Create a jsoncppConfig.cmake file, even if building under meson (#1486)

* Create a jsoncppConfig.cmake file, even if building under meson

* Hardcode many fewer things in the meson-generated cmake files

* use join_paths for constructing paths in the output Config.cmake

---------

Co-authored-by: Jordan Bayles <[email protected]>

Author: wdouglass

jsoncppConfig.cmake.meson.in

@@ -0,0 +1,8 @@
+@PACKAGE_INIT@
+
+@MESON_SHARED_TARGET@
+@MESON_STATIC_TARGET@
+
+include ( "${CMAKE_CURRENT_LIST_DIR}/jsoncpp-namespaced-targets.cmake" )
+
+check_required_components(JsonCpp)

meson.build

@@ -15,7 +15,7 @@ project(
     'cpp_std=c++11',
     'warning_level=1'],
   license : 'Public Domain',
-  meson_version : '>= 0.49.0')
+  meson_version : '>= 0.54.0')
 
 
 jsoncpp_headers = files([
@@ -62,6 +62,43 @@ import('pkgconfig').generate(
   filebase : 'jsoncpp',
   description : 'A C++ library for interacting with JSON')
 
+cmakeconf = configuration_data()
+cmakeconf.set('MESON_LIB_DIR', get_option('libdir'))
+cmakeconf.set('MESON_INCLUDE_DIR', get_option('includedir'))
+
+fs = import('fs')
+if get_option('default_library') == 'shared'
+  shared_name = fs.name(jsoncpp_lib.full_path())
+endif
+if get_option('default_library') == 'static'
+  static_name = fs.name(jsoncpp_lib.full_path())
+endif
+if get_option('default_library') == 'both'
+  shared_name = fs.name(jsoncpp_lib.get_shared_lib().full_path())
+  static_name = fs.name(jsoncpp_lib.get_static_lib().full_path())
+endif
+
+if get_option('default_library') == 'shared' or get_option('default_library') == 'both'
+   cmakeconf.set('MESON_SHARED_TARGET', '''
+add_library(jsoncpp_lib IMPORTED SHARED)
+set_target_properties(jsoncpp_lib PROPERTIES
+  IMPORTED_LOCATION "''' + join_paths('${PACKAGE_PREFIX_DIR}', get_option('libdir'), shared_name) + '''"
+  INTERFACE_INCLUDE_DIRECTORIES "''' + join_paths('${PACKAGE_PREFIX_DIR}', get_option('includedir')) + '")')
+endif
+if get_option('default_library') == 'static' or get_option('default_library') == 'both'
+   cmakeconf.set('MESON_STATIC_TARGET', '''
+add_library(jsoncpp_static IMPORTED STATIC)
+set_target_properties(jsoncpp_static PROPERTIES
+  IMPORTED_LOCATION "''' + join_paths('${PACKAGE_PREFIX_DIR}', get_option('libdir'), static_name) + '''"
+  INTERFACE_INCLUDE_DIRECTORIES "''' + join_paths('${PACKAGE_PREFIX_DIR}', get_option('includedir')) + '")')
+endif
+
+import('cmake').configure_package_config_file(
+  name: 'jsoncpp',
+  input: 'jsoncppConfig.cmake.meson.in',
+  configuration: cmakeconf)
+install_data('jsoncpp-namespaced-targets.cmake', install_dir : join_paths(get_option('libdir'), 'cmake', jsoncpp_lib.name()))
+
 # for libraries bundling jsoncpp
 jsoncpp_dep = declare_dependency(
   include_directories : jsoncpp_include_directories,