Merge branch '2_0'v2.0.0

8 files changed, 621 insertions, 295 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..8b4ba45
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,29 @@
+# Changelog
+
+This is the changelog for `cxxopts`, a C++11 library for parsing command line
+options. The project adheres to semantic versioning.
+
+## 2.0
+
+### Changed
+
+* `Options::parse` returns a ParseResult rather than storing the parse
+  result internally.
+* Options with default values now get counted as appearing once if they
+  were not specified by the user.
+
+### Added
+
+* A new `ParseResult` object that is the immutable result of parsing. It
+  responds to the same `count` and `operator[]` as `Options` of 1.x did.
+* The function `ParseResult::arguments` returns a vector of the parsed
+  arguments to iterate through in the order they were provided.
+* The symbol `cxxopts::version` for the version of the library.
+* Booleans can be specified with various strings and explicitly set false.
+
+## 1.x
+
+The 1.x series was the first major version of the library, with release numbers
+starting to follow semantic versioning, after 0.x being unstable.  It never had
+a changelog maintained for it. Releases mostly contained bug fixes, with the
+occasional feature added.
diff --git a/README.md b/README.md
index 355417e..cd869b8 100644
--- a/README.md
+++ b/README.md
@@ -39,12 +39,12 @@ Any type can be given as long as it can be parsed, with operator>>.
 
 To parse the command line do:
 
-    options.parse(argc, argv);
+    auto result = options.parse(argc, argv);
 
-To retrieve an option use `options.count("option")` to get the number of times
+To retrieve an option use `result.count("option")` to get the number of times
 it appeared, and
 
-    options["opt"].as<type>()
+    result["opt"].as<type>()
 
 to get its value. If "opt" doesn't exist, or isn't of the right type, then an
 exception will be thrown.
@@ -84,6 +84,17 @@ If an option had both, then not specifying it would give the value `"value"`,
 writing it on the command line as `--option` would give the value `"implicit"`,
 and writing `--option=another` would give it the value `"another"`.
 
+Note that the default and implicit value is always stored as a string,
+regardless of the type that you want to store it in. It will be parsed as
+though it was given on the command line.
+
+## Boolean values
+
+Boolean options have a default implicit value of `"true"`, which can be
+overridden. The effect is that writing `-o` by itself will set option `o` to
+`true`. However, they can also be written with various strings using either
+`=value` or the next argument.
+
 # Linking
 
 This is a header only library.
@@ -93,9 +104,7 @@ This is a header only library.
 The only build requirement is a C++ compiler that supports C++11 regular
 expressions. For example GCC >= 4.9 or clang with libc++.
 
-
 # TODO list
 
 * Allow unrecognised options.
 * Various help strings.
-* Unicode aware for help strings.
diff --git a/include/cxxopts.hpp b/include/cxxopts.hpp
index 17bb590..3117e9d 100644
--- a/include/cxxopts.hpp
+++ b/include/cxxopts.hpp
@@ -22,13 +22,8 @@ THE SOFTWARE.
 
 */
 
-#ifndef CXX_OPTS_HPP
-#define CXX_OPTS_HPP
-
-#if defined(__GNUC__)
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
-#endif
+#ifndef CXXOPTS_HPP_INCLUDED
+#define CXXOPTS_HPP_INCLUDED
 
 #include <cstring>
 #include <cctype>
@@ -39,9 +34,17 @@ THE SOFTWARE.
 #include <regex>
 #include <sstream>
 #include <string>
+#include <unordered_map>
 #include <unordered_set>
 #include <vector>
 
+namespace cxxopts
+{
+  static constexpr struct {
+    uint8_t major, minor, patch;
+  } version = {2, 0, 0};
+}
+
 //when we ask cxxopts to use Unicode, help strings are processed using ICU,
 //which results in the correct lengths being computed for strings when they
 //are formatted for the help output
@@ -168,12 +171,14 @@ namespace cxxopts
 
 namespace std
 {
+  inline
   cxxopts::UnicodeStringIterator
   begin(const icu::UnicodeString& s)
   {
     return cxxopts::UnicodeStringIterator(&s, 0);
   }
 
+  inline
   cxxopts::UnicodeStringIterator
   end(const icu::UnicodeString& s)
   {
@@ -258,6 +263,12 @@ namespace cxxopts
   {
     public:
 
+    virtual ~Value() = default;
+
+    virtual
+    std::shared_ptr<Value>
+    clone() const = 0;
+
     virtual void
     parse(const std::string& text) const = 0;
 
@@ -265,9 +276,6 @@ namespace cxxopts
     parse() const = 0;
 
     virtual bool
-    has_arg() const = 0;
-
-    virtual bool
     has_default() const = 0;
 
     virtual bool
@@ -287,6 +295,9 @@ namespace cxxopts
 
     virtual std::shared_ptr<Value>
     implicit_value(const std::string& value) = 0;
+
+    virtual bool
+    is_boolean() const = 0;
   };
 
   class OptionException : public std::exception
@@ -385,7 +396,7 @@ namespace cxxopts
     )
     : OptionParseException(
         u8"Option " + LQUOTE + option + RQUOTE +
-        u8" does not take an argument, but argument" +
+        u8" does not take an argument, but argument " +
         LQUOTE + arg + RQUOTE + " given"
       )
     {
@@ -432,6 +443,10 @@ namespace cxxopts
     {
       std::basic_regex<char> integer_pattern
         ("(-)?(0x)?([1-9a-zA-Z][0-9a-zA-Z]*)|((0x)?0)");
+      std::basic_regex<char> truthy_pattern
+        ("t|true|T|True");
+      std::basic_regex<char> falsy_pattern
+        ("(f|false|F|False)?");
     }
 
