Merge pull request #48 from lichray/bind-in-action

Bind in action

.clang-format

@@ -91,8 +91,10 @@ PenaltyExcessCharacter: 1000000
 PenaltyReturnTypeOnItsOwnLine: 60
 PointerAlignment: Right
 RawStringFormats:
-  - Delimiter:       pb
+  - Language: TextProto
-    Language:        TextProto
+    Delimiters:
+      - 'pb'
+      - 'proto'
     BasedOnStyle: google
 ReflowComments:  true
 SortIncludes:    true

include/argparse.hpp

@@ -40,6 +40,7 @@ SOFTWARE.
 #include <sstream>
 #include <stdexcept>
 #include <string>
+#include <tuple>
 #include <type_traits>
 #include <variant>
 #include <vector>
@@ -73,7 +74,23 @@ using enable_if_container = std::enable_if_t<is_container_v<T>, T>;
 
 template <typename T>
 using enable_if_not_container = std::enable_if_t<!is_container_v<T>, T>;
-} // namespace
+
+template <class F, class Tuple, class Extra, size_t... I>
+constexpr decltype(auto) apply_plus_one_impl(F &&f, Tuple &&t, Extra &&x,
+                                             std::index_sequence<I...>) {
+  return std::invoke(std::forward<F>(f), std::get<I>(std::forward<Tuple>(t))...,
+                     std::forward<Extra>(x));
+}
+
+template <class F, class Tuple, class Extra>
+constexpr decltype(auto) apply_plus_one(F &&f, Tuple &&t, Extra &&x) {
+  return details::apply_plus_one_impl(
+      std::forward<F>(f), std::forward<Tuple>(t), std::forward<Extra>(x),
+      std::make_index_sequence<
+          std::tuple_size_v<std::remove_reference_t<Tuple>>>{});
+}
+
+} // namespace details
 
 class ArgumentParser;
 
@@ -115,14 +132,22 @@ public:
     return *this;
   }
 
-  template <class F>
+  template <class F, class... Args>
-  auto action(F &&aAction)
+  auto action(F &&aAction, Args &&... aBound)
-      -> std::enable_if_t<std::is_invocable_v<F, std::string const>,
+      -> std::enable_if_t<std::is_invocable_v<F, Args..., std::string const>,
                           Argument &> {
-    if constexpr (std::is_void_v<std::invoke_result_t<F, std::string const>>)
+    using action_type = std::conditional_t<
-      mAction.emplace<void_action>(std::forward<F>(aAction));
+        std::is_void_v<std::invoke_result_t<F, Args..., std::string const>>,
+        void_action, valued_action>;
+    if constexpr (sizeof...(Args) == 0)
+      mAction.emplace<action_type>(std::forward<F>(aAction));
     else
-      mAction.emplace<valued_action>(std::forward<F>(aAction));
+      mAction.emplace<action_type>(
+          [f = std::forward<F>(aAction),
+           tup = std::make_tuple(std::forward<Args>(aBound)...)](
+              std::string const &opt) mutable {
+            return details::apply_plus_one(f, tup, opt);
+          });
     return *this;
   }
 

test/test_actions.hpp

@@ -1,6 +1,7 @@
 #pragma once
 #include <catch.hpp>
 #include <argparse.hpp>
+#include <string_view>
 
 TEST_CASE("Users can use default value inside actions", "[actions]") {
   argparse::ArgumentParser program("test");
@@ -39,3 +40,82 @@ TEST_CASE("Users can add actions that return nothing", "[actions]") {
     REQUIRE(program.get<int>("button") == 42);
   }
 }
+
+class Image {
+public:
+  int w = 0, h = 0;
+
+  void resize(std::string_view geometry) {
+    std::stringstream s;
+    s << geometry;
+    s >> w;
+    s.ignore();
+    s >> h;
+  }
+
+  static auto create(int w, int h, std::string_view format) -> Image {
+    auto factor = [=] {
+      if (format == "720p")
+        return std::min(1280. / w, 720. / h);
+      else if (format == "1080p")
+        return std::min(1920. / w, 1080. / h);
+      else
+        return 1.;
+    }();
+
+    return {static_cast<int>(w * factor), static_cast<int>(h * factor)};
+  }
+};
+
+TEST_CASE("Users can bind arguments to actions", "[actions]") {
+  argparse::ArgumentParser program("test");
+
+  GIVEN("an default initialized object bounded by reference") {
+    Image img;
+    program.add_argument("--size").action(&Image::resize, std::ref(img));
+
+    WHEN("provided no command-line arguments") {
+      program.parse_args({"test"});
+
+      THEN("the object is not updated") {
+        REQUIRE(img.w == 0);
+        REQUIRE(img.h == 0);
+      }
+    }
+
+    WHEN("provided command-line arguments") {
+      program.parse_args({"test", "--size", "320x98"});
+
+      THEN("the object is updated accordingly") {
+        REQUIRE(img.w == 320);
+        REQUIRE(img.h == 98);
+      }
+    }
+  }
+
+  GIVEN("a command-line option waiting for the last argument in its action") {
+    program.add_argument("format").action(Image::create, 400, 300);
+
+    WHEN("provided such an argument") {
+      program.parse_args({"test", "720p"});
+
+      THEN("the option object is created as if providing all arguments") {
+        auto img = program.get<Image>("format");
+
+        REQUIRE(img.w == 960);
+        REQUIRE(img.h == 720);
+      }
+    }
+
+    WHEN("provided a different argument") {
+      program.parse_args({"test", "1080p"});
+
+      THEN("a different option object is created") {
+        auto img = program.get<Image>("format");
+
+        REQUIRE(img.w == 1440);
+        REQUIRE(img.h == 1080);
+      }
+    }
+  }
+}