From c1fcf226196e700df9f6ad43dc1325f5e67f0591 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sun, 6 Mar 2016 12:42:01 +0100
Subject: [PATCH] Group Args, so we enforce that only _one_ of them can be
 specified

---
 imag-view/src/ui.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/imag-view/src/ui.rs b/imag-view/src/ui.rs
index 2c5818de..619e4f27 100644
--- a/imag-view/src/ui.rs
+++ b/imag-view/src/ui.rs
@@ -1,4 +1,4 @@
-use clap::{Arg, App, SubCommand};
+use clap::{Arg, App, ArgGroup, SubCommand};
 
 pub fn build_ui<'a>(app: App<'a, 'a>) -> App<'a, 'a> {
     app
@@ -86,6 +86,15 @@ pub fn build_ui<'a>(app: App<'a, 'a>) -> App<'a, 'a> {
                         .takes_value(true) // non-optional, call-string
                         .required(false)
                         .help("View content in custom program, for example 'libreoffice %e', replace '%e' with entry path"))
+
+                   .group(ArgGroup::with_name("viewer")
+                          .args(&["view-in-stdout",
+                                  "view-in-ui",
+                                  "view-in-browser",
+                                  "view-in-texteditor",
+                                  "view-in-custom",
+                          ])
+                          .required(false))
                    )
 
         .subcommand(SubCommand::with_name("compile")