     namespace detail
@@ -561,11 +576,6 @@ namespace cxxopts
         value = checked_negate<T>(result,
           text,
           std::integral_constant<bool, is_signed>());
-        //if (!is_signed)
-        //{
-        //  throw argument_incorrect_type(text);
-        //}
-        //value = -result;
       }
       else
       {
@@ -641,11 +651,25 @@ namespace cxxopts
 
     inline
     void
-    parse_value(const std::string& /*text*/, bool& value)
+    parse_value(const std::string& text, bool& value)
     {
-      //TODO recognise on, off, yes, no, enable, disable
-      //so that we can write --long=yes explicitly
-      value = true;
+      std::smatch result;
+      std::regex_match(text, result, truthy_pattern);
+
+      if (!result.empty())
+      {
+        value = true;
+        return;
+      }
+
+      std::regex_match(text, result, falsy_pattern);
+      if (!result.empty())
+      {
+        value = false;
+        return;
+      }
+
+      throw argument_incorrect_type(text);
     }
 
     inline
@@ -674,18 +698,6 @@ namespace cxxopts
     }
 
     template <typename T>
-    struct value_has_arg
-    {
-      static constexpr bool value = true;
-    };
-
-    template <>
-    struct value_has_arg<bool>
-    {
-      static constexpr bool value = false;
-    };
-
-    template <typename T>
     struct type_is_container
     {
       static constexpr bool value = false;
@@ -698,20 +710,42 @@ namespace cxxopts
     };
 
     template <typename T>
-    class standard_value final : public Value
+    class abstract_value : public Value
     {
+      using Self = abstract_value<T>;
+
       public:
-      standard_value()
+      abstract_value()
       : m_result(std::make_shared<T>())
       , m_store(m_result.get())
       {
       }
 
-      standard_value(T* t)
+      abstract_value(T* t)
       : m_store(t)
       {
       }
 
+      virtual ~abstract_value() = default;
+
+      abstract_value(const abstract_value& rhs)
+      {
+        if (rhs.m_result)
+        {
+          m_result = std::make_shared<T>();
+          m_store = m_result.get();
+        }
+        else
+        {
+          m_store = rhs.m_store;
+        }
+
+        m_default = rhs.m_default;
+        m_implicit = rhs.m_implicit;
+        m_default_value = rhs.m_default_value;
+        m_implicit_value = rhs.m_implicit_value;
+      }
+
       void
       parse(const std::string& text) const
       {
@@ -731,12 +765,6 @@ namespace cxxopts
       }
 
       bool
-      has_arg() const
-      {
-        return value_has_arg<T>::value;
-      }
-
-      bool
       has_default() const
       {
         return m_default;
@@ -748,15 +776,17 @@ namespace cxxopts
         return m_implicit;
       }
 
-      virtual std::shared_ptr<Value>
-      default_value(const std::string& value){
+      std::shared_ptr<Value>
+      default_value(const std::string& value)
+      {
         m_default = true;
         m_default_value = value;
         return shared_from_this();
       }
 
-      virtual std::shared_ptr<Value>
-      implicit_value(const std::string& value){
+      std::shared_ptr<Value>
+      implicit_value(const std::string& value)
+      {
         m_implicit = true;
         m_implicit_value = value;
         return shared_from_this();
@@ -774,6 +804,12 @@ namespace cxxopts
         return m_implicit_value;
       }
 
+      bool
+      is_boolean() const
+      {
+        return std::is_same<T, bool>::value;
+      }
+
       const T&
       get() const
       {
@@ -790,11 +826,59 @@ namespace cxxopts
       protected:
       std::shared_ptr<T> m_result;
       T* m_store;
+
       bool m_default = false;
-      std::string m_default_value;
       bool m_implicit = false;
+
+      std::string m_default_value;
       std::string m_implicit_value;
     };
+
+    template <typename T>
+    class standard_value : public abstract_value<T>
+    {
+      public:
+      using abstract_value<T>::abstract_value;
+
+      std::shared_ptr<Value>
+      clone() const
+      {
+        return std::make_shared<standard_value<T>>(*this);
+      }
+    };
+
+    template <>
+    class standard_value<bool> : public abstract_value<bool>
+    {
+      public:
+      ~standard_value() = default;
+
+      standard_value()
+      {
+        set_implicit();
+      }
+
+      standard_value(bool* b)
+      : abstract_value(b)
+      {
+        set_implicit();
+      }
+
+      std::shared_ptr<Value>
+      clone() const
+      {
+        return std::make_shared<standard_value<bool>>(*this);
+      }
+
+      private:
+
+      void
+      set_implicit()
+      {
+        m_implicit = true;
+        m_implicit_value = "true";
+      }
+    };
   }
 
   template <typename T>
@@ -818,62 +902,59 @@ namespace cxxopts
     public:
     OptionDetails
     (
+      const std::string& short_name,
+      const std::string& long_name,
       const String& desc,
       std::shared_ptr<const Value> val
     )
-    : m_desc(desc)
+    : m_short(short_name)
+    , m_long(long_name)
+    , m_desc(desc)
     , m_value(val)
     , m_count(0)
     {
     }
 
