Add benchmarks

CMakeLists.txt

@@ -24,6 +24,7 @@ endif()
 option(TRX_USE_CONAN "Should Conan package manager be used?" OFF)
 option(TRX_BUILD_TESTS "Build trx tests" OFF)
 option(TRX_BUILD_EXAMPLES "Build trx example commandline programs" ON)
+option(TRX_BUILD_BENCHMARKS "Build trx benchmarks" OFF)
 option(TRX_ENABLE_CLANG_TIDY "Run clang-tidy during builds" OFF)
 option(TRX_ENABLE_INSTALL "Install trx-cpp targets" ${TRX_IS_TOP_LEVEL})
 option(TRX_BUILD_DOCS "Build API documentation with Doxygen/Sphinx" OFF)
@@ -68,7 +69,11 @@ elseif(TARGET zip::zip)
 else()
     message(FATAL_ERROR "No suitable libzip target (expected libzip::libzip or zip::zip)")
 endif()
-find_package(Eigen3 CONFIG QUIET)
+# Prefer Eigen3_ROOT so -DEigen3_ROOT=/path/to/eigen-3.4 is used over system Eigen
+if(Eigen3_ROOT)
+  list(PREPEND CMAKE_PREFIX_PATH "${Eigen3_ROOT}")
+endif()
+find_package(Eigen3 3.4 CONFIG QUIET)
 if (NOT Eigen3_FOUND)
     find_package(Eigen3 REQUIRED) # try module mode
 endif()
@@ -148,6 +153,21 @@ if(TRX_BUILD_TESTS)
     endif()
 endif()
 
+if(TRX_BUILD_BENCHMARKS)
+    find_package(benchmark CONFIG QUIET)
+    if(NOT benchmark_FOUND)
+        set(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "Disable benchmark tests" FORCE)
+        set(BENCHMARK_ENABLE_GTEST_TESTS OFF CACHE BOOL "Disable benchmark gtest" FORCE)
+        FetchContent_Declare(
+            benchmark
+            GIT_REPOSITORY https://github.com/google/benchmark.git
+            GIT_TAG v1.8.3
+        )
+        FetchContent_MakeAvailable(benchmark)
+    endif()
+    add_subdirectory(bench)
+endif()
+
 if(TRX_ENABLE_NIFTI)
     find_package(ZLIB REQUIRED)
     add_library(trx-nifti

bench/CMakeLists.txt

@@ -0,0 +1,3 @@
+add_executable(bench_trx_stream bench_trx_stream.cpp)
+target_link_libraries(bench_trx_stream PRIVATE trx benchmark::benchmark)
+target_compile_features(bench_trx_stream PRIVATE cxx_std_17)