added completion support

cmd/root.go

@@ -54,6 +54,26 @@ func Execute() {
 		sortmode    cfg.Sortmode
 	)
 
+	var completionCmd = &cobra.Command{
+		Use:                   "completion [bash|zsh|fish|powershell]",
+		Short:                 "Generate completion script",
+		DisableFlagsInUseLine: true,
+		ValidArgs:             []string{"bash", "zsh", "fish", "powershell"},
+		Args:                  cobra.MatchAll(cobra.ExactArgs(1), cobra.OnlyValidArgs),
+		Run: func(cmd *cobra.Command, args []string) {
+			switch args[0] {
+			case "bash":
+				cmd.Root().GenBashCompletion(os.Stdout)
+			case "zsh":
+				cmd.Root().GenZshCompletion(os.Stdout)
+			case "fish":
+				cmd.Root().GenFishCompletion(os.Stdout, true)
+			case "powershell":
+				cmd.Root().GenPowerShellCompletionWithDesc(os.Stdout)
+			}
+		},
+	}
+
 	var rootCmd = &cobra.Command{
 		Use:   "tablizer [regex] [file, ...]",
 		Short: "[Re-]tabularize tabular data",
@@ -81,6 +101,8 @@ func Execute() {
 		},
 	}
 
+	rootCmd.AddCommand(completionCmd)
+
 	// options
 	rootCmd.PersistentFlags().BoolVarP(&conf.Debug, "debug", "d", false, "Enable debugging")
 	rootCmd.PersistentFlags().BoolVarP(&conf.NoNumbering, "no-numbering", "n", false, "Disable header numbering")

cmd/tablizer.go

@@ -199,6 +199,46 @@ DESCRIPTION
     <T_COLUMNS> - comma separated list of columns to output, like -c
     <NO_COLORS> - disable colorization of matches, like -N
 
+  COMPLETION
+    Bash:
+           source <(%[1]s completion bash)
+
+        To load completions for each session, execute once:
+
+          # Linux:
+          $ tablizer completion bash > /etc/bash_completion.d/%[1]s
+
+          # macOS:
+          $ tablizer completion bash > $(brew --prefix)/etc/bash_completion.d/%[1]s
+
+    Zsh:
+        If shell completion is not already enabled in your environment, you
+        will need to enable it. You can execute the following once:
+
+          echo "autoload -U compinit; compinit" >> ~/.zshrc
+
+        To load completions for each session, execute once:
+
+          $ tablizer completion zsh > "${fpath[1]}/_%[1]s"
+
+        You will need to start a new shell for this setup to take effect.
+
+    fish:
+           tablizer completion fish | source
+
+        To load completions for each session, execute once:
+
+           tablizer completion fish > ~/.config/fish/completions/%[1]s.fish
+
+    PowerShell:
+           tablizer completion powershell | Out-String | Invoke-Expression
+
+        To load completions for every new session, run:
+
+           tablizer completion powershell > tablizer.ps1
+
+        and source this file from your PowerShell profile.
+
 BUGS
     In order to report a bug, unexpected behavior, feature requests or to
     submit a patch, please open an issue on github: