macro (bool_to_int VAR)
  if (${VAR})
    set (${VAR} 1)
  else ()
    set (${VAR} 0)
  endif ()
endmacro ()

# ----------------------------------------------------------------------------
## Extract version numbers from version string
function (version_numbers version major minor patch)
  if (version MATCHES "([0-9]+)(\\.[0-9]+)?(\\.[0-9]+)?(rc[1-9][0-9]*|[a-z]+)?")
    if (CMAKE_MATCH_1)
      set (_major ${CMAKE_MATCH_1})
    else ()
      set (_major 0)
    endif ()
    if (CMAKE_MATCH_2)
      set (_minor ${CMAKE_MATCH_2})
      string (REGEX REPLACE "^\\." "" _minor "${_minor}")
    else ()
      set (_minor 0)
    endif ()
    if (CMAKE_MATCH_3)
      set (_patch ${CMAKE_MATCH_3})
      string (REGEX REPLACE "^\\." "" _patch "${_patch}")
    else ()
      set (_patch 0)
    endif ()
  else ()
    set (_major 0)
    set (_minor 0)
    set (_patch 0)
  endif ()
  set ("${major}" "${_major}" PARENT_SCOPE)
  set ("${minor}" "${_minor}" PARENT_SCOPE)
  set ("${patch}" "${_patch}" PARENT_SCOPE)
endfunction ()

# ----------------------------------------------------------------------------
## Determine if cache entry exists
macro (gflags_is_cached retvar varname)
  if (DEFINED ${varname})
    get_property (${retvar} CACHE ${varname} PROPERTY TYPE SET)
  else ()
    set (${retvar} FALSE)
  endif ()
endmacro ()

# ----------------------------------------------------------------------------
## Add gflags configuration variable
#
# The default value of the (cached) configuration value can be overridden either
# on the CMake command-line or the super-project by setting the GFLAGS_<varname>
# variable. When gflags is a subproject of another project (GFLAGS_IS_SUBPROJECT),
# the variable is not added to the CMake cache. Otherwise it is cached.
macro (gflags_define type varname docstring default)
  # note that ARGC must be expanded here, as it is not a "real" variable
  # (see the CMake documentation for the macro command)
  if ("${ARGC}" GREATER 5)
    message (FATAL_ERROR "gflags_variable: Too many macro arguments")
  endif ()
  if (NOT DEFINED GFLAGS_${varname})
    if (GFLAGS_IS_SUBPROJECT AND "${ARGC}" EQUAL 5)
      set (GFLAGS_${varname} "${ARGV4}")
    else ()
      set (GFLAGS_${varname} "${default}")
    endif ()
  endif ()
  if (GFLAGS_IS_SUBPROJECT)
    if (NOT DEFINED ${varname})
      set (${varname} "${GFLAGS_${varname}}")
    endif ()
  else ()
    set (${varname} "${GFLAGS_${varname}}" CACHE ${type} "${docstring}")
  endif ()
endmacro ()

# ----------------------------------------------------------------------------
## Set property of cached gflags configuration variable
macro (gflags_property varname property value)
  gflags_is_cached (_cached ${varname})
  if (_cached)
    # note that property must be expanded here, as it is not a "real" variable
    # (see the CMake documentation for the macro command)
    if ("${property}" STREQUAL "ADVANCED")
      if (${value})
        mark_as_advanced (FORCE ${varname})
      else ()
        mark_as_advanced (CLEAR ${varname})
      endif ()
    else ()
      set_property (CACHE ${varname} PROPERTY "${property}" "${value}")
    endif ()
  endif ()
  unset (_cached)
endmacro ()

# ----------------------------------------------------------------------------
## Modify value of gflags configuration variable
macro (gflags_set varname value)
  gflags_is_cached (_cached ${varname})
  if (_cached)
    set_property (CACHE ${varname} PROPERTY VALUE "${value}")
  else ()
    set (${varname} "${value}")
  endif ()
  unset (_cached)
endmacro ()

# ----------------------------------------------------------------------------
## Configure public header files
function (configure_headers out)
  set (tmp)
  foreach (src IN LISTS ARGN)
    if (IS_ABSOLUTE "${src}")
      list (APPEND tmp "${src}")
    elseif (EXISTS "${PROJECT_SOURCE_DIR}/src/${src}.in")
      configure_file ("${PROJECT_SOURCE_DIR}/src/${src}.in" "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}" @ONLY)
      list (APPEND tmp "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}")
    else ()
	    configure_file ("${PROJECT_SOURCE_DIR}/src/${src}" "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}" COPYONLY)
      list (APPEND tmp "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}")
    endif ()
  endforeach ()
  set (${out} "${tmp}" PARENT_SCOPE)
endfunction ()

