int
BreadthFirstSearch(List<NodeType> &startstatelist,
BinaryTree_AVL<DataType> &startlist,
BinaryTree_AVL<DataType> &otherlist)
{
int status;
// track all states created
BinaryTree_AVL<String> allstates;
// create open priority queue
List<Proxy<NodeType> > openpq;
// copy list of start states
int nodedepth = 1;
ListIterator<NodeType> startstateIter(startstatelist);
for ( ; !startstateIter.done(); startstateIter++)
{
// copy start state
Proxy<NodeType> pstart(startstateIter());
// set start node depth
pstart->setDepth(nodedepth);
// insert start state into open queue
if ((status = openpq.insertAtEnd(pstart)) != OK)
{
ERRORD("insertAtFront() failed.", status, errno);
return(status);
}
}
// start search loop
for (Proxy<NodeType> pnode; ! openpq.isEmpty(); )
{
// remove next node from priority open queue
if ((status = openpq.removeAtFront(pnode)) != OK)
{
ERRORD("removeAtFront() failed.", status, errno);
return(status);
}
// set current node depth
nodedepth = pnode->getDepth();
// check if we have a goal node or not
status = pnode->isGoal(startlist, otherlist);
switch (status)
{
case OK:
break;
case NOMATCH:
case MAXDEPTHEXCEEDED:
// no clauses were generated. skip further
// processing of this node.
continue;
case VALID:
// goal node, print solution
PrintSolution(pnode);
PrintRenameVariables(pnode);
// check if more than one solutions is required
solutionsfound += 1;
statistics[SolutionsFound] += 1;
totalstatistics[TotalSolutionsFound] += 1;
if (solutionsfound >= solutionsrequired)
return(VALID);
continue;
case MAXCLAUSEEXCEEDED:
// check if any solutions were found
if (solutionsfound > 0)
return(VALID);
else
return(NOTPROVEN);
default:
// some type of error
ERRORD("isGoal() failed.", status, errno);
return(status);
}
// generate the children of the current node
if ((status = pnode->expand(startlist, otherlist)) != OK)
{
ERRORD("expand() failed.", status, errno);
return(status);
}
// set up links to parent and calculate the heuristic value
ListIterator<Proxy<NodeType> >
childrenIter(*pnode->getChildren());
for ( ; !childrenIter.done(); childrenIter++)
{
// pointer to child
Proxy<NodeType> pchild(childrenIter());
// set up link to parent
if (reporttype == ReportParent ||
reporttype == ReportBoth)
pchild->setParent(pnode);
// insert into queue
if (!bfswithchecks)
{
pchild->setDepth(nodedepth+1);
if ((status = openpq.insertAtEnd(
pchild)) != OK)
{
ERRORD("insertAtEnd() failed.",
status, errno);
return(status);
}
}
else
{
statistics[RedundantClauseTestsAttempted] += 1;
totalstatistics[TotalRedundantClauseTestsAttempted] += 1;
String newnode(pchild->getNormalizedClauses());
if (allstates.retrieve(newnode) == NOMATCH)
{
pchild->setDepth(nodedepth+1);
if ((status = openpq.insertAtEnd(
pchild)) != OK)
{
ERRORD("insertAtEnd() failed.",
status, errno);
return(status);
}
}
else
{
statistics[RedundantClausesRejected] += 1;
totalstatistics[TotalRedundantClausesRejected] += 1;
}
}
}
if (bfswithchecks)
{
if (allstates.insert(pnode->getNormalizedClauses()) != OK)
{
ERRORD("insert() failed.", status, errno);
return(status);
}
}
}
// check if any solutions were found
if (solutionsfound > 0)
return(VALID);
else
return(NOTPROVEN);
}
int
updatepath(int &nodedepth, int &olddepth, Proxy<NodeType> &pnode,
List<Proxy<NodeType> > ¤tpath)
{
int status;
// get new node depth
nodedepth = pnode->getDepth();
// update path if reporting is on
if (reporttype != ReportStack && reporttype != ReportBoth)
return(OK);
// update path in stack
if (currentpath.isEmpty())
{
if ((status = currentpath.insertAtFront(pnode)) != OK)
{
ERRORD("insertAtFront() failed.",
status, errno);
return(status);
}
olddepth = nodedepth;
}
else if (nodedepth <= olddepth)
{
int nodestopop = olddepth - nodedepth + 1;
for (int inode = 1; inode <= nodestopop; inode++)
{
Proxy<NodeType> ppathnode;
if ((status = currentpath.removeAtFront(
ppathnode)) != OK)
{
ERRORD("removeAtFront() failed.",
status, errno);
return(status);
}
}
if ((status = currentpath.insertAtFront(pnode)) != OK)
{
ERRORD("insertAtFront() failed.",
status, errno);
return(status);
}
olddepth = nodedepth;
}
else if (nodedepth > olddepth)
{
if ((status = currentpath.insertAtFront(pnode)) != OK)
{
ERRORD("insertAtFront() failed.",
status, errno);
return(status);
}
olddepth = nodedepth;
}
else
{
MustBeTrue(0);
}
// all done
return(OK);
}