fix case with short options only

include/cxxopts.hpp

@@ -337,13 +337,21 @@ class value_base : public std::enable_shared_from_this<value_base> {
   }
 
 private:
+  /// A default value for the option.
   std::string default_value_{};
+  /// A name of an environment variable from which a default
+  /// value will be read.
   std::string env_var_{};
+  /// An implicit value for the option.
   std::string implicit_value_{};
+  /// Configuration of the value parser.
   parse_context parse_ctx_{};
 
+  /// The default value has been set.
   bool default_{false};
+  /// The environment variable has been set.
   bool env_{false};
+  /// The implicit value has been set.
   bool implicit_{false};
 };
 #if defined(__GNUC__)
@@ -768,7 +776,6 @@ class options {
 
   struct help_group_details {
     std::string name{};
-    std::string description{};
     std::vector<help_option_details> options{};
   };
 
@@ -792,33 +799,6 @@ class options {
 public:
   explicit options(std::string program, std::string help_string = {});
 
-  options&
-  positional_help(std::string help_text);
-
-  options&
-  custom_help(std::string help_text);
-
-  options&
-  show_positional_help();
-
-  options&
-  allow_unrecognised_options();
-
-  options&
-  set_tab_expansion(bool expansion = true);
-
-  options&
-  set_width(size_t width);
-
-  /**
-   * Stop parsing at first positional argument.
-   */
-  options&
-  stop_on_positional();
-
-  option_adder
-  add_options(std::string group = {});
-
   /**
    * Adds list of options to the specific group.
    */
@@ -835,6 +815,15 @@ class options {
     const std::string& group,
     const option& option);
 
+  option_adder
+  add_options(std::string group = {});
+
+  options&
+  allow_unrecognised_options(const bool value = true);
+
+  options&
+  custom_help(std::string help_text);
+
   template <typename ... Args>
   void
   parse_positional(Args&& ... args) {
@@ -853,6 +842,34 @@ class options {
   void
   parse_positional(std::vector<std::string> options);
 
+  options&
+  positional_help(std::string help_text);
+
+  options&
+  set_tab_expansion(bool expansion = true);
+
+  options&
+  set_width(size_t width);
+
+  options&
+  show_positional_help(const bool value = true);
+
+  /**
+   * Stop parsing at first positional argument.
+   */
+  options&
+  stop_on_positional(const bool value = true);
+
+public:
+  /**
+   * Parses the command line arguments according to the current specification.
+   */
+  parse_result
+  parse(int argc, const char* const* argv) const;
+
+  /**
+   * Generates help for the options.
+   */
   std::string
   help(const std::vector<std::string>& groups = {}) const;
 
@@ -865,19 +882,12 @@ class options {
   const help_group_details&
   group_help(const std::string& group) const;
 
-public:
-  /**
-   * Parses the command line arguments according to the current specification.
-   */
-  parse_result
-  parse(int argc, const char* const* argv) const;
-
 private:
   void
   add_option(
     const std::string& group,
-    const std::string& s,
-    const std::string& l,
+    std::string s,
+    std::string l,
     std::string desc,
     const std::shared_ptr<detail::value_base>& value,
     std::string arg_help);

src/cxxopts.cpp

@@ -223,7 +223,7 @@ static const std::basic_regex<char> option_matcher
   ("--([[:alnum:]][-_[:alnum:]]+)(=(.*))?|-(\\?|[[:alnum:]]+)");
 
 static const std::basic_regex<char> option_specifier
-  ("((\\?|[[:alnum:]]),)?[ ]*([[:alnum:]][-_[:alnum:]]*)?");
+  ("((\\?|[[:alnum:]]),)?[ ]*(\\?|([[:alnum:]][-_[:alnum:]]*))?");
 
 static const std::basic_regex<char> integer_pattern
   ("(-)?(0x)?([0-9a-zA-Z]+)|((0x)?0)");
@@ -797,6 +797,7 @@ class options::option_parser {
 
             if (oi == options_.end()) {
               if (allow_unrecognised_) {
+                // TODO: keep unrecognized.
                 continue;
               }
               // Error.
@@ -1015,8 +1016,8 @@ options::options(std::string program, std::string help_string)
 }
 
 options&
-options::positional_help(std::string help_text) {
-  positional_help_ = std::move(help_text);
+options::allow_unrecognised_options(const bool value) {
+  allow_unrecognised_ = value;
   return *this;
 }
 
