Re: dtc expressions

On 03/15/2012 06:29 PM, David Gibson wrote:

On Wed, Mar 14, 2012 at 09:40:13AM -0600, Stephen Warren wrote:

quoted

On 03/14/2012 08:46 AM, David Gibson wrote:

quoted

So, in order to actually make progress on the dtc expressions / macros
/ whatnot stuff, I really think I should dust off my integer (constant)
expressions patch, and we can apply that.

While we still have disagreements on a bunch of stuff here, I think
we're at least agreed on what integer expressions should look like.
And even if we change approaches later (e.g. to your ifs and fors in
dtc approach) the integer expression syntax won't change, only the
implementation.

I'd love to see something like that. I've don't think I've actually
looked through your patches for that yet; I briefly looked at Jon's
since they're in a branch in the dtc repo, but I don't think I managed
to track down the patches you sent for this.

It was quite a while back that I posted.  I've got a version below,
but it's *very* bitrotted and won't even go close to applying at
present.  I'm meaning to update it, but it will take a little time.

That looks like a good set of integer expressions.

Do you think it'd be easy to agree on a simple "#define foo (expr)"-like
syntax on top of this? I think that'd cover a lot of the use-cases
people are looking for right now, which are more about
creating/naming/using constants rather than building whole nodes or
properties in some programmatic way.

Index: dtc/dtc-lexer.l

...

+<*>"<<"		{ return DT_LSHIFT; };
+<*>">>"		{ return DT_RSHIFT; };
+<*>"<="		{ return DT_LE; };
+<*>">="		{ return DT_GE; };
+<*>"=="		{ return DT_EQ; };
+<*>"!="		{ return DT_NE; };
+<*>"&&"		{ return DT_AND; };
+<*>"||"		{ return DT_OR; };

For my education, why aren't all the operators in the lexer file? When I
first looked at this file, it seemed like a bunch were missing because
they're only represented in the parser, as literal strings.