-    const String&
-    description() const
+    OptionDetails(const OptionDetails& rhs)
+    : m_desc(rhs.m_desc)
+    , m_count(rhs.m_count)
     {
-      return m_desc;
+      m_value = rhs.m_value->clone();
     }
 
-    bool
-    has_arg() const
-    {
-      return m_value->has_arg();
-    }
+    OptionDetails(OptionDetails&& rhs) = default;
 
-    void
-    parse(const std::string& text)
+    const String&
+    description() const
     {
-      m_value->parse(text);
-      ++m_count;
+      return m_desc;
     }
 
-    void
-    parse_default()
-    {
-      m_value->parse();
+    const Value& value() const {
+        return *m_value;
     }
 
-    int
-    count() const
+    std::shared_ptr<Value>
+    make_storage() const
     {
-      return m_count;
+      return m_value->clone();
     }
 
-    const Value& value() const {
-        return *m_value;
+    const std::string&
+    short_name() const
+    {
+      return m_short;
     }
 
-    template <typename T>
-    const T&
-    as() const
+    const std::string&
+    long_name() const
     {
-#ifdef CXXOPTS_NO_RTTI
-      return static_cast<const values::standard_value<T>&>(*m_value).get();
-#else
-      return dynamic_cast<const values::standard_value<T>&>(*m_value).get();
-#endif
+      return m_long;
     }
 
     private:
+    std::string m_short;
+    std::string m_long;
     String m_desc;
     std::shared_ptr<const Value> m_value;
     int m_count;
@@ -884,13 +965,13 @@ namespace cxxopts
     std::string s;
     std::string l;
     String desc;
-    bool has_arg;
     bool has_default;
     std::string default_value;
     bool has_implicit;
     std::string implicit_value;
     std::string arg_help;
     bool is_container;
+    bool is_boolean;
   };
 
   struct HelpGroupDetails
@@ -900,45 +981,104 @@ namespace cxxopts
     std::vector<HelpOptionDetails> options;
   };
 
-  class Options
+  class OptionValue
   {
     public:
+    void
+    parse
+    (
+      std::shared_ptr<const OptionDetails> details,
+      const std::string& text
+    )
+    {
+      ensure_value(details);
+      ++m_count;
+      m_value->parse(text);
+    }
 
-    Options(std::string program, std::string help_string = "")
-    : m_program(std::move(program))
-    , m_help_string(toLocalString(std::move(help_string)))
-    , m_positional_help("positional parameters")
-    , m_next_positional(m_positional.end())
+    void
+    parse_default(std::shared_ptr<const OptionDetails> details)
     {
+      ensure_value(details);
+      m_value->parse();
+      m_count++;
     }
 
-    inline
-    Options&
-    positional_help(std::string help_text)
+    size_t
+    count() const
     {
-      m_positional_help = std::move(help_text);
-      return *this;
+      return m_count;
     }
 
-    inline
+    template <typename T>
+    const T&
+    as() const
+    {
+#ifdef CXXOPTS_NO_RTTI
+      return static_cast<const values::standard_value<T>&>(*m_value).get();
+#else
+      return dynamic_cast<const values::standard_value<T>&>(*m_value).get();
+#endif
+    }
+
+    private:
     void
-    parse(int& argc, char**& argv);
+    ensure_value(std::shared_ptr<const OptionDetails> details)
+    {
+      if (m_value == nullptr)
+      {
+        m_value = details->make_storage();
+      }
+    }
 
-    inline
-    OptionAdder
-    add_options(std::string group = "");
+    std::shared_ptr<Value> m_value;
+    size_t m_count = 0;
+  };
 
-    inline
-    void
-    add_option
-    (
-      const std::string& group,
-      const std::string& s,
-      const std::string& l,
-      std::string desc,
-      std::shared_ptr<const Value> value,
-      std::string arg_help
-    );
+  class KeyValue
+  {
+    public:
+    KeyValue(std::string key, std::string value)
+    : m_key(std::move(key))
+    , m_value(std::move(value))
+    {
+    }
+
+    const
+    std::string&
+    key() const
+    {
+      return m_key;
+    }
+
+    const std::string
+    value() const
+    {
+      return m_value;
+    }
+
+    template <typename T>
+    T
+    as() const
+    {
+      T result;
+      values::parse_value(m_value, result);
+      return result;
+    }
+
+    private:
+    std::string m_key;
+    std::string m_value;
+  };
+
+  class ParseResult
+  {
+    public:
+
+    ParseResult(
+      const std::unordered_map<std::string, std::shared_ptr<OptionDetails>>&,
+      std::vector<std::string>,
+      int&, char**&);
 
     int
     count(const std::string& o) const
@@ -949,10 +1089,12 @@ namespace cxxopts
         return 0;
       }
 
-      return iter->second->count();
+      auto riter = m_results.find(iter->second);
+
+      return riter->second.count();
     }
 
-    const OptionDetails&
+    const OptionValue&
     operator[](const std::string& option) const
     {
       auto iter = m_options.find(option);
@@ -962,49 +1104,31 @@ namespace cxxopts
         throw option_not_present_exception(option);
       }
 
-      return *iter->second;
-    }
-
-    //parse positional arguments into the given option
-    inline
-    void
-    parse_positional(std::string option);
+      auto riter = m_results.find(iter->second);
 