@@ -1027,32 +1028,32 @@ options::custom_help(std::string help_text) {
 }
 
 options&
-options::show_positional_help() {
-  show_positional_ = true;
+options::positional_help(std::string help_text) {
+  positional_help_ = std::move(help_text);
   return *this;
 }
 
 options&
-options::allow_unrecognised_options() {
-  allow_unrecognised_ = true;
+options::show_positional_help(const bool value) {
+  show_positional_ = value;
   return *this;
 }
 
 options&
-options::set_width(size_t width) {
-  width_ = width;
+options::set_tab_expansion(bool expansion) {
+  tab_expansion_ = expansion;
   return *this;
 }
 
 options&
-options::set_tab_expansion(bool expansion) {
-  tab_expansion_ = expansion;
+options::set_width(size_t width) {
+  width_ = width;
   return *this;
 }
 
 options&
-options::stop_on_positional() {
-  stop_on_positional_ = true;
+options::stop_on_positional(const bool value) {
+  stop_on_positional_ = value;
   return *this;
 }
 
@@ -1090,8 +1091,8 @@ options::add_option(const std::string& group, const option& opt) {
 void
 options::add_option(
   const std::string& group,
-  const std::string& s,
-  const std::string& l,
+  std::string s,
+  std::string l,
   std::string desc,
   const std::shared_ptr<detail::value_base>& value,
   std::string arg_help)
@@ -1292,8 +1293,7 @@ options::help_one_group(const std::string& g) const {
   }
 
   for (const auto& o : group->second.options) {
-    if (positional_set_.find(o.l) != positional_set_.end() &&
-        !show_positional_)
+    if (!show_positional_ && positional_set_.find(o.l) != positional_set_.end())
     {
       continue;
     }
@@ -1312,8 +1312,7 @@ options::help_one_group(const std::string& g) const {
 
   auto fiter = format.begin();
   for (const auto& o : group->second.options) {
-    if (positional_set_.find(o.l) != positional_set_.end() &&
-        !show_positional_)
+    if (!show_positional_ && positional_set_.find(o.l) != positional_set_.end())
     {
       continue;
     }
@@ -1439,9 +1438,12 @@ options::option_adder::operator()(
     throw_or_mimic<invalid_option_format_error>(opts);
   }
 
-  const auto& short_match = result[2];
-  const auto& long_match = result[3];
+  std::string short_match = result[2].str();
+  std::string long_match = result[3].str();
 
+  if (short_match.empty() && long_match.length() == 1) {
+    std::swap(short_match, long_match);
+  }
   if ((!short_match.length() && !long_match.length()) ||
       ( short_match.length() &&  long_match.length() == 1))
   {
@@ -1450,8 +1452,8 @@ options::option_adder::operator()(
 
   options_.add_option(
     group_,
-    short_match.str(),
-    long_match.str(),
+    std::move(short_match),
+    std::move(long_match),
     desc,
     value,
     std::move(arg_help));

test/options.cpp

@@ -57,6 +57,14 @@ TEST_CASE("Value", "traits") {
   CHECK(cxxopts::value<std::vector<std::string>>()->is_container());
 }
 
+TEST_CASE("Question mark only", "[options]") {
+  cxxopts::options options("test_short", " - test question mark");
+  options.add_options()("?", "show help");
+
+  const Argv argv({"test_short", "-?"});
+  CHECK(options.parse(argv.argc(), argv.argv()).count("?") == 1);
+}
+
 TEST_CASE("Question mark help", "[options]") {
     cxxopts::options options("test_short", " - test question mark");