Split string by delimiter, but not if it is escaped

How can I split a string by a delimiter, but not if it is escaped? For example, I have a string:

1|2\|2|3\\|4\\\|4

The delimiter is | and an escaped delimiter is \|. Furthermore I want to ignore escaped backslashes, so in \\| the | would still be a delimiter.

So with the above string the result should be:

[0] => 1
[1] => 2\|2
[2] => 3\\
[3] => 4\\\|4