src/vs/editor/common/model/bracketPairsTextModelPart/bracketPairsTree/brackets.ts/BracketTokens/getRegExpStr
class BracketTokens:	getRegExpStr(): string | null {
		if (this.isEmpty) {
			return null;
		} else {
			const keys = [...this.map.keys()];
			keys.sort();
			keys.reverse();
			return keys.map(k => prepareBracketForRegExp(k)).join('|');
		}
	}