#277 Added in-built support for string_type choices

include/argparse/argparse.hpp

@@ -509,10 +509,12 @@ public:
       m_num_args_range = NArgsRange{0, 1};
       break;
     case nargs_pattern::any:
-      m_num_args_range = NArgsRange{0, (std::numeric_limits<std::size_t>::max)()};
+      m_num_args_range =
+          NArgsRange{0, (std::numeric_limits<std::size_t>::max)()};
       break;
     case nargs_pattern::at_least_one:
-      m_num_args_range = NArgsRange{1, (std::numeric_limits<std::size_t>::max)()};
+      m_num_args_range =
+          NArgsRange{1, (std::numeric_limits<std::size_t>::max)()};
       break;
     }
     return *this;
@@ -523,6 +525,80 @@ public:
     return nargs(nargs_pattern::any);
   }
 
+  void add_choice(const std::string &choice) {
+    if (!m_choices.has_value()) {
+      /// create it
+      m_choices = std::vector<std::string>{};
+    }
+    m_choices.value().push_back(choice);
+  }
+
+  Argument &choices() {
+    if (!m_choices.has_value()) {
+      throw std::runtime_error("Zero choices provided");
+    }
+    return *this;
+  }
+
+  template <typename... T>
+  Argument &choices(const std::string &first, T &...rest) {
+    add_choice(first);
+    choices(rest...);
+
+    return *this;
+  }
+
+  template <typename... T> Argument &choices(const char *first, T &...rest) {
+    add_choice(first);
+    choices(rest...);
+
+    return *this;
+  }
+
+  void find_default_value_in_choices_or_throw() const {
+
+    const auto &choices = m_choices.value();
+
+    if (m_default_value.has_value()) {
+      if (std::find(choices.begin(), choices.end(), m_default_value_repr) ==
+          choices.end()) {
+        // provided arg not in list of allowed choices
+        // report error
+
+        std::string choices_as_csv =
+            std::accumulate(choices.begin(), choices.end(), std::string(),
+                            [](const std::string &a, const std::string &b) {
+                              return a + (a.empty() ? "" : ", ") + b;
+                            });
+
+        throw std::runtime_error(
+            std::string{"Invalid default value "} + m_default_value_repr +
+            " - allowed options: {" + choices_as_csv + "}");
+      }
+    }
+  }
+
+  template <typename Iterator>
+  void find_value_in_choices_or_throw(Iterator it) const {
+
+    const auto &choices = m_choices.value();
+
+    if (std::find(choices.begin(), choices.end(), *it) == choices.end()) {
+      // provided arg not in list of allowed choices
+      // report error
+
+      std::string choices_as_csv =
+          std::accumulate(choices.begin(), choices.end(), std::string(),
+                          [](const std::string &a, const std::string &b) {
+                            return a + (a.empty() ? "" : ", ") + b;
+                          });
+
+      throw std::runtime_error(std::string{"Invalid argument "} +
+                               details::repr(*it) + " - allowed options: {" +
+                               choices_as_csv + "}");
+    }
+  }
+
   template <typename Iterator>
   Iterator consume(Iterator start, Iterator end,
                    std::string_view used_name = {}) {
@@ -532,6 +608,14 @@ public:
     m_is_used = true;
     m_used_name = used_name;
 
+    if (m_choices.has_value()) {
+      // Check each value in (start, end) and make sure
+      // it is in the list of allowed choices/options
+      for (auto it = start; it != end; ++it) {
+        find_value_in_choices_or_throw(it);
+      }
+    }
+
     const auto num_args_max = m_num_args_range.get_max();
     const auto num_args_min = m_num_args_range.get_min();
     std::size_t dist = 0;
@@ -602,6 +686,12 @@ public:
         throw_nargs_range_validation_error();
       }
     }
+
+    if (m_choices.has_value()) {
+      // Make sure the default value (if provided)
+      // is in the list of choices
+      find_default_value_in_choices_or_throw();
+    }
   }
 
   std::string get_inline_usage() const {
@@ -738,8 +828,7 @@ public:
       using ValueType = typename T::value_type;
       auto lhs = get<T>();
       return std::equal(std::begin(lhs), std::end(lhs), std::begin(rhs),
-                        std::end(rhs),
-                        [](const auto &a, const auto &b) {
+                        std::end(rhs), [](const auto &a, const auto &b) {
                           return std::any_cast<const ValueType &>(a) == b;
                         });
     }
@@ -1064,6 +1153,7 @@ private:
   std::any m_default_value;
   std::string m_default_value_repr;
   std::any m_implicit_value;
+  std::optional<std::vector<std::string>> m_choices{std::nullopt};
   using valued_action = std::function<std::any(const std::string &)>;
   using void_action = std::function<void(const std::string &)>;
   std::variant<valued_action, void_action> m_action{
@@ -1152,16 +1242,11 @@ public:
   }
 
