chore: initial commit

command_exec.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"os"
+	"strings"
+	"syscall"
+	"text/template"
+
+	"github.com/spf13/cobra"
+)
+
+func execCommand() (*cobra.Command, error) {
+	cmd := &cobra.Command{
+		Use: "exec <binary> [args]...",
+		Short: "Execute named binary from current " +
+			"Emacs version",
+		Args:                  cobra.MinimumNArgs(1),
+		SilenceUsage:          true,
+		DisableFlagParsing:    true,
+		DisableFlagsInUseLine: true,
+		Hidden:                true,
+		ValidArgsFunction:     execValidArgs,
+		RunE:                  execRunE,
+	}
+
+	return cmd, nil
+}
+
+func execRunE(cmd *cobra.Command, args []string) error {
+	conf, err := getConfig()
+	if err != nil {
+		return err
+	}
+
+	version, err := newEmacsVersion(conf, conf.Current.Version)
+	if err != nil {
+		return err
+	}
+
+	if bin, ok := version.BinPath(args[0]); ok {
+		select {
+		case <-cmd.Context().Done():
+			return cmd.Context().Err()
+		default:
+		}
+
+		execArgs := append([]string{bin}, args[1:]...)
+		execEnv := os.Environ()
+		for i := 0; i < len(execEnv); i++ {
+			if strings.HasPrefix(execEnv[i], "PATH=") {
+				execEnv[i] = "PATH=" + version.Bin + ":" + execEnv[i][5:]
+			}
+		}
+
+		return syscall.Exec(bin, execArgs, execEnv)
+	}
+
+	versions, err := newEmacsVersions(conf)
+	if err != nil {
+		return err
+	}
+
+	var availableIn []string
+	for _, ev := range versions {
+		if _, ok := ev.BinPath(args[0]); ok {
+			availableIn = append(availableIn, ev.Version)
+		}
+	}
+
+	var buf bytes.Buffer
+	err = execOtherVersionsTemplate.Execute(&buf, &execOtherVersionsData{
+		Name:        args[0],
+		Current:     conf.Current.Version,
+		AvailableIn: availableIn,
+	})
+	if err != nil {
+		return err
+	}
+
+	return errors.New(buf.String())
+}
+
+func execValidArgs(
+	_ *cobra.Command,
+	args []string,
+	toComplete string,
+) ([]string, cobra.ShellCompDirective) {
+	var r []string
+
+	if len(args) > 0 {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	conf, err := getConfig()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	version, err := newEmacsVersion(conf, conf.Current.Version)
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	for _, bin := range version.Binaries {
+		if toComplete == "" || strings.HasPrefix(bin, toComplete) {
+			r = append(r, bin)
+		}
+	}
+
+	return r, cobra.ShellCompDirectiveNoFileComp
+}
+
+type execOtherVersionsData struct {
+	Name        string
+	Current     string
+	AvailableIn []string
+}
+
+var execOtherVersionsTemplate = template.Must(template.New("other").Parse(
+	`{{ if gt (len .AvailableIn) 0 -}}
+Current Emacs version ({{.Current}}) does not have a "{{.Name}}" executable.
+
+"{{.Name}}" is available in the following Emacs versions:
+{{- range .AvailableIn }}
+  - {{ . }}
+{{- end -}}
+{{ else -}}
+"{{.Name}}" executable is not available in any installed Emacs version.
+{{- end }}
+
+Change version with: evm use <version>
+List all installed versions with: evm list`,
+))