graphP MakeGraph(int Size, char command)
{
graphP theGraph;
if ((theGraph = gp_New()) == NULL || gp_InitGraph(theGraph, Size) != OK)
{
ErrorMessage("Error creating space for a graph of the given size.\n");
gp_Free(&theGraph);
return NULL;
}
// Enable the appropriate feature. Although the same code appears in SpecificGraph,
// it is deliberately not separated to a common utility because SpecificGraph is
// used as a self-contained tutorial. It is not that hard to update both locations
// when new algorithms are added.
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
return theGraph;
}
void AttachAlgorithm(graphP theGraph, char command)
{
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
}
int SpecificGraph(char command, char *infileName, char *outfileName, char *outfile2Name)
{
graphP theGraph, origGraph;
platform_time start, end;
int Result;
// Get the filename of the graph to test
if ((infileName = ConstructInputFilename(infileName)) == NULL)
return NOTOK;
// Create the graph and, if needed, attach the correct algorithm to it
theGraph = gp_New();
switch (command)
{
case 'd' : gp_AttachDrawPlanar(theGraph); break;
case '2' : gp_AttachK23Search(theGraph); break;
case '3' : gp_AttachK33Search(theGraph); break;
case '4' : gp_AttachK4Search(theGraph); break;
case 'c' : gp_AttachColorVertices(theGraph); break;
}
// Read the graph into memory
Result = gp_Read(theGraph, infileName);
if (Result == NONEMBEDDABLE)
{
Message("The graph contains too many edges.\n");
// Some of the algorithms will still run correctly with some edges removed.
if (strchr("pdo234", command))
{
Message("Some edges were removed, but the algorithm will still run correctly.\n");
Result = OK;
}
}
// If there was an unrecoverable error, report it
if (Result != OK)
ErrorMessage("Failed to read graph\n");
// Otherwise, call the correct algorithm on it
else
{
// Copy the graph for integrity checking
origGraph = gp_DupGraph(theGraph);
// Run the algorithm
if (strchr("pdo234", command))
{
int embedFlags = GetEmbedFlags(command);
platform_GetTime(start);
// gp_CreateDFSTree(theGraph);
// gp_SortVertices(theGraph);
// gp_Write(theGraph, "debug.before.txt", WRITE_DEBUGINFO);
// gp_SortVertices(theGraph);
Result = gp_Embed(theGraph, embedFlags);
platform_GetTime(end);
Result = gp_TestEmbedResultIntegrity(theGraph, origGraph, Result);
}
else
{
platform_GetTime(start);
if (command == 'c')
{
if ((Result = gp_ColorVertices(theGraph)) == OK)
Result = gp_ColorVerticesIntegrityCheck(theGraph, origGraph);
}
else
Result = NOTOK;
platform_GetTime(end);
}
// Write what the algorithm determined and how long it took
WriteAlgorithmResults(theGraph, Result, command, start, end, infileName);
// Free the graph obtained for integrity checking.
gp_Free(&origGraph);
}
// Report an error, if there was one, free the graph, and return
if (Result != OK && Result != NONEMBEDDABLE)
{
ErrorMessage("AN ERROR HAS BEEN DETECTED\n");
Result = NOTOK;
// gp_Write(theGraph, "debug.after.txt", WRITE_DEBUGINFO);
}
// Provide the output file(s)
else
{
// Restore the vertex ordering of the original graph (undo DFS numbering)
if (strchr("pdo234", command))
gp_SortVertices(theGraph);
// Determine the name of the primary output file
outfileName = ConstructPrimaryOutputFilename(infileName, outfileName, command);
// For some algorithms, the primary output file is not always written
if ((strchr("pdo", command) && Result == NONEMBEDDABLE) ||
(strchr("234", command) && Result == OK))
{
// Do not write the file
}
// Write the primary output file, if appropriate to do so
else
{
gp_Write(theGraph, outfileName, WRITE_ADJLIST);
}
// NOW WE WANT TO WRITE THE SECONDARY OUTPUT FILE
// When called from the menu system, we want to write the planar or outerplanar
// obstruction, if one exists. For planar graph drawing, we want the character
// art rendition. An empty but non-NULL string is passed to indicate the necessity
// of selecting a default name for the second output file.