   explicit operator bool() const {
-    auto arg_used = std::any_of(m_argument_map.cbegin(),
-                                m_argument_map.cend(),
-                                [](auto &it) {
-                                    return it.second->m_is_used;
-                                });
-    auto subparser_used = std::any_of(m_subparser_used.cbegin(),
-                                      m_subparser_used.cend(),
-                                      [](auto &it) {
-                                          return it.second;
-                                      });
+    auto arg_used = std::any_of(m_argument_map.cbegin(), m_argument_map.cend(),
+                                [](auto &it) { return it.second->m_is_used; });
+    auto subparser_used =
+        std::any_of(m_subparser_used.cbegin(), m_subparser_used.cend(),
+                    [](auto &it) { return it.second; });
 
     return m_is_parsed && (arg_used || subparser_used);
   }
@@ -1215,8 +1300,7 @@ public:
   /* Getter for arguments and subparsers.
    * @throws std::logic_error in case of an invalid argument or subparser name
    */
-  template <typename T = Argument>
-  T& at(std::string_view name) {
+  template <typename T = Argument> T &at(std::string_view name) {
     if constexpr (std::is_same_v<T, Argument>) {
       return (*this)[name];
     } else {
@@ -1692,7 +1776,8 @@ private:
     }
     std::size_t max_size = 0;
     for ([[maybe_unused]] const auto &[unused, argument] : m_argument_map) {
-      max_size = std::max<std::size_t>(max_size, argument->get_arguments_length());
+      max_size =
+          std::max<std::size_t>(max_size, argument->get_arguments_length());
     }
     for ([[maybe_unused]] const auto &[command, unused] : m_subparser_map) {
       max_size = std::max<std::size_t>(max_size, command.size());

test/CMakeLists.txt

@@ -29,6 +29,7 @@ file(GLOB ARGPARSE_TEST_SOURCES
     test_append.cpp
     test_as_container.cpp
     test_bool_operator.cpp
+    test_choices.cpp
     test_compound_arguments.cpp
     test_container_arguments.cpp
     test_const_correct.cpp

test/test_append.cpp

@@ -5,8 +5,8 @@ import argparse;
 #endif
 #include <doctest.hpp>
 
-#include <vector>
 #include <string>
+#include <vector>
 
 using doctest::test_suite;
 

test/test_as_container.cpp

@@ -28,8 +28,8 @@ TEST_CASE("Get argument with .at()" * test_suite("as_container")) {
 
   SUBCASE("with unknown argument") {
     program.parse_args({"test"});
-    REQUIRE_THROWS_WITH_AS(program.at("--folder"),
-                           "No such argument: --folder", std::logic_error);
+    REQUIRE_THROWS_WITH_AS(program.at("--folder"), "No such argument: --folder",
+                           std::logic_error);
   }
 }
 
@@ -44,7 +44,8 @@ TEST_CASE("Get subparser with .at()" * test_suite("as_container")) {
   SUBCASE("and its argument") {
     program.parse_args({"test", "walk", "4km/h"});
     REQUIRE(&(program.at<argparse::ArgumentParser>("walk")) == &walk_cmd);
-    REQUIRE(&(program.at<argparse::ArgumentParser>("walk").at("speed")) == &speed);
+    REQUIRE(&(program.at<argparse::ArgumentParser>("walk").at("speed")) ==
+            &speed);
     REQUIRE(program.at<argparse::ArgumentParser>("walk").is_used("speed"));
   }
 

test/test_bool_operator.cpp

@@ -8,8 +8,7 @@ import argparse;
 
 using doctest::test_suite;
 
-TEST_CASE("ArgumentParser in bool context" *
-          test_suite("argument_parser")) {
+TEST_CASE("ArgumentParser in bool context" * test_suite("argument_parser")) {
   argparse::ArgumentParser program("test");
   program.add_argument("cases").remaining();
 

