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// Copyright 1996 Michael E. Stillman
// This should probably be done by:
// (a) making a type const FreeModule, 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:
// const FreeModule
// routines that should be implemented in this class:
// add_to, compare, get_ring, remove
// vecterm *
// fields of this structure type should include:
// next, coeff
// GEOHEAP_SIZE: defined in style.hpp
// heap_size: defined in object.cpp
class vecHeap
{
const FreeModule *F; // Our elements will be vectors in here
const Ring *K; // The coefficient ring
vecterm *heap[GEOHEAP_SIZE];
int top_of_heap;
int mLead; // set after a call to get_lead_term.
// set negative after each call to add,
// or remove_lead_term
public:
vecHeap(const FreeModule *F);
~vecHeap();
void add(vecterm *p);
const vecterm *get_lead_term(); // Returns NULL if none.
vecterm *remove_lead_term(); // Returns NULL if none.
const FreeModule *get_target() const { return F; }
vecterm *value(); // Returns the linearized value, and resets the vecHeap.
vecterm *debug_list(int i)
{
return heap[i];
} // DO NOT USE, except for debugging purposes!
vecterm *current_value()
const; // Adds up all the elements and returns this value
// Mainly used for debugging.
};
inline vecHeap::vecHeap(const FreeModule *FF)
: F(FF), K(FF->get_ring()), top_of_heap(-1), mLead(-1)
{
// set K
int i;
for (i = 0; i < GEOHEAP_SIZE; i++) heap[i] = NULL;
}
inline vecHeap::~vecHeap()
{
// 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 vecHeap::add(vecterm *p)
{
mLead = -1;
int len = K->n_nonzero_terms(p);
int i = 0;
while (len >= heap_size[i]) i++;
K->add_vec_to(heap[i], p);
len = K->n_nonzero_terms(heap[i]);
p = NULL;
while (len >= heap_size[i])
{
i++;
K->add_vec_to(heap[i], heap[i - 1]);
len = K->n_nonzero_terms(heap[i]);
heap[i - 1] = NULL;
}
if (i > top_of_heap) top_of_heap = i;
}
static int compare(const vecterm *t, const vecterm *s)
{
int cmp = t->comp - s->comp;
if (cmp < 0) return LT;
if (cmp > 0) return GT;
return EQ;
}
inline const vecterm *vecHeap::get_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 = 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);
vecterm *tmp = heap[i];
heap[i] = tmp->next;
tmp->next = NULL;
K->remove_vec(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;
K->remove_vec(tmp);
lead_so_far = -1;
i = -1;
}
}
mLead = lead_so_far;
if (lead_so_far < 0) return NULL;
vecterm *result = heap[lead_so_far];
return result;
}
inline vecterm *vecHeap::remove_lead_term()
{
if (mLead < 0) get_lead_term();
if (mLead < 0) return NULL;
vecterm *result = heap[mLead];
heap[mLead] = result->next;
result->next = NULL;
mLead = -1;
return result;
}
inline vecterm *vecHeap::value()
{
vecterm *result = NULL;
for (int i = 0; i <= top_of_heap; i++)
{
if (heap[i] == NULL) continue;
K->add_vec_to(result, heap[i]);
heap[i] = NULL;
}
top_of_heap = -1;
return result;
}
inline vecterm *vecHeap::current_value() const
{
vecterm *result = NULL;
for (int i = 0; i <= top_of_heap; i++)
{
if (heap[i] == NULL) continue;
vecterm *tmp = K->copy_vec(heap[i]);
K->add_vec_to(result, tmp);
}
return result;
}
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
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