Re: multi-character syntactic entities in syntax tables

[Erik Charlebois <erikcharlebois@gmail.com>]

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ruby-forward-sexp works fine. It's more for things like % (under vim
emulation, I'm not sure what the Emacs-equivalent is) to jump to the
matching brace and show-paren-mode.


On Fri, Apr 26, 2013 at 3:26 PM, Stefan Monnier <monnier@iro.umontreal.ca>wrote:

> > One of the items in etc/TODO is:
> > ** Beefed-up syntax-tables.
> > *** recognize multi-character syntactic entities like `begin' and `end'.
>
> > Lately I'm using languages where this would be quite useful and would be
> > interested in adding support. Before I dive in, are there any strong
> > opinions about how this should be implemented?
>
> > The approach I was thinking of taking is defining a new syntax character
> > class (let's say, *) which inherits from the previous character
> > (recursively if the previous character is *). The important distinction
> is
> > that they would not be treated as a new instance of that syntax class, so
> > point movement by syntax class or paren matching would work (e.g. begin
> > would be (****, and would only add 1 level of paren nesting).
>
> I see.  So you'd rely on syntax-propertize-function to recognize those
> multi-char entities and label them with one of the current syntaxes for
> the first char and "*" for the other ones, thus labelling the symbol as
> forming a single entity.
>
> That's interesting.  The main drawback I see with it is the heavy
> reliance on syntax-propertize, which can imply a significant performance
> cost when jumping to the end of a largish buffer (forcing the whole
> buffer to be lexed).
>
> But it sounds like an attractive "easy" way to extend syntax tables to
> support multi-char entities.
>
> BTW: have you tried to set forward-sexp-function to something like
> ruby-forward-sexp?
>
>
>         Stefan
>

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