-    inline
-    void
-    parse_positional(std::vector<std::string> options);
+      return riter->second;
+    }
 
-    inline
-    std::string
-    help(const std::vector<std::string>& groups = {""}) const;
+    const std::vector<KeyValue>&
+    arguments() const
+    {
+      return m_sequential;
+    }
 
-    inline
-    const std::vector<std::string>
-    groups() const;
+    private:
 
-    inline
-    const HelpGroupDetails&
-    group_help(const std::string& group) const;
+    OptionValue&
+    get_option(std::shared_ptr<OptionDetails>);
 
-    private:
+    void
+    parse(int& argc, char**& argv);
 
-    inline
     void
-    add_one_option
-    (
-      const std::string& option,
-      std::shared_ptr<OptionDetails> details
-    );
+    add_to_option(const std::string& option, const std::string& arg);
 
-    inline
     bool
     consume_positional(std::string a);
 
-    inline
-    void
-    add_to_option(const std::string& option, const std::string& arg);
-
-    inline
     void
     parse_option
     (
@@ -1013,7 +1137,9 @@ namespace cxxopts
       const std::string& arg = ""
     );
 
-    inline
+    void
+    parse_default(std::shared_ptr<OptionDetails> details);
+
     void
     checked_parse_arg
     (
@@ -1024,11 +1150,88 @@ namespace cxxopts
       const std::string& name
     );
 
-    inline
+    const std::unordered_map<std::string, std::shared_ptr<OptionDetails>>
+      &m_options;
+    std::vector<std::string> m_positional;
+    std::vector<std::string>::iterator m_next_positional;
+    std::unordered_set<std::string> m_positional_set;
+    std::unordered_map<std::shared_ptr<OptionDetails>, OptionValue> m_results;
+
+    std::vector<KeyValue> m_sequential;
+  };
+
+  class Options
+  {
+    public:
+
+    Options(std::string program, std::string help_string = "")
+    : m_program(std::move(program))
+    , m_help_string(toLocalString(std::move(help_string)))
+    , m_positional_help("positional parameters")
+    , m_show_positional(false)
+    , m_next_positional(m_positional.end())
+    {
+    }
+
+    Options&
+    positional_help(std::string help_text)
+    {
+      m_positional_help = std::move(help_text);
+      return *this;
+    }
+
+    Options&
+    show_positional_help()
+    {
+      m_show_positional = true;
+      return *this;
+    }
+
+    ParseResult
+    parse(int& argc, char**& argv);
+
+    OptionAdder
+    add_options(std::string group = "");
+
+    void
+    add_option
+    (
+      const std::string& group,
+      const std::string& s,
+      const std::string& l,
+      std::string desc,
+      std::shared_ptr<const Value> value,
+      std::string arg_help
+    );
+
+    //parse positional arguments into the given option
+    void
+    parse_positional(std::string option);
+
+    void
+    parse_positional(std::vector<std::string> options);
+
+    std::string
+    help(const std::vector<std::string>& groups = {""}) const;
+
+    const std::vector<std::string>
+    groups() const;
+
+    const HelpGroupDetails&
+    group_help(const std::string& group) const;
+
+    private:
+
+    void
+    add_one_option
+    (
+      const std::string& option,
+      std::shared_ptr<OptionDetails> details
+    );
+
     String
     help_one_group(const std::string& group) const;
 
-    inline
     void
     generate_group_help
     (
@@ -1036,15 +1239,15 @@ namespace cxxopts
       const std::vector<std::string>& groups
     ) const;
 
-    inline
     void
     generate_all_groups_help(String& result) const;
 
     std::string m_program;
     String m_help_string;
     std::string m_positional_help;
+    bool m_show_positional;
 
-    std::map<std::string, std::shared_ptr<OptionDetails>> m_options;
+    std::unordered_map<std::string, std::shared_ptr<OptionDetails>> m_options;
     std::vector<std::string> m_positional;
     std::vector<std::string>::iterator m_next_positional;
     std::unordered_set<std::string> m_positional_set;
@@ -1062,7 +1265,6 @@ namespace cxxopts
     {
     }
 
-    inline
     OptionAdder&
     operator()
     (
@@ -1078,24 +1280,6 @@ namespace cxxopts
     std::string m_group;
   };
 
-  // A helper function for setting required arguments
-  inline
-  void
-  check_required
-  (
-    const Options& options,
-    const std::vector<std::string>& required
-  )
-  {
-    for (auto& r : required)
-    {
-      if (options.count(r) == 0)
-      {
-        throw option_required_exception(r);
-      }
-    }
-  }
-
   namespace
   {
     constexpr int OPTION_LONGEST = 30;
@@ -1132,10 +1316,10 @@ namespace cxxopts
         result += " --" + toLocalString(l);
       }
 
-      if (o.has_arg)
-      {
-        auto arg = o.arg_help.size() > 0 ? toLocalString(o.arg_help) : "arg";
+      auto arg = o.arg_help.size() > 0 ? toLocalString(o.arg_help) : "arg";
 
+      if (!o.is_boolean)
+      {
         if (o.has_implicit)
         {
           result += " [=" + arg + "(=" + toLocalString(o.implicit_value) + ")]";
@@ -1213,12 +1397,28 @@ namespace cxxopts
     }
   }
 
