François Pinard wrote: > [Mikolaj Machowski] >> [Mohsin]: > >>> Vim only has syntax coloring with regexps. Emacs has functions to >>> apply properties to text blocks, and I was hoping vim has something >>> comparable. > >> Of course it is possible: > >> :help /\%l >> :help /\%c > > Humph, not really! > > Text properties in Emacs span text regions, which move, expand or shrink > while text is being edited outside or within them. Besides > highlighting, text properties may also be used for making regions > invisible (fully collapsed, not using any estate on the display), > intangible (the cursor skips over them as if they were a single > character), and many other things as well. > > Efficiently adjusting tons of text properties in a buffer is a > computational challenge: markers just cannot be used, as the time for > updating markers at each editing action is proportional to the number of > markers. If I remember well, text boundaries for an Emacs buffer are > all held within a single heap structure. I think some people called > them "priority queues", Python lovers may look for module "heapq", and > the boundaries only get updated when the cursor moves through them. To > understand this, one should know that within Emacs, the buffer text is > split into the physical memory buffer as two parts on each end, with all > the free space (nicknamed "the hole") kept in the middle. The cursor > coincides with the hole, moving the cursor moves bits of the text over > that hole. The heap helps at quickly finding the nearest boundaries for > text properties, and updating them rather lazily, not far from the least > often possible. > > I would not think (but I do not really know) that users could easily > reimplement equivalent features in Vim. This particular problem > interests me somehow: I once wrote an Emacs package called `xxml.el' > which does a decent job at highlighting SGML, HTML and XML, or cleverly > refilling it (building over an astonishingly powerful packages named > PSGML, written by Lennart Staflin). More than once, I pondered porting > this `xxml.el' to Vim, but as it heavily uses text properties, I would > have needed a replacement first. Reimplementing PSGML for Vim would > have been a major undertaking as well, yet here, I would have went the > Python way, in a Python-enabled Vim. Dreams, dreams, dreams... :-) >
[snip entire para Tony wrote.] Tony, Your comments arent applicable to Francois. --Suresh
