CODEWITHSUNDEEP
c++
msemelman
msemelman

Reputation: 2937

How to extract declarations (a .hpp file) from implementation (a .cpp file)?

I was wondering if there was a tool (maybe GNU C++ compiler) to obtain from a .cpp file full of functions a .hpp file with the mentioned functions declarations.

Example:

I have:
magic.cpp

int foo() { return 42; }
char bar() { return 'z'; }

And I would like to obtain this after applying the wonderful tool:
magic.hpp

int foo();
char bar();

Upvotes: 5

Views: 896

Answers (3)

Eduardo Ivanec
Eduardo Ivanec

Reputation: 11862

On Debian-based distributions:

apt-get install cproto

Then cproto magic.cpp gives the following output:

/* magic.cpp */
int foo(void);
char bar(void);

Upvotes: 4

Ira Baxter
Ira Baxter

Reputation: 95392

To do this accurately, you need a full C++ parser and name resolver because you need not only the function declarations but also the context that makes them well defined. For instance, if you have a declaration

 void foo<T>(...){ ... }

in the file, and there's a type T in the file, you better retain the declaration for T, and whatever declarations are used to define T, etc. So you have keep the web of definitions supporting foo... and you have to decide if you want to keep those that come from include files or not.

Our DMS Software Reengineering Toolkit is customizable general purpose program analysis and transformation machinery. With its C++ Front End, one can parse C++ code (including #includes), build Abstract Syntax Trees (ASTs), resolve names and types out of the box. Customization code would then determine the web of references necessary, and for each reference, convert it into a signature (instead of an implementation) if necessary, by applying source-to-source program transformations to the ASTs. DMS's prettyprinter could then produce the final output text.

DMS has been used for large scale C++ (re)engineering on other big projects.

Of course, you can always write some bad hack to simulate this, if you don't mind an answer you are likely to have to patch by hand.

Upvotes: 2

Dark Falcon
Dark Falcon

Reputation: 44191

Please see Dehydra or Treehydra. One of these two tools should allow you perform this via GCC.

Dehydra is a lightweight, scriptable, general purpose static analysis tool capable of application-specific analyses of C++ code.

Upvotes: 3

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