Add 'Eigen' as an external module (#182)

This commit adds 'Eigen' module which provides 'eigen' interface library
if it is successfully loaded.

Signed-off-by: Jonghyun Park <jh1302.park@samsung.com>

diff --git a/cmake/packages/EigenConfig.cmake b/cmake/packages/EigenConfig.cmake
new file mode 100644 (file)
index 0000000..ac5164f
--- /dev/null
+++ b/cmake/packages/EigenConfig.cmake
@@ -0,0 +1,17 @@
+function(_Eigen_import)
+  nncc_find_package(EigenSource QUIET)
+
+  if(NOT EigenSource_FOUND)
+    set(Eigen_FOUND FALSE PARENT_SCOPE)
+    return()
+  endif(NOT EigenSource_FOUND)
+
+  if(NOT TARGET eigen)
+    add_library(eigen INTERFACE)
+    target_include_directories(eigen INTERFACE "${EigenSource_DIR}")
+  endif(NOT TARGET eigen)
+
+  set(EigenSource_FOUND TRUE PARENT_SCOPE)
+endfunction(_Eigen_import)
+
+_Eigen_import()