add ActionFlag

2 files changed, 55 insertions, 0 deletions

diff --git a/args.hxx b/args.hxx
index 7af24c4..7a4ccf7 100644
--- a/args.hxx
+++ b/args.hxx
@@ -2577,6 +2577,42 @@ namespace args
             }
     };
 
+    /** A flag class that calls a function when it's matched
+     */
+    class ActionFlag : public FlagBase
+    {
+        private:
+            std::function<void(const std::vector<std::string> &)> action;
+            Nargs nargs;
+
+        public:
+            ActionFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, Nargs nargs_, std::function<void(const std::vector<std::string> &)> action_, Options options_ = {}):
+                FlagBase(name_, help_, std::move(matcher_), options_), action(std::move(action_)), nargs(nargs_)
+            {
+                group_.Add(*this);
+            }
+
+            ActionFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, std::function<void(const std::string &)> action_, Options options_ = {}):
+                FlagBase(name_, help_, std::move(matcher_), options_), nargs(1)
+            {
+                group_.Add(*this);
+                action = [action_](const std::vector<std::string> &a) { return action_(a.at(0)); };
+            }
+
+            ActionFlag(Group &group_, const std::string &name_, const std::string &help_, Matcher &&matcher_, std::function<void()> action_, Options options_ = {}):
+                FlagBase(name_, help_, std::move(matcher_), options_), nargs(0)
+            {
+                group_.Add(*this);
+                action = [action_](const std::vector<std::string> &) { return action_(); };
+            }
+
+            virtual Nargs NumberOfArguments() const noexcept override
+            { return nargs; }
+
+            virtual void ParseValue(const std::vector<std::string> &value) override
+            { action(value); }
+    };
+
     /** A default Reader class for argument classes
      *
      * Simply uses a std::istringstream to read into the destination type, and
diff --git a/test.cxx b/test.cxx
index 1189f97..5f97c87 100644
--- a/test.cxx
+++ b/test.cxx
@@ -1066,6 +1066,25 @@ TEST_CASE("HelpParams work as expected", "[args]")
 
 }
 
+TEST_CASE("ActionFlag works as expected", "[args]")
+{
+    args::ArgumentParser p("parser");
+    std::string s;
+
+    args::ActionFlag action0(p, "name", "description", {'x'}, [&]() { s = "flag"; });
+    args::ActionFlag action1(p, "name", "description", {'y'}, [&](const std::string &arg) { s = arg; });
+    args::ActionFlag actionN(p, "name", "description", {'z'}, 2, [&](const std::vector<std::string> &arg) { s = arg[0] + arg[1]; });
+
+    p.ParseArgs(std::vector<std::string>{"-x"});
+    REQUIRE(s == "flag");
+
+    p.ParseArgs(std::vector<std::string>{"-y", "a"});
+    REQUIRE(s == "a");
+
+    p.ParseArgs(std::vector<std::string>{"-z", "a", "b"});
+    REQUIRE(s == "ab");
+}
+
 #undef ARGS_HXX
 #define ARGS_TESTNAMESPACE
 #define ARGS_NOEXCEPT