+inline
+ParseResult::ParseResult
+(
+  const std::unordered_map<std::string, std::shared_ptr<OptionDetails>>& options,
+  std::vector<std::string> positional,
+  int& argc, char**& argv
+)
+: m_options(options)
+, m_positional(std::move(positional))
+, m_next_positional(m_positional.begin())
+{
+  parse(argc, argv);
+}
+
+inline
 OptionAdder
 Options::add_options(std::string group)
 {
   return OptionAdder(*this, std::move(group));
 }
 
+inline
 OptionAdder&
 OptionAdder::operator()
 (
@@ -1276,19 +1476,31 @@ OptionAdder::operator()
   return *this;
 }
 
+inline
+void
+ParseResult::parse_default(std::shared_ptr<OptionDetails> details)
+{
+  m_results[details].parse_default(details);
+}
+
+inline
 void
-Options::parse_option
+ParseResult::parse_option
 (
   std::shared_ptr<OptionDetails> value,
   const std::string& /*name*/,
   const std::string& arg
 )
 {
-  value->parse(arg);
+  auto& result = m_results[value];
+  result.parse(value, arg);
+
+  m_sequential.emplace_back(value->long_name(), arg);
 }
 
+inline
 void
-Options::checked_parse_arg
+ParseResult::checked_parse_arg
 (
   int argc,
   char* argv[],
@@ -1322,8 +1534,9 @@ Options::checked_parse_arg
   }
 }
 
+inline
 void
-Options::add_to_option(const std::string& option, const std::string& arg)
+ParseResult::add_to_option(const std::string& option, const std::string& arg)
 {
   auto iter = m_options.find(option);
 
@@ -1335,17 +1548,19 @@ Options::add_to_option(const std::string& option, const std::string& arg)
   parse_option(iter->second, option, arg);
 }
 
+inline
 bool
-Options::consume_positional(std::string a)
+ParseResult::consume_positional(std::string a)
 {
   while (m_next_positional != m_positional.end())
   {
     auto iter = m_options.find(*m_next_positional);
     if (iter != m_options.end())
     {
+      auto& result = m_results[iter->second];
       if (!iter->second->value().is_container()) 
       {
-        if (iter->second->count() == 0)
+        if (result.count() == 0)
         {
           add_to_option(*m_next_positional, a);
           ++m_next_positional;
@@ -1369,12 +1584,14 @@ Options::consume_positional(std::string a)
   return false;
 }
 
+inline
 void
 Options::parse_positional(std::string option)
 {
   parse_positional(std::vector<std::string>{option});
 }
 
+inline
 void
 Options::parse_positional(std::vector<std::string> options)
 {
@@ -1384,9 +1601,18 @@ Options::parse_positional(std::vector<std::string> options)
   m_positional_set.insert(m_positional.begin(), m_positional.end());
 }
 
-void
+inline
+ParseResult
 Options::parse(int& argc, char**& argv)
 {
+  ParseResult result(m_options, m_positional, argc, argv);
+  return result;
+}
+
+inline
+void
+ParseResult::parse(int& argc, char**& argv)
+{
   int current = 1;
 
   int nextKeep = 1;
@@ -1440,27 +1666,19 @@ Options::parse(int& argc, char**& argv)
 
           auto value = iter->second;
 
-          //if no argument then just add it
-          if (!value->has_arg())
+          if (i + 1 == s.size())
+          {
+            //it must be the last argument
+            checked_parse_arg(argc, argv, current, value, name);
+          }
+          else if (value->value().has_implicit())
           {
-            parse_option(value, name);
+            parse_option(value, name, value->value().get_implicit_value());
           }
           else
           {
-            //it must be the last argument
-            if (i + 1 == s.size())
-            {
-              checked_parse_arg(argc, argv, current, value, name);
-            }
-            else if (value->value().has_implicit())
-            {
-              parse_option(value, name, value->value().get_implicit_value());
-            }
-            else
-            {
-              //error
-              throw option_requires_argument_exception(name);
-            }
+            //error
+            throw option_requires_argument_exception(name);
           }
         }
       }
@@ -1482,26 +1700,12 @@ Options::parse(int& argc, char**& argv)
         {
           //parse the option given
 
-          //but if it doesn't take an argument, this is an error
-          if (!opt->has_arg())
-          {
-            throw option_not_has_argument_exception(name, result[3]);
-          }
-
           parse_option(opt, name, result[3]);
         }
         else
         {
-          if (opt->has_arg())
-          {
-            //parse the next argument
-            checked_parse_arg(argc, argv, current, opt, name);
-          }
-          else
-          {
-            //parse with empty argument
-            parse_option(opt, name);
-          }
+          //parse the next argument
+          checked_parse_arg(argc, argv, current, opt, name);
         }
       }
 
@@ -1515,8 +1719,10 @@ Options::parse(int& argc, char**& argv)
     auto& detail = opt.second;
     auto& value = detail->value();
 
-    if(!detail->count() && value.has_default()){
-      detail->parse_default();
+    auto& store = m_results[detail];
+
+    if(!store.count() && value.has_default()){
+      parse_default(detail);
     }
   }
 
@@ -1542,6 +1748,7 @@ Options::parse(int& argc, char**& argv)
 
