[cfe-dev] Preprocessing and whitespace collapsing

[Manuel Klimek]

+val, the author of ycm


On Wed, Jan 15, 2014 at 10:07 AM, Anders Bakken <agbakken at gmail.com> wrote:

> We're aware of the project. I think his project focuses mostly on
> completion whereas ours focuses most on indexing. Certainly there's a
> lot of duplicated efforts in both projects but they're both quite
> mature and fully functional. I kinda doubt that either project would
> want to replace itself with the other one tbh but one could maybe
> imagine a world where both projects would work for either editor but
> our ipc mechanisms are different enough that I'm not convinced there
> would be much savings in terms of workload.
>
> Anders
>
> On Mon, Jan 13, 2014 at 9:58 PM, Matt Fowles <matt.fowles at gmail.com>
> wrote:
> > Anders~
> >
> > YouCompleteMe (the vim plugin) is built with a parser and completion
> engine
> > server and a client process that sits inside vim.  Not sure how far your
> > implementation is, but you may wish to consider sharing work it.
> >
> > https://github.com/Valloric/YouCompleteMe
> >
> > Matt
> >
> >
> > On Tue, Jan 14, 2014 at 12:46 AM, Anders Bakken <agbakken at gmail.com>
> wrote:
> >>
> >> Hi
> >>
> >> We're using to make an indexer daemon which can be queried from emacs
> >> (or other editors if so desired). In doing this we, for various
> >> reasons, preprocess the file first using internal APIs and then invoke
> >> clang_parseTranslationUnit on the preprocessed content. The code for
> >> this is here:
> >>
> >>
> >>
> https://github.com/Andersbakken/rtags/blob/multi-process/src/RTagsClang.cpp
> >>
> >> Starting at line 450.
> >>
> >> The problem we're facing is that clang seems to collapse things like
> this:
> >>
> >> struct A
> >> {
> >>     void               foo();
> >> };
> >>
> >> into this:
> >>
> >> struct A
> >> {
> >>     void foo();
> >> };
> >>
> >> int main()
> >> {
> >>     A a;
> >>     a.foo();
> >> }
> >>
> >> I realize the standard (at least according to GCC) permits this and
> >> that it of course would speed up parsing of the resulting code ever so
> >> slightly. My question is, is it possible to:
> >>
> >> A) Turn this behavior off with an option?
> >> or
> >> B) Someone query which lines had what amounts of space removed.
> >>
> >> I assume something can be done since if I let
> >> clang_parseTranslationUnit index it without preprocessing myself
> >> everything works as expected.
> >>
> >> From (
> http://gcc.gnu.org/onlinedocs/gcc-3.3/cpp/Preprocessor-Output.html)
> >>
> >> The ISO standard specifies that it is implementation defined whether a
> >> preprocessor preserves whitespace between tokens, or replaces it with
> >> e.g. a single space. In GNU CPP, whitespace between tokens is
> >> collapsed to become a single space, with the exception that the first
> >> token on a non-directive line is preceded with sufficient spaces that
> >> it appears in the same column in the preprocessed output that it
> >> appeared in the original source file. This is so the output is easy to
> >> read. See Differences from previous versions. CPP does not insert any
> >> whitespace where there was none in the original source, except where
> >> necessary to prevent an accidental token paste.
> >>
> >> Thanks and kudos for an awesome project.
> >>
> >> regards
> >>
> >> Anders
> >> _______________________________________________
> >> cfe-dev mailing list
> >> cfe-dev at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
> >
> >
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