class
	EL_ENVIRON_VARIABLE

inherit
	ANY
		redefine
			default_create
		end

	EL_MODULE_EXECUTION_ENVIRONMENT

	EL_STRING_GENERAL_ROUTINES

create
	make, make_assigned, default_create

convert
	make_assigned ({STRING_32, STRING_8, ZSTRING})

feature {NONE} -- Initialization

	default_create
		do
			create name.make_empty
			create value.make_empty
		end

	make (a_name, a_value: READABLE_STRING_GENERAL)
		do
			name := as_zstring (a_name); value := as_zstring (a_value)
		end

	make_assigned (str: READABLE_STRING_GENERAL)
		local
			parts: EL_ZSTRING_LIST
		do
			create parts.make_split (str, '=')
			if parts.count = 2 then
				make (parts.first, parts.last)
			else
				default_create
			end
		end

feature -- Access

	name: ZSTRING

	value: ZSTRING

	substituted_value: ZSTRING
		do
			Result := Execution_environment.substituted (value)
		end

feature -- Status query

	has_variable: BOOLEAN
		-- `True' if value has substitution variables
		do
			Result := value.has ('$')
		end

	is_valid: BOOLEAN
		do
			Result := not is_empty and then is_valid_name
		end

	is_empty: BOOLEAN
		do
			Result := name.is_empty and value.is_empty
		end

	is_valid_name: BOOLEAN
		do
			Result := name.count > 0 and then name.is_code_identifier
		end

feature -- Basic operations

	apply
		require
			valid_name_value_pair: is_valid
		do
			if has_variable then
				Execution_environment.put (substituted_value, name)
			else
				Execution_environment.put (value, name)
			end
		ensure
			assigned_value: not has_variable implies Execution_environment.item (name) ~ value
			assigned_substituted_value: has_variable implies Execution_environment.item (name) ~ substituted_value
		end

end