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// Copyright 1996 Michael E. Stillman
// This should probably be done by:
// (a) making a type Ring, that FreeModule, and res_poly
// both can inherit from: but this is a bit of a kludge...
// (b) making a vector type with a next and coeff field, that
// is then inherited by vecterm, resterm.
// Redefine:
// Ring
// routines that should be implemented in this class:
// add_to, compare, get_ring, remove
// Nterm *
// fields of this structure type should include:
// next, coeff
class polyheap
{
const PolynomialRing *F; // Our elements will be vectors in here
const Ring *K; // The coefficient ring
Nterm *heap[GEOHEAP_SIZE];
int top_of_heap;
public:
polyheap(const PolynomialRing *F);
~polyheap();
void add(Nterm *p);
Nterm *remove_lead_term(); // Returns NULL if none.
Nterm *value(); // Returns the linearized value, and resets the polyheap.
Nterm *debug_list(int i)
{
return heap[i];
} // DO NOT USE, except for debugging purposes!
};
inline polyheap::polyheap(const PolynomialRing *FF)
: F(FF), K(FF->getCoefficientRing()), top_of_heap(-1)
{
// set K
int i;
for (i = 0; i < GEOHEAP_SIZE; i++) heap[i] = NULL;
}
inline polyheap::~polyheap()
{
// The user of this class must insure that all 'vecterm's
// have been removed first. Thus, we don't need to
// do anything here.
}
inline void polyheap::add(Nterm *p)
{
int len = F->n_terms(p);
int i = 0;
while (len >= heap_size[i]) i++;
ring_elem tmp1 = heap[i];
ring_elem tmp2 = p;
F->add_to(tmp1, tmp2);
heap[i] = tmp1;
len = F->n_terms(heap[i]);
p = NULL;
while (len >= heap_size[i])
{
i++;
tmp1 = heap[i];
tmp2 = heap[i - 1];
F->add_to(tmp1, tmp2);
heap[i] = tmp1;
len = F->n_terms(heap[i]);
heap[i - 1] = NULL;
}
if (i > top_of_heap) top_of_heap = i;
}
inline Nterm *polyheap::remove_lead_term()
{
int lead_so_far = -1;
for (int i = 0; i <= top_of_heap; i++)
{
if (heap[i] == NULL) continue;
if (lead_so_far < 0)
{
lead_so_far = i;
continue;
}
int cmp = EQ; // F->compare(heap[lead_so_far], heap[i]);
if (cmp == GT) continue;
if (cmp == LT)
{
lead_so_far = i;
continue;
}
// At this point we have equality
K->add_to(heap[lead_so_far]->coeff, heap[i]->coeff);
Nterm *tmp = heap[i];
heap[i] = tmp->next;
tmp->next = NULL;
F->remove(reinterpret_cast<ring_elem &>(tmp));
if (K->is_zero(heap[lead_so_far]->coeff))
{
// Remove, and start over
tmp = heap[lead_so_far];
heap[lead_so_far] = tmp->next;
tmp->next = NULL;
F->remove(reinterpret_cast<ring_elem &>(tmp));
lead_so_far = -1;
i = -1;
}
}
if (lead_so_far < 0) return NULL;
Nterm *result = heap[lead_so_far];
heap[lead_so_far] = result->next;
result->next = NULL;
return result;
}
inline Nterm *polyheap::value()
{
Nterm *result = NULL;
for (int i = 0; i <= top_of_heap; i++)
{
if (heap[i] == NULL) continue;
ring_elem tmp1 = result;
ring_elem tmp2 = heap[i];
F->add_to(tmp1, tmp2);
result = tmp1;
heap[i] = NULL;
}
top_of_heap = -1;
return result;
}
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
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