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fixed hash bug

This commit is contained in:
Pavel Emeliyanenko 2008-02-07 14:02:48 +00:00
parent 043806eff9
commit 22288d24af
1 changed files with 22 additions and 21 deletions
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43
Algebraic_kernel_d/include/CGAL/Algebraic_curve_kernel_2/LRU_hashed_map.h
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@ -234,33 +234,34 @@ struct Poly_hasher {
template <class Poly_2>
std::size_t operator()(const Poly_2& p) const {
// std::cerr << "poly: " << p << "; hash: " <<
// static_cast<std::size_t>(ceil_log2_abs(
// typename NiX::Polynomial_traits<Poly_2>::Innermost_lcoeff()(p)
// * (NiX::total_degree(p)))) << "\n";
if(p.is_zero())
return 0xDeadBeef;
typedef typename Poly_2::NT Poly_1;
typedef typename Poly_1::NT NT;
return static_cast<std::size_t>(ceil_log2_abs(
typename NiX::Polynomial_traits<Poly_2>::Innermost_lcoeff()(p)
* (NiX::total_degree(p) + 1)));
const Poly_1& v = p[0];
typename Poly_1::const_iterator cit;
NT res(0);
int i;
// take at most 3 trailing coeffs
for(cit = v.begin(); i < 3 && cit != v.end(); i++) {
res += *cit;
}
if(res == NT(0))
return 0xDeadBeef;
// randomization of the result
return static_cast<std::size_t>(ceil_log2_abs(res * NT(0x12341234)));
}
};
//! \brief a simple curve pair hasher
//!
//! computes hashes of two curves and then combines them
template <class Curve_analysis_2>
struct Curve_pair_hasher_2
{
typedef std::pair<Curve_analysis_2, Curve_analysis_2> Pair_of_curves_2;
typedef Pair_of_curves_2 argument_type;
struct Pair_id_hasher {
typedef size_t result_type;
size_t operator()(const Pair_of_curves_2& p) const {
// uses code from boost::hash_combine
// TODO use this again? Poly_hasher hasher;
// answer: no need to, since curve analyses are cached and therefore
// can be uniquely enumerated by ids
template <class T1, class T2>
size_t operator()(const std::pair<T1, T2>& p) const {
std::size_t seed = p.first.id() + 0x9e3779b9;
seed ^= p.second.id() + 0x9e3779b9 + (seed << 6) + (seed >> 2);
return seed;