protected internal override Expression VisitSelect(SelectExpression select)
{
this.aliases.Add(select.Alias);
return(base.VisitSelect(select));
}
protected internal override Expression VisitSelect(SelectExpression select)
{
bool isOuterMost = select == outerMostSelect;
if (select.IsOrderAlsoByKeys || select.HasIndex || select.Top != null && hasProjectionInProjector)
{
if (gatheredKeys == null)
{
gatheredKeys = new List <ColumnExpression>();
}
}
List <ColumnExpression>?savedKeys = null;
if (gatheredKeys != null && (select.IsDistinct || select.GroupBy.HasItems() || select.IsAllAggregates))
{
savedKeys = gatheredKeys.ToList();
}
if ((AggregateFinder.GetAggregates(select.Columns)?.Any(a => a.AggregateFunction.OrderMatters()) ?? false) && select.From is SelectExpression from)
{
var oldOuterMostSelect = outerMostSelect;
outerMostSelect = from;
select = (SelectExpression)base.VisitSelect(select);
outerMostSelect = oldOuterMostSelect;
}
else
{
select = (SelectExpression)base.VisitSelect(select);
}
if (savedKeys != null)
{
gatheredKeys = savedKeys;
}
List <ColumnDeclaration>?newColumns = null;
if (select.GroupBy.HasItems())
{
gatheredOrderings = null;
if (gatheredKeys != null)
{
ColumnGenerator cg = new ColumnGenerator(select.Columns);
var newKeys = new List <ColumnDeclaration>();
foreach (var ge in select.GroupBy)
{
var cd = cg.Columns.NotNull().FirstOrDefault(a => DbExpressionComparer.AreEqual(a.Expression, ge));
if (cd != null)
{
newKeys.Add(cd);
}
else
{
newKeys.Add(cg.NewColumn(ge));
}
}
if (cg.Columns.Count() != select.Columns.Count)
{
newColumns = cg.Columns.NotNull().ToList();
}
gatheredKeys.AddRange(newKeys.Select(cd => new ColumnExpression(cd.Expression.Type, select.Alias, cd.Name)));
}
}
if (select.IsAllAggregates)
{
if (gatheredKeys != null)
{
gatheredKeys.AddRange(select.Columns.Select(cd => new ColumnExpression(cd.Expression.Type, select.Alias, cd.Name)));
}
}
if (select.IsDistinct)
{
gatheredOrderings = null;
if (gatheredKeys != null)
{
gatheredKeys.AddRange(select.Columns.Select(cd => cd.GetReference(select.Alias)));
}
}
if (select.IsReverse && !gatheredOrderings.IsNullOrEmpty())
{
gatheredOrderings = gatheredOrderings.Select(o => new OrderExpression(
o.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
o.Expression)).ToReadOnly();
}
if (select.OrderBy.Count > 0)
{
this.PrependOrderings(select.OrderBy);
}
ReadOnlyCollection <OrderExpression>?orderings = null;
if (isOuterMost && !IsCountSumOrAvg(select) || select.Top != null)
{
AppendKeys();
orderings = gatheredOrderings;
gatheredOrderings = null;
}
if (AreEqual(select.OrderBy, orderings) && !select.IsReverse && newColumns == null)
{
return(select);
}
return(new SelectExpression(select.Alias, select.IsDistinct, select.Top, (IEnumerable <ColumnDeclaration>?)newColumns ?? select.Columns,
select.From, select.Where, orderings, select.GroupBy, select.SelectOptions & ~SelectOptions.Reverse));
}
private bool IsKey(SelectExpression source, HashSet <ColumnExpression> columns)
{
var keys = KeyFinder.Keys(source);
return(keys.All(k => k != null && columns.Contains(k)));
}
protected internal override Expression VisitProjection(ProjectionExpression proj)
{
if (currentSource == null)
{
currentSource = WithoutOrder(proj.Select);
Expression projector = this.Visit(proj.Projector);
if (projector != proj.Projector)
{
proj = new ProjectionExpression(proj.Select, projector, proj.UniqueFunction, proj.Type);
}
currentSource = null;
return(proj);
}
else
{
HashSet <ColumnExpression> columns = ExternalColumnGatherer.Gatherer(proj, currentSource.Alias);
if (columns.Count == 0)
{
Expression projector = Visit(proj.Projector);
ConstantExpression key = Expression.Constant(0);
Type kvpType = typeof(KeyValuePair <,>).MakeGenericType(key.Type, projector.Type);
