Re: xref and GNU Global?

[Eric Ludlam <eric@siege-engine.com>]

On 08/21/2015 08:37 AM, Stephen Leake wrote:
> Nicolas Petton <nicolas@petton.fr> writes:
>
>> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>
>>>> I find GNU Global to be far superior to etags or ctags.  Is there any
>>>> plan to have support for it in xref.el? (Or maybe there is and I missed
>>>> it).
>>>
>>> Yes.  IIRC the plan is to wait for Nicolas Petton to start working on
>>> it.
>>
>> Hmm, right.  First I'll have a look at what semantic & xref already have
>> to offer :)
>
> One approach is to use what semantic currently has for gnu global;
> that's in emacs/lisp/cedet/semantic/db-global.el. I'm not clear if all
> of that is accessible via the xref interface yet.
>
> I suspect semantic/db-global.el provides the same functionality as
> ggtags, possibly without as much UI; the current design goal is for xref
> to be the UI for semantic cross-reference features.

Global support from cedet/semantic comes from a few different places. 
The core interface is a few calls in cedet-global.el.  Helpful for 
getting some raw data.

The semantic/db-global.el is for using GNU Global as a database backend. 
  Stand-alone, it is not useful.  With Semantic and it's generic 
database system, it provides a way to find symbol declarations across a 
project.  You would use this if you wanted to write or use an existing 
tool using semantic's tag finding APIs to find declarations. 
semantic-complete-jump is an example that uses that.  The nice thing 
about semantic's database system is it can mix multiple tools together, 
for example global for project wide, and Semantic's parser system for 
buffers you are editing that global doesn't know about yet.

semantic/symref/global.el is another place with global support.  This 
one is pretty simple as far as running and parsing output for use with 
the semantic symref searching system.   This tool is useful for finding 
references, and also providing other tag information along with the 
different hits.


Eric