bkietz commented on a change in pull request #8680:
URL: https://github.com/apache/arrow/pull/8680#discussion_r534352213
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File path: cpp/src/arrow/util/future.h
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@@ -19,63 +19,150 @@
#include <atomic>
#include <cmath>
+#include <functional>
#include <memory>
#include <type_traits>
#include <utility>
#include <vector>
#include "arrow/result.h"
#include "arrow/status.h"
+#include "arrow/util/functional.h"
#include "arrow/util/macros.h"
+#include "arrow/util/type_fwd.h"
#include "arrow/util/visibility.h"
namespace arrow {
+namespace detail {
+
+struct Empty {
+ static Result<Empty> ToResult(Status s) {
+ if (ARROW_PREDICT_TRUE(s.ok())) {
+ return Empty{};
+ }
+ return s;
+ }
+};
+
+template <typename>
+struct is_future : std::false_type {};
+
+template <typename T>
+struct is_future<Future<T>> : std::true_type {};
+
+template <typename Signature>
+using result_of_t = typename std::result_of<Signature>::type;
+
+constexpr struct ContinueFuture {
+ template <typename Return>
+ struct ForReturnImpl;
+
+ template <typename Return>
+ using ForReturn = typename ForReturnImpl<Return>::type;
+
+ template <typename Signature>
+ using ForSignature = ForReturn<result_of_t<Signature>>;
+
+ template <typename F, typename... A, typename R = result_of_t<F && (A &&
...)>,
Review comment:
will do
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