Re: [CEDET-devel] Is there a way to locally parse from point to the outer most scope, or just current buffer?

[Tu Do <tuh...@gm...>]

Thanks Eric.

I will make use of these valuable information effectively.

Regards,

Tu.

On Tue, Jan 27, 2015 at 12:43 AM, Eric Ludlam <eri...@gm...> wrote:

> On 01/26/2015 10:02 AM, Tu Do wrote:
>
>> Hi Eric,
>>
>> I implemented some initial refactoring tools using Semantic. You can see
>> the demos here: https://github.com/chrisbarrett/emacs-refactor/pull/5
>>
>> In the future, I intend to implement Semantic query and replace, in
>> combination with GNU Global to find all references without burdening
>> Semantic up-front parsing. Using GNU Global to retrieve a list of
>> references, then just parse enought the scope of each reference to get
>> sufficient information to decide which symbol is to be replaced, to avoid
>> freezing Emacs for too long.
>>
>> Is it possible to prevent whole buffer parsing when visiting a buffer
>> with Semantic enabled?
>>
>
> Howdy,
>
> You can temporarily suppress buffer parsing for a specific file by adding
> something to semantic--before-fetch-tags-hook, and you don't need to
> disable semantic for entire modes to do it.
>
> Since your intent is to use GNU Global, you can also use
> `semanticdb-enable-gnu-global-databases' so that whenever a set of file
> tags is needed, it uses GNU Global instead of the usual parsing mechanism
> which also speeds things up.  This is used primarily for finding tags by
> name, not as a replacement when a file is in a buffer, as global tags do
> not have the needed features.
>
> Your project for refactoring tools sounds great.  I had long planned to do
> refactoring as well and have a few core pieces in place.
>
> The `semantic-symref' tool knows how to query GNU Global (and several
> other tools) into a structure you can work with. You should try it out, as
> it has a simple "rename" type feature in it already, and the symref mode
> lets you select which entries you want the rename to operate on in case the
> search gets a false positive.  I didn't get very far with refactoring
> tricks though.
>
> There is a comment deep in the symref code referring to a place where we
> want to verify every hit really is the thing we are looking for which I
> never implemented.  This almost sounds like what you are trying to do
> (verify without parsing everything.)  I hadn't thought of trying to shorten
> parsing like that.  Usually a single buffer parses very quickly.
>
> Parsing a subset of the buffer is the job of `semantic-parse-region', and
> the incremental parser.  Unfortunately, you need the guidelines of a
> previously parsed buffer in order to make it work accurately.
>
> There is also the local context parser you can get to from
> `semantic-get-local-variables' but that also needs a full buffer parsed.
>
> This is why I ended up with using the symref mode where you can take a
> peek and pick out which are safe replacements, and which are not before
> running the operation.  It gets simple functional stuff right almost all
> the time, but it doesn't decipher complex OO constructs where the text is
> the same but the actual referred to thing could be different.  It could use
> the semantic analyzer on the code hits to determine which are of the
> correct class, etc, but that would be pretty slow for a lot of hits.  That
> would require some infrastructure for doing that operation in idle-time.
> Since each individual analysis is typically under 1 sec once key headers
> are loaded, that should be a problem.
>
> Eric
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