ConstructorInfo ciKVP = kvpType.GetConstructor(new[] { key.Type, projector.Type }) !;
Type projType = proj.UniqueFunction == null ? typeof(IEnumerable <>).MakeGenericType(kvpType) : kvpType;
var childProj = new ProjectionExpression(proj.Select,
Expression.New(ciKVP, key, projector), proj.UniqueFunction, projType);
return(new ChildProjectionExpression(childProj,
Expression.Constant(0), inMList != null, inMList ?? proj.Type, new LookupToken()));
}
else
{
SelectExpression external;
IEnumerable <ColumnExpression> externalColumns;
if (!IsKey(currentSource, columns))
{
Alias aliasDistinct = aliasGenerator.GetUniqueAlias(currentSource.Alias.Name + "D");
ColumnGenerator generatorDistinct = new ColumnGenerator();
List <ColumnDeclaration> columnDistinct = columns.Select(ce => generatorDistinct.MapColumn(ce)).ToList();
external = new SelectExpression(aliasDistinct, true, null, columnDistinct, currentSource, null, null, null, 0);
Dictionary <ColumnExpression, ColumnExpression> distinctReplacements = columnDistinct.ToDictionary(
cd => (ColumnExpression)cd.Expression,
cd => cd.GetReference(aliasDistinct));
proj = (ProjectionExpression)ColumnReplacer.Replace(proj, distinctReplacements);
externalColumns = distinctReplacements.Values.ToHashSet();
}
else
{
external = currentSource;
externalColumns = columns;
}
ColumnGenerator generatorSM = new ColumnGenerator();
List <ColumnDeclaration> columnsSMExternal = externalColumns.Select(ce => generatorSM.MapColumn(ce)).ToList();
List <ColumnDeclaration> columnsSMInternal = proj.Select.Columns.Select(cd => generatorSM.MapColumn(cd.GetReference(proj.Select.Alias))).ToList();
SelectExpression @internal = ExtractOrders(proj.Select, out List <OrderExpression>?innerOrders);
Alias aliasSM = aliasGenerator.GetUniqueAlias(@internal.Alias.Name + "SM");
SelectExpression selectMany = new SelectExpression(aliasSM, false, null, columnsSMExternal.Concat(columnsSMInternal),
new JoinExpression(JoinType.CrossApply,
external,
@internal, null), null, innerOrders, null, 0);
SelectExpression old = currentSource;
currentSource = WithoutOrder(selectMany);
var selectManyReplacements = selectMany.Columns.ToDictionary(
cd => (ColumnExpression)cd.Expression,
cd => cd.GetReference(aliasSM));
Expression projector = ColumnReplacer.Replace(proj.Projector, selectManyReplacements);
projector = Visit(projector);
currentSource = old;
Expression key = TupleReflection.TupleChainConstructor(columnsSMExternal.Select(cd => MakeEquatable(cd.GetReference(aliasSM))));
Type kvpType = typeof(KeyValuePair <,>).MakeGenericType(key.Type, projector.Type);
ConstructorInfo ciKVP = kvpType.GetConstructor(new[] { key.Type, projector.Type }) !;
Type projType = proj.UniqueFunction == null ? typeof(IEnumerable <>).MakeGenericType(kvpType) : kvpType;
var childProj = new ProjectionExpression(selectMany,
Expression.New(ciKVP, key, projector), proj.UniqueFunction, projType);
return(new ChildProjectionExpression(childProj,
TupleReflection.TupleChainConstructor(columns.Select(a => MakeEquatable(a))), inMList != null, inMList ?? proj.Type, new LookupToken()));
}
}
}
public ScalarExpression(Type type, SelectExpression select)
: base(DbExpressionType.Scalar, type, select)
{
}
public ExistsExpression(SelectExpression select)
: base(DbExpressionType.Exists, typeof(bool), select)
{
}
protected SubqueryExpression(DbExpressionType nodeType, Type type, SelectExpression select)
: base(nodeType, type)
{
System.Diagnostics.Debug.Assert(nodeType == DbExpressionType.Scalar || nodeType == DbExpressionType.Exists || nodeType == DbExpressionType.In);
this.Select = select;
}
static bool HasJoins(SelectExpression s)
{
return(s.From is JoinExpression || s.From is SelectExpression s2 && HasJoins(s2));
}
