Nik Everett 8d3ef742db Painless: =~ and ==~ operators
Adds support for the find operator (=~) and the match operator (==~)
to painless's regexes. Also whitelists most of the Matcher class and
documents regex support in painless.

The find operator (=~) returns a boolean that is the result of building
a matcher on the lhs with the Pattern on the RHS and calling `find` on
it. Use it like this:

```
if (ctx._source.last =~ /b/)
```

The match operator (==~) returns boolean like find but instead of calling
`find` on the Matcher it calls `matches`.

```
if (ctx._source.last ==~ /[^aeiou].*[aeiou]/)
```

Finally, if you want the actual matcher you do:

```
Matcher m = /[aeiou]/.matcher(ctx._source.last)
```
2016-06-16 08:42:33 -04:00
..