Map CMake install components to conda library packages (rapidsai#653)

This extends rapidsai#648 and maps the CMake install components to capture what I think is the desire to have them map to conda packages.

Mapping:

- CMake 'raft' componet => conda raft-headers
- CMake 'raft_nn' componet => conda libraft-component
- CMake 'raft_distance' componet => conda libraft-distance

Authors:
  - Robert Maynard (https://github.com/robertmaynard)

Approvers:
  - Jordan Jacobelli (https://github.com/Ethyling)
  - Corey J. Nolet (https://github.com/cjnolet)

URL: rapidsai#653

cpp/CMakeLists.txt

@@ -352,12 +352,12 @@ install(TARGETS raft
 
 install(TARGETS raft_distance
         DESTINATION ${lib_dir}
-        COMPONENT raft_distance
+        COMPONENT raft
         EXPORT raft-distance-exports)
 
 install(TARGETS raft_nn
         DESTINATION ${lib_dir}
-        COMPONENT raft_nn
+        COMPONENT raft
         EXPORT raft-nn-exports)
 
 if(TARGET raft_distance_lib)
@@ -390,6 +390,44 @@ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/include/raft/version_config.hpp
         COMPONENT raft
         DESTINATION include/raft)
 
+##############################################################################
+# - export/install optional components  --------------------------------------
+
+include("${rapids-cmake-dir}/export/write_dependencies.cmake")
+
+set(raft_components distance nn)
+set(raft_install_comp "" "")
+if(TARGET raft_distance_lib)
+  list(APPEND raft_components distance-lib)
+  list(APPEND raft_install_comp _distance)
+endif()
+if(TARGET raft_nn_lib)
+  list(APPEND raft_components  nn-lib)
+  list(APPEND raft_install_comp _nn)
+endif()
+
+foreach(comp install_comp IN ZIP_LISTS raft_components raft_install_comp)
+  install(
+          EXPORT raft-${comp}-exports
+          FILE raft-${comp}-targets.cmake
+          NAMESPACE raft::
+          DESTINATION "${lib_dir}/cmake/raft"
+          COMPONENT raft${install_comp}
+  )
+  export(
+          EXPORT raft-${comp}-exports
+          FILE ${RAFT_BINARY_DIR}/raft-${comp}-targets.cmake
+          NAMESPACE raft::
+  )
+  rapids_export_write_dependencies(
+          BUILD raft-${comp}-exports "${PROJECT_BINARY_DIR}/raft-${comp}-dependencies.cmake"
+  )
+  rapids_export_write_dependencies(
+          INSTALL raft-${comp}-exports "${PROJECT_BINARY_DIR}/rapids-cmake/raft/export/${install_comp}/raft-${comp}-dependencies.cmake"
+  )
+
+endforeach()
+
 ##############################################################################
 # - install export -----------------------------------------------------------
 set(doc_string
@@ -458,44 +496,6 @@ raft_export(BUILD raft
         NAMESPACE raft::
         FINAL_CODE_BLOCK code_string)
 
-##############################################################################
-# - export/install optional components  --------------------------------------
-
-include("${rapids-cmake-dir}/export/write_dependencies.cmake")
-
-set(raft_components distance nn)
-set(raft_install_comp distance nn)
-if(TARGET raft_distance_lib)
-  list(APPEND raft_components distance-lib)
-  list(APPEND raft_install_comp distance)
-endif()
-if(TARGET raft_nn_lib)
-  list(APPEND raft_components  nn-lib)
-  list(APPEND raft_install_comp nn)
-endif()
-
-foreach(comp install_comp IN ZIP_LISTS raft_components raft_install_comp)
-  install(
-          EXPORT raft-${comp}-exports
-          FILE raft-${comp}-targets.cmake
-          NAMESPACE raft::
-          DESTINATION "${lib_dir}/cmake/raft"
-          COMPONENT raft_${install_comp}
-  )
-  export(
-          EXPORT raft-${comp}-exports
-          FILE ${RAFT_BINARY_DIR}/raft-${comp}-targets.cmake
-          NAMESPACE raft::
-  )
-  rapids_export_write_dependencies(
-          BUILD raft-${comp}-exports "${PROJECT_BINARY_DIR}/raft-${comp}-dependencies.cmake"
-  )
-  rapids_export_write_dependencies(
-          INSTALL raft-${comp}-exports "${PROJECT_BINARY_DIR}/rapids-cmake/raft/export/${install_comp}/raft-${comp}-dependencies.cmake"
-  )
-
-endforeach()
-
 ##############################################################################
 # - build test executable ----------------------------------------------------
 

cpp/cmake/modules/raft_export.cmake

@@ -210,6 +210,10 @@ function(raft_export type project_name)
       file(MAKE_DIRECTORY "${scratch_dir}")
       install(DIRECTORY "${scratch_dir}" DESTINATION "${install_location}"
         COMPONENT raft_${comp})
+      if(EXISTS "${scratch_dir}/raft-${comp}-dependencies.cmake")
+        install(FILES "${scratch_dir}/raft-${comp}-dependencies.cmake" DESTINATION "${install_location}"
+          COMPONENT raft)
+      endif()
     endforeach()
 
   else()