if (outfile2Name != NULL)
{
if ((command == 'p' || command == 'o') && Result == NONEMBEDDABLE)
{
// By default, use the same name as the primary output filename
if (strlen(outfile2Name) == 0)
outfile2Name = outfileName;
gp_Write(theGraph, outfile2Name, WRITE_ADJLIST);
}
else if (command == 'd' && Result == OK)
{
// By default, add ".render.txt" to the primary output filename
if (strlen(outfile2Name) == 0)
strcat((outfile2Name = outfileName), ".render.txt");
gp_DrawPlanar_RenderToFile(theGraph, outfile2Name);
}
}
}
// Free the graph
gp_Free(&theGraph);
// Flush any remaining message content to the user, and return the result
FlushConsole(stdout);
return Result;
}
Obj boyers_planarity_check(Obj digraph, int flags, bool krtwsk) {
DIGRAPHS_ASSERT(flags == EMBEDFLAGS_PLANAR || flags == EMBEDFLAGS_OUTERPLANAR
|| flags == EMBEDFLAGS_SEARCHFORK23
|| flags == EMBEDFLAGS_SEARCHFORK4
|| flags == EMBEDFLAGS_SEARCHFORK33);
if (CALL_1ARGS(IsDigraph, digraph) != True) {
ErrorQuit("Digraphs: boyers_planarity_check (C): the 1st argument must be "
"a digraph, not %s",
(Int) TNAM_OBJ(digraph),
0L);
}
Obj const out = FuncOutNeighbours(0L, digraph);
if (FuncIS_ANTISYMMETRIC_DIGRAPH(0L, out) != True) {
ErrorQuit("Digraphs: boyers_planarity_check (C): the 1st argument must be "
"an antisymmetric digraph",
0L,
0L);
}
Int V = DigraphNrVertices(digraph);
Int E = DigraphNrEdges(digraph);
if (V > INT_MAX) {
// Cannot currently test this, it might always be true, depending on the
// definition of Int.
ErrorQuit("Digraphs: boyers_planarity_check (C): the maximum number of "
"nodes is %d, found %d",
INT_MAX,
V);
return 0L;
} else if (2 * E > INT_MAX) {
// Cannot currently test this
ErrorQuit("Digraphs: boyers_planarity_check (C): the maximum number of "
"edges is %d, found %d",
INT_MAX / 2,
E);
return 0L;
}
graphP theGraph = gp_New();
switch (flags) {
case EMBEDFLAGS_SEARCHFORK33:
gp_AttachK33Search(theGraph);
break;
case EMBEDFLAGS_SEARCHFORK23:
gp_AttachK23Search(theGraph);
break;
case EMBEDFLAGS_SEARCHFORK4:
gp_AttachK4Search(theGraph);
break;
}
if (gp_InitGraph(theGraph, V) != OK) {
gp_Free(&theGraph);
ErrorQuit("Digraphs: boyers_planarity_check (C): invalid number of nodes!",
0L,
0L);
return 0L;
} else if (gp_EnsureArcCapacity(theGraph, 2 * E) != OK) {
gp_Free(&theGraph);
ErrorQuit("Digraphs: boyers_planarity_check (C): invalid number of edges!",
0L,
0L);
return 0L;
}
int status;
for (Int v = 1; v <= LEN_LIST(out); ++v) {
DIGRAPHS_ASSERT(gp_VertexInRange(theGraph, v));
gp_SetVertexIndex(theGraph, v, v);
Obj const out_v = ELM_LIST(out, v);
for (Int w = 1; w <= LEN_LIST(out_v); ++w) {
DIGRAPHS_ASSERT(gp_VertexInRange(theGraph, w));
int u = INT_INTOBJ(ELM_LIST(out_v, w));
if (v != u) {
status = gp_AddEdge(theGraph, v, 0, u, 0);
if (status != OK) {
// Cannot currently test this, i.e. it shouldn't happen (and
// currently there is no example where it does happen)
gp_Free(&theGraph);
ErrorQuit("Digraphs: boyers_planarity_check (C): internal error, "
"can't add edge from %d to %d",
(Int) v,
(Int) u);
return 0L;
}
}
}
}
status = gp_Embed(theGraph, flags);
if (status == NOTOK) {
// Cannot currently test this, i.e. it shouldn't happen (and
// currently there is no example where it does happen)
gp_Free(&theGraph);
ErrorQuit("Digraphs: boyers_planarity_check (C): status is not ok", 0L, 0L);
}
Obj res;
if (krtwsk) {
// Kuratowski subgraph isolator
gp_SortVertices(theGraph);
Obj subgraph = NEW_PLIST_IMM(T_PLIST, theGraph->N);
SET_LEN_PLIST(subgraph, theGraph->N);
for (int i = 1; i <= theGraph->N; ++i) {
int nr = 0;
Obj list = NEW_PLIST_IMM(T_PLIST, 0);
int j = theGraph->V[i].link[1];
while (j) {
if (CALL_3ARGS(IsDigraphEdge,
digraph,
INTOBJ_INT((Int) i),
INTOBJ_INT((Int) theGraph->E[j].neighbor))
== True) {
AssPlist(list, ++nr, INTOBJ_INT(theGraph->E[j].neighbor));
}
j = theGraph->E[j].link[1];
}
if (nr == 0) {
RetypeBag(list, T_PLIST_EMPTY);
}
SET_ELM_PLIST(subgraph, i, list);
CHANGED_BAG(subgraph);
}
res = NEW_PLIST_IMM(T_PLIST, 2);
SET_LEN_PLIST(res, 2);
SET_ELM_PLIST(res, 1, (status == NONEMBEDDABLE ? False : True));
SET_ELM_PLIST(res, 2, subgraph);
CHANGED_BAG(res);
} else if (status == NONEMBEDDABLE) {
res = False;
} else {
res = True;
}
gp_Free(&theGraph);
return res;
}
