CleanDirectoryList.cmake

# - Removes duplicate entries and non-directories from a provided list
#
#  clean_directory_list(<listvar> [<additional list items>...])
#
# Requires CMake 2.6 or newer (uses the 'function' command)
#
# Original Author:
# 2009-2010 Ryan Pavlik <rpavlik@iastate.edu> <abiryan@ryand.net>
# http://academic.cleardefinition.com
# Iowa State University HCI Graduate Program/VRAC
#
# Copyright Iowa State University 2009-2010.
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE_1_0.txt or copy at
# http://www.boost.org/LICENSE_1_0.txt)

if(__clean_directory_list)
    return()
endif()
set(__clean_directory_list YES)

function(clean_directory_list _var)
    # combine variable's current value with additional list items
    set(_in ${${_var}} ${ARGN})

    if(_in)
        # Initial list cleaning
        list(REMOVE_DUPLICATES _in)

        # Grab the absolute path of each actual directory
        set(_out)
        foreach(_dir ${_in})
            if(IS_DIRECTORY "${_dir}")
                get_filename_component(_dir "${_dir}" ABSOLUTE)
                file(TO_CMAKE_PATH "${_dir}" _dir)
                list(APPEND _out "${_dir}")
            endif()
        endforeach()

        if(_out)
            # Clean up the output list now
            list(REMOVE_DUPLICATES _out)
        endif()

        # return _out
        set(${_var} "${_out}" PARENT_SCOPE)
    endif()
endfunction()