add choices and default strings to argument description

2 files changed, 224 insertions, 45 deletions

diff --git a/args.hxx b/args.hxx
index ed9325b..223525b 100644
--- a/args.hxx
+++ b/args.hxx
@@ -635,6 +635,21 @@ namespace args
          */
         std::string valueClose = "]";
 
+        /** Add choices to argument description
+         */
+        bool addChoices = false;
+
+        /** The prefix for choices
+         */
+        std::string choiceString = "\nOne of: ";
+
+        /** Add default values to argument description
+         */
+        bool addDefault = false;
+
+        /** The prefix for default values
+         */
+        std::string defaultString = "\nDefault: ";
     };
 
     /** Base class for all match types
@@ -771,17 +786,63 @@ namespace args
         protected:
             const std::string name;
             bool kickout = false;
+            std::string defaultString;
+            bool defaultStringManual = false;
+            std::string choicesString;
+            bool choicesStringManual = false;
+
+            virtual std::string GetDefaultString(const HelpParams&) const { return {}; }
+
+            virtual std::string GetChoicesString(const HelpParams&) const { return {}; }
+
+            virtual std::string GetNameString(const HelpParams&) const { return Name(); }
+
+            void AddDescriptionPostfix(std::string &dest, const bool isManual, const std::string &manual, bool isGenerated, const std::string &generated, const std::string &str) const
+            {
+                if (isManual && !manual.empty())
+                {
+                    dest += str;
+                    dest += manual;
+                }
+                else if (!isManual && isGenerated && !generated.empty())
+                {
+                    dest += str;
+                    dest += generated;
+                }
+            }
 
         public:
             NamedBase(const std::string &name_, const std::string &help_, Options options_ = {}) : Base(help_, options_), name(name_) {}
             virtual ~NamedBase() {}
 
-            virtual std::vector<std::tuple<std::string, std::string, unsigned>> GetDescription(const HelpParams &, const unsigned indentLevel) const override
+            /** Sets default value string that will be added to argument description.
+             *  Use empty string to disable it for this argument.
+             */
+            void HelpDefault(const std::string &str)
+            {
+                defaultStringManual = true;
+                defaultString = str;
+            }
+
+            /** Sets choices string that will be added to argument description.
+             *  Use empty string to disable it for this argument.
+             */
+            void HelpChoices(const std::string &str)
+            {
+                choicesStringManual = true;
+                choicesString = str;
+            }
+
+            virtual std::vector<std::tuple<std::string, std::string, unsigned>> GetDescription(const HelpParams &params, const unsigned indentLevel) const override
             {
                 std::tuple<std::string, std::string, unsigned> description;
-                std::get<0>(description) = Name();
+                std::get<0>(description) = GetNameString(params);
                 std::get<1>(description) = help;
                 std::get<2>(description) = indentLevel;
+
+                AddDescriptionPostfix(std::get<1>(description), choicesStringManual, choicesString, params.addChoices, GetChoicesString(params), params.choiceString);
+                AddDescriptionPostfix(std::get<1>(description), defaultStringManual, defaultString, params.addDefault, GetDefaultString(params), params.defaultString);
+
                 return { std::move(description) };
             }
 
@@ -825,6 +886,30 @@ namespace args
         }
     };
 
+    namespace detail
+    {
+        template <typename T, typename = int>
+        struct IsConvertableToString : std::false_type {};
+
+        template <typename T>
+        struct IsConvertableToString<T, decltype(std::declval<std::ostringstream&>() << std::declval<T>(), int())> : std::true_type {};
+
+        template <typename T>
+        typename std::enable_if<IsConvertableToString<T>::value, std::string>::type
+        ToString(const T &value)
+        {
+            std::ostringstream s;
+            s << value;
+            return s.str();
+        }
+        template <typename T>
+        typename std::enable_if<!IsConvertableToString<T>::value, std::string>::type
+        ToString(const T &)
+        {
+            return {};
+        }
+    }
+
     /** Base class for all flag options
      */
     class FlagBase : public NamedBase
@@ -832,6 +917,33 @@ namespace args
         protected:
             const Matcher matcher;
 
