add new feature

2 files changed, 59 insertions, 5 deletions

diff --git a/args.hxx b/args.hxx
index ac9ccfc..26cb4f6 100644
--- a/args.hxx
+++ b/args.hxx
@@ -175,6 +175,15 @@ namespace args
             virtual ~MapError() {};
     };
 
+    /** Error that occurs when a singular flag is specified multiple times
+     */
+    class ExtraError : public ParseError
+    {
+        public:
+            ExtraError(const std::string &problem) : ParseError(problem) {}
+            virtual ~ExtraError() {};
+    };
+
     /** An exception that indicates that the user has requested help
      */
     class Help : public Error
@@ -393,11 +402,14 @@ namespace args
      */
     class FlagBase : public NamedBase
     {
+        private:
+            const bool extraError;
+
         protected:
             const Matcher matcher;
 
         public:
-            FlagBase(const std::string &name, const std::string &help, Matcher &&matcher) : NamedBase(name, help), matcher(std::move(matcher)) {}
+            FlagBase(const std::string &name, const std::string &help, Matcher &&matcher, const bool extraError = false) : NamedBase(name, help), extraError(extraError), matcher(std::move(matcher)) {}
 
             virtual ~FlagBase() {}
 
@@ -405,6 +417,12 @@ namespace args
             {
                 if (matcher.Match(flag))
                 {
+                    if (extraError && matched)
+                    {
+                        std::ostringstream problem;
+                        problem << "Flag '" << flag << "' was passed multiple times, but should only be allowed to be passed once";
+                        throw ExtraError(problem.str());
+                    }
                     matched = true;
                     return this;
                 }
@@ -415,6 +433,12 @@ namespace args
             {
                 if (matcher.Match(flag))
                 {
+                    if (extraError && matched)
+                    {
+                        std::ostringstream problem;
+                        problem << "Flag '" << flag << "' was passed multiple times, but should only be allowed to be passed once";
+                        throw ExtraError(problem.str());
+                    }
                     matched = true;
                     return this;
                 }
@@ -445,7 +469,7 @@ namespace args
     class ValueFlagBase : public FlagBase
     {
         public:
-            ValueFlagBase(const std::string &name, const std::string &help, Matcher &&matcher) : FlagBase(name, help, std::move(matcher)) {}
+            ValueFlagBase(const std::string &name, const std::string &help, Matcher &&matcher, const bool extraError = false) : FlagBase(name, help, std::move(matcher), extraError) {}
             virtual ~ValueFlagBase() {}
             virtual void ParseValue(const std::string &value) = 0;
 
@@ -1254,7 +1278,7 @@ namespace args
     class Flag : public FlagBase
     {
         public:
-            Flag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher): FlagBase(name, help, std::move(matcher))
+            Flag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher, const bool extraError = false): FlagBase(name, help, std::move(matcher), extraError)
             {
                 group.Add(*this);
             }
@@ -1389,7 +1413,7 @@ namespace args
 
         public:
 
-            ValueFlag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher, const T &defaultValue = T()): ValueFlagBase(name, help, std::move(matcher)), value(defaultValue)
+            ValueFlag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher, const T &defaultValue = T(), const bool extraError = false): ValueFlagBase(name, help, std::move(matcher), extraError), value(defaultValue)
             {
                 group.Add(*this);
             }
@@ -1469,7 +1493,7 @@ namespace args
 
         public:
 
-            MapFlag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher, const Map &map, const T &defaultValue = T()): ValueFlagBase(name, help, std::move(matcher)), map(map), value(defaultValue)
+            MapFlag(Group &group, const std::string &name, const std::string &help, Matcher &&matcher, const Map &map, const T &defaultValue = T(), const bool extraError = false): ValueFlagBase(name, help, std::move(matcher), extraError), map(map), value(defaultValue)
             {
                 group.Add(*this);
             }
diff --git a/test.cxx b/test.cxx
index b4c451b..c368bf9 100644
--- a/test.cxx
+++ b/test.cxx
@@ -412,3 +412,33 @@ TEST_CASE("Mapping types work as needed", "[args]")
     REQUIRE((args::get(mpl) == std::vector<MappingEnum>{MappingEnum::red, MappingEnum::def}));
     REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--mf=YeLLoW"}), args::MapError);
 }
+
+TEST_CASE("An exception should be thrown when a single-argument flag is matched multiple times and the constructor option is specified", "[args]")
+{
+    std::unordered_map<std::string, MappingEnum> map{
+        {"default", MappingEnum::def},
+        {"foo", MappingEnum::foo},
+        {"bar", MappingEnum::bar},
+        {"red", MappingEnum::red},
+        {"yellow", MappingEnum::yellow},
+        {"green", MappingEnum::green}};
+
+    std::ostream null(nullptr);
+    args::ArgumentParser parser("Test command");
+    args::Flag foo(parser, "Foo", "Foo", {'f', "foo"}, true);
+    args::ValueFlag<std::string> bar(parser, "Bar", "Bar", {'b', "bar"}, "", true);
+    args::Flag bix(parser, "Bix", "Bix", {'x', "bix"});
+    args::MapFlag<std::string, MappingEnum> baz(parser, "Baz", "Baz", {'B', "baz"}, map, MappingEnum::def, true);
+    REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--foo", "-f", "-bblah"}), args::ExtraError);
+    REQUIRE_NOTHROW(parser.ParseArgs(std::vector<std::string>{"--foo", "-xxx", "--bix", "-bblah", "--bix"}));
+    REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--foo", "-bblah", "-blah"}), args::ExtraError);
+    REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--foo", "-bblah", "--bar", "blah"}), args::ExtraError);
+    REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--baz=red", "-B", "yellow"}), args::ExtraError);
+    REQUIRE_THROWS_AS(parser.ParseArgs(std::vector<std::string>{"--baz", "red", "-Byellow"}), args::ExtraError);
+    REQUIRE_NOTHROW(parser.ParseArgs(std::vector<std::string>{"--foo", "-Bgreen"}));
+    REQUIRE(foo);
+    REQUIRE_FALSE(bar);
+    REQUIRE_FALSE(bix);
+    REQUIRE(baz);
+    REQUIRE(args::get(baz) == MappingEnum::green);
+}