The hooks you are proposing satisfies my needs very well and appreciate
that you add these hooks to Wave as it makes and will make my life a
lot easier. I agree to your point on the comments and  can build
the rest I need on top of Wave. When and how should I expect to be able
to test a new Wave version with these hooks? <br>
<br>
Thanks,<br>
Andreas<br>
<br><div><span class="gmail_quote">On 11/1/05, <b class="gmail_sendername">Hartmut Kaiser</b> &lt;<a href="mailto:hartmut.kaiser@gmail.com">hartmut.kaiser@gmail.com</a>&gt; wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
extracting the C/C++ statement or expression<br>
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; that the unexpanded macro (and expanded) is<br>
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
a part of.<br>I was thinking about to add new hooks to the preprocessing hooks template<br>from the very beginning. Sorry for not beeing consise enough.<br><br>For consistency reasons I'ld suggest to add a hook:<br><br>&nbsp;&nbsp;&nbsp;&nbsp;template &lt;typename TokenT&gt;
<br>&nbsp;&nbsp;&nbsp;&nbsp;void<br>&nbsp;&nbsp;&nbsp;&nbsp;found_directive(TokenT const&amp; directive);<br><br>Where directive refers to the token containing the found pp directive.<br><br>&gt;<br>&gt;&nbsp;&nbsp;yes, so that I can extract the unexpanded preprocessor<br>
&gt; conditional expression and when this expression is<br>&gt; (macro-)expanded if the result is positive or negative.<br>&gt; For instance in the example<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #define BAR<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #ifdef BAR<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int x;
<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #ifdef FOO<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int y;<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #endif<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #endif<br>&gt; I would be interested in extracting '#ifdef BAR' and also<br>&gt; that it is evaluated as true. I would also be interested in
<br>&gt; extracting '#ifdef FOO' and that it is evaluated as false.<br><br>What about:<br><br>&nbsp;&nbsp;&nbsp;&nbsp;template &lt;typename ContainerT&gt;<br>&nbsp;&nbsp;&nbsp;&nbsp;void<br>&nbsp;&nbsp;&nbsp;&nbsp;evaluated_conditional_expression(ContainerT const&amp; expression,<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;bool expression_value);<br><br>Where:<br>- expression contains the (not expanded) expression tokensequence and<br>- expression_value is the result of the evaluation of this expression.<br><br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*after evaluating the preprocessor conditional,<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; extract the portion which was evaluated as false as a string<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt;<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#define
positive<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
#ifdef int positive<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; #endif /*Extract this false part as string*/ int x; #endif<br><br>&nbsp;&nbsp;&nbsp;&nbsp;template &lt;typename ContainerT&gt;<br>&nbsp;&nbsp;&nbsp;&nbsp;void<br>&nbsp;&nbsp;&nbsp;&nbsp;skipped_token(TokenT const&amp; token);<br><br>Where token is the skipped token. This hook will be called for each token
<br>which gets skipped due to a false preproccessing condition.<br><br>&gt; I am only interested in defined macros. To be more specific I<br>&gt; am interested in when the preprocessor recognises a macro.<br>&gt; For each macro it is interesting to extract the value and
<br>&gt; position in the file. The macro can be found in two forms;<br>&gt; the one before macro-expansion and the one after. Both forms<br>&gt; are interesting. But this is from what I have seen already<br>&gt; handled in struct default_preprocessing_hooks.
<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1:&nbsp;&nbsp;#define
FOO int x;<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;2:&nbsp;&nbsp;FOO<br>&gt; On line 2 in this example code the macro FOO is found. This<br>&gt; macro can be expanded to 'int x', which to the preprocessor<br>&gt; is equivalent to the unexpanded macro FOO found on line 1.
<br><br>Yeah, I was already wondering how you might want to decide whether a<br>identifier actually is a 'undefined' macro :-P<br>This information already should be avalable through the existing<br>preproceesing hooks.<br>
<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*extracting the C/C++ statement or expression<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; that the unexpanded macro (and expanded) is<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
a part of.<br>&gt;<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; This conceptually isn't possible at the preprocessor<br>&gt; level because it has no<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; notion of a C++ statement/expression.<br><br>I would not like to put any functionality into the library which does not
<br>belong to its purpose: preprocessing C++. I'm pretty sure, that you'll be<br>able to build this on top of Wave.<br><br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
*extract the value and position of all C and<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &gt; C++ comments<br>&gt;<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; This one is easy. Just enable the preserve comments<br>&gt; mode and all the comment<br>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; tokens will be part of the generated output token sequence.
<br>&gt;<br>&gt; Great. :) What about making a hook for this within stuct<br>&gt; default_preprocessing_hooks also?<br><br>Why? The preprocessing hooks are there to allow to access information not<br>available from the generated token stream itself, 
i.e. information about the<br>actual work inside the preprocessor. But the comments are available in the<br>generated token stream already. If I would add such a hook, somebody else<br>would like to have a special hook for line endings etc.
<br><br>&gt; It would be very interesting to do some work on this, and it<br>&gt; would be useful to hear what you think about adding the<br>&gt; additional hooks we have been talking about. Maybe these<br>&gt; hooks should be better specified.
<br><br>Do these new hooks satisfy your needs?<br><br>Regards Hartmut<br><br><br><br><br>_______________________________________________<br>Boost-users mailing list<br><a href="mailto:Boost-users@lists.boost.org">Boost-users@lists.boost.org
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