add loggers

CMakeLists.txt

@@ -3,12 +3,42 @@ project(snipplib VERSION 0.1.0 LANGUAGES CXX)
 
 option(SNPLIB_BUILD_EXAMPLES "Build examples" ON)
 
+option(SNPLIB_USE_SPDLOG "Use of spdlog library" ON)
+
+if(SNPLIB_USE_SPDLOG)
+    find_package(spdlog CONFIG)
+    if(NOT spdlog_FOUND)
+        FetchContent_Declare(
+            spdlog
+            GIT_REPOSITORY "https://github.com/gabime/spdlog.git"
+            GIT_TAG "v1.17.0"
+            GIT_SHALLOW TRUE
+            GIT_SUBMODULES ""
+            GIT_PROGRESS TRUE
+            # CMAKE_ARGS
+            # -DSPDLOG_USE_STD_FORMAT=ON
+            # -DSPDLOG_FMT_EXTERNAL=OFF
+            OVERRIDE_FIND_PACKAGE
+        )
+
+        set(SPDLOG_USE_STD_FORMAT ON CACHE INTERNAL "Use of C++20 std::format")
+        set(SPDLOG_FMT_EXTERNAL
+            OFF
+            CACHE INTERNAL
+            "Turn off external fmt library"
+        )
+        set(SPDLOG_INSTALL ON CACHE BOOL "Enable spdlog installation" FORCE)
+        FetchContent_MakeAvailable(spdlog)
+    endif()
+endif(SNPLIB_USE_SPDLOG)
+
 set(LIB_HEADERS
     include/snipplib/concepts/snplib_concepts.h
     include/snipplib/concepts/snplib_traits.h
     include/snipplib/utils/snplib_hash.h
     include/snipplib/utils/snplib_string.h
     include/snipplib/utils/snplib_keyvalue_expr.h
+    include/snipplib/utils/snplib_logger.h
     include/snipplib/utils/snplib_utils.h
     include/snipplib/containers/snplib_hmap.h
     include/snipplib/containers/snplib_hvec.h
@@ -24,6 +54,16 @@ target_include_directories(
         "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
         "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>"
 )
+if(SNPLIB_USE_SPDLOG)
+    target_compile_definitions(
+        ${PROJECT_NAME}
+        INTERFACE
+            SPDLOG_USE_STD_FORMAT=1
+            SPDLOG_FMT_EXTERNAL=0
+            SNPLIB_SPDLOGGER=1
+    )
+    target_link_libraries(${PROJECT_NAME} INTERFACE spdlog::spdlog_header_only)
+endif()
 
 if(SNPLIB_BUILD_EXAMPLES)
     set(EXAM_STRING str_exam)