 }
 
+inline
 void
 Options::add_option
 (
@@ -1554,7 +1761,7 @@ Options::add_option
 )
 {
   auto stringDesc = toLocalString(std::move(desc));
-  auto option = std::make_shared<OptionDetails>(stringDesc, value);
+  auto option = std::make_shared<OptionDetails>(s, l, stringDesc, value);
 
   if (s.size() > 0)
   {
@@ -1570,13 +1777,14 @@ Options::add_option
   auto& options = m_help[group];
 
   options.options.emplace_back(HelpOptionDetails{s, l, stringDesc,
-      value->has_arg(),
       value->has_default(), value->get_default_value(),
       value->has_implicit(), value->get_implicit_value(),
       std::move(arg_help),
-      value->is_container()});
+      value->is_container(),
+      value->is_boolean()});
 }
 
+inline
 void
 Options::add_one_option
 (
@@ -1592,6 +1800,7 @@ Options::add_one_option
   }
 }
 
+inline
 String
 Options::help_one_group(const std::string& g) const
 {
@@ -1616,7 +1825,9 @@ Options::help_one_group(const std::string& g) const
 
   for (const auto& o : group->second.options)
   {
-    if (o.is_container && m_positional_set.find(o.l) != m_positional_set.end())
+    if (o.is_container &&
+        m_positional_set.find(o.l) != m_positional_set.end() &&
+        !m_show_positional)
     {
       continue;
     }
@@ -1634,7 +1845,9 @@ Options::help_one_group(const std::string& g) const
   auto fiter = format.begin();
   for (const auto& o : group->second.options)
   {
-    if (o.is_container && m_positional_set.find(o.l) != m_positional_set.end())
+    if (o.is_container &&
+        m_positional_set.find(o.l) != m_positional_set.end() &&
+        !m_show_positional)
     {
       continue;
     }
@@ -1662,6 +1875,7 @@ Options::help_one_group(const std::string& g) const
   return result;
 }
 
+inline
 void
 Options::generate_group_help
 (
@@ -1684,6 +1898,7 @@ Options::generate_group_help
   }
 }
 
+inline
 void
 Options::generate_all_groups_help(String& result) const
 {
@@ -1698,6 +1913,7 @@ Options::generate_all_groups_help(String& result) const
   generate_group_help(result, all_groups);
 }
 
+inline
 std::string
 Options::help(const std::vector<std::string>& help_groups) const
 {
@@ -1722,6 +1938,7 @@ Options::help(const std::vector<std::string>& help_groups) const
   return toUTF8String(result);
 }
 
+inline
 const std::vector<std::string>
 Options::groups() const
 {
@@ -1740,6 +1957,7 @@ Options::groups() const
   return g;
 }
 
+inline
 const HelpGroupDetails&
 Options::group_help(const std::string& group) const
 {
@@ -1748,8 +1966,4 @@ Options::group_help(const std::string& group) const
 
 }
 
-#if defined(__GNUC__)
-#pragma GCC diagnostic pop
-#endif
-
-#endif //CXX_OPTS_HPP
+#endif //CXXOPTS_HPP_INCLUDED
diff --git a/src/example.cpp b/src/example.cpp
index 44271b4..b541774 100644
--- a/src/example.cpp
+++ b/src/example.cpp
@@ -31,7 +31,9 @@ int main(int argc, char* argv[])
   try
   {
     cxxopts::Options options(argv[0], " - example command line options");
-    options.positional_help("[optional args]");
+    options
+      .positional_help("[optional args]")
+      .show_positional_help();
 
     bool apple = false;
 
@@ -63,9 +65,9 @@ int main(int argc, char* argv[])
 
     options.parse_positional({"input", "output", "positional"});
 
-    options.parse(argc, argv);
+    auto result = options.parse(argc, argv);
 
-    if (options.count("help"))
+    if (result.count("help"))
     {
       std::cout << options.help({"", "Group"}) << std::endl;
       exit(0);
@@ -73,18 +75,18 @@ int main(int argc, char* argv[])
 
     if (apple)
     {
-      std::cout << "Saw option ‘a’ " << options.count("a") << " times " <<
+      std::cout << "Saw option ‘a’ " << result.count("a") << " times " <<
         std::endl;
     }
 
-    if (options.count("b"))
+    if (result.count("b"))
     {
       std::cout << "Saw option ‘b’" << std::endl;
     }
 
-    if (options.count("f"))
+    if (result.count("f"))
     {
-      auto& ff = options["f"].as<std::vector<std::string>>();
+      auto& ff = result["f"].as<std::vector<std::string>>();
       std::cout << "Files" << std::endl;
       for (const auto& f : ff)
       {
@@ -92,36 +94,36 @@ int main(int argc, char* argv[])
       }
     }
 
-    if (options.count("input"))
+    if (result.count("input"))
     {
-      std::cout << "Input = " << options["input"].as<std::string>()
+      std::cout << "Input = " << result["input"].as<std::string>()
         << std::endl;
     }
 
-    if (options.count("output"))
+    if (result.count("output"))
     {
-      std::cout << "Output = " << options["output"].as<std::string>()
+      std::cout << "Output = " << result["output"].as<std::string>()
         << std::endl;
     }
 
-    if (options.count("positional"))
+    if (result.count("positional"))
     {
       std::cout << "Positional = {";
-      auto& v = options["positional"].as<std::vector<std::string>>();
+      auto& v = result["positional"].as<std::vector<std::string>>();
       for (const auto& s : v) {
         std::cout << s << ", ";
       }
       std::cout << "}" << std::endl;
     }
 
