gemfile_version.go

package version

import (
	"strings"
)

// Gemfile.lock doesn't follow a spec, the best documentation comes
// from `gem help platform`. Gemfile.lock versions may have "{cpu}-{os}"
// or "{cpu}-{os}-{version}"
// after the semvVer, for example, 12.2.1-alpha-x86_64-darwin-8, where `2.2.1-alpha`
// is a valid and comparable semVer, and `x86_64-darwin-8` is not a semVer due to
// the underscore. Also, we can't sort based on arch and OS in a way that make sense
// for versions. SemVer is a characteristic of the code, not which arch OS it runs on.
//
// Bunlder's code: https://github.com/rubygems/rubygems/blob/2070231bf0c7c4654bbc2e4c08882bf414840360/bundler/spec/install/gemfile/platform_spec.rb offers more info on possible architecture values, for example `mswin32` may appead without arch.
//
// Spec for pre-release info: https://github.com/rubygems/rubygems/blob/2070231bf0c7c4654bbc2e4c08882bf414840360/bundler/spec/install/gemfile/path_spec.rb#L186
//
// CPU/arch is the most structured value present in gemfile.lock versions, we use it
// to split the version info in half, the first half has semVer, and
// the second half has arch and OS which we ignore.
// When there is no arch we split the version string with: {java, delvik, mswin}
func extractSemVer(raw string) string {
	platforms := []string{"x86", "universal", "arm", "java", "dalvik", "x64", "powerpc", "sparc", "mswin"}
	dash := "-"
	for _, p := range platforms {
		vals := strings.SplitN(raw, dash+p, 2)
		if len(vals) == 2 {
			return vals[0]
		}
	}

	return raw
}

func newGemfileVersion(raw string) (*semanticVersion, error) {
	cleaned := extractSemVer(raw)
	return newSemanticVersion(cleaned)
}