Allow Complex Regexes

[cpmcgrath]

The current Regex engine is the default javascript one. This is fine for simple cases, but doesn't let you specify group names like the c# regex implementation. This is required for the "Special Group Names" feature.

For more details see https://github.com/cpmcgrath/codealignment/wiki/Aligning-using-Regular-expressions

[cpmcgrath]

Implementation of this will be considered a Major version release.

[cpmcgrath]

http://xregexp.com/ offers named captures, but currently only returns the value not the index. We need the index.
I've logged an enhancement request - slevithan/xregexp#217 but might have to look for an alternate library.

[cpmcgrath]

It looks like this is currently just a limitation of Javascript. So this is on hold for the moment.

Luckily I can do Align by space without it, which is the main reason for it. But I can't see a way to do "Align after comma" without this (Without an ugly hack)

[cpmcgrath]

Few random thoughts, they don't really lead to any conclusions...

In terms of usage, I would say there's three main use cases

1. Align by space (which we can do without complex regexes)
2. I want to align by the word AFTER the delimiter (e.g. Align after comma)
3. I want to align by something, by put the spaces at a different place (right alignment)

The third case is rare and I really can't see a way to do it nicely without the regex engine in javascript being updated. So let's ignore that for now.

So that leaves us with the second case. What we could do is allow multiple regexes to be ran and we just use the last regex for the alignment. In the case of align after comma...

,
\s[^s]

The problem with this is that you still want to specify it in a single string, without breaking other potentially valid regexes (Let's make the separator #, but what if I want to align by the word after #?).

I was thinking ^ as it represents the start of the line, and thought that wouldn't make sense anywhere except the start of the regex (as long as you also handled ^ correctly) but you could theoretically have (a|^b) Align by a or b if it is at the start of the line.

[cpmcgrath]

Complex Regexes also allowed for the "Align by equals" to ignore !=