Translate a License field into an SPDX expression

Looks up License strings from DESCRIPTION files in a table precomputed from R's own license analysis (tools::analyze_license() and R's license database). An expression is returned only when every alternative maps to SPDX, no alternative is file LICENSE alone, and every + file LICENSE is attached to a license that R's license database marks extensible: MIT, BSD, GPL-3, LGPL-3, AGPL-3 and the CC BY 4.0 family. So GPL-3 + file LICENSE becomes GPL-3.0-only, while GPL-2 + file LICENSE has no expression. R expands version ranges, so GPL (>= 2) becomes GPL-2.0-only OR GPL-3.0-only.

Usage

license_spdx(x)

Arguments

x

A character vector of License field values.

Value

A character vector the same length as x, with NA where there is no SPDX expression.

Examples

license_spdx(c("MIT + file LICENSE", "GPL (>= 2)", "file LICENSE"))
#> [1] "MIT"                          "GPL-2.0-only OR GPL-3.0-only"
#> [3] NA