-    if (options.count("int"))
+    if (result.count("int"))
     {
-      std::cout << "int = " << options["int"].as<int>() << std::endl;
+      std::cout << "int = " << result["int"].as<int>() << std::endl;
     }
 
-    if (options.count("float"))
+    if (result.count("float"))
     {
-      std::cout << "float = " << options["float"].as<float>() << std::endl;
+      std::cout << "float = " << result["float"].as<float>() << std::endl;
     }
 
     std::cout << "Arguments remain = " << argc << std::endl;
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 0920e90..1969545 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -29,4 +29,7 @@ if (CXXOPTS_BUILD_TESTS)
         "-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}"
         "-DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}"
     )
+
+    add_executable(link_test link_a.cpp link_b.cpp)
+    target_link_libraries(link_test cxxopts)
 endif()
diff --git a/test/link_a.cpp b/test/link_a.cpp
new file mode 100644
index 0000000..3611692
--- /dev/null
+++ b/test/link_a.cpp
@@ -0,0 +1,6 @@
+#include "cxxopts.hpp"
+
+int main(int, char**)
+{
+  return 0;
+}
diff --git a/test/link_b.cpp b/test/link_b.cpp
new file mode 100644
index 0000000..e48e22a
--- /dev/null
+++ b/test/link_b.cpp
@@ -0,0 +1 @@
+#include <cxxopts.hpp>
diff --git a/test/options.cpp b/test/options.cpp
index d428f9a..afd7292 100644
--- a/test/options.cpp
+++ b/test/options.cpp
@@ -71,17 +71,27 @@ TEST_CASE("Basic options", "[options]")
   char** actual_argv = argv.argv();
   auto argc = argv.argc();
 
-  options.parse(argc, actual_argv);
-
-  CHECK(options.count("long") == 1);
-  CHECK(options.count("s") == 1);
-  CHECK(options.count("value") == 1);
-  CHECK(options.count("a") == 1);
-  CHECK(options["value"].as<std::string>() == "value");
-  CHECK(options["a"].as<std::string>() == "b");
-  CHECK(options.count("6") == 1);
-  CHECK(options.count("p") == 2);
-  CHECK(options.count("space") == 2);
+  auto result = options.parse(argc, actual_argv);
+
+  CHECK(result.count("long") == 1);
+  CHECK(result.count("s") == 1);
+  CHECK(result.count("value") == 1);
+  CHECK(result.count("a") == 1);
+  CHECK(result["value"].as<std::string>() == "value");
+  CHECK(result["a"].as<std::string>() == "b");
+  CHECK(result.count("6") == 1);
+  CHECK(result.count("p") == 2);
+  CHECK(result.count("space") == 2);
+
+  auto& arguments = result.arguments();
+  REQUIRE(arguments.size() == 7);
+  CHECK(arguments[0].key() == "long");
+  CHECK(arguments[0].value() == "true");
+  CHECK(arguments[0].as<bool>() == true);
+
+  CHECK(arguments[1].key() == "short");
+  CHECK(arguments[2].key() == "value");
+  CHECK(arguments[3].key() == "av");
 }
 
 TEST_CASE("Short options", "[options]")
@@ -96,36 +106,15 @@ TEST_CASE("Short options", "[options]")
   auto actual_argv = argv.argv();
   auto argc = argv.argc();
 
-  options.parse(argc, actual_argv);
+  auto result = options.parse(argc, actual_argv);
 
-  CHECK(options.count("a") == 1);
-  CHECK(options["a"].as<std::string>() == "value");
+  CHECK(result.count("a") == 1);
+  CHECK(result["a"].as<std::string>() == "value");
 
   REQUIRE_THROWS_AS(options.add_options()("", "nothing option"), 
     cxxopts::invalid_option_format_error);
 }
 
-TEST_CASE("Required arguments", "[options]")
-{
-  cxxopts::Options options("required", " - test required options");
-  options.add_options()
-    ("one", "one option")
-    ("two", "second option")
-  ;
-
-  Argv argv({
-    "required",
-    "--one"
-  });
-
-  auto aargv = argv.argv();
-  auto argc = argv.argc();
-
-  options.parse(argc, aargv);
-  REQUIRE_THROWS_AS(cxxopts::check_required(options, {"two"}),
-    cxxopts::option_required_exception);
-}
-
 TEST_CASE("No positional", "[positional]")
 {
   cxxopts::Options options("test_no_positional",
@@ -135,7 +124,7 @@ TEST_CASE("No positional", "[positional]")
 
   char** argv = av.argv();
   auto argc = av.argc();
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
   REQUIRE(argc == 4);
   CHECK(strcmp(argv[1], "a") == 0);
@@ -158,7 +147,7 @@ TEST_CASE("All positional", "[positional]")
 
   options.parse_positional("positional");
 
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
   REQUIRE(argc == 1);
   REQUIRE(positional.size() == 3);
@@ -186,14 +175,14 @@ TEST_CASE("Some positional explicit", "[positional]")
   char** argv = av.argv();
   auto argc = av.argc();
 
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
   CHECK(argc == 1);
-  CHECK(options.count("output"));
-  CHECK(options["input"].as<std::string>() == "b");
-  CHECK(options["output"].as<std::string>() == "a");
+  CHECK(result.count("output"));
+  CHECK(result["input"].as<std::string>() == "b");
+  CHECK(result["output"].as<std::string>() == "a");
 
