Re: [AUCTeX-devel] Feature Request

[Tassilo Horn]

Mosè Giordano <address@hidden> writes:

Hi all,

>>    > I have been recommended to mail the list with a feature request, I
>>    > hope this is the right place.
>>
>>    > Currently if file.tex has \cite{ref2} and ref2 does not exist in the
>>    > bib file, it displays no differently to \cite{ref1} which does.
>>
>>    > Is it possible to get some sort of visual indication that ref2
>>    > does not exist in the bib file? A red squiggly line, highlight,
>>    > different colour, something?

This would be a very nice feature.  RefTeX basically has the
functionality to know which citations are available in the bib file(s).
See `reftex-extract-bib-entries' and
`reftex-extract-bib-entries-from-thebibliography'.

So we could add some variable like `reftex-known-bibtex-entry-keys'
containing all known reftex entry keys.  I guess a hash-table would be
best because we need a fast contains-check.

> Anyway, AUCTeX holds the list of known bibliography items in
> `LaTeX-bibitem-list',

That only contains the \bibitems of a thebibliography environment, not
the entries of standalone bibtex files.

> but I'm not expert enough of font-locking to implement this feature
> without some hints.

It shouldn't be overly hard in general, i.e., you write 2 functions
`font-latex-match-(un)known-citation' which search for the next

  "\\\\cite{\\([[:alnum:]:-]+\\)}"

[1] where the group 1 is (not) contained in the hash-table.  Then these
functions could be used as font-lock matchers, e.g.

  (font-latex-match-known-citation 1 font-latex-known-citation-face)
  (font-latex-match-unknown-citation 1 font-latex-unknown-citation-face)

The only problem I see is with updates.  Point one is that we don't get
notifications about updates of bibtex entries, and re-computing all keys
can be slow.  I have a rfc.bib which contains all IETF RFCs amounting to
almost 100.000 lines.  Extracting all entries from that file takes about
3 seconds.  However, `reftex-extract-bib-entries' does much more than
just extracting the keys, so we could easily add a much faster version
just for that purpose and then update the hash-table in an
`after-save-hook' or so.

Point two is that font-lock is lazy and won't re-font-lock a region
which has not changed.  That is, even when our
`reftex-known-bibtex-entry-keys' hash-table has been just updated, we'd
need to `font-lock-flush' all \cite's arguments which is yet another
search across the complete document.

Bye,
Tassilo

[1] Since \cite{ref1,ref2} is also legal and ref1 could be known but
ref2 not, the functions should actually match both keys separately.