I want to enable my users to specify the allowed characters in a given string. 

So... Regex's are great but too tough for my users. 

my plan is to enable users to specify a list of allowed characters - for example

```
a-z|A-Z|0-9|,

```

i can transform this into a regex which does the matching as such:

```
[a-zA-Z0-9,]*

```

However i'm a little lost to deal with all the escaping - imagine if a user specified

```
a-z|A-Z|0-9| |,|||\|*|[|]|{|}|(|)

```

Clearly one option is to deal with every case individually but before i write such a nasty solution - is there some nifty way to do this? 

Thanks

David