adding example for things that require set_done (#31)

fbshipit-source-id: a79daf051453f6b189330891fa290be4e9cd6549

folly/experimental/pushmi/buildSingleHeader.cmake

@@ -51,6 +51,7 @@ set(header_files
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/on.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/tap.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/transform.h"
+    "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/filter.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/via.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/request_via.h"
     "${CMAKE_CURRENT_SOURCE_DIR}/include/pushmi/o/share.h"

folly/experimental/pushmi/examples/CMakeLists.txt

@@ -9,3 +9,4 @@ add_subdirectory(then_execute)
 add_subdirectory(composition)
 add_subdirectory(for_each)
 add_subdirectory(reduce)
+add_subdirectory(set_done)

folly/experimental/pushmi/examples/set_done/CMakeLists.txt

+
+
+add_executable(set_done_2 set_done_2.cpp)
+target_link_libraries(set_done_2
+  pushmi
+  examples
+  Threads::Threads)

folly/experimental/pushmi/examples/set_done/set_done_2.cpp

+#include <vector>
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+
+#include <pushmi/o/just.h>
+#include <pushmi/o/tap.h>
+#include <pushmi/o/filter.h>
+#include <pushmi/o/transform.h>
+#include <pushmi/o/empty.h>
+
+using namespace pushmi::aliases;
+
+const bool setting_exists = false;
+
+auto get_setting() {
+  return mi::make_single_deferred(
+    [](auto out){
+      if(setting_exists) {
+        op::just(42) | op::submit(out);
+      } else {
+        op::empty<int>() | op::submit(out);
+      }
+    }
+  );
+}
+
+auto println = [](auto v){std::cout << v << std::endl;};
+
+// concat not yet implemented
+auto concat =
+  [](auto in){
+    return mi::make_single_deferred(
+      [in](auto out) mutable {
+        ::pushmi::submit(in, mi::make_single(out,
+        [](auto out, auto v){
+          // ::pushmi::submit(v, out);
+        }));
+      });
+  };
+
+int main()
+{
+  get_setting() |
+    op::transform([](int i){ return std::to_string(i); }) |
+    op::submit(println);
+
+  op::just(42) |
+    op::filter([](int i){ return i < 42; }) |
+    op::transform([](int i){ return std::to_string(i); }) |
+    op::submit(println);
+
+    op::just(42) |
+      op::transform([](int i) {
+        if (i < 42) {
+          return mi::any_single_deferred<std::string>{op::empty<std::string>()};
+        }
+        return mi::any_single_deferred<std::string>{op::just(std::to_string(i))};
+      }) |
+      concat |
+      op::submit(println);
+
+  std::cout << "OK" << std::endl;
+}

folly/experimental/pushmi/include/pushmi.h

@@ -922,7 +922,6 @@ PUSHMI_CONCEPT_DEF(
 
 #if __cpp_lib_invoke >= 201411
 using std::invoke;
-using std::invoke_result_t;
 #else
 PUSHMI_TEMPLATE (class F, class...As)
   (requires requires (
@@ -940,10 +939,10 @@ decltype(auto) invoke(F f, As&&...as)
     noexcept(noexcept(std::declval<decltype(std::mem_fn(f))>()((As&&) as...))) {
   return std::mem_fn(f)((As&&) as...);
 }
+#endif
 template <class F, class...As>
 using invoke_result_t =
   decltype(pushmi::invoke(std::declval<F>(), std::declval<As>()...));
-#endif
 
 PUSHMI_CONCEPT_DEF(
   template (class F, class... Args)
@@ -6113,6 +6112,55 @@ PUSHMI_INLINE_VAR constexpr detail::transform_fn transform{};
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the root directory of this source tree.
 
+//#include "../piping.h"
+//#include "extension_operators.h"
+
+namespace pushmi {
+
+namespace detail {
+
+struct filter_fn {
+  PUSHMI_TEMPLATE(class Predicate)
+    (requires SemiMovable<Predicate>)
+  auto operator()(Predicate p) const {
+    return constrain(lazy::Sender<_1>, [p = std::move(p)](auto in) {
+      using In = decltype(in);
+      return ::pushmi::detail::deferred_from<In, single<>>(
+        std::move(in),
+        ::pushmi::detail::submit_transform_out<In>(
+          constrain(lazy::Receiver<_1>, [p](auto out) {
+            using Out = decltype(out);
+            return ::pushmi::detail::out_from_fn<In>()(
+              std::move(out),
+              // copy 'p' to allow multiple calls to submit
+              ::pushmi::on_value([p](auto& out, auto&& v) {
+                if (p(as_const(v))) {
+                  ::pushmi::set_value(out, std::move(v));
+                } else {
+                  ::pushmi::set_done(out);
+                }
+              })
+            );
+          })
+        )
+      );
+    });
+  }
+};
+
+} // namespace detail
+
+namespace operators {
+PUSHMI_INLINE_VAR constexpr detail::filter_fn filter{};
+} // namespace operators
+
+} // namespace pushmi
+//#pragma once
+// Copyright (c) 2018-present, Facebook, Inc.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
 //#include "../piping.h"
 //#include "../executor.h"
 //#include "extension_operators.h"

folly/experimental/pushmi/include/pushmi/o/filter.h

+#pragma once
+// Copyright (c) 2018-present, Facebook, Inc.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
+
+#include "../piping.h"
+#include "extension_operators.h"
+
+namespace pushmi {
+
+namespace detail {
+
+struct filter_fn {
+  PUSHMI_TEMPLATE(class Predicate)
+    (requires SemiMovable<Predicate>)
+  auto operator()(Predicate p) const {
+    return constrain(lazy::Sender<_1>, [p = std::move(p)](auto in) {
+      using In = decltype(in);
+      return ::pushmi::detail::deferred_from<In, single<>>(
+        std::move(in),
+        ::pushmi::detail::submit_transform_out<In>(
+          constrain(lazy::Receiver<_1>, [p](auto out) {
+            using Out = decltype(out);
+            return ::pushmi::detail::out_from_fn<In>()(
+              std::move(out),
+              // copy 'p' to allow multiple calls to submit
+              ::pushmi::on_value([p](auto& out, auto&& v) {
+                if (p(as_const(v))) {
+                  ::pushmi::set_value(out, std::move(v));
+                } else {
+                  ::pushmi::set_done(out);
+                }
+              })
+            );
+          })
+        )
+      );
+    });
+  }
+};
+
+} // namespace detail
+
+namespace operators {
+PUSHMI_INLINE_VAR constexpr detail::filter_fn filter{};
+} // namespace operators
+
+} // namespace pushmi