Re: progmodes/project.el and search paths

[Dmitry Gutov]

On 08/14/2015 02:52 PM, Eric Ludlam wrote:

> 2) Parsers don't check types, etc as they go, and are flexible about the
> symbols they accept.
>
> This means you can get irrational tags.  This is for a combination of
> handling incomplete code, speed (less to do) and because most folks just
> go an run their compiler at some point anyway.

Doesn't that mean that code completion at the end of a chain of calls 
can be inaccurate (with e.g. lots of false positives), even if code is 
otherwise valid?

> 3) Iterative parsing, so each invocation of the parser only executes
> across a single tag.
>
> This means that if parsing fails, we just move forward one lexical token
> and try again.  This lets the parser just wash over anything it doesn't
> get.

AFAIK, parsers in general try to ignore errors, or else you wouldn't be 
able to get any useful information, after compilation fails, about any 
errors after the first one.

> 4) Incremental parser
>
> Emacs watches you edit, tracks your changes, and matches it up against
> previously parsed tags.  If things are 'broken' in the code you edit,
> but you didn't touch the boundaries of the other nearby tags, it lets it
> be until next time.  This means all the previously captured data is
> available for use, including the active broken tag you might be editing.

That sounds useful.

> It also has the typical bison error handling, but that tends not to be
> necessary.
>
> In summary; Semantic can extract useful data out of pretty badly trashed
> code, and track your changes while you edit in a robust way.

It seems I stand corrected, thanks. However, it would be interesting to 
do a comparison on some real file, against a widely used compiler, such 
as Clang.