public static GroupByClauseExpressions GetGroupByRollupExpressions(
IList<GroupByClauseElement> groupByElements,
SelectClauseSpecRaw selectClauseSpec,
ExprNode optionalHavingNode,
IList<OrderByItem> orderByList,
ExpressionCopier expressionCopier)
{
if (groupByElements == null || groupByElements.Count == 0) {
return null;
}
// walk group-by-elements, determine group-by expressions and rollup nodes
var groupByExpressionInfo = GroupByToRollupNodes(groupByElements);
// obtain expression nodes, collect unique nodes and assign index
IList<ExprNode> distinctGroupByExpressions = new List<ExprNode>();
IDictionary<ExprNode, int> expressionToIndex = new Dictionary<ExprNode, int>();
foreach (var exprNode in groupByExpressionInfo.Expressions) {
var found = false;
for (var i = 0; i < distinctGroupByExpressions.Count; i++) {
ExprNode other = distinctGroupByExpressions[i];
// find same expression
if (ExprNodeUtilityCompare.DeepEquals(exprNode, other, false)) {
expressionToIndex.Put(exprNode, i);
found = true;
break;
}
}
// not seen before
if (!found) {
expressionToIndex.Put(exprNode, distinctGroupByExpressions.Count);
distinctGroupByExpressions.Add(exprNode);
}
}
// determine rollup, validate it is either (not both)
var hasGroupingSet = false;
var hasRollup = false;
foreach (var element in groupByElements) {
if (element is GroupByClauseElementGroupingSet) {
hasGroupingSet = true;
}
if (element is GroupByClauseElementRollupOrCube) {
hasRollup = true;
}
}
// no-rollup or grouping-sets means simply validate
ExprNode[] groupByExpressions = distinctGroupByExpressions.ToArray();
if (!hasRollup && !hasGroupingSet) {
return new GroupByClauseExpressions(groupByExpressions);
}
// evaluate rollup node roots
var nodes = groupByExpressionInfo.Nodes;
var perNodeCombinations = new object[nodes.Count][];
var context = new GroupByRollupEvalContext(expressionToIndex);
try {
for (var i = 0; i < nodes.Count; i++) {
GroupByRollupNodeBase node = nodes[i];
var combinations = node.Evaluate(context);
perNodeCombinations[i] = new object[combinations.Count];
for (var j = 0; j < combinations.Count; j++) {
perNodeCombinations[i][j] = combinations[j];
}
}
}
catch (GroupByRollupDuplicateException ex) {
if (ex.Indexes.Length == 0) {
throw new ExprValidationException(
"Failed to validate the group-by clause, found duplicate specification of the overall grouping '()'");
}
var writer = new StringWriter();
var delimiter = "";
for (var i = 0; i < ex.Indexes.Length; i++) {
writer.Write(delimiter);
writer.Write(
ExprNodeUtilityPrint.ToExpressionStringMinPrecedenceSafe(groupByExpressions[ex.Indexes[i]]));
delimiter = ", ";
}
throw new ExprValidationException(
"Failed to validate the group-by clause, found duplicate specification of expressions (" +
writer +
")");
}
// enumerate combinations building an index list
var combinationEnumeration = new CombinationEnumeration(perNodeCombinations);
var combination = new SortedSet<int>();
var indexList = new LinkedHashSet<MultiKeyArrayInt>();
while (combinationEnumeration.MoveNext()) {
combination.Clear();
object[] combinationOA = combinationEnumeration.Current;
foreach (var indexes in combinationOA) {
var indexarr = (int[]) indexes;
foreach (var anIndex in indexarr) {
combination.Add(anIndex);
}
}
var indexArr = CollectionUtil.IntArray(combination);
indexList.Add(new MultiKeyArrayInt(indexArr));
}
// obtain rollup levels
var rollupLevels = new int[indexList.Count][];
var count = 0;
foreach (var mk in indexList) {
rollupLevels[count++] = mk.Keys;
}
var numberOfLevels = rollupLevels.Length;
if (numberOfLevels == 1 && rollupLevels[0].Length == 0) {
throw new ExprValidationException(
"Failed to validate the group-by clause, the overall grouping '()' cannot be the only grouping");
}
// obtain select-expression copies for rewrite
var expressions = selectClauseSpec.SelectExprList;
var selects = new ExprNode[numberOfLevels][];
for (var i = 0; i < numberOfLevels; i++) {
selects[i] = new ExprNode[expressions.Count];
for (var j = 0; j < expressions.Count; j++) {
SelectClauseElementRaw selectRaw = expressions[j];
if (!(selectRaw is SelectClauseExprRawSpec)) {
throw new ExprValidationException(
"Group-by with rollup requires that the select-clause does not use wildcard");
}
var compiled = (SelectClauseExprRawSpec) selectRaw;
selects[i][j] = CopyVisitExpression(compiled.SelectExpression, expressionCopier);
}
}
// obtain having-expression copies for rewrite
ExprNode[] optHavingNodeCopy = null;
if (optionalHavingNode != null) {
optHavingNodeCopy = new ExprNode[numberOfLevels];
for (var i = 0; i < numberOfLevels; i++) {
optHavingNodeCopy[i] = CopyVisitExpression(optionalHavingNode, expressionCopier);
}
}
// obtain orderby-expression copies for rewrite
ExprNode[][] optOrderByCopy = null;
if (orderByList != null && orderByList.Count > 0) {
optOrderByCopy = new ExprNode[numberOfLevels][];
for (var i = 0; i < numberOfLevels; i++) {
optOrderByCopy[i] = new ExprNode[orderByList.Count];
for (var j = 0; j < orderByList.Count; j++) {
OrderByItem element = orderByList[j];
optOrderByCopy[i][j] = CopyVisitExpression(element.ExprNode, expressionCopier);
}
}
}
return new GroupByClauseExpressions(
groupByExpressions,
rollupLevels,
selects,
optHavingNodeCopy,
optOrderByCopy);
}
/// <summary>
/// Adds an select expression within the select clause.
/// </summary>
/// <param name="element">is the expression to add</param>
public void Add(SelectClauseElementRaw element)
{
_selectClauseElements.Add(element);
}