#-------------------------------------------------------------------------------
# Copyright (c) 2017, Arm Limited. All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause
#
#-------------------------------------------------------------------------------

# Append a value to a string if not already present
#
# Append an item to a string if no item with matching key is already on the string.
# This function's intended purpose is to append unique flags to command line switches.
#
# Examples:
#  string_append_unique_item(STRING C_FLAGS KEY "--target" VAL "--target=armv8m-arm-none-eabi")
#
# INPUTS:
#    STRING  - (mandatory) - name of the string to operate on
#    KEY   - (mandatory) - string to look for
#    VAL   - (mandatory) - value to put be added to the string
#
# OUTPUTS
#    STRING is modified as needed.
#
function(string_append_unique_item)
	#Parse our arguments
	set( _OPTIONS_ARGS )					#No option (on/off) arguments (e.g. IGNORE_CASE)
	set( _ONE_VALUE_ARGS  STRING KEY VAL)	#Single option arguments (e.g. PATH "./foo/bar")
	set( _MULTI_VALUE_ARGS )		 		#List arguments (e.g. LANGUAGES C ASM CXX)
	cmake_parse_arguments(_MY_PARAMS "${_OPTIONS_ARGS}" "${_ONE_VALUE_ARGS}" "${_MULTI_VALUE_ARGS}" ${ARGN} )

	#Check mandatory parameters
	if(NOT _MY_PARAMS_STRING)
		failure("string_append_unique_item(): Missing STRING parameter!")
	endif()
	set(_STRING ${_MY_PARAMS_STRING})

	if(NOT _MY_PARAMS_KEY)
		failure("string_append_unique_item(): Missing KEY parameter!")
	endif()
	set(_KEY ${_MY_PARAMS_KEY})

	if(NOT _MY_PARAMS_VAL)
		failure("string_append_unique_item(): Missing VAL parameter!")
	endif()
    set(_VAL ${_MY_PARAMS_VAL})

    #Scan the string.
    STRING(REGEX MATCH "( |^) *${_KEY}" _FOUND "${${_STRING}}")
    if("${_FOUND}" STREQUAL "")
		set(${_STRING} "${${_STRING}}  ${_VAL}" PARENT_SCOPE)
    endif()
endfunction()