# By escaping `self` to C, how many more bytes will be needed ?
	#
	# This enables a double-optimization in `escape_to_c` since if this
	# method returns 0, then `self` does not need escaping and can be
	# returned as-is
	fun chars_to_escape_to_c: Int do
		var its = _items
		var max = last_byte
		var pos = first_byte
		var req_esc = 0
		while pos <= max do
			var c = its[pos]
			if c == u'\n' then
				req_esc += 1
			else if c == u'\t' then
				req_esc += 1
			else if c == u'"' then
				req_esc += 1
			else if c == u'\'' then
				req_esc += 1
			else if c == u'\\' then
				req_esc += 1
			else if c == u'?' then
				var j = pos + 1
				if j < length then
					var next = its[j]
					# We ignore `??'` because it will be escaped as `??\'`.
					if
						next == 0x21 or
						next == 0x28 or
						next == 0x29 or
						next == 0x2D or
						next == 0x2F or
						next == 0x3C or
						next == 0x3D or
						next == 0x3E
					then req_esc += 1
				end
			else if c < 32 then
				req_esc += 3
			end
			pos += 1
		end
		return req_esc
	end