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|
/* LIBDGL -- a Directed Graph Library implementation
* Copyright (C) 2002 Roberto Micarelli
*
* 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 Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
* best view with tabstop=4
*/
/*
* Build the depth-first spanning tree of 'pgraphIn' into 'pgraphOut'
* - pgraphOut must have been previously initialized by the caller and is returned in TREE state
* - I prefer using a iterative approach with a stack for 'waiting edges' instead of recursion: it's
* cheaper to stack 8 bytes for each edge than the whole function stack
* - The visited network is passed by the caller because this function can be used for two purposes:
* 1. generate a single spanning tree (dglDepthSpanning)
* 2. part of a loop for generating connected-components of the graph (dglDepthComponents)
*/
int DGL_SPAN_DEPTHFIRST_SPANNING_FUNC(dglGraph_s * pgraphIn,
dglGraph_s * pgraphOut,
dglInt32_t nVertex,
void *pvVisited,
dglSpanClip_fn fnClip, void *pvClipArg)
{
struct _stackItem
{
dglInt32_t *pnHead;
dglInt32_t *pnEdge;
int iWay;
};
struct _stackItem stackItem;
struct _stackItem *pStackItem;
dglInt32_t *pHead;
dglInt32_t *pTail;
dglInt32_t *pEdgeset;
dglInt32_t *pEdge;
long istack = 0;
unsigned char *pstack = NULL;
int nret;
dglSpanClipInput_s clipInput;
dglTreeNode_s findVisited;
dglEdgesetTraverser_s laT;
if ((pHead = dglGetNode(pgraphIn, nVertex)) == NULL) {
pgraphIn->iErrno = DGL_ERR_HeadNodeNotFound;
goto dfs_error;
}
/*
* the simplest case is when vertex node is alone or has no outgoing edges, the result
* of the spanning is a graph having only one node
*/
if (DGL_NODE_STATUS(pHead) & DGL_NS_ALONE ||
(!(DGL_NODE_STATUS(pHead) & DGL_NS_HEAD) &&
DGL_NODE_STATUS(pHead) & DGL_NS_TAIL)) {
nret =
DGL_ADD_NODE_FUNC(pgraphOut, DGL_NODE_ID(pHead),
DGL_NODE_ATTR_PTR(pHead), 0);
if (nret < 0) {
goto dfs_error;
}
return 0;
}
if ((DGL_NODE_STATUS(pHead) & DGL_NS_HEAD) || pgraphIn->Version == 3) {
pEdgeset = _DGL_OUTEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) < 0) {
goto dfs_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
stackItem.pnHead = pHead;
stackItem.pnEdge = pEdge;
stackItem.iWay = 0;
if ((pstack =
dgl_mempush(pstack, &istack, sizeof(stackItem),
&stackItem)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
if (pgraphIn->Version == 3) {
pEdgeset = _DGL_INEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) < 0) {
goto dfs_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
if (DGL_EDGE_STATUS(pEdge) & DGL_ES_DIRECTED)
continue;
stackItem.pnHead = pHead;
stackItem.pnEdge = pEdge;
stackItem.iWay = 1;
if ((pstack =
dgl_mempush(pstack, &istack, sizeof(stackItem),
&stackItem)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
}
if (dglTreeNodeAdd(pvVisited, DGL_NODE_ID(pHead)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
}
while ((pStackItem =
(struct _stackItem *)dgl_mempop(pstack, &istack,
sizeof(stackItem))) != NULL) {
pHead = pStackItem->pnHead;
pEdge = pStackItem->pnEdge;
if (pStackItem->iWay == 0)
pTail = _DGL_EDGE_TAILNODE(pgraphIn, pEdge);
