private static bool AttemptRangeSetMerge(Variable v, FunctionExpression rangeSetTerm, Expression toMergeWith, string logicalOpName)
{
if (toMergeWith is FunctionExpression) {
FunctionExpression functionExp = (FunctionExpression) toMergeWith;
// If the type is the same logical operation, we recurse
string funType = functionExp.Name;
if (funType.Equals(logicalOpName)) {
// Recurse condition, we try left and right merge
// We attempt left and right param
if (AttemptRangeSetMerge(v, rangeSetTerm, (Expression)functionExp.Parameters[0], logicalOpName))
return true;
return AttemptRangeSetMerge(v, rangeSetTerm, (Expression) functionExp.Parameters[1], logicalOpName);
}
// If it's a range set,
if (funType.Equals("range_set")) {
// Get the var
Variable targetVariable = ((FetchVariableExpression) functionExp.Parameters[0]).Variable;
// If they match, we merge
if (v.Equals(targetVariable)) {
// Get the range sets
SelectableRange rangeSet1 = (SelectableRange) functionExp.Parameters[1];
SelectableRange rangeSet2 = (SelectableRange) rangeSetTerm.Parameters[1];
// Make sure the range types are the same
SqlObject[] ob1 = (SqlObject[])toMergeWith.GetArgument("full_range_object");
SqlObject[] ob2 = (SqlObject[])rangeSetTerm.GetArgument("full_range_object");
if (ob1.Length != 1 || ob2.Length != 1)
// PENDING: Handle composite terms,
return false;
SqlType rs1Type = ob1[0].Type;
SqlType rs2Type = ob2[0].Type;
if (!rs1Type.Equals(rs2Type))
// Types are not strictly comparable, therefore can't merge,
return false;
// Merge (note that range_set1 which is part of 'to_merge_with'
// will be modified).
if (logicalOpName.Equals("@and_sql")) {
// intersect (and)
rangeSet1 = rangeSet1.Intersect(rangeSet2);
} else {
// union (or)
rangeSet1 = rangeSet1.Union(rangeSet2);
}
// Update the simplified term,
functionExp.Parameters[1] = rangeSet1;
return true;
}
// Not equal variables so return false
return false;
}
// fun_type isn't named "range_set", "or" or "and" so we return false
// indicating no merge is possible.
return false;
}
return false;
}