[ntuple] Extract RNTupleComposer from RNTupleProcessor

The composition of RNTuples can also serve as the backend for other
data loading interfaces, most notably `RDataSource`, which is fully
separate from the processing interface offered by `RNTupleProcessor`.
It therefore makes sense to split both components into their own class.

Author: enirolf

tree/ntuple/CMakeLists.txt

@@ -27,6 +27,7 @@ HEADERS
   ROOT/RNTupleAttrUtils.hxx
   ROOT/RNTupleAttrWriting.hxx
   ROOT/RNTupleDescriptor.hxx
+  ROOT/RNTupleComposer.hxx
   ROOT/RNTupleFillContext.hxx
   ROOT/RNTupleFillStatus.hxx
   ROOT/RNTupleImtTaskScheduler.hxx
@@ -71,6 +72,7 @@ SOURCES
   src/RNTuple.cxx
   src/RNTupleAttrReading.cxx
   src/RNTupleAttrWriting.cxx
+  src/RNTupleComposer.cxx
   src/RNTupleDescriptor.cxx
   src/RNTupleDescriptorFmt.cxx
   src/RNTupleFillContext.cxx
@@ -79,7 +81,6 @@ SOURCES
   src/RNTupleMetrics.cxx
   src/RNTupleModel.cxx
   src/RNTupleParallelWriter.cxx
-  src/RNTupleProcessor.cxx
   src/RNTupleProcessorEntry.cxx
   src/RNTupleReader.cxx
   src/RNTupleSerialize.cxx

tree/ntuple/inc/ROOT/RNTupleComposer.hxx

@@ -56,9 +56,9 @@ ROOT_ADD_GTEST(ntuple_multi_stream ntuple_multi_stream.cxx LIBRARIES ROOTNTuple)
 ROOT_ADD_GTEST(ntuple_packing ntuple_packing.cxx LIBRARIES ROOTNTuple)
 ROOT_ADD_GTEST(ntuple_pages ntuple_pages.cxx LIBRARIES ROOTNTuple)
 ROOT_ADD_GTEST(ntuple_print ntuple_print.cxx LIBRARIES ROOTNTuple CustomStruct)
-ROOT_ADD_GTEST(ntuple_processor ntuple_processor.cxx LIBRARIES ROOTNTuple)
-ROOT_ADD_GTEST(ntuple_processor_chain ntuple_processor_chain.cxx LIBRARIES ROOTNTuple)
-ROOT_ADD_GTEST(ntuple_processor_join ntuple_processor_join.cxx LIBRARIES ROOTNTuple)
+ROOT_ADD_GTEST(ntuple_composer ntuple_composer.cxx LIBRARIES ROOTNTuple)
+ROOT_ADD_GTEST(ntuple_composer_chain ntuple_composer_chain.cxx LIBRARIES ROOTNTuple)
+ROOT_ADD_GTEST(ntuple_composer_join ntuple_composer_join.cxx LIBRARIES ROOTNTuple)
 ROOT_ADD_GTEST(ntuple_project ntuple_project.cxx LIBRARIES ROOTNTuple)
 ROOT_ADD_GTEST(ntuple_modelext ntuple_modelext.cxx LIBRARIES ROOTNTuple MathCore CustomStruct)
 ROOT_ADD_GTEST(ntuple_serialize ntuple_serialize.cxx LIBRARIES ROOTNTuple)