else
pTail = _DGL_EDGE_HEADNODE(pgraphIn, pEdge);
findVisited.nKey = DGL_NODE_ID(pTail);
if (avl_find(pvVisited, &findVisited)) { /* already visited */
continue;
}
if (fnClip) {
clipInput.pnNodeFrom = pHead;
clipInput.pnEdge = pEdge;
clipInput.pnNodeTo = pTail;
if (fnClip(pgraphIn, pgraphOut, &clipInput, NULL, pvClipArg))
continue;
}
if (dglTreeNodeAdd(pvVisited, DGL_NODE_ID(pTail)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
/* add this edge */
nret = DGL_ADD_EDGE_FUNC(pgraphOut,
DGL_NODE_ID(pHead),
DGL_NODE_ID(pTail),
DGL_EDGE_COST(pEdge),
DGL_EDGE_ID(pEdge),
DGL_NODE_ATTR_PTR(pHead),
DGL_NODE_ATTR_PTR(pTail),
DGL_EDGE_ATTR_PTR(pEdge), 0);
if (nret < 0) {
goto dfs_error;
}
if ((DGL_NODE_STATUS(pHead) & DGL_NS_HEAD) || pgraphIn->Version == 3) {
pEdgeset = _DGL_OUTEDGESET(pgraphIn, pTail);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) < 0) {
goto dfs_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
stackItem.pnHead = pTail;
stackItem.pnEdge = pEdge;
stackItem.iWay = 0;
if ((pstack =
dgl_mempush(pstack, &istack, sizeof(stackItem),
&stackItem)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
if (pgraphIn->Version == 3) {
pEdgeset = _DGL_INEDGESET(pgraphIn, pTail);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) <
0) {
goto dfs_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
if (DGL_EDGE_STATUS(pEdge) & DGL_ES_DIRECTED)
continue;
stackItem.pnHead = pTail;
stackItem.pnEdge = pEdge;
stackItem.iWay = 1;
if ((pstack =
dgl_mempush(pstack, &istack, sizeof(stackItem),
&stackItem)) == NULL) {
pgraphIn->iErrno = DGL_ERR_MemoryExhausted;
goto dfs_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
}
}
}
if (pstack)
free(pstack);
return 0;
dfs_error:
if (pstack)
free(pstack);
return -pgraphIn->iErrno;
}
/*
* Use a edge prioritized, tree growing scheme (aka Prim algorithm) in order to
* be appliable to both undirected graphs (minimum spanning tree - MST) and
* digraphs (minimum arborescense tree - MAT)
* The vertex argument is ignored in MST (when algorithm is applied to a
* version 3 undirected graph).
*/
int DGL_SPAN_MINIMUM_SPANNING_FUNC(dglGraph_s * pgraphIn,
dglGraph_s * pgraphOut,
dglInt32_t nVertex,
dglSpanClip_fn fnClip, void *pvClipArg)
{
dglInt32_t *pHead, *pTail, *pEdgeset, *pEdge;
dglHeap_s FrontEdgeHeap;
dglHeapData_u HeapData;
dglHeapNode_s HeapItem;
dglTreeNode_s *pPredistItem, findItem;
dglEdgesetTraverser_s laT;
int nret;
dglHeapInit(&FrontEdgeHeap);
if (pgraphIn->Version == 3) { /* undirected: pick up the first node */
dglNodeTraverser_s pT;
DGL_NODE_T_INITIALIZE_FUNC(pgraphIn, &pT);
pHead = DGL_NODE_T_FIRST_FUNC(&pT);
DGL_NODE_T_RELEASE_FUNC(&pT);
}
else { /* directed: pick up the arborescense origin */
pHead = DGL_GET_NODE_FUNC(pgraphIn, nVertex);
}
if (pHead == NULL) {
pgraphIn->iErrno = DGL_ERR_HeadNodeNotFound;
goto mst_error;
}
if (DGL_NODE_STATUS(pHead) & DGL_NS_HEAD ||
DGL_NODE_STATUS(pHead) & DGL_NS_ALONE) {
if ((DGL_NODE_STATUS(pHead) & DGL_NS_HEAD) ||
(DGL_NODE_STATUS(pHead) & DGL_NS_ALONE) ||
pgraphIn->Version == 3) {
if (DGL_ADD_NODE_FUNC
(pgraphOut, DGL_NODE_ID(pHead), DGL_NODE_ATTR_PTR(pHead),
