README

GNOCCHI - A COMPLEXITY ANALYSER FOR C++

Gnocchi calculates cyclomatic and the NPATH complexity measures.

It reads the coverage information produced by GCC and determines the
complexity of all functions. If code is compiled with -fprofile-arcs
or -ftest-coverage (depending on compiler version) GCC creates a .gcno
file for every object file. 

Gnocchi is free software.
See the end of the file for license conditions.


EXAMPLE SESSION

Running gnocchi on its own build tree 
./gnocchi --threshold 20 ~/gnocchi/trunk/
/usr/include/c++/4.1.2/bits/basic_string.tcc:137: mccabe=7 npath=42 
/home/epronk/gnocchi/trunk/test_input.c:101: mccabe=9 npath=80 
/home/epronk/gnocchi/trunk/main.cpp:129: mccabe=11 npath=512 
/home/epronk/gnocchi/trunk/gcov_reader.cpp:251: mccabe=29 npath=20194 
/home/epronk/gnocchi/trunk/gcov_reader.cpp:251: mccabe=29 npath=20194 

This is compiler style output pointing out which functions have a high
complexity. By default it outputs all functions with a NPATH
complexity higher than 200.

C++ EXCEPTIONS

For every function call, GCC inserts extra paths which are used when
an exception occurs. This "experimental" measure is now part of the
output.

mccabe=5(+4) means the complexity is 5 + 4 = 9 if exceptions are considered.
 
./gnocchi -t 1  test_input.gcno 
test_input.c:10: mccabe=2 npath=2
test_input.c:19: mccabe=2(+1) npath=2(+1) 
test_input.c:28: mccabe=2 npath=2
test_input.c:40: mccabe=4 npath=4
test_input.c:145: mccabe=3 npath=4
test_input.c:159: mccabe=3 npath=4
test_input.c:118: mccabe=5 npath=5
test_input.c:89: mccabe=5(+4) npath=16(+15) 
test_input.c:67: mccabe=9 npath=80

GETTING GNOCCHI

Get a release from:

	http://sourceforge.net/project/showfiles.php?group_id=197216

or get the latest sources from

   svn co https://gnocchi.svn.sourceforge.net/svnroot/gnocchi gnocchi


RUNNING GNOCCHI

	./configure
	make

	gcc -fprofile-arcs -ftest-coverage -c test_input.c 
	./gnocchi --threshold 4 test_input.gcno 

	outputs:
	test_input.c:118: mccabe=5 npath=5 
	test_input.c:89: mccabe=5 npath=16 
	test_input.c:67: mccabe=9 npath=80 


ACKNOWLEDGEMENTS
		
I wrote Gnocchi after seeing a demo of Complexian for Java. [4]
Thanks to Marty Andrews for his presentation about complexity at MXPEG.
		

REFERENCES

[1] T.J. McCabe, "A complexity measure," IEEE Trans.
	Software Eng. vol. SE2, no 4, pp 308-320, 1976
[2] B.A. Nejmeh, "NPATH: a measure of execution path complexity and its applications,"
	Commun, ACM, vol 31, no 2, pp 188-200, 1988.
[3] http://en.wikipedia.org/wiki/Cyclomatic_complexity
[4] Complexity Analyser for Java,
	http://www.martyandrews.net/resources/complexian.html
	http://www.cogentconsulting.com.au/products/index.html


Any feedback can be sent to Eddy Pronk <epronk@muftor.com>
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Gnocchi is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

Gnocchi is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.

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