Does a tool exist to apply C preprocessor expansion to a C source only
partially, i.e. replace only some directives? I want to replace some
#if's by their expansions, e.g. all #ifdef SOME_SYMBOL, but keep all
other #ifdef OTHER_SYMBOL and all #include directives.
urs 6 2421
Urs Thuermann said: Does a tool exist to apply C preprocessor expansion to a C source only partially, i.e. replace only some directives? I want to replace some #if's by their expansions, e.g. all #ifdef SOME_SYMBOL, but keep all other #ifdef OTHER_SYMBOL and all #include directives.
I know of no such tool, but it shouldn't be too hard to write one. See
Exercise 6-6 of K&R2, on page 145.
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999 http://www.cpax.org.uk
email: rjh at above domain (but drop the www, obviously)
Urs Thuermann wrote: Does a tool exist to apply C preprocessor expansion to a C source only partially, i.e. replace only some directives? I want to replace some #if's by their expansions, e.g. all #ifdef SOME_SYMBOL, but keep all other #ifdef OTHER_SYMBOL and all #include directives.
urs
<OT>
If what you are wanting to do is simply remove some of this
conditionally compiled code, you can write a quick perl script that will
do this. This is a rather trivial task and if you don't need the speed
of C (e.g., if you are only doing this to 20 or so files) then it would
be the easiest method.
</OT>
Another method would be to open the file for reading, see if you have
your #ifdef SOMECONSTANT and if so discard every line until you
encounter an #endif. This is a trivial task to do and if you adhere to
keeping all preprocessor directives at column 0 then it should work
without a problem. Note that this method does not take into
consideration embedded conditionals. E.g.,
#ifdef SOMECONSTANT
#ifndef SOMEOTHERCONSTA NT
/* code */
#endif /* !defined(SOMEOT HERCONSTANT) */
#endif /* defined(SOEMCON STANT) */
The above method will not work on the above code (unless you want to
remove the conditional embedded in the SOMECONSTANT conditional).
Hope that helps,
Joe
"Urs Thuermann" <ur*@isnogud.es cape.de> wrote in message
news:m2******** ****@janus.isno gud.escape.de.. . Does a tool exist to apply C preprocessor expansion to a C source only partially, i.e. replace only some directives? I want to replace some #if's by their expansions, e.g. all #ifdef SOME_SYMBOL, but keep all other #ifdef OTHER_SYMBOL and all #include directives.
We've used the DMS Software Reengineering Toolkit to do exactly this.
The basic idea is to pick up the conditional directives, symbolically
substitute the status of each #define symbol
(e.g., 0 --> "I'll never use this define again",
1 --> "Assume this is always true",
or the symbol name --> "Leave this conditional"),
simplify the resulting boolean formula symbolically,
and resubstitute the resulting formula. A last optimization
handles the cases of #if 0 or #if 1,
#elseif 0, #elseif 1, #else, etc. to strip away
the dead branches of the conditionals.
There's a paper on how to do this with DMS that
gives more details:
Baxter, I. and Mehlich, M.
Preprocessor Conditional Removal by Simple Partial Evaluation,
2001 Workshop on Analysis, Slicing and Transformation, 2001 ,
available at our website: http://www.semanticdesigns.com/Company/Publications/
and we have done this multi-million lines systems.
So yes, such a tool exists.
--
Ira Baxter, CTO www.semanticdesigns.com
"Ira Baxter" <id******@semde signs.com> writes: "Urs Thuermann" <ur*@isnogud.es cape.de> wrote in message news:m2******** ****@janus.isno gud.escape.de.. . Does a tool exist to apply C preprocessor expansion to a C source only partially, i.e. replace only some directives? I want to replace some #if's by their expansions, e.g. all #ifdef SOME_SYMBOL, but keep all other #ifdef OTHER_SYMBOL and all #include directives.
We've used the DMS Software Reengineering Toolkit to do exactly this. The basic idea is to pick up the conditional directives, symbolically substitute the status of each #define symbol (e.g., 0 --> "I'll never use this define again", 1 --> "Assume this is always true", or the symbol name --> "Leave this conditional"), simplify the resulting boolean formula symbolically, and resubstitute the resulting formula. A last optimization handles the cases of #if 0 or #if 1, #elseif 0, #elseif 1, #else, etc. to strip away the dead branches of the conditionals.
<QUIBBLE>
#elif, not #elseif
</QUIBBLE>
--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.
Keith Thompson <ks***@mib.or g> wrote: "Ira Baxter" <id******@semde signs.com> writes: and resubstitute the resulting formula. A last optimization handles the cases of #if 0 or #if 1, #elseif 0, #elseif 1, #else, etc. to strip away the dead branches of the conditionals.
<QUIBBLE> #elif, not #elseif </QUIBBLE>
*Shrug* What do you expect from an itinerant spammer?
Richard
"Richard Bos" <rl*@hoekstra-uitgeverij.nl> wrote in message
news:44******** ********@news.x s4all.nl... Keith Thompson <ks***@mib.or g> wrote:
"Ira Baxter" <id******@semde signs.com> writes: and resubstitute the resulting formula. A last optimization handles the cases of #if 0 or #if 1, #elseif 0, #elseif 1, #else, etc. to strip away the dead branches of the conditionals.
<QUIBBLE> #elif, not #elseif </QUIBBLE>
*Shrug* What do you expect from an itinerant spammer?
I'm happy with Keith's quibble. Our tools work with a wide variety
of languages, and I don't code a lot in C directly, so I sometimes
make minor technical errors in writing down language constructs.
My response was to a question posed by original poster,
and it answered his question directly.
You have problem with that?
--
Ira Baxter, CTO www.semanticdesigns.com This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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