custom preprocessor?

[magland]

Is there a nice way to implement my own preprocessor (before standard C++ preprocessing) from within qmake framework.

I envision something like this in the .pro file:

SOURCES += file1.cpp
SPECIAL_SOURCES += file2.cpp
include(process_special_sources.pri)

SOURCES += file1.cpp
SPECIAL_SOURCES += file2.cpp
include(process_special_sources.pri)

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Here, process_special_sources.pri would somehow preprocess file2.cpp and create special_file2.cpp and add it to the SOURCES variable.

Does this sound feasible? Is there a better way?

Thanks!

[marcel]

Depends on what you want it to preprocess.
Why can't you make use of the compiler preprocessor for replacing macros and other stuff?

[magland]

Depends on what you want it to preprocess.

I want to preprocess source code. Input is source code, and output is modified source code.

Why can't you make use of the compiler preprocessor for replacing macros and other stuff?

Macros aren't flexible enough to do what I want to do. I want to have an external program do custom preprocessing.

Any ideas?

[marcel]

Then you want to do something similar to what moc does.
Sounds a lot of work. Maybe you can reuse some pars of moc.

[magland]

Then you want to do something similar to what moc does.
Sounds a lot of work. Maybe you can reuse some pars of moc.

Yes, you are right. I want to do something similar to moc. However, the difference is that moc reads the source files and creates new (additional) source files. Whereas I need to modify the source files in place. Aaccording to wysota, Q_OBJECT, signals, slots, etc. are just macros (although they do give information to moc), so there's really no preprocessing that takes place by moc, in the sense that I want.

[marcel]

There is no ready functionality to do what you want. That is why I suggested you should reuse some moc parts, such as the code parsing.

I am aware that you want top modify the same source file, not generate a new one, but as I said, you have to create a new tool to do that. It is better to reuse moc functionality since it clearly works, and you won't have to write new things and test them.

[magland]

Okay, thanks marcel. I'll look into that. In the meantime if anyone has experience with setting up this type of thing, please let me know.

[magland]

For information of those who are curious.

I got the custom preprocessor to work very nicely using only the following code in .pri file!

for(file, CHAINLINK_SOURCES) {
	system($$(CHAINLINK_DIR)\bin\cpp_preprocessor $${file} CHAINLINK_$${file})
	SOURCES += CHAINLINK_$${file}
}

for(file, CHAINLINK_SOURCES) {
	system($$(CHAINLINK_DIR)\bin\cpp_preprocessor $${file} CHAINLINK_$${file})
	SOURCES += CHAINLINK_$${file}
}

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Then when preprocessing the file I keep the line numbers updated using the #line macro... so that to the user it's seamless, i.e. when there is an error in the source file, the compiler output points to the original source (not the pre-processed source).

Really quite a simple system... but it opens huge possibilities (which I need to be careful not to abuse )

Any comments, suggestions?

[marcel]

OK, nice, but you should really have mentioned what exactly you need to preprocess .
I initially thought you had some code+macro constructs that you needed to be expanded to something by a 3rd party preprocessor.

[magland]

OK, nice, but you should really have mentioned what exactly you need to preprocess .
I initially thought you had some code+macro constructs that you needed to be expanded to something by a 3rd party preprocessor.

Yes, sorry about that... I didn't want to confuse the issue before the specific problem was solved. Here's what I can do now (and I'll release this software sometime soon). ~~ very exciting ~~

//I include this single header /////////////////////
//and link to chainlink_engine library ///////////
#include "chainlink_engine.h" 
 
int main(int argc, char *argv[]) {
 
QString str1=argv[1];
 
CHAINLINK(QString str1) {
  %in this block I execute arbitrary chainlink (Matlab) commands!
  X=1:1000;
  Y=sqrt(1:1000);
  H=plot(X,Y);
  setWindowTitle(H,str1); %I can even use variables passed in from C++
  str1=str1+' hello world'; %and even modify these!
}
 
cout << str1; //and see the result in C++
 
//now we are getting somewhere :)
 
return 0;
 
}

//I include this single header /////////////////////
//and link to chainlink_engine library ///////////
#include "chainlink_engine.h" 

int main(int argc, char *argv[]) {

QString str1=argv[1];

CHAINLINK(QString str1) {
  %in this block I execute arbitrary chainlink (Matlab) commands!
  X=1:1000;
  Y=sqrt(1:1000);
  H=plot(X,Y);
  setWindowTitle(H,str1); %I can even use variables passed in from C++
  str1=str1+' hello world'; %and even modify these!
}

cout << str1; //and see the result in C++

//now we are getting somewhere :)

return 0;

}

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[mchara]

Maybe a little cheating - name your application moc.exe, rename original moc as i.e. Qtmoc,
do your tasks in your moc and call qtmoc from inside...