protected internal override Expression VisitSelect(SelectExpression select)
{
bool isFirst = sb.Length == 0;
if (!isFirst)
{
AppendNewLine(Indentation.Inner);
sb.Append('(');
}
sb.Append("SELECT ");
if (select.IsDistinct)
{
sb.Append("DISTINCT ");
}
if (select.Top != null && !this.isPostgres)
{
sb.Append("TOP (");
Visit(select.Top);
sb.Append(") ");
}
if (select.Columns.Count == 0)
{
sb.Append("0 as Dummy");
}
else
{
this.AppendNewLine(Indentation.Inner);
for (int i = 0, n = select.Columns.Count; i < n; i++)
{
ColumnDeclaration column = select.Columns[i];
AppendColumn(column);
if (i < (n - 1))
{
sb.Append(", ");
this.AppendNewLine(Indentation.Same);
}
else
{
this.Indent(Indentation.Outer);
}
}
}
if (select.From != null)
{
this.AppendNewLine(Indentation.Same);
sb.Append("FROM ");
this.VisitSource(select.From);
}
if (select.Where != null)
{
this.AppendNewLine(Indentation.Same);
sb.Append("WHERE ");
this.Visit(select.Where);
}
if (select.GroupBy.Count > 0)
{
this.AppendNewLine(Indentation.Same);
sb.Append("GROUP BY ");
for (int i = 0, n = select.GroupBy.Count; i < n; i++)
{
Expression exp = select.GroupBy[i];
if (i > 0)
{
sb.Append(", ");
}
this.Visit(exp);
}
}
if (select.OrderBy.Count > 0)
{
this.AppendNewLine(Indentation.Same);
sb.Append("ORDER BY ");
for (int i = 0, n = select.OrderBy.Count; i < n; i++)
{
OrderExpression exp = select.OrderBy[i];
if (i > 0)
{
sb.Append(", ");
}
this.Visit(exp.Expression);
if (exp.OrderType != OrderType.Ascending)
{
sb.Append(" DESC");
}
}
}
if (select.Top != null && this.isPostgres)
{
this.AppendNewLine(Indentation.Same);
sb.Append("LIMIT ");
Visit(select.Top);
}
if (select.IsForXmlPathEmpty)
{
this.AppendNewLine(Indentation.Same);
sb.Append("FOR XML PATH('')");
}
if (!isFirst)
{
sb.Append(')');
AppendNewLine(Indentation.Outer);
}
return(select);
}
internal static bool IsInitialProjection(SelectExpression select)
{
return(select.From is TableExpression);
}
static bool CanMergeWithFrom(SelectExpression select, bool isTopLevel)
{
SelectExpression?fromSelect = GetLeftMostSelect(select.From !);
if (fromSelect == null)
{
return(false);
}
if (!IsColumnProjection(fromSelect))
{
return(false);
}
bool selHasOrderBy = select.OrderBy.Count > 0;
bool selHasGroupBy = select.GroupBy.Count > 0;
bool frmHasOrderBy = fromSelect.OrderBy.Count > 0;
bool frmHasGroupBy = fromSelect.GroupBy.Count > 0;
// both cannot have orderby
if (selHasOrderBy && frmHasOrderBy)
{
return(false);
}
// both cannot have groupby
if (selHasGroupBy && frmHasGroupBy)
{
return(false);
}
// this are distinct operations
if (select.IsReverse || fromSelect.IsReverse)
{
return(false);
}
// cannot move forward order-by if outer has group-by
if (frmHasOrderBy && (selHasGroupBy || select.IsDistinct || AggregateChecker.HasAggregates(select)))
{
return(false);
}
// cannot move forward group-by if outer has where clause
if (frmHasGroupBy /*&& (select.Where != null)*/) // need to assert projection is the same in order to move group-by forward
{
return(false);
}
// cannot move forward a take if outer has take or skip or distinct
if (fromSelect.Top != null && (select.Top != null || /*select.Skip != null ||*/ select.IsDistinct || selHasGroupBy || HasApplyJoin(select.From !) || select.Where != null))
{
return(false);
}
// cannot move forward a skip if outer has skip or distinct
//if (fromSelect.Skip != null && (select.Skip != null || select.Distinct || selHasAggregates || selHasGroupBy))
// return false;
// cannot move forward a distinct if outer has take, skip, groupby or a different projection
if (fromSelect.IsDistinct && (select.Top != null || /*select.Skip != null ||*/ !IsNameMapProjection(select) || selHasGroupBy || (selHasOrderBy && !isTopLevel) || AggregateChecker.HasAggregates(select)))
{
return(false);
}
return(true);
}