src/vs/editor/contrib/snippet/snippetParser.ts/Transform/toTextmateString
class Transform:	toTextmateString(): string {
		return `/${this.regexp.source}/${this.children.map(c => c.toTextmateString())}/${(this.regexp.ignoreCase ? 'i' : '') + (this.regexp.global ? 'g' : '')}`;
	}