private void addJoinConditionToGraph(
VariableJoinCondition joinCondition, JoinGraph joinGraph, SimpleConjunctiveQuery view) {
SetAlias fromVariable = findVariable(joinCondition.getFromVariable(), view);
SetAlias toVariable = findVariable(joinCondition.getToVariable(), view);
joinGraph.addSuccessor(fromVariable, toVariable, joinCondition);
if (!joinCondition.isMonodirectional()) {
joinGraph.addSuccessor(toVariable, fromVariable, joinCondition);
}
}
//////////////// JOIN GRAPH CONSTRUCTION ////////////////////
JoinGraph initializeJoinGraph(SimpleConjunctiveQuery view) {
JoinGraph joinGraph = new JoinGraph();
for (SetAlias variable : view.getGenerators()) {
joinGraph.addNode(variable);
}
for (VariableJoinCondition joinCondition : view.getJoinConditions()) {
addJoinConditionToGraph(joinCondition, joinGraph, view);
}
return joinGraph;
}
private void visitForPath(
SetAlias variable,
JoinGraph joinGraph,
List<SetAlias> visitedVariables,
List<JoinEdge> visitedEdges) {
visitedVariables.add(variable);
if (logger.isDebugEnabled())
logger.debug("Visiting graph searching for path from set: " + variable);
List<JoinEdge> edges = joinGraph.getSuccessors().get(variable);
for (JoinEdge edge : edges) {
if (!visitedEdges.contains(edge)) {
SetAlias successor = edge.getDestinationVariable();
if (!visitedVariables.contains(successor)) {
visitedEdges.add(edge);
visitForPath(successor, joinGraph, visitedVariables, visitedEdges);
}
}
}
}