/// <inheritdoc/>
public override ITable Evaluate(IQueryContext context)
{
var t = Child.Evaluate(context);
var exp = Expression;
// Assert that all variables in the expression are identical.
var columnNames = exp.DiscoverReferences();
ObjectName columnName = null;
foreach (var cv in columnNames) {
if (columnName != null && !cv.Equals(columnName))
throw new InvalidOperationException("Range plan does not contain common column.");
columnName = cv;
}
// Find the variable field in the table.
var col = t.IndexOfColumn(columnName);
if (col == -1)
throw new InvalidOperationException("Could not find column reference in table: " + columnName);
var field = t.TableInfo[col];
// Calculate the range
var range = new IndexRangeSet();
var calculator = new RangeSetCalculator(context, field, range);
range = calculator.Calculate(exp);
// Select the range from the table
var ranges = range.ToArray();
return t.SelectRange(columnName, ranges);
}
/// <summary>
/// Unions the current range set with the given range set.
/// </summary>
public IndexRangeSet Union(IndexRangeSet unionTo)
{
lock (this) {
var rangeSet = new List<IndexRange>(ranges);
var inputSet = unionTo.ranges;
int inSz = inputSet.Count;
int n = 0;
while (n < inSz) {
var inRange = inputSet[n];
int sz = rangeSet.Count;
var i = rangeSet.GetRange(0, sz);
int j = 0;
while (j < i.Count) {
var range = i[j];
if (IntersectedBy(inRange, range)) {
i.RemoveAt(j);
inRange = ChangeRangeSizeToEncompass(inRange, range);
}
j++;
}
// Insert into sorted position
var startPoint = inRange.StartOffset;
var start = inRange.StartValue;
var endPoint = inRange.EndOffset;
var end = inRange.EndValue;
if (start == IndexRange.FirstInSet) {
rangeSet.Insert(0, inRange);
} else {
var startCell = start;
i = rangeSet.GetRange(0, rangeSet.Count);
j = 0;
while (j < i.Count) {
var range = i[j];
var curStart = range.StartValue;
if (!curStart.Equals(IndexRange.FirstInSet)) {
if (curStart.CompareTo(startCell) > 0) {
i[j] = i[j - 1];
break;
}
}
j++;
}
i.Add(inRange);
}
n++;
}
return new IndexRangeSet(rangeSet);
}
}
public RangeSetUpdater(IQueryContext context, ColumnInfo field, IndexRangeSet indexRangeSet)
{
this.context = context;
this.field = field;
this.indexRangeSet = indexRangeSet;
}
public override SqlExpression VisitBinary(SqlBinaryExpression binaryEpression)
{
var op = binaryEpression.ExpressionType;
// Evaluate to an object
var value = binaryEpression.Right.EvaluateToConstant(context, null);
// If the evaluated object is not of a comparable type, then it becomes
// null.
var fieldType = field.ColumnType;
if (!value.Type.IsComparable(fieldType))
value = DataObject.Null(fieldType);
// Intersect this in the range set
indexRangeSet = indexRangeSet.Intersect(op, value);
return base.VisitBinary(binaryEpression);
}
private IndexRangeSet CalcExpression(SqlExpression expression)
{
var indexRangeSet = new IndexRangeSet();
var calculator = new RangeSetCalculator(context, field, indexRangeSet);
return calculator.Calculate(expression);
}
public override SqlExpression VisitBinary(SqlBinaryExpression binaryEpression)
{
if (binaryEpression.ExpressionType == SqlExpressionType.And) {
rangeSet = UpdateRange(binaryEpression.Left);
rangeSet = UpdateRange(binaryEpression.Right);
} else if (binaryEpression.ExpressionType == SqlExpressionType.Or) {
var left = CalcExpression(binaryEpression.Left);
var right = CalcExpression(binaryEpression.Right);
rangeSet = rangeSet.Union(left);
rangeSet = rangeSet.Union(right);
} else {
rangeSet = UpdateRange(binaryEpression);
}
return base.VisitBinary(binaryEpression);
}
public RangeSetCalculator(IQueryContext context, ColumnInfo field, IndexRangeSet rangeSet)
{
this.context = context;
this.field = field;
this.rangeSet = rangeSet;
}
/// <summary>
/// Unions the current range set with the given range set.
/// </summary>
public IndexRangeSet Union(IndexRangeSet unionTo)
{
lock (this) {
var rangeSet = new List <IndexRange>(ranges);
var inputSet = unionTo.ranges;
int inSz = inputSet.Count;
int n = 0;
while (n < inSz)
{
var inRange = inputSet[n];
int sz = rangeSet.Count;
var i = rangeSet.GetRange(0, sz);
int j = 0;
while (j < i.Count)
{
var range = i[j];
if (IntersectedBy(inRange, range))
{
i.RemoveAt(j);
inRange = ChangeRangeSizeToEncompass(inRange, range);
}
j++;
}
// Insert into sorted position
var startPoint = inRange.StartOffset;
var start = inRange.StartValue;
var endPoint = inRange.EndOffset;
var end = inRange.EndValue;
if (start == IndexRange.FirstInSet)
{
rangeSet.Insert(0, inRange);
}
else
{
var startCell = start;
i = rangeSet.GetRange(0, rangeSet.Count);
j = 0;
while (j < i.Count)
{
var range = i[j];
var curStart = range.StartValue;
if (!curStart.Equals(IndexRange.FirstInSet))
{
if (curStart.CompareTo(startCell) > 0)
{
i[j] = i[j - 1];
break;
}
}
j++;
}
i.Add(inRange);
}
n++;
}
return(new IndexRangeSet(rangeSet));
}
}
public static IEnumerable<int> SelectRows(this ITable table, int column, SqlExpressionType op, DataObject value)
{
// If the cell is of an incompatible type, return no results,
var colType = table.TableInfo[column].ColumnType;
if (!value.Type.IsComparable(colType)) {
// Types not comparable, so return 0
return new List<int>(0);
}
// Get the selectable scheme for this column
var index = table.GetIndex(column);
// If the operator is a standard operator, use the interned SelectableScheme
// methods.
if (op == SqlExpressionType.Equal)
return index.SelectEqual(value);
if (op == SqlExpressionType.NotEqual)
return index.SelectNotEqual(value);
if (op == SqlExpressionType.GreaterThan)
return index.SelectGreater(value);
if (op == SqlExpressionType.SmallerThan)
return index.SelectLess(value);
if (op == SqlExpressionType.GreaterOrEqualThan)
return index.SelectGreaterOrEqual(value);
if (op == SqlExpressionType.SmallerOrEqualThan)
return index.SelectLessOrEqual(value);
// If it's not a standard operator (such as IS, NOT IS, etc) we generate the
// range set especially.
var rangeSet = new IndexRangeSet();
rangeSet = rangeSet.Intersect(op, value);
return index.SelectRange(rangeSet.ToArray());
}
