From 2ab47054758b10ff282619c52280b0d02f885f1e Mon Sep 17 00:00:00 2001
From: tastytea <tastytea@tastytea.de>
Date: Mon, 24 May 2021 05:45:42 +0200
Subject: [PATCH] Make --regexp required, show help if it is not given.

---
 src/options.cpp | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/options.cpp b/src/options.cpp
index f6912d6..74539e8 100644
--- a/src/options.cpp
+++ b/src/options.cpp
@@ -27,6 +27,7 @@
 #include <boost/program_options/variables_map.hpp>
 
 #include <cstdlib>
+#include <exception>
 #include <fstream>
 #include <iostream>
 #include <string>
@@ -61,8 +62,8 @@ po::variables_map parse_options(int argc, char *argv[])
         ("ignore-case,i",
          translate("Ignore case distinctions in pattern and data.")
          .str().data())
-        ("regexp,e", po::value<std::vector<std::string>>()->composing()
-         ->value_name(translate("PATTERN")),
+        ("regexp,e", po::value<std::vector<std::string>>()
+         ->value_name(translate("PATTERN"))->composing()->required(),
          translate("Use additional PATTERN for matching.").str().data())
     ;
 
@@ -89,7 +90,15 @@ po::variables_map parse_options(int argc, char *argv[])
     po::store(po::parse_config_file(configfile, options_visible, true), vm);
     configfile.close();
 
-    po::notify(vm);
+    try
+    {
+        po::notify(vm);
+    }
+    catch (const boost::program_options::required_option &e)
+    {
+        cout << options_visible;
+        std::rethrow_exception(std::current_exception());
+    }
 
     if (vm.count("help") != 0)
     {