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/**************************************************************************
* *
* Regina - A Normal Surface Theory Calculator *
* Computational Engine *
* *
* Copyright (c) 1999-2008, Ben Burton *
* For further details contact Ben Burton (bab@debian.org). *
* *
* This program 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 of the *
* License, or (at your option) any later version. *
* *
* This program 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 this program; if not, write to the Free *
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, *
* MA 02110-1301, USA. *
* *
**************************************************************************/
/* end stub */
#include <vector>
#include "algebra/nabeliangroup.h"
#include "manifold/nhandlebody.h"
#include "subcomplex/nspiralsolidtorus.h"
#include "triangulation/ntriangulation.h"
namespace regina {
NSpiralSolidTorus* NSpiralSolidTorus::clone() const {
NSpiralSolidTorus* ans = new NSpiralSolidTorus(nTet);
for (unsigned long i = 0; i < nTet; i++) {
ans->tet[i] = tet[i];
ans->vertexRoles[i] = vertexRoles[i];
}
return ans;
}
void NSpiralSolidTorus::reverse() {
NTetrahedron** newTet = new NTetrahedron*[nTet];
NPerm* newRoles = new NPerm[nTet];
NPerm switchPerm(3, 2, 1, 0);
for (unsigned long i = 0; i < nTet; i++) {
newTet[i] = tet[nTet - 1 - i];
newRoles[i] = vertexRoles[nTet - 1 - i] * switchPerm;
}
delete[] tet;
delete[] vertexRoles;
tet = newTet;
vertexRoles = newRoles;
}
void NSpiralSolidTorus::cycle(unsigned long k) {
NTetrahedron** newTet = new NTetrahedron*[nTet];
NPerm* newRoles = new NPerm[nTet];
for (unsigned long i = 0; i < nTet; i++) {
newTet[i] = tet[(i + k) % nTet];
newRoles[i] = vertexRoles[(i + k) % nTet];
}
delete[] tet;
delete[] vertexRoles;
tet = newTet;
vertexRoles = newRoles;
}
bool NSpiralSolidTorus::makeCanonical(const NTriangulation* tri) {
unsigned long i, index;
unsigned long baseTet = 0;
unsigned long baseIndex = tri->tetrahedronIndex(tet[0]);
for (i = 1; i < nTet; i++) {
index = tri->tetrahedronIndex(tet[i]);
if (index < baseIndex) {
baseIndex = index;
baseTet = i;
}
}
bool reverseAlso = (vertexRoles[baseTet][0] > vertexRoles[baseTet][3]);
if (baseTet == 0 && (! reverseAlso))
return false;
NTetrahedron** newTet = new NTetrahedron*[nTet];
NPerm* newRoles = new NPerm[nTet];
if (reverseAlso) {
// Make baseTet into tetrahedron 0 and reverse.
NPerm switchPerm(3, 2, 1, 0);
for (unsigned long i = 0; i < nTet; i++) {
newTet[i] = tet[(baseTet + nTet - i) % nTet];
newRoles[i] = vertexRoles[(baseTet + nTet - i) % nTet] *
switchPerm;
}
} else {
// Make baseTet into tetrahedron 0 but don't reverse.
for (unsigned long i = 0; i < nTet; i++) {
newTet[i] = tet[(i + baseTet) % nTet];
newRoles[i] = vertexRoles[(i + baseTet) % nTet];
}
}
delete[] tet;
delete[] vertexRoles;
tet = newTet;
vertexRoles = newRoles;
return true;
}
bool NSpiralSolidTorus::isCanonical(const NTriangulation* tri) const {
if (vertexRoles[0][0] > vertexRoles[0][3])
return false;
long baseIndex = tri->tetrahedronIndex(tet[0]);
for (unsigned long i = 1; i < nTet; i++)
if (tri->tetrahedronIndex(tet[i]) < baseIndex)
return false;
return true;
}
NSpiralSolidTorus* NSpiralSolidTorus::formsSpiralSolidTorus(NTetrahedron* tet,
NPerm useVertexRoles) {
NPerm invRoleMap(1, 2, 3, 0); // Maps upper roles to lower roles.
NTetrahedron* base = tet;
NPerm baseRoles(useVertexRoles);
std::vector<NTetrahedron*> tets;
std::vector<NPerm> roles;
stdhash::hash_set<NTetrahedron*, HashPointer> usedTets;
tets.push_back(tet);
roles.push_back(useVertexRoles);
usedTets.insert(tet);
NTetrahedron* adjTet;
NPerm adjRoles;
while (1) {
// Examine the tetrahedron beyond tet.
adjTet = tet->getAdjacentTetrahedron(useVertexRoles[0]);
adjRoles = tet->getAdjacentTetrahedronGluing(useVertexRoles[0]) *
useVertexRoles * invRoleMap;
// Check that we haven't hit the boundary.
if (adjTet == 0)
return 0;
if (adjTet == base) {
// We're back at the beginning of the loop.
// Check that everything is glued up correctly.
if (adjRoles != baseRoles)
return 0;
// Success!
break;
}
if (usedTets.count(adjTet))
return 0;
// Move on to the next tetrahedron.
tet = adjTet;
useVertexRoles = adjRoles;
tets.push_back(tet);
roles.push_back(useVertexRoles);
usedTets.insert(tet);
}
// We've found a spiralled solid torus.
NSpiralSolidTorus* ans = new NSpiralSolidTorus(tets.size());
copy(tets.begin(), tets.end(), ans->tet);
copy(roles.begin(), roles.end(), ans->vertexRoles);
return ans;
}
NManifold* NSpiralSolidTorus::getManifold() const {
return new NHandlebody(1, true);
}
NAbelianGroup* NSpiralSolidTorus::getHomologyH1() const {
NAbelianGroup* ans = new NAbelianGroup();
ans->addRank();
return ans;
}
} // namespace regina
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