+            virtual std::string GetNameString(const HelpParams &params) const override
+            {
+                const std::string postfix = !params.showValueName || NumberOfArguments() == 0 ? std::string() : Name();
+                std::string flags;
+                const auto flagStrings = matcher.GetFlagStrings();
+                const bool useValueNameOnce = flagStrings.size() == 1 ? false : params.useValueNameOnce;
+                for (auto it = flagStrings.begin(); it != flagStrings.end(); ++it)
+                {
+                    auto &flag = *it;
+                    if (it != flagStrings.begin())
+                    {
+                        flags += ", ";
+                    }
+
+                    flags += flag.isShort ? params.shortPrefix : params.longPrefix;
+                    flags += flag.str();
+
+                    if (!postfix.empty() && (!useValueNameOnce || it + 1 == flagStrings.end()))
+                    {
+                        flags += flag.isShort ? params.shortSeparator : params.longSeparator;
+                        flags += params.valueOpen + postfix + params.valueClose;
+                    }
+                }
+
+                return flags;
+            }
+
         public:
             FlagBase(const std::string &name_, const std::string &help_, Matcher &&matcher_, const bool extraError_ = false) : NamedBase(name_, help_, extraError_ ? Options::Single : Options()), matcher(std::move(matcher_)) {}
 
@@ -894,37 +1006,6 @@ namespace args
                                       : params.proglineNonrequiredOpen + res + params.proglineNonrequiredClose };
             }
 
-            virtual std::vector<std::tuple<std::string, std::string, unsigned>> GetDescription(const HelpParams &params, const unsigned indentLevel) const override
-            {
-                std::tuple<std::string, std::string, unsigned> description;
-                const std::string postfix = !params.showValueName || NumberOfArguments() == 0 ? std::string() : Name();
-                std::string flags;
-                const auto flagStrings = matcher.GetFlagStrings();
-                const bool useValueNameOnce = flagStrings.size() == 1 ? false : params.useValueNameOnce;
-                for (auto it = flagStrings.begin(); it != flagStrings.end(); ++it)
-                {
-                    auto &flag = *it;
-                    if (it != flagStrings.begin())
-                    {
-                        flags += ", ";
-                    }
-
-                    flags += flag.isShort ? params.shortPrefix : params.longPrefix;
-                    flags += flag.str();
-
-                    if (!postfix.empty() && (!useValueNameOnce || it + 1 == flagStrings.end()))
-                    {
-                        flags += flag.isShort ? params.shortSeparator : params.longSeparator;
-                        flags += params.valueOpen + postfix + params.valueClose;
-                    }
-                }
-
-                std::get<0>(description) = std::move(flags);
-                std::get<1>(description) = help;
-                std::get<2>(description) = indentLevel;
-                return { std::move(description) };
-            }
-
             virtual bool HasFlag() const override
             {
                 return true;
@@ -2703,13 +2784,19 @@ namespace args
     {
         protected:
             T value;
+            T defaultValue;
+
+            virtual std::string GetDefaultString(const HelpParams&) const
+            {
+                return detail::ToString(defaultValue);
+            }
 
         private:
             Reader reader;
 
         public:
 
-            ValueFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, const T &defaultValue_, Options options_): ValueFlagBase(name_, help_, std::move(matcher_), options_), value(defaultValue_)
+            ValueFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, const T &defaultValue_, Options options_): ValueFlagBase(name_, help_, std::move(matcher_), options_), value(defaultValue_), defaultValue(defaultValue_)
             {
                 group_.Add(*this);
             }
@@ -2738,12 +2825,25 @@ namespace args
 #endif
             }
 
+            virtual void Reset() noexcept override
+            {
+                ValueFlagBase::Reset();
+                value = defaultValue;
+            }
+
             /** Get the value
              */
             T &Get() noexcept
             {
                 return value;
             }
+
+            /** Get the default value
+             */
+            const T &GetDefault() noexcept
+            {
+                return defaultValue;
+            }
     };
 
     /** An optional argument-accepting flag class
@@ -2757,24 +2857,22 @@ namespace args
     class ImplicitValueFlag : public ValueFlag<T, Reader>
     {
         protected:
-
             T implicitValue;
-            T defaultValue;
 
         public:
 
             ImplicitValueFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, const T &implicitValue_, const T &defaultValue_ = T(), Options options_ = {})
-                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), defaultValue_, options_), implicitValue(implicitValue_), defaultValue(defaultValue_)
+                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), defaultValue_, options_), implicitValue(implicitValue_)
             {
             }
 
             ImplicitValueFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, const T &defaultValue_ = T(), Options options_ = {})
-                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), defaultValue_, options_), implicitValue(defaultValue_), defaultValue(defaultValue_)
+                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), defaultValue_, options_), implicitValue(defaultValue_)
             {
             }
 
             ImplicitValueFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, Options options_)
-                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), {}, options_), implicitValue(), defaultValue()
+                : ValueFlag<T, Reader>(group_, name_, help_, std::move(matcher_), {}, options_), implicitValue()
             {
             }
 
@@ -2795,12 +2893,6 @@ namespace args
                     ValueFlag<T, Reader>::ParseValue(value_);
                 }
             }
-
-            virtual void Reset() noexcept override
-            {
-                this->value = defaultValue;
-                ValueFlag<T, Reader>::Reset();
-            }
     };
 
     /** A variadic arguments accepting flag class
@@ -3028,6 +3120,31 @@ namespace args
             T value;
             Reader reader;
 
+        protected:
+            virtual std::string GetChoicesString(const HelpParams &) const override
+            {
+                std::string res;
+                if (detail::IsConvertableToString<K>::value)
+                {
+                    std::vector<std::string> values;
+                    for (const auto &p : map)
+                    {
+                        values.push_back(detail::ToString(p.first));
+                    }
+
+                    std::sort(values.begin(), values.end());
+                    for (const auto &s : values)
+                    {
+                        if (!res.empty())
+                        {
+                            res += ", ";
+                        }
+                        res += s;
+                    }
+                }
+                return res;
+            }
+
         public:
 
             MapFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, const Map<K, T> &map_, const T &defaultValue_, Options options_): ValueFlagBase(name_, help_, std::move(matcher_), options_), map(map_), value(defaultValue_)
diff --git a/test.cxx b/test.cxx
index 44cde49..a8d1676 100644
--- a/test.cxx
+++ b/test.cxx
@@ -1088,6 +1088,68 @@ TEST_CASE("ActionFlag works as expected", "[args]")
     REQUIRE_THROWS_AS(p.ParseArgs(std::vector<std::string>{"-v"}), std::runtime_error);
 }
 
+TEST_CASE("Default values work as expected", "[args]")
+{
+    args::ArgumentParser p("parser");
+    args::ValueFlag<std::string> f(p, "name", "description", {'f', "foo"}, "abc");
+    args::MapFlag<std::string, int> b(p, "name", "description", {'b', "bar"}, {{"a", 1}, {"b", 2}, {"c", 3}});
+    p.Prog("prog");
+    REQUIRE(p.Help() == R"(  prog {OPTIONS}
+
+    parser
+
+  OPTIONS:
+
+      -f[name], --foo=[name]            description
+      -b[name], --bar=[name]            description
+
+)");
+
+    p.helpParams.addDefault = true;
+    p.helpParams.addChoices = true;
+
+    REQUIRE(p.Help() == R"(  prog {OPTIONS}
+
+    parser
+
+  OPTIONS:
+
+      -f[name], --foo=[name]            description
+                                        Default: abc
+      -b[name], --bar=[name]            description
+                                        One of: a, b, c
+
+)");
+
+    f.HelpDefault("123");
+    b.HelpChoices("1, 2, 3");
+    REQUIRE(p.Help() == R"(  prog {OPTIONS}
+
+    parser
+
+  OPTIONS:
+
+      -f[name], --foo=[name]            description
+                                        Default: 123
+      -b[name], --bar=[name]            description
+                                        One of: 1, 2, 3
+
+)");
+
+    f.HelpDefault({});
+    b.HelpChoices({});
+    REQUIRE(p.Help() == R"(  prog {OPTIONS}
+
+    parser
+
+  OPTIONS:
+
+      -f[name], --foo=[name]            description
+      -b[name], --bar=[name]            description
+
+)");
+}
+
 #undef ARGS_HXX
 #define ARGS_TESTNAMESPACE
 #define ARGS_NOEXCEPT