Nikolay Pavlov wrote: > > On Jul 9, 2013 4:58 PM, "Bram Moolenaar" <[email protected]> wrote: >> >> >> Grüner_Gimpel wrote: >> >> > I noticed that using Vim 7.4a the Vimwiki plugin works measurably >> > slower with re=0 than with re=1. I figured out the reason is this >> > regexp in the syntax definition: >> > >> > >> > [[:alnum:]]\@<!\%(\%(\%(http\|https\|file\|ftp\|gopher\|telnet\|nntp\|ldap\|rsync\|imap\|pop\|irc\|ircs\|cvs\|svn\|svn+ssh\|git\|ssh\|fish\|sftp\):\%(\/\/\)\)\|\%(mailto\|news\|xmpp\|sip\|sips\|doi\|urn\|tel\):\)\S\{-1,}\%(([^ >> > \t()]*)\)\=\S* >> > >> > You may know what it is supposed to match. >> > Removing some of the branches makes it faster and so does removing >> > [[:alnum:]]\@<! >> > >> > I don't know if there is a standard method for measuring speed of the >> > syntax highlight, but here is what I have done: >> > - open a relatively large file >> > - :set syn=off >> > - :syntax match Number >> > /[[:alnum:]]\@<!\%(\%(\%(http\|https\|file\|ftp\|gopher\|telnet\|nntp\|ldap\|rsync\|imap\|pop\|irc\|ircs\|cvs\|svn\|svn+ssh\|git\|ssh\|fish\|sftp\):\%(\/\/\)\)\|\%(mailto\|news\|xmpp\|sip\|sips\|doi\|urn\|tel\):\)\S\{-1,}\%(([^ >> > \t()]*)\)\=\S*/ >> > - scroll with <c-e> and <c-y> >> > - extremely slow with re=0 but normal slow (*wink*) with re=1 >> > >> > So, can this behavior be considered as a bug? >> >> The main problem is the [[:alnum:]]\@<! item. Have you tried adding a >> limit? Should be [[:alnum:]]\@1<! >> >> Or perhaps using \< instead will work. >> >> For measuring times: use :syntime. > > Could not it deduce a limit by itself in such simple cases?
In this case the [[:alnum:]]\@<! is likely to be the root cause as was already said. However, alternative with \| are also costly because as far as I know, the regexp engine has to either backtrack (with old engine, re=1) or look for all alternatives at the same time (with new engine, re=0). I wonder: does the regexp engine attempts to simplify regexps with alternatives? I'm thinking about this kind of optimizations: https\|http --> https\= svn+ssh\|svn --> svn\%(+ssh\)\= So at least the common prefix is checked only once in the new engine. And with the old engine, there is no backtracking when matching fails already in the common prefix. Regards Dominique -- -- You received this message from the "vim_dev" maillist. Do not top-post! Type your reply below the text you are replying to. For more information, visit http://www.vim.org/maillist.php --- You received this message because you are subscribed to the Google Groups "vim_dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