-  auto& positional = options["positional"].as<std::vector<std::string>>();
+  auto& positional = result["positional"].as<std::vector<std::string>>();
 
   REQUIRE(positional.size() == 2);
   CHECK(positional[0] == "c");
@@ -234,10 +223,58 @@ TEST_CASE("Empty with implicit value", "[implicit]")
   char** argv = av.argv();
   auto argc = av.argc();
 
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
-  REQUIRE(options.count("implicit") == 1);
-  REQUIRE(options["implicit"].as<std::string>() == "");
+  REQUIRE(result.count("implicit") == 1);
+  REQUIRE(result["implicit"].as<std::string>() == "");
+}
+
+TEST_CASE("Default values", "[default]")
+{
+  cxxopts::Options options("defaults", "has defaults");
+  options.add_options()
+    ("default", "Has implicit", cxxopts::value<int>()
+      ->default_value("42"));
+
+  SECTION("Sets defaults") {
+    Argv av({"implicit"});
+
+    char** argv = av.argv();
+    auto argc = av.argc();
+
+    auto result = options.parse(argc, argv);
+    CHECK(result.count("default") == 1);
+    CHECK(result["default"].as<int>() == 42);
+  }
+
+  SECTION("When values provided") {
+    Argv av({"implicit", "--default", "5"});
+
+    char** argv = av.argv();
+    auto argc = av.argc();
+
+    auto result = options.parse(argc, argv);
+    CHECK(result.count("default") == 1);
+    CHECK(result["default"].as<int>() == 5);
+  }
+}
+
+TEST_CASE("Parse into a reference", "[reference]")
+{
+  int value = 0;
+
+  cxxopts::Options options("into_reference", "parses into a reference");
+  options.add_options()
+    ("ref", "A reference", cxxopts::value(value));
+
+  Argv av({"into_reference", "--ref", "42"});
+
+  auto argv = av.argv();
+  auto argc = av.argc();
+
+  auto result = options.parse(argc, argv);
+  CHECK(result.count("ref") == 1);
+  CHECK(value == 42);
 }
 
 TEST_CASE("Integers", "[options]")
@@ -252,11 +289,12 @@ TEST_CASE("Integers", "[options]")
   auto argc = av.argc();
 
   options.parse_positional("positional");
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
-  REQUIRE(options.count("positional") == 7);
+  REQUIRE(result.count("positional") == 7);
 
-  auto& positional = options["positional"].as<std::vector<int>>();
+  auto& positional = result["positional"].as<std::vector<int>>();
+  REQUIRE(positional.size() == 7);
   CHECK(positional[0] == 5);
   CHECK(positional[1] == 6);
   CHECK(positional[2] == -6);
@@ -295,11 +333,11 @@ TEST_CASE("Integer bounds", "[integer]")
     auto argc = av.argc();
 
     options.parse_positional("positional");
-    options.parse(argc, argv);
+    auto result = options.parse(argc, argv);
 
-    REQUIRE(options.count("positional") == 5);
+    REQUIRE(result.count("positional") == 5);
 
-    auto& positional = options["positional"].as<std::vector<int8_t>>();
+    auto& positional = result["positional"].as<std::vector<int8_t>>();
     CHECK(positional[0] == 127);
     CHECK(positional[1] == -128);
     CHECK(positional[2] == 0x7f);
@@ -351,14 +389,14 @@ TEST_CASE("Floats", "[options]")
   auto argc = av.argc();
 
   options.parse_positional("positional");
-  options.parse(argc, argv);
+  auto result = options.parse(argc, argv);
 
-  REQUIRE(options.count("double") == 1);
-  REQUIRE(options.count("positional") == 4);
+  REQUIRE(result.count("double") == 1);
+  REQUIRE(result.count("positional") == 4);
 
-  CHECK(options["double"].as<double>() == 0.5);
+  CHECK(result["double"].as<double>() == 0.5);
 
-  auto& positional = options["positional"].as<std::vector<float>>();
+  auto& positional = result["positional"].as<std::vector<float>>();
   CHECK(positional[0] == 4);
   CHECK(positional[1] == -4);
   CHECK(positional[2] == 1.5e6);
@@ -378,3 +416,27 @@ TEST_CASE("Invalid integers", "[integer]") {
     options.parse_positional("positional");
     CHECK_THROWS_AS(options.parse(argc, argv), cxxopts::argument_incorrect_type);
 }
+
+TEST_CASE("Booleans", "[boolean]") {
+  cxxopts::Options options("parses_floats", "parses floats correctly");
+  options.add_options()
+    ("bool", "A Boolean", cxxopts::value<bool>())
+    ("debug", "Debugging", cxxopts::value<bool>())
+    ("timing", "Timing", cxxopts::value<bool>())
+    ;
+
+  Argv av({"booleans", "--bool=false", "--debug", "true", "--timing"});
+
+  char** argv = av.argv();
+  auto argc = av.argc();
+
+  auto result = options.parse(argc, argv);
+
+  REQUIRE(result.count("bool") == 1);
+  REQUIRE(result.count("debug") == 1);
+  REQUIRE(result.count("timing") == 1);
+
+  CHECK(result["bool"].as<bool>() == false);
+  CHECK(result["debug"].as<bool>() == true);
+  CHECK(result["timing"].as<bool>() == true);
+}