# ----------------------------------------------------------------------------
## Configure source files with .in suffix
function (configure_sources out)
  set (tmp)
  foreach (src IN LISTS ARGN)
    if (src MATCHES ".h$" AND EXISTS "${PROJECT_SOURCE_DIR}/src/${src}.in")
      configure_file ("${PROJECT_SOURCE_DIR}/src/${src}.in" "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}" @ONLY)
      list (APPEND tmp "${PROJECT_BINARY_DIR}/include/${GFLAGS_INCLUDE_DIR}/${src}")
    else ()
      list (APPEND tmp "${PROJECT_SOURCE_DIR}/src/${src}")
    endif ()
  endforeach ()
  set (${out} "${tmp}" PARENT_SCOPE)
endfunction ()

# ----------------------------------------------------------------------------
## Add usage test
#
# Using PASS_REGULAR_EXPRESSION and FAIL_REGULAR_EXPRESSION would
# do as well, but CMake/CTest does not allow us to specify an
# expected exit status. Moreover, the execute_test.cmake script
# sets environment variables needed by the --fromenv/--tryfromenv tests.
macro (add_gflags_test name expected_rc expected_output unexpected_output cmd)
  set (args "--test_tmpdir=${PROJECT_BINARY_DIR}/Testing/Temporary"
            "--srcdir=${PROJECT_SOURCE_DIR}/test")
  add_test (
    NAME    ${name}
    COMMAND "${CMAKE_COMMAND}" "-DCOMMAND:STRING=$<TARGET_FILE:${cmd}>;${args};${ARGN}"
                               "-DEXPECTED_RC:STRING=${expected_rc}"
                               "-DEXPECTED_OUTPUT:STRING=${expected_output}"
                               "-DUNEXPECTED_OUTPUT:STRING=${unexpected_output}"
                               -P "${PROJECT_SOURCE_DIR}/cmake/execute_test.cmake"
    WORKING_DIRECTORY "${GFLAGS_FLAGFILES_DIR}"
  )
endmacro ()

# ------------------------------------------------------------------------------
## Register installed package with CMake
#
# This function adds an entry to the CMake registry for packages with the
# path of the directory where the package configuration file of the installed
# package is located in order to help CMake find the package in a custom
# installation prefix. This differs from CMake's export(PACKAGE) command
# which registers the build directory instead.
function (register_gflags_package CONFIG_DIR)
  if (NOT IS_ABSOLUTE "${CONFIG_DIR}")
    set (CONFIG_DIR "${CMAKE_INSTALL_PREFIX}/${CONFIG_DIR}")
  endif ()
  string (MD5 REGISTRY_ENTRY "${CONFIG_DIR}")
  if (WIN32)
    install (CODE
      "execute_process (
         COMMAND reg add \"HKCU\\\\Software\\\\Kitware\\\\CMake\\\\Packages\\\\${PACKAGE_NAME}\" /v \"${REGISTRY_ENTRY}\" /d \"${CONFIG_DIR}\" /t REG_SZ /f
         RESULT_VARIABLE RT
         ERROR_VARIABLE  ERR
         OUTPUT_QUIET
       )
       if (RT EQUAL 0)
         message (STATUS \"Register:   Added HKEY_CURRENT_USER\\\\Software\\\\Kitware\\\\CMake\\\\Packages\\\\${PACKAGE_NAME}\\\\${REGISTRY_ENTRY}\")
       else ()
         string (STRIP \"\${ERR}\" ERR)
         message (STATUS \"Register:   Failed to add registry entry: \${ERR}\")
       endif ()"
    )
  elseif (IS_DIRECTORY "$ENV{HOME}")
    file (WRITE "${PROJECT_BINARY_DIR}/${PACKAGE_NAME}-registry-entry" "${CONFIG_DIR}")
    install (
      FILES       "${PROJECT_BINARY_DIR}/${PACKAGE_NAME}-registry-entry"
      DESTINATION "$ENV{HOME}/.cmake/packages/${PACKAGE_NAME}"
      RENAME      "${REGISTRY_ENTRY}"
    )
  endif ()
endfunction ()
