[json] Add cmake files to find json library

cmake/modules/CMakeLists.txt

@@ -6,6 +6,7 @@ set(modules
   DumuxTestMacros.cmake
   FindGLPK.cmake
   FindGstat.cmake
+  FindJsonCpp.cmake
   FindNLOPT.cmake
   FindPVPython.cmake)
 include(GNUInstallDirs)

cmake/modules/DumuxMacros.cmake

@@ -9,6 +9,7 @@ find_package(Gnuplot)
 set(HAVE_GNUPLOT ${GNUPLOT_FOUND})
 find_package(Gstat)
 find_package(Gmsh)
+find_package(JsonCpp)
 find_package(NLOPT)
 find_package(PTScotch)
 include(AddPTScotchFlags)

cmake/modules/FindJsonCpp.cmake

+# .. cmake_module::
+#
+#    Find the JsonCpp library
+#
+#    You may set the following variables to modify the
+#    behaviour of this module:
+#
+#    :ref:`JSONCPP_INCLUDE_DIR`
+#       Path to include dir of library.
+#
+#    Sets the following variables:
+#
+#    :code:`JsonCpp_FOUND`
+#       True if the JsonCpp library was found.
+#
+# .. cmake_variable:: JSONCPP_INCLUDE_DIR
+#
+#   You may set this variable to have :ref:`FinJsonCpp` a look
+#   for the JsonCpp library in the given path before inspecting
+#   system paths.
+#
+
+# Add a feature summary for this package
+include(FeatureSummary)
+set_package_properties(JsonCpp PROPERTIES
+  DESCRIPTION "JSON for Modern C++ library"
+  URL "https://github.com/nlohmann/json"
+)
+
+# Try to locate the libraries and their headers, using pkg-config hints
+find_path(JSONCPP_INCLUDE_DIR "nlohmann/json.hpp"
+          HINTS ${CMAKE_SOURCE_DIR} "${CMAKE_SOURCE_DIR}/.."
+          PATH_SUFFIXES "include" "json/include/")
+
+# check version of JSONCpp
+find_file(JSONCPP_HEADER "nlohmann/json.hpp"
+  HINTS ${JSONCPP_INCLUDE_DIR}
+  NO_DEFAULT_PATH)
+if(JSONCPP_HEADER)
+  file(READ "${JSONCPP_HEADER}" jsoncppheader)
+  # get version number from defines in header file
+  string(REGEX REPLACE ".*#define NLOHMANN_JSON_VERSION_MAJOR[ \t]+([0-9]+).*" "\\1"
+    JSONCPP_MAJOR_VERSION  "${jsoncppheader}")
+  string(REGEX REPLACE ".*#define NLOHMANN_JSON_VERSION_MINOR[ \t]+([0-9]+).*" "\\1"
+    JSONCPP_MINOR_VERSION  "${jsoncppheader}")
+  string(REGEX REPLACE ".*#define NLOHMANN_JSON_VERSION_PATCH[ \t]+([0-9]+).*" "\\1"
+    JSONCPP_PATCH_VERSION "${jsoncppheader}")
+  if(JSONCPP_MAJOR_VERSION GREATER_EQUAL 0)
+    set(JSONCPP_VERSION "${JSONCPP_MAJOR_VERSION}")
+  endif()
+  if (JSONCPP_MINOR_VERSION GREATER_EQUAL 0)
+    set(JSONCPP_VERSION "${JSONCPP_VERSION}.${JSONCPP_MINOR_VERSION}")
+  endif()
+  if (JSONCPP_PATCH_VERSION GREATER_EQUAL 0)
+    set(JSONCPP_VERSION "${JSONCPP_VERSION}.${JSONCPP_PATCH_VERSION}")
+  endif()
+endif ()
+
+# set if components found
+if (JSONCPP_INCLUDE_DIR)
+  set(JsonCpp_FOUND TRUE)
+endif ()
+
+# dependencies between components
+if (NOT JsonCpp_FOUND)
+  set(JsonCpp_FOUND FALSE)
+endif ()
+
+# Remove these variables from cache inspector
+mark_as_advanced(JSONCPP_INCLUDE_DIR)
+
+# Behave like a CMake module is supposed to behave
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args("JsonCpp"
+  REQUIRED_VARS
+    JSONCPP_INCLUDE_DIR
+  VERSION_VAR
+    JSONCPP_VERSION
+)
+
+# Set targets
+if(JsonCpp_FOUND AND NOT TARGET nlohmann_json::nlohmann_json)
+  add_library(nlohmann_json::nlohmann_json UNKNOWN IMPORTED)
+  set_target_properties(nlohmann_json::nlohmann_json PROPERTIES
+    IMPORTED_LOCATION ${JSONCPP_INCLUDE_DIR}
+    INTERFACE_INCLUDE_DIRECTORIES ${JSONCPP_INCLUDE_DIR}
+  )
+  # log result
+  file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+    "Determining location of JsonCpp succeeded:\n"
+    "Include directory: ${JSONCPP_INCLUDE_DIR}\n")
+else()
+  # log erroneous result
+  file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+    "Determining location of JsonCpp failed:\n"
+    "Include directory: ${JSONCPP_INCLUDE_DIR}\n")
+endif()
+
+# register all JasonCpp related flags
+if(JsonCpp_FOUND)
+  dune_register_package_flags(INCLUDE_DIRS ${JSONCPP_INCLUDE_DIR})
+endif()