###########################################################################
#
#  Library:   CTK
#
#  Copyright (c) Kitware Inc.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.commontk.org/LICENSE
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.
#
###########################################################################

#
# Convenient macro allowing to define a "empty" project in case an external one is provided
# using for example <proj>_DIR. 
# Doing so allows to keep the external project dependency system happy.
#
MACRO(ctkMacroEmptyExternalProject proj dependencies)

  ExternalProject_Add(${proj}
    SOURCE_DIR ${CMAKE_BINARY_DIR}/${proj}
    BINARY_DIR ${proj}-build
    DOWNLOAD_COMMAND ""
    CONFIGURE_COMMAND ""
    BUILD_COMMAND ""
    INSTALL_COMMAND ""
    DEPENDS 
      ${dependencies}
    )
ENDMACRO()