cmake/modules/SwiftUtils.cmake

include(CMakeParseArguments)

function(precondition var)
  cmake_parse_arguments(
    PRECONDITION # prefix
    "NEGATE" # options
    "MESSAGE" # single-value args
    "" # multi-value args
    ${ARGN})

  if (PRECONDITION_NEGATE)
    if (${var})
      if (PRECONDITION_MESSAGE)
        message(FATAL_ERROR "Error! ${PRECONDITION_MESSAGE}")
      else()
        message(FATAL_ERROR "Error! Variable ${var} is true.")
      endif()
    endif()
  else()
    if (NOT ${var})
      if (PRECONDITION_MESSAGE)
        message(FATAL_ERROR "Error! ${PRECONDITION_MESSAGE}")
      else()
        message(FATAL_ERROR "Error! Variable ${var} is false or not set.")
      endif()
    endif()
  endif()
endfunction()

# Assert is 'NOT ${LHS} ${OP} ${RHS}' is true.
function(precondition_binary_op OP LHS RHS)
  cmake_parse_arguments(
    PRECONDITIONBINOP # prefix
    "NEGATE" # options
    "MESSAGE" # single-value args
    "" # multi-value args
    ${ARGN})

  if (PRECONDITIONBINOP_NEGATE)
    if (${LHS} ${OP} ${RHS})
      if (PRECONDITIONBINOP_MESSAGE)
        message(FATAL_ERROR "Error! ${PRECONDITIONBINOP_MESSAGE}")
      else()
        message(FATAL_ERROR "Error! ${LHS} ${OP} ${RHS} is true!")
      endif()
    endif()
  else()
    if (NOT ${LHS} ${OP} ${RHS})
      if (PRECONDITIONBINOP_MESSAGE)
        message(FATAL_ERROR "Error! ${PRECONDITIONBINOP_MESSAGE}")
      else()
        message(FATAL_ERROR "Error! ${LHS} ${OP} ${RHS} is false!")
      endif()
    endif()
  endif()
endfunction()

# Translate a yes/no variable to the presence of a given string in a
# variable.
#
# Usage:
#   translate_flag(is_set flag_name var_name)
#
# If is_set is true, sets ${var_name} to ${flag_name}. Otherwise,
# unsets ${var_name}.
function(translate_flag is_set flag_name var_name)
  if(${is_set})
    set("${var_name}" "${flag_name}" PARENT_SCOPE)
  else()
    set("${var_name}" "" PARENT_SCOPE)
  endif()
endfunction()

macro(translate_flags prefix options)
  foreach(var ${options})
    translate_flag("${${prefix}_${var}}" "${var}" "${prefix}_${var}_keyword")
  endforeach()
endmacro()

# Set ${outvar} to ${${invar}}, asserting if ${invar} is not set.
function(precondition_translate_flag invar outvar)
  precondition(${invar})
  set(${outvar} "${${invar}}" PARENT_SCOPE)
endfunction()

function(is_build_type_optimized build_type result_var_name)
  if("${build_type}" STREQUAL "Debug")
    set("${result_var_name}" FALSE PARENT_SCOPE)
  elseif("${build_type}" STREQUAL "RelWithDebInfo" OR
         "${build_type}" STREQUAL "Release" OR
         "${build_type}" STREQUAL "MinSizeRel")
    set("${result_var_name}" TRUE PARENT_SCOPE)
  else()
    message(FATAL_ERROR "Unknown build type: ${build_type}")
  endif()
endfunction()

function(is_build_type_with_debuginfo build_type result_var_name)
  if("${build_type}" STREQUAL "Debug" OR
     "${build_type}" STREQUAL "RelWithDebInfo")
    set("${result_var_name}" TRUE PARENT_SCOPE)
  elseif("${build_type}" STREQUAL "Release" OR
         "${build_type}" STREQUAL "MinSizeRel")
    set("${result_var_name}" FALSE PARENT_SCOPE)
  else()
    message(FATAL_ERROR "Unknown build type: ${build_type}")
  endif()
endfunction()

# Set variable to value if value is not null or false. Otherwise set variable to
# default_value.
function(set_with_default variable value)
  cmake_parse_argument(
    SWD
    ""
    "DEFAULT"
    "" ${ARGN})
  precondition(SWD_DEFAULT
    MESSAGE "Must specify a default argument")
  if (value)
    set(${variable} ${value} PARENT_SCOPE)
  else()
    set(${variable} ${SWD_DEFAULT} PARENT_SCOPE)
  endif()
endfunction()