0) < 0) {
goto mst_error;
}
if (DGL_NODE_STATUS(pHead) & DGL_NS_ALONE) {
dglHeapFree(&FrontEdgeHeap, NULL);
return 0;
}
pEdgeset = _DGL_OUTEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) < 0) {
goto mst_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
HeapData.pv = pEdge;
if (dglHeapInsertMin
(&FrontEdgeHeap, DGL_EDGE_COST(pEdge), 0, HeapData) < 0) {
pgraphIn->iErrno = DGL_ERR_HeapError;
goto mst_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
if (pgraphIn->Version == 3) {
pEdgeset = _DGL_INEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) <
0) {
goto mst_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
if (DGL_EDGE_STATUS(pEdge) & DGL_ES_DIRECTED)
continue;
HeapData.pv = pEdge;
if (dglHeapInsertMin
(&FrontEdgeHeap, DGL_EDGE_COST(pEdge), 1,
HeapData) < 0) {
pgraphIn->iErrno = DGL_ERR_HeapError;
goto mst_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
}
}
}
else {
pgraphIn->iErrno = DGL_ERR_BadEdge;
goto mst_error;
}
while (dglHeapExtractMin(&FrontEdgeHeap, &HeapItem) == 1) {
pEdge = HeapItem.value.pv;
if (HeapItem.flags == 0) {
if ((pHead = _DGL_EDGE_HEADNODE(pgraphIn, pEdge)) == NULL) {
pgraphIn->iErrno = DGL_ERR_UnexpectedNullPointer;
goto mst_error;
}
if ((pTail = _DGL_EDGE_TAILNODE(pgraphIn, pEdge)) == NULL) {
pgraphIn->iErrno = DGL_ERR_UnexpectedNullPointer;
goto mst_error;
}
}
else if (pgraphIn->Version == 3) {
if ((pTail = _DGL_EDGE_HEADNODE(pgraphIn, pEdge)) == NULL) {
pgraphIn->iErrno = DGL_ERR_UnexpectedNullPointer;
goto mst_error;
}
if ((pHead = _DGL_EDGE_TAILNODE(pgraphIn, pEdge)) == NULL) {
pgraphIn->iErrno = DGL_ERR_UnexpectedNullPointer;
goto mst_error;
}
}
else
continue;
findItem.nKey = DGL_NODE_ID(pTail);
if ((pPredistItem =
avl_find(pgraphOut->pNodeTree, &findItem)) != NULL) {
continue;
}
nret = DGL_ADD_EDGE_FUNC(pgraphOut,
DGL_NODE_ID(pHead),
DGL_NODE_ID(pTail),
DGL_EDGE_COST(pEdge),
DGL_EDGE_ID(pEdge),
DGL_NODE_ATTR_PTR(pHead),
DGL_NODE_ATTR_PTR(pTail),
DGL_EDGE_ATTR_PTR(pEdge), 0);
if (nret < 0) {
goto mst_error;
}
pHead = pTail;
if ((DGL_NODE_STATUS(pHead) & DGL_NS_HEAD) || pgraphIn->Version == 3) {
pEdgeset = _DGL_OUTEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) < 0) {
goto mst_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
HeapData.pv = pEdge;
if (dglHeapInsertMin
(&FrontEdgeHeap, DGL_EDGE_COST(pEdge), 0, HeapData) < 0) {
pgraphIn->iErrno = DGL_ERR_HeapError;
goto mst_error;
}
}
if (pgraphIn->Version == 3) {
DGL_EDGESET_T_RELEASE_FUNC(&laT);
pEdgeset = _DGL_OUTEDGESET(pgraphIn, pHead);
if (DGL_EDGESET_T_INITIALIZE_FUNC(pgraphIn, &laT, pEdgeset) <
0) {
goto mst_error;
}
for (pEdge = DGL_EDGESET_T_FIRST_FUNC(&laT);
pEdge; pEdge = DGL_EDGESET_T_NEXT_FUNC(&laT)
) {
if (DGL_EDGE_STATUS(pEdge) & DGL_ES_DIRECTED)
continue;
HeapData.pv = pEdge;
if (dglHeapInsertMin
(&FrontEdgeHeap, DGL_EDGE_COST(pEdge), 1,
HeapData) < 0) {
pgraphIn->iErrno = DGL_ERR_HeapError;
goto mst_error;
}
}
DGL_EDGESET_T_RELEASE_FUNC(&laT);
}
}
}
dglHeapFree(&FrontEdgeHeap, NULL);
return 0;
mst_error:
dglHeapFree(&FrontEdgeHeap, NULL);
return -pgraphIn->iErrno;
}
|
