int _ChooseTypeOfNonOuterplanarityMinor(graphP theGraph, int v, int R)
{
int X, Y, W;
// Create the initial non-outerplanarity obstruction isolator state.
if (_InitializeNonplanarityContext(theGraph, v, R) != OK)
return NOTOK;
R = theGraph->IC.r;
X = theGraph->IC.x;
Y = theGraph->IC.y;
W = theGraph->IC.w;
// If the root copy is not a root copy of the current vertex v,
// then the Walkdown terminated on a descendant bicomp, which is Minor A.
if (gp_GetPrimaryVertexFromRoot(theGraph, R) != v)
{
theGraph->IC.minorType |= MINORTYPE_A;
return OK;
}
// If W has a pertinent child bicomp, then we've found Minor B.
// Notice this is different from planarity, in which minor B is indicated
// only if the pertinent child bicomp is also future pertinent.
if (gp_IsVertex(gp_GetVertexPertinentRootsList(theGraph, W)))
{
theGraph->IC.minorType |= MINORTYPE_B;
return OK;
}
// The only other result is minor E (we will search for the X-Y path later)
theGraph->IC.minorType |= MINORTYPE_E;
return OK;
}
int _ChooseTypeOfNonplanarityMinor(graphP theGraph, int I, int R)
{
int N, X, Y, W, Px, Py, Z, DFSChild, RootId;
/* Create the initial non-planarity minor state in the isolator context */
if (_InitializeNonplanarityContext(theGraph, I, R) != OK)
return NOTOK;
N = theGraph->N;
R = theGraph->IC.r;
X = theGraph->IC.x;
Y = theGraph->IC.y;
W = theGraph->IC.w;
/* If the root copy is not a root copy of the current vertex I,
then the Walkdown terminated because it couldn't find
a viable path along a child bicomp, which is Minor A. */
if (theGraph->V[R - N].DFSParent != I)
{
theGraph->IC.minorType |= MINORTYPE_A;
return OK;
}
/* If W has an externally active pertinent child bicomp, then
we've found Minor B */
if (theGraph->V[W].pertinentBicompList != NIL)
{
RootId = LCGetPrev(theGraph->BicompLists,
theGraph->V[W].pertinentBicompList, NIL);
DFSChild = RootId;
if (theGraph->V[DFSChild].Lowpoint < I)
{
theGraph->IC.minorType |= MINORTYPE_B;
return OK;
}
}
/* Find the highest obstructing X-Y path */
if (_MarkHighestXYPath(theGraph) != TRUE)
return NOTOK;
Px = theGraph->IC.px;
Py = theGraph->IC.py;
/* If either point of attachment is 'high' (P_x closer to R than X
or P_y closer to R than Y along external face), then we've
matched Minor C. */
if (theGraph->G[Px].type == VERTEX_HIGH_RXW ||
theGraph->G[Py].type == VERTEX_HIGH_RYW)
{
theGraph->IC.minorType |= MINORTYPE_C;
return OK;
}
/* For Minor D, we search for a path from an internal
vertex Z along the X-Y path up to the root R of the bicomp. */
if (_MarkZtoRPath(theGraph) != OK)
return NOTOK;
if (theGraph->IC.z != NIL)
{
theGraph->IC.minorType |= MINORTYPE_D;
return OK;
}
/* For Minor E, we search for an externally active vertex Z
below the points of attachment of the X-Y path */
Z = _FindExtActivityBelowXYPath(theGraph);
if (Z != NIL)
{
theGraph->IC.z = Z;
theGraph->IC.minorType |= MINORTYPE_E;
return OK;
}
return NOTOK;
}
