I have this highlight rules in custom mode that inherits TextHighlightRules:

this.$rules = {
    "start": [
        {
            token: "variable",
            regex: '{[a-zA-Z0-9_.]+}'
        }
    ]
};

It works for strings like {foo} {bar}.
In this case editor.session.getTokens(0) will return two tokens.

But for some reason it doesn’t work for strings like: {foo}{bar}
In this case editor.session.getTokens(0) will return only one token {foo}{bar}.

How can I solve this issue?

I’ve tried separating token and it somehow worked correctly:

this.$rules = {
    "start": [
        {
            token: ["variableStart", "variable", "variableEnd"],
            regex: '({)([a-zA-Z0-9_.]+)(})'
        }
    ]
};

But I hope there are other ways to solve it.