cmake: add support for building and installing interfaces

cmake/Msg-Interface.cmake

@@ -0,0 +1,75 @@
+find_program(IFC
+	NAMES ifc
+	REQUIRED
+	HINTS ${BUILD_TOOLS_DIR})
+message(STATUS "Found interface compiler: ${IFC}")
+
+function(add_interface)
+	set(options)
+	set(one_value_args NAME PARENT_DIR PATH)
+	set(multi_value_args)
+
+	cmake_parse_arguments(PARSE_ARGV 0 arg
+		"${options}"
+		"${one_value_args}"
+		"${multi_value_args}")
+
+	message(STATUS "Building interface ${arg_NAME}")
+	file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${arg_PARENT_DIR})
+	set(header_path ${CMAKE_CURRENT_BINARY_DIR}/${arg_PARENT_DIR}/${arg_NAME}.h)
+
+	add_custom_command(
+		OUTPUT ${header_path}
+		COMMAND	${IFC} ${arg_PATH}
+		WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${arg_PARENT_DIR}
+		COMMENT "Compiling interface: ${arg_NAME}")
+
+	add_custom_target(ifgen-${arg_NAME} ALL
+		DEPENDS ${header_path})
+
+	set_target_properties(ifgen-${arg_NAME} PROPERTIES
+		iface_header_path ${header_path}
+		iface_parent_dir ${arg_PARENT_DIR})
+
+	add_library(iflib-${arg_NAME} INTERFACE)
+	set_target_properties(iflib-${arg_NAME} PROPERTIES
+		INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_CURRENT_BINARY_DIR})
+	add_dependencies(iflib-${arg_NAME} ifgen-${arg_NAME})
+	add_library(interface::${arg_NAME} ALIAS iflib-${arg_NAME})
+endfunction(add_interface)
+
+function(iface_get_header_path)
+	set(options)
+	set(one_value_args NAME OUT)
+	set(multi_value_args)
+
+	cmake_parse_arguments(PARSE_ARGV 0 arg
+		"${options}"
+		"${one_value_args}"
+		"${multi_value_args}")
+
+	get_property(
+		value
+		TARGET ifgen-${name}
+		PROPERTY iface_header_path)
+
+	set(${arg_OUT} ${value} PARENT_SCOPE)
+endfunction(iface_get_header_path)
+
+function(iface_get_parent_dir)
+	set(options)
+	set(one_value_args NAME OUT)
+	set(multi_value_args)
+
+	cmake_parse_arguments(PARSE_ARGV 0 arg
+		"${options}"
+		"${one_value_args}"
+		"${multi_value_args}")
+
+	get_property(
+		value
+		TARGET ifgen-${name}
+		PROPERTY iface_parent_dir)
+
+	set(${arg_OUT} ${value} PARENT_SCOPE)
+endfunction(iface_get_parent_dir)