Add regexes to parse operators

from https://hexdocs.pm/elixir/operators.html:

> Elixir is capable of parsing a predefined set of operators; this means
> that it's not possible to define new operators (like one could do in
> Haskell, for example). However, not all operators that Elixir can
> parse are *used* by Elixir: for example, `+` and `||` are used by
> Elixir for addition and boolean *or*, but `<~>` is not used (but
> valid).

The following is a list of all the operators that Elixir is capable of
parsing, but that are not used by default (separated by a comma):

|, |||, &&&, <<<, >>>, <<~, ~>>, <~, ~>, <~>, <|>, ^^^, ~~~

They could be expressed in a regex atom `(&&&|<~|<~>|etc...)` but I
think it can be reduced (I don't know the difference in efficiency) to:

`[\|\^&<>~]{1,3}`

Adding to that bracket expression the rest of the characters and words
used for the defined operators (which can be overriden):

`([\|\^\/&<>~.=!*+-]{1,3}|and|or|not|in|not in)`

But since the regex engine used in exhuberant-ctags can't do lookahead,
I'm not gonna bother to try and make the operator regex exhaustive...
plus it's also bad practice to override the default operators.

Author: dreamtigers

.ctags

@@ -7,7 +7,11 @@
 --regex-Elixir=/^[ \t]*defguard(p?)[ \t]+(is_[a-zA-Z0-9_?!]+)/\2/g,guard,guards (defguard ...)/
 --regex-Elixir=/^[ \t]*defimpl[ \t]+([A-Z][a-zA-Z0-9_]*\.)*([A-Z][a-zA-Z0-9_?!]*)/\2/i,implementation,implementations (defimpl ...)/
 --regex-Elixir=/^[ \t]*defmacro(p?)[ \t]+([a-z_][a-zA-Z0-9_?!]*)(.[^\|\^\/&<>~.=!*+-]+)/\2/a,macro,macros (defmacro ...)/
---regex-Elixir=/^[ \t]*defmacro(p?)[ \t]+([a-zA-Z0-9_?!]+)?[ \t]+([^ \tA-Za-z0-9_]+)[ \t]*[a-zA-Z0-9_!?!]/\3/o,operator,operators (e.g. "defmacro a <<< b")/
+
+# These are the operators (which can be defined with def(p) and defmacro(p))
+--regex-Elixir=/^[ \t]*def(p?)[ \t]+([a-zA-Z0-9_?!]+)[ \t]+([\|\^\/&<>~.=!*+-]{1,3})[ \t]+[a-zA-Z0-9_!?!]/\3/o,operator,operators (e.g. "def a <<< b")/
+--regex-Elixir=/^[ \t]*defmacro(p?)[ \t]+([a-zA-Z0-9_?!]+)[ \t]+([\|\^\/&<>~.=!*+-]{1,3})[ \t]+[a-zA-Z0-9_!?!]/\3/o,operator,operators (e.g. "defmacro a <<< b")/
+
 --regex-Elixir=/^[ \t]*defmodule[ \t]+([A-Z][a-zA-Z0-9_]*\.)*([A-Z][a-zA-Z0-9_?!]*)/\2/m,module,modules (defmodule ...)/
 --regex-Elixir=/^[ \t]*defprotocol[ \t]+([A-Z][a-zA-Z0-9_]*\.)*([A-Z][a-zA-Z0-9_?!]*)/\2/p,protocol,protocols (defprotocol...)/
 --regex-Elixir=/^[ \t]*Record\.defrecord(p?)[ \t(]+:([a-zA-Z0-9_]+)(\)?)/\2/r,record,records (defrecord...)/