Added support for metavar and improved help/usage based on #187

README.md

@@ -338,15 +338,15 @@ The square of 4 is 16
 
 ```
 foo@bar:/home/dev/$ ./main --help
-Usage: main [options] square
+Usage: main [-h] [--verbose] square
 
 Positional arguments:
   square       	display the square of a given number
 
 Optional arguments:
--h --help       shows help message and exits [default: false]
+  -h, --help   	shows help message and exits
--v --version    prints version information and exits [default: false]
+  -v, --version	prints version information and exits
---verbose       [default: false]
+  --verbose
 ```
 
 You may also get the help message in string via `program.help().str()`.
@@ -357,30 +357,36 @@ You may also get the help message in string via `program.help().str()`.
 information. `ArgumentParser::add_epilog` will add text after all other help output.
 
 ```cpp
-argparse::ArgumentParser program("main");
+#include <argparse/argparse.hpp>
+
+int main(int argc, char *argv[]) {
+  argparse::ArgumentParser program("main");
+  program.add_argument("thing").help("Thing to use.").metavar("THING");
+  program.add_argument("--member").help("The alias for the member to pass to.").metavar("ALIAS");
+  program.add_argument("--verbose").default_value(false).implicit_value(true);
 
-program.add_argument("thing")
-  .help("Thing to use.");
   program.add_description("Forward a thing to the next member.");
   program.add_epilog("Possible things include betingalw, chiz, and res.");
 
   program.parse_args(argc, argv);
 
   std::cout << program << std::endl;
+}
 ```
 
 ```console
-foo@bar:/home/dev/$ ./main --help
+Usage: main [-h] [--member ALIAS] [--verbose] THING
-Usage: main thing
 
 Forward a thing to the next member.
 
 Positional arguments:
-thing           Thing to use.
+  THING         	Thing to use.
 
 Optional arguments:
--h --help       shows help message and exits [default: false]
+  -h, --help    	shows help message and exits
--v --version    prints version information and exits [default: false]
+  -v, --version 	prints version information and exits
+  --member ALIAS	The alias for the member to pass to.
+  --verbose     	
 
 Possible things include betingalw, chiz, and res.
 ```
@@ -710,12 +716,14 @@ int main(int argc, char *argv[]) {
 
   // git add subparser
   argparse::ArgumentParser add_command("add");
+  add_command.add_description("Add file contents to the index");
   add_command.add_argument("files")
     .help("Files to add content from. Fileglobs (e.g.  *.c) can be given to add all matching files.")
     .remaining();
 
   // git commit subparser
   argparse::ArgumentParser commit_command("commit");
+  commit_command.add_description("Record changes to the repository");
   commit_command.add_argument("-a", "--all")
     .help("Tell the command to automatically stage files that have been modified and deleted.")
     .default_value(false)
@@ -726,6 +734,7 @@ int main(int argc, char *argv[]) {
 
   // git cat-file subparser
   argparse::ArgumentParser catfile_command("cat-file");
+  catfile_command.add_description("Provide content or type and size information for repository objects");
   catfile_command.add_argument("-t")
     .help("Instead of the content, show the object type identified by <object>.");
 
