Support for mentions with . in the username

[akhilacubrio]

E.g. @dani.winks @ellie.unicorn.klein

[nfrasser]

Hi @akhilacubrio, I have issues both for (#175) and against (#245) this behaviour. I'm going to err on leaving it as is (no mentions with .) to match allowed GitHub and Twitter mentions.

As a workaround, you can add mentions with dots yourself with a custom plugin (using the existing mention plugin as a reference):

import { createTokenClass, registerPlugin } from 'linkifyjs';

const MentionToken = createTokenClass('mention', {
	isLink: true,
	toHref() {
		return '/' + this.toString().slice(1);
	}
});

registerPlugin('mention', ({ scanner, parser }) => {
	const { DOT, HYPHEN, SLASH, UNDERSCORE, AT } = scanner.tokens;
	const { domain } = scanner.tokens.groups;

	// @
	const At = parser.start.tt(AT); // @

	// Begin with hyphen (not mention unless contains other characters)
	const AtHyphen = At.tt(HYPHEN);
	AtHyphen.tt(HYPHEN, AtHyphen);

	// Valid mention (not made up entirely of symbols)
	const Mention = At.tt(UNDERSCORE, MentionToken);

	At.ta(domain, Mention);
	AtHyphen.tt(UNDERSCORE, Mention);
	AtHyphen.ta(domain, Mention);

	// More valid mentions
	Mention.ta(domain, Mention);
	Mention.tt(HYPHEN, Mention);
	Mention.tt(UNDERSCORE, Mention);

	// Mention with a divider
	const MentionDivider = Mention.tt(SLASH);

	// Once we get a word token, mentions can start up again
	MentionDivider.ta(domain, Mention);
	MentionDivider.tt(UNDERSCORE, Mention);
	MentionDivider.tt(HYPHEN, Mention);

	// ADDED: . transitions
	const MentionDot = Mention.tt(DOT);
	MentionDot.ta(domain, Mention);
	MentionDot.tt(HYPHEN, Mention);
	MentionDot.tt(UNDERSCORE, Mention);

})