Async: initial support for native chaining of KJobs

It is now possible use KJob-derived jobs with libasync without having to write
lambda wrappers.

auto job = Async::start<ReturnType, MyKJob, MyKJob::result, Args ...)
           .then<ReturnType, OtherKJob, OtherKJob::result, PrevKJobReturnType>();

job.exec(arg1, arg2, ...);

The reason for this approach (instead of taking KJob* as an argument is that
we usually want the KJob ctor arguments to depend on result of previous job.
At least in case of Async::start() however it makes sense to support passing
KJob* as an argument (not yet implemented).

In future we should also support custom error handlers.

The KJob integration is build-time optional, but enabled by default (pass
-DWITH_KJOB=FALSE to CMake to disable).

Adds KCoreAddons dependency.

1 files changed, 10 insertions, 0 deletions

diff --git a/async/CMakeLists.txt b/async/CMakeLists.txt
index 19ac407..a6b53f8 100644
--- a/async/CMakeLists.txt
+++ b/async/CMakeLists.txt
@@ -1,2 +1,12 @@
+project(libasync)
+
+option(WITH_KJOB "Enable native support for KJob in libasync API (enabled by default)" ON)
+
+if (WITH_KJOB)
+    set(MINUMUM_FRAMEWORKS_VERSION "5.8.0")
+    find_package(KF5CoreAddons REQUIRED ${MINUMUM_FRAMEWORKS_VERSION})
+    add_definitions(-DWITH_KJOB)
+endif()
+
 add_subdirectory(src)
 add_subdirectory(autotests)
\ No newline at end of file