add nf7::AggregatePromise

CMakeLists.txt

@@ -64,6 +64,7 @@ target_sources(nf7
     theme.hh
 
     common/aggregate_command.hh
+    common/aggregate_promise.hh
     common/audio_queue.hh
     common/dir.hh
     common/dir_item.hh

common/aggregate_promise.hh

@@ -0,0 +1,68 @@
+#pragma once
+
+#include <memory>
+
+#include "nf7.hh"
+
+#include "common/future.hh"
+
+
+namespace nf7 {
+
+class AggregatePromise final :
+    public std::enable_shared_from_this<AggregatePromise> {
+ public:
+  AggregatePromise() = delete;
+  AggregatePromise(const std::shared_ptr<nf7::Context>& ctx) noexcept :
+      data_(std::make_shared<Data>(ctx)) {
+    data_->Ref();
+  }
+  ~AggregatePromise() noexcept {
+    data_->Unref();
+  }
+
+  AggregatePromise(const AggregatePromise&) = delete;
+  AggregatePromise(AggregatePromise&&) = delete;
+  AggregatePromise& operator=(const AggregatePromise&) = delete;
+  AggregatePromise& operator=(AggregatePromise&&) = delete;
+
+  AggregatePromise& Add(auto& fu) noexcept {
+    data_->Ref();
+    fu.Then([data = data_](auto&) { data->Unref(); });
+    return *this;
+  }
+
+  nf7::Future<std::monostate> future() noexcept {
+    return data_->future();
+  }
+
+ private:
+  struct Data {
+   public:
+    Data() = delete;
+    Data(const std::shared_ptr<nf7::Context>& ctx) noexcept :
+        pro_(ctx) {
+    }
+
+    void Ref() noexcept {
+      ++refcnt_;
+    }
+    void Unref() noexcept {
+      if (0 == --refcnt_) {
+        pro_.Return({});
+      }
+    }
+
+    nf7::Future<std::monostate> future() const noexcept {
+      return pro_.future();
+    }
+
+   private:
+    nf7::Future<std::monostate>::Promise pro_;
+
+    std::atomic<size_t> refcnt_ = 0;
+  };
+  std::shared_ptr<Data> data_;
+};
+
+}  // namespace nf7

common/future.hh

@@ -324,11 +324,14 @@ class Future final {
     return !imm_ && data_->state == kYet;
   }
   bool done() const noexcept {
-    return (imm_ && std::holds_alternative<T>(*imm_)) || data_->state == kDone;
+    return
+        (imm_  && std::holds_alternative<T>(*imm_)) ||
+        (data_ && data_->state == kDone);
   }
   bool error() const noexcept {
-    return (imm_ && std::holds_alternative<std::exception_ptr>(*imm_)) ||
-        data_->state == kError;
+    return
+        (imm_  && std::holds_alternative<std::exception_ptr>(*imm_)) ||
+        (data_ && data_->state == kError);
   }
 
   bool await_ready() const noexcept { return !yet(); }