{"action":"created","issue":{"url":"https://api.github.com/repos/yandex/pire/issues/21","labels_url":"https://api.github.com/repos/yandex/pire/issues/21/labels{/name}","comments_url":"https://api.github.com/repos/yandex/pire/issues/21/comments","events_url":"https://api.github.com/repos/yandex/pire/issues/21/events","html_url":"https://github.com/yandex/pire/issues/21","id":98959763,"number":21,"title":"Which Regexp syntax is used ?","user":{"login":"buhtr","id":11796071,"avatar_url":"https://avatars.githubusercontent.com/u/11796071?v=3","gravatar_id":"","url":"https://api.github.com/users/buhtr","html_url":"https://github.com/buhtr","followers_url":"https://api.github.com/users/buhtr/followers","following_url":"https://api.github.com/users/buhtr/following{/other_user}","gists_url":"https://api.github.com/users/buhtr/gists{/gist_id}","starred_url":"https://api.github.com/users/buhtr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/buhtr/subscriptions","organizations_url":"https://api.github.com/users/buhtr/orgs","repos_url":"https://api.github.com/users/buhtr/repos","events_url":"https://api.github.com/users/buhtr/events{/privacy}","received_events_url":"https://api.github.com/users/buhtr/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-08-04T12:46:59Z","updated_at":"2015-08-04T14:04:18Z","closed_at":null,"body":"Hello, I am considering to replace RE2 library with PIRE in a high load application which works with a stream. I am stuck with a regexp syntax, could you clarify which one do I need to use? \r\n"},"comment":{"url":"https://api.github.com/repos/yandex/pire/issues/comments/127623385","html_url":"https://github.com/yandex/pire/issues/21#issuecomment-127623385","issue_url":"https://api.github.com/repos/yandex/pire/issues/21","id":127623385,"user":{"login":"buhtr","id":11796071,"avatar_url":"https://avatars.githubusercontent.com/u/11796071?v=3","gravatar_id":"","url":"https://api.github.com/users/buhtr","html_url":"https://github.com/buhtr","followers_url":"https://api.github.com/users/buhtr/followers","following_url":"https://api.github.com/users/buhtr/following{/other_user}","gists_url":"https://api.github.com/users/buhtr/gists{/gist_id}","starred_url":"https://api.github.com/users/buhtr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/buhtr/subscriptions","organizations_url":"https://api.github.com/users/buhtr/orgs","repos_url":"https://api.github.com/users/buhtr/repos","events_url":"https://api.github.com/users/buhtr/events{/privacy}","received_events_url":"https://api.github.com/users/buhtr/received_events","type":"User","site_admin":false},"created_at":"2015-08-04T14:04:18Z","updated_at":"2015-08-04T14:04:18Z","body":"If it correct to say there are several standards, they are much the same but have some differences in supported constructions, for example, POSIX BRE/ERE, Perlre.\r\n\r\nCurrently, we allow our users to use Perl syntax for regexp in our application, but we have advised them not to use some \"heavy expressions\". Mainly, these regexps are applied for searching patterns in a stream and we try to avoid backtracking and similar stuff. \r\n\r\nAs I guessed from you comment your have removed the ability of backtracking, am I right ? I think it would be great to have info in docs which regexp constructions from Perlre (or something else?) can be used or just which of them we cannot use.  \r\n\r\nThus, If we move to PIRE I will need just disallow backtracking and some ranges? Could you point where I can read about ranges limitations? Ranges are not widely used in our current regexps but I would like to understand which of them need to be corrected if we replace RE2 lib with your lib.\r\n\r\nI will definitely try example which you have suggested but I need to understand the whole scope of limitation. "}}