@@ -734,7 +743,9 @@ int main(int argc, char *argv[]) {
 
   // git submodule subparser
   argparse::ArgumentParser submodule_command("submodule");
+  submodule_command.add_description("Initialize, update or inspect submodules");
   argparse::ArgumentParser submodule_update_command("update");
+  submodule_update_command.add_description("Update the registered submodules to match what the superproject expects");
   submodule_update_command.add_argument("--init")
     .default_value(false)
     .implicit_value(true);
@@ -763,11 +774,11 @@ int main(int argc, char *argv[]) {
 
 ```console
 foo@bar:/home/dev/$ ./git --help
-Usage: git [options] <command> [<args>]
+Usage: git [-h] {add,cat-file,commit,submodule}
 
 Optional arguments:
--h --help    	shows help message and exits [default: false]
+  -h, --help   	shows help message and exits
--v --version 	prints version information and exits [default: false]
+  -v, --version	prints version information and exits
 
 Subcommands:
   add           Add file contents to the index
@@ -776,7 +787,7 @@ commit       	Record changes to the repository
   submodule     Initialize, update or inspect submodules
 
 foo@bar:/home/dev/$ ./git add --help
-Usage: git add [options] files 
+Usage: add [-h] files
 
 Add file contents to the index
 
@@ -784,17 +795,28 @@ Positional arguments:
   files        	Files to add content from. Fileglobs (e.g.  *.c) can be given to add all matching files.
 
 Optional arguments:
--h --help    	shows help message and exits [default: false]
+  -h, --help   	shows help message and exits
--v --version 	prints version information and exits [default: false]
+  -v, --version	prints version information and exits
+
+foo@bar:/home/dev/$ ./git commit --help
+Usage: commit [-h] [--all] [--message VAR]
+
+Record changes to the repository
+
+Optional arguments:
+  -h, --help   	shows help message and exits
+  -v, --version	prints version information and exits
+  -a, --all    	Tell the command to automatically stage files that have been modified and deleted.
+  -m, --message	Use the given <msg> as the commit message.
 
 foo@bar:/home/dev/$ ./git submodule --help
-Usage: git submodule [options] <command> [<args>]
+Usage: submodule [-h] {update}
 
 Initialize, update or inspect submodules
 
 Optional arguments:
--h --help    	shows help message and exits [default: false]
+  -h, --help   	shows help message and exits
--v --version 	prints version information and exits [default: false]
+  -v, --version	prints version information and exits
 
 Subcommands:
   update        Update the registered submodules to match what the superproject expects

include/argparse/argparse.hpp

@@ -36,6 +36,7 @@ SOFTWARE.
 #include <charconv>
 #include <cstdlib>
 #include <functional>
+#include <iomanip>
 #include <iostream>
 #include <iterator>
 #include <limits>
@@ -329,6 +330,21 @@ template <class T> struct parse_number<T, chars_format::fixed> {
   }
 };
 
+template <typename StrIt>
+std::string join(StrIt first, StrIt last, const std::string &separator) {
+  if (first == last) {
+    return "";
+  }
+  std::stringstream value;
+  value << *first;
+  ++first;
+  while (first != last) {
+    value << separator << *first;
+    ++first;
+  }
+  return value.str();
+}
+
 } // namespace details
 
 enum class nargs_pattern { optional, any, at_least_one };
@@ -379,6 +395,11 @@ public:
     return *this;
   }
 
+  Argument &metavar(std::string metavar) {
+    m_metavar = std::move(metavar);
+    return *this;
+  }
+
   template <typename T> Argument &default_value(T &&value) {
     m_default_value_repr = details::repr(value);
     m_default_value = std::forward<T>(value);
@@ -573,21 +594,82 @@ public:
     }
   }
 
+  std::string get_inline_usage() const {
+    std::stringstream usage;
+    // Find the longest variant to show in the usage string
+    std::string longest_name = m_names[0];
+    for (const auto &s : m_names) {
+      if (s.size() > longest_name.size()) {
+        longest_name = s;
+      }
+    }
+    if (!m_is_required) {
+      usage << "[";
+    }
+    usage << longest_name;
+    const std::string metavar = !m_metavar.empty() ? m_metavar : "VAR";
+    if (m_num_args_range.get_max() > 0) {
+      usage << " " << metavar;
+      if (m_num_args_range.get_max() > 1) {
+        usage << "...";
+      }
+    }
+    if (!m_is_required) {
+      usage << "]";
+    }
+    return usage.str();
+  }
+
   std::size_t get_arguments_length() const {
-    return std::accumulate(std::begin(m_names), std::end(m_names),
+
-                           std::size_t(0), [](const auto &sum, const auto &s) {
+    std::size_t names_size = std::accumulate(
-                             return sum + s.size() +
+        std::begin(m_names), std::end(m_names), std::size_t(0),
-                                    1; // +1 for space between names
+        [](const auto &sum, const auto &s) { return sum + s.size(); });
-                           });
+
+    if (is_positional(m_names.front(), m_prefix_chars)) {
+      // A set metavar means this replaces the names
+      if (!m_metavar.empty()) {
+        // Indent and metavar
+        return 2 + m_metavar.size();
+      }
+
+      // Indent and space-separated
