> On 3 Nov 2017, at 19:22, Dimitre Novatchev <> wrote:
>
>> not(contains(replace(., '\\,', ''), ','))
>
> And, of course:
>
> not(matches(., '[^\\],'))
>
I don't think that detects an unescaped comma at the start of the string.
Also, Roger didn't state the rule, but I suspect that there must only be one backslash before the comma: if there are two ("\\,") then the comma is not escaped because the "\\" represents a real backslash. In fact the rule is then that the number of backslashes preceding the comma must be an odd number.
There may be a more elegant way, but I'd be inclined to do it by first getting rid of all "\\" sequences:
not(matches(replace(., '\\\\', ''), '^,|[^\\],'))
Michael Kay
Saxonica