test/test_choices.cpp

@@ -0,0 +1,70 @@
+#ifdef WITH_MODULE
+import argparse;
+#else
+#include <argparse/argparse.hpp>
+#endif
+
+#include <doctest.hpp>
+
+using doctest::test_suite;
+
+TEST_CASE("Parse argument that is provided zero choices" *
+          test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  REQUIRE_THROWS_WITH_AS(program.add_argument("color").choices(),
+                         "Zero choices provided", std::runtime_error);
+}
+
+TEST_CASE("Parse argument that is in the fixed number of allowed choices" *
+          test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("color").choices("red", "green", "blue");
+
+  program.parse_args({"test", "red"});
+}
+
+TEST_CASE("Parse argument that is in the fixed number of allowed choices, with "
+          "invalid default" *
+          test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("color").default_value("yellow").choices("red", "green",
+                                                                "blue");
+
+  REQUIRE_THROWS_WITH_AS(
+      program.parse_args({"test"}),
+      "Invalid default value \"yellow\" - allowed options: {red, green, blue}",
+      std::runtime_error);
+}
+
+TEST_CASE("Parse invalid argument that is not in the fixed number of allowed "
+          "choices" *
+          test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("color").choices("red", "green", "blue");
+
+  REQUIRE_THROWS_WITH_AS(
+      program.parse_args({"test", "red2"}),
+      "Invalid argument \"red2\" - allowed options: {red, green, blue}",
+      std::runtime_error);
+}
+
+TEST_CASE(
+    "Parse multiple arguments that are in the fixed number of allowed choices" *
+    test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("color").nargs(2).choices("red", "green", "blue");
+
+  program.parse_args({"test", "red", "green"});
+}
+
+TEST_CASE("Parse multiple arguments one of which is not in the fixed number of "
+          "allowed choices" *
+          test_suite("choices")) {
+  argparse::ArgumentParser program("test");
+  program.add_argument("color").nargs(2).choices("red", "green", "blue");
+
+  REQUIRE_THROWS_WITH_AS(
+      program.parse_args({"test", "red", "green2"}),
+      "Invalid argument \"green2\" - allowed options: {red, green, blue}",
+      std::runtime_error);
+}

test/test_default_args.cpp

@@ -5,9 +5,9 @@ import argparse;
 #endif
 #include <doctest.hpp>
 
+#include <iostream>
 #include <sstream>
 #include <streambuf>
-#include <iostream>
 
 using doctest::test_suite;
 

test/test_equals_form.cpp

@@ -6,8 +6,8 @@ import argparse;
 #include <doctest.hpp>
 
 #include <iostream>
-#include <vector>
 #include <string>
+#include <vector>
 
 using doctest::test_suite;
 

test/test_help.cpp

@@ -5,8 +5,8 @@ import argparse;
 #endif
 #include <doctest.hpp>
 
-#include <sstream>
 #include <optional>
+#include <sstream>
 
 using doctest::test_suite;
 
@@ -82,22 +82,19 @@ TEST_CASE("Users can replace default -h/--help" * test_suite("help")) {
 
 TEST_CASE("Multiline help message alignment") {
   // '#' is used at the beginning of each help message line to simplify testing.
-  // It is important to ensure that this character doesn't appear elsewhere in the test case.
-  // Default arguments (e.g., -h/--help, -v/--version) are not included in this test.
+  // It is important to ensure that this character doesn't appear elsewhere in
+  // the test case. Default arguments (e.g., -h/--help, -v/--version) are not
+  // included in this test.
   argparse::ArgumentParser program("program");
-  program.add_argument("INPUT1")
-      .help(
+  program.add_argument("INPUT1").help(
       "#This is the first line of help message.\n"
-        "#And this is the second line of help message."
-      );
-  program.add_argument("program_input2")
-      .help("#There is only one line.");
+      "#And this is the second line of help message.");
+  program.add_argument("program_input2").help("#There is only one line.");
   program.add_argument("-p", "--prog_input3")
       .help(
           R"(#Lorem ipsum dolor sit amet, consectetur adipiscing elit.
 #Sed ut perspiciatis unde omnis iste natus error sit voluptatem
-#accusantium doloremque laudantium, totam rem aperiam...)"
-      );
+#accusantium doloremque laudantium, totam rem aperiam...)");
   program.add_argument("--verbose").default_value(false).implicit_value(true);
 
   std::ostringstream stream;
@@ -107,7 +104,8 @@ R"(#Lorem ipsum dolor sit amet, consectetur adipiscing elit.
   auto help_message_start = std::string::npos;
   std::string line;
   while (std::getline(iss, line)) {
-    // Find the position of '#', which indicates the start of the help message line
+    // Find the position of '#', which indicates the start of the help message
+    // line
     auto pos = line.find('#');
 
     if (pos == std::string::npos) {

test/test_parse_known_args.cpp

@@ -5,8 +5,8 @@ import argparse;
 #endif
 #include <doctest.hpp>
 
-#include <vector>
 #include <string>
+#include <vector>
 
 using doctest::test_suite;
 

test/test_repr.cpp

@@ -6,8 +6,8 @@ import argparse.details;
 #endif
 #include <doctest.hpp>
 
-#include <set>
 #include <list>
+#include <set>
 #include <sstream>
 
 using doctest::test_suite;

test/test_subparsers.cpp

@@ -6,8 +6,8 @@ import argparse;
 #include <doctest.hpp>
 
 #include <cmath>
-#include <vector>
 #include <string>
+#include <vector>
 
 using doctest::test_suite;