Extract and pad the leading numeric R version from a version string

Pulls the leading X, X.Y, or X.Y.Z numeric prefix from a resolved r_version string and pads it to three components, so it can be safely compared with package_version(). Handles the shapes resolved_version can take: a bare major version ("4"), CUDA/Ubuntu suffixes ("4.4.0-cuda12.2-ubuntu22.04"), and the non-numeric tags "latest" and "devel", for which it returns NA_character_ – both always resolve to the current rocker-versioned2 image lineage, so callers should treat NA here as "no floor applies."

Usage

.extract_r_version_prefix(x)

Arguments

x

Character string. A resolved R version, as produced by generate_dockerfile()'s r_version/"current" resolution step.

Value

A three-component version string (e.g. "4.4.0"), or NA_character_ if x has no leading numeric portion.