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Throw exception if RNG is used with invalid bounds.

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This commit is contained in:
Mark Morschhäuser 2014-03-11 09:41:37 +01:00
parent 9a20e5e2e2
commit 4eb845d438
2 changed files with 20 additions and 7 deletions
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18
common/rng_sfmt.cpp
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@ -1,6 +1,7 @@
#include "rng_sfmt.h" #include "rng_sfmt.h"
#include <QDateTime> #include <QDateTime>
#include <algorithm> #include <algorithm>
#include <stdexcept>
// This is from gcc sources, namely from fixincludes/inclhack.def // This is from gcc sources, namely from fixincludes/inclhack.def
// On C++11 systems, <cstdint> could be included instead. // On C++11 systems, <cstdint> could be included instead.
@ -57,12 +58,17 @@ RNG_SFMT::RNG_SFMT(QObject *parent)
*/ */
unsigned int RNG_SFMT::getNumber(unsigned int min, unsigned int max) unsigned int RNG_SFMT::getNumber(unsigned int min, unsigned int max)
{ {
// This all makes no sense if min > max. // This all makes no sense if min > max, which should never happen.
// So in debug mode Q_ASSERT will print a warning... if(min > max) {
Q_ASSERT(min <= max); throw std::invalid_argument(
// ... and at runtime min and max will be swapped; this should never happen. QString("Invalid bounds for RNG: min > max! Values were: min = " +
if(min > max) QString::number(min) + ", max = " +
std::swap(min, max); QString::number(max) +
". This is either a bug or something even more serious happened."
).toStdString());
// at this point, the method exits. No return value is needed, because
// basically the exception itself is returned.
}
// First compute the diameter (aka size, length) of the [min, max] interval // First compute the diameter (aka size, length) of the [min, max] interval
const unsigned int diameter = max - min + 1; const unsigned int diameter = max - min + 1;

9
common/rng_sfmt.h
View file

@ -7,7 +7,14 @@
/** /**
* This class represents the random number generator. * This class represents the random number generator.
* It uses the SIMD-oriented Fast Mersenne Twister code v1.4.1 from * Usage instructions:
* Create an instance of RNG_SFMT, then call getNumber(min, max).
* You should never call this function with min > max, this throws a
* std::invalid_argument exception. It is best practice to use getNumber() in a try block
* and catch the exception if min, max are entered by the user or computed somehow.
*
* Technical details:
* The RNG uses the SIMD-oriented Fast Mersenne Twister code v1.4.1 from
* http://www.math.sci.hiroshima-u.ac.jp/~%20m-mat/MT/SFMT/index.html * http://www.math.sci.hiroshima-u.ac.jp/~%20m-mat/MT/SFMT/index.html
* To use this RNG, the class needs a sfmt_t structure for the RNG's internal state. * To use this RNG, the class needs a sfmt_t structure for the RNG's internal state.
* It has to be initialized by sfmt_init_gen_rand() which is done in the constructor. * It has to be initialized by sfmt_init_gen_rand() which is done in the constructor.