+      return 2 + names_size + (m_names.size() - 1);
+    }
+    // Is an option - include both names _and_ metavar
+    // size = text + (", " between names)
+    std::size_t size = names_size + 2 * (m_names.size() - 1);
+    if (!m_metavar.empty() && m_num_args_range == NArgsRange{1, 1}) {
+      size += m_metavar.size() + 1;
+    }
+    return size + 2; // indent
   }
 
   friend std::ostream &operator<<(std::ostream &stream,
                                   const Argument &argument) {
     std::stringstream name_stream;
-    std::copy(std::begin(argument.m_names), std::end(argument.m_names),
+    name_stream << "  "; // indent
-              std::ostream_iterator<std::string>(name_stream, " "));
+    if (argument.is_positional(argument.m_names.front(),
+                               argument.m_prefix_chars)) {
+      if (!argument.m_metavar.empty()) {
+        name_stream << argument.m_metavar;
+      } else {
+        name_stream << details::join(argument.m_names.begin(),
+                                     argument.m_names.end(), " ");
+      }
+    } else {
+      name_stream << details::join(argument.m_names.begin(),
+                                   argument.m_names.end(), ", ");
+      // If we have a metavar, and one narg - print the metavar
+      if (!argument.m_metavar.empty() &&
+          argument.m_num_args_range == NArgsRange{1, 1}) {
+        name_stream << " " << argument.m_metavar;
+      }
+    }
     stream << name_stream.str() << "\t" << argument.m_help;
-    if (argument.m_default_value.has_value()) {
+
+    if (argument.m_default_value.has_value() &&
+        argument.m_num_args_range != NArgsRange{0, 0}) {
       if (!argument.m_help.empty()) {
         stream << " ";
       }
@@ -647,6 +729,12 @@ private:
     std::size_t get_min() const { return m_min; }
 
     std::size_t get_max() const { return m_max; }
+
+    bool operator==(const NArgsRange &rhs) const {
+      return rhs.m_min == m_min && rhs.m_max == m_max;
+    }
+
+    bool operator!=(const NArgsRange &rhs) const { return !(*this == rhs); }
   };
 
   void throw_nargs_range_validation_error() const {
@@ -913,6 +1001,7 @@ private:
   std::vector<std::string> m_names;
   std::string_view m_used_name;
   std::string m_help;
+  std::string m_metavar;
   std::any m_default_value;
   std::string m_default_value_repr;
   std::any m_implicit_value;
@@ -1171,17 +1260,10 @@ public:
   friend auto operator<<(std::ostream &stream, const ArgumentParser &parser)
       -> std::ostream & {
     stream.setf(std::ios_base::left);
-    stream << "Usage: " << parser.m_parser_path << " [options] ";
-    for (const auto &argument : parser.m_positional_arguments) {
-      stream << argument.m_names.front() << " ";
-    }
 
-    if (!parser.m_subparser_map.empty()) {
+    auto longest_arg_length = parser.get_length_of_longest_argument();
-      stream << (parser.m_positional_arguments.empty() ? "" : " ")
+
-             << "<command> [<args>]";
+    stream << parser.usage() << "\n\n";
-    }
-    std::size_t longest_arg_length = parser.get_length_of_longest_argument();
-    stream << "\n\n";
 
     if (!parser.m_description.empty()) {
       stream << parser.m_description << "\n\n";
@@ -1212,8 +1294,10 @@ public:
                      : "\n")
              << "Subcommands:\n";
       for (const auto &[command, subparser] : parser.m_subparser_map) {
-        stream.width(static_cast<std::streamsize>(longest_arg_length));
+        stream << std::setw(2) << " ";
-        stream << command << "\t" << subparser->get().m_description << "\n";
+        stream << std::setw(static_cast<int>(longest_arg_length - 2))
+               << command;
+        stream << " " << subparser->get().m_description << "\n";
       }
     }
 
@@ -1232,6 +1316,48 @@ public:
     return out;
   }
 
+  // Format usage part of help only
+  auto usage() const -> std::string {
+    std::stringstream stream;
+
+    stream << "Usage: " << this->m_program_name;
+
+    // Add any options inline here
+    for (const auto &argument : this->m_optional_arguments) {
+      if (argument.m_names[0] == "-v") {
+        continue;
+      } else if (argument.m_names[0] == "-h") {
+        stream << " [-h]";
+      } else {
+        stream << " " << argument.get_inline_usage();
+      }
+    }
+    // Put positional arguments after the optionals
+    for (const auto &argument : this->m_positional_arguments) {
+      if (!argument.m_metavar.empty()) {
+        stream << " " << argument.m_metavar;
+      } else {
+        stream << " " << argument.m_names.front();
+      }
+    }
+    // Put subcommands after positional arguments
+    if (!m_subparser_map.empty()) {
+      stream << " {";
+      std::size_t i{0};
+      for (const auto &[command, unused] : m_subparser_map) {
+        if (i == 0) {
+          stream << command;
+        } else {
+          stream << "," << command;
+        }
+        ++i;
+      }
+      stream << "}";
+    }
+
+    return stream.str();
+  }
+
   // Printing the one and only help message
   // I've stuck with a simple message format, nothing fancy.
   [[deprecated("Use cout << program; instead.  See also help().")]] std::string