expression)
}

Matching uses normalized whole-text hashes and exact token sequences. It does not use fuzzy or sequence matching, so edits within a license can prevent a match.

Corpus

The ScanCode commit is pinned in CORPUS_VERSION. Regenerate the embedded index from a clean checkout at that commit:

go run ./cmd/corpusgen \
  -scancode /path/to/scancode-toolkit \
  -version-file CORPUS_VERSION \
  -output internal/corpus/corpus.bin.gz

Conformance

The exact matcher passes 1,535 of 1,786 cases (85.95%) from ScanCode's four active data-driven detection suites. Run the suite against a ScanCode checkout at the commit in CORPUS_VERSION:

SCANCODE_TESTDATA=/path/to/scancode-toolkit/tests/licensedcode/data \
  go test . -run '^TestScanCodeConformanceExact$' -v

Known differences are recorded in the conformance baseline. CI fails if an existing result changes or a new difference appears.

Benchmarks

Run the matching benchmarks with:

GOMAXPROCS=1 go test \
  -run '^$' \
  -bench . \
  -benchmem \
  -benchtime 1s \
  -count 5 \
  .

Use the standard go test flags to select benchmarks or change their duration and sample count.

License

The Go code is released under the MIT License. ScanCode's license and rule data is licensed under CC-BY-4.0. See NOTICE for attribution and modification details.