Function use

cli/use.go:33–90

(ctx *cli.Context)

)

func use(ctx *cli.Context) error {
	vname := ctx.Args().First()
	if vname == "" {
		// Uses go.mod if available and version is omitted
		goModData, err := os.ReadFile("go.mod")
		if err != nil {
			if errors.Is(err, os.ErrNotExist) {
				return cli.Exit(wrapstring("No go.mod file found"), 1)
			}
			return cli.Exit(errstring(err), 1)
		}

		goDirective := getGoDirective(goModData)
		wd, err := os.Getwd()
		if err != nil {
			wd = "."
		}
		if goDirective == "" {
			return cli.Exit(wrapstring(fmt.Sprintf("Go directive does not exist in %q files", filepath.Join(wd, "go.mod"))), 1)
		}
		fmt.Printf("Found %q with version <%s>\n", filepath.Join(wd, "go.mod"), goDirective)
		vname = goDirective
	}

	versions, err := listLocalVersions(versionsDir)
	if err != nil {
		return cli.Exit(errstring(err), 1)
	}

	// Try to match the version number strictly first
	for i := range versions {
		if versions[i].Name() != vname {
			continue
		}
		if err = switchVersion(versions[i].Name()); err != nil {
			return cli.Exit(errstring(err), 1)
		}
		return nil
	}

	// Try fuzzy matching the version number again
	cs, err := semver.NewConstraint(vname)
	if err != nil {
		return cli.Exit(errstring(err), 1)
	}

	for j := len(versions) - 1; j >= 0; j-- {
		if !versions[j].MatchConstraint(cs) {
			continue
		}
		if err = switchVersion(versions[j].Name()); err != nil {
			return cli.Exit(errstring(err), 1)
		}
		return nil
	}

	return cli.Exit(wrapstring(fmt.Sprintf("The %q version does not exist, please install it first.", vname)), 1)
}