private ColumnProjector(Expression expression, IEnumerable <ColumnDeclaration> existingColumns, TableAlias newAlias, IEnumerable <TableAlias> existingAliases)
{
this.newAlias = newAlias;
this.existingAliases = new HashSet <TableAlias>(existingAliases, TableAlias.Comparer);
this.map = new Dictionary <ColumnExpression, ColumnExpression>();
if (existingColumns != null)
{
this.columns = new List <ColumnDeclaration>(existingColumns);
this.columnNames = new HashSet <string>(existingColumns.Select(c => c.Name), StringComparer.Ordinal);
}
else
{
this.columns = new List <ColumnDeclaration>();
this.columnNames = new HashSet <string>(StringComparer.Ordinal);
}
this.candidates = Nominator.Nominate(expression);
}
private bool GetEquiJoinKeyExpressions(Expression predicate, TableAlias outerAlias, List <Expression> outerExpressions, List <Expression> innerExpressions)
{
if (predicate.NodeType == ExpressionType.Equal)
{
var b = (BinaryExpression)predicate;
ColumnExpression leftCol = this.GetColumnExpression(b.Left);
ColumnExpression rightCol = this.GetColumnExpression(b.Right);
if (leftCol != null && rightCol != null)
{
if (leftCol.Alias == outerAlias)
{
outerExpressions.Add(b.Left);
innerExpressions.Add(b.Right);
return(true);
}
else if (rightCol.Alias == outerAlias)
{
innerExpressions.Add(b.Left);
outerExpressions.Add(b.Right);
return(true);
}
}
}
bool hadKey = false;
var parts = predicate.Split(ExpressionType.And, ExpressionType.AndAlso);
if (parts.Length > 1)
{
foreach (var part in parts)
{
bool hasOuterAliasReference = ReferencedAliasGatherer.Gather(part).Contains(outerAlias);
if (hasOuterAliasReference)
{
if (!GetEquiJoinKeyExpressions(part, outerAlias, outerExpressions, innerExpressions))
{
return(false);
}
hadKey = true;
}
}
}
return(hadKey);
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
if (isTopLevel)
{
isTopLevel = false;
this.currentSelect = proj.Select;
Expression projector = this.Visit(proj.Projector);
if (projector != proj.Projector || this.currentSelect != proj.Select)
{
return(new ProjectionExpression(this.currentSelect, projector, proj.Aggregator));
}
return(proj);
}
if (proj.IsSingleton && this.CanJoinOnServer(this.currentSelect))
{
TableAlias newAlias = new TableAlias();
this.currentSelect = this.currentSelect.AddRedundantSelect(newAlias);
// remap any references to the outer select to the new alias;
SelectExpression source = (SelectExpression)ColumnMapper.Map(proj.Select, newAlias, this.currentSelect.Alias);
// add outer-join test
ProjectionExpression pex = this.dialect.AddOuterJoinTest(new ProjectionExpression(source, proj.Projector));
var pc = ColumnProjector.ProjectColumns(pex.Projector, this.currentSelect.Columns, this.currentSelect.Alias, newAlias, proj.Select.Alias);
JoinExpression join = new JoinExpression(JoinType.OuterApply, this.currentSelect.From, pex.Select, null);
this.currentSelect = new SelectExpression(this.currentSelect.Alias, pc.Columns, join, null);
return(this.Visit(pc.Projector));
}
var saveTop = this.isTopLevel;
var saveSelect = this.currentSelect;
this.isTopLevel = true;
this.currentSelect = null;
Expression result = base.VisitProjection(proj);
this.isTopLevel = saveTop;
this.currentSelect = saveSelect;
return(result);
}
private Expression MakeSubquery(Expression expression)
{
var newAlias = new TableAlias();
var aliases = TableAliasGatherer.Gather(expression);
var decls = new List <ColumnDeclaration>();
foreach (var ta in aliases)
{
foreach (var col in this.columns[ta])
{
string name = decls.GetAvailableColumnName(col.Name);
var decl = new ColumnDeclaration(name, col, col.SqlType);
decls.Add(decl);
var newCol = new ColumnExpression(col.Type, col.SqlType, newAlias, name);
this.map.Add(col, newCol);
}
}
return(new SelectExpression(newAlias, decls, expression, null));
}
public SelectExpression(
TableAlias alias,
IEnumerable <ColumnDeclaration> columns,
Expression from,
Expression where,
IEnumerable <OrderExpression> orderBy,
IEnumerable <Expression> groupBy,
bool isDistinct,
Expression skip,
Expression take,
bool reverse
)
: base(DbExpressionType.Select, typeof(void), alias)
{
this.columns = columns.ToReadOnly();
this.isDistinct = isDistinct;
this.from = from;
this.where = where;
this.orderBy = orderBy.ToReadOnly();
this.groupBy = groupBy.ToReadOnly();
this.take = take;
this.skip = skip;
this.reverse = reverse;
}
public static ProjectedColumns ProjectColumns(Expression expression, IEnumerable <ColumnDeclaration> existingColumns, TableAlias newAlias, params TableAlias[] existingAliases)
{
return(ProjectColumns(expression, existingColumns, newAlias, (IEnumerable <TableAlias>)existingAliases));
}
public static ProjectedColumns ProjectColumns(Expression expression, IEnumerable <ColumnDeclaration> existingColumns, TableAlias newAlias, IEnumerable <TableAlias> existingAliases)
{
ColumnProjector projector = new ColumnProjector(expression, existingColumns, newAlias, existingAliases);
Expression expr = projector.Visit(expression);
return(new ProjectedColumns(expr, projector.columns.AsReadOnly()));
}
/// <summary>
/// Rebind order expressions to reference a new alias and add to column declarations if necessary
/// </summary>
protected virtual BindResult RebindOrderings(IEnumerable <OrderExpression> orderings, TableAlias alias, HashSet <TableAlias> existingAliases, IEnumerable <ColumnDeclaration> existingColumns)
{
List <ColumnDeclaration> newColumns = null;
List <OrderExpression> newOrderings = new List <OrderExpression>();
foreach (OrderExpression ordering in orderings)
{
Expression expr = ordering.Expression;
ColumnExpression column = expr as ColumnExpression;
if (column == null || (existingAliases != null && existingAliases.Contains(column.Alias)))
{
// check to see if a declared column already contains a similar expression
int iOrdinal = 0;
foreach (ColumnDeclaration decl in existingColumns)
{
ColumnExpression declColumn = decl.Expression as ColumnExpression;
if (decl.Expression == ordering.Expression ||
(column != null && declColumn != null && column.Alias == declColumn.Alias && column.Name == declColumn.Name))
{
// found it, so make a reference to this column
expr = new ColumnExpression(column.Type, column.SqlType, alias, decl.Name);
break;
}
iOrdinal++;
}
// if not already projected, add a new column declaration for it
if (expr == ordering.Expression)
{
if (newColumns == null)
{
newColumns = new List <ColumnDeclaration>(existingColumns);
existingColumns = newColumns;
}
string colName = column != null ? column.Name : "c" + iOrdinal;
colName = newColumns.GetAvailableColumnName(colName);
var colType = SqlType.Get(expr.Type);
newColumns.Add(new ColumnDeclaration(colName, ordering.Expression, colType));
expr = new ColumnExpression(expr.Type, colType, alias, colName);
}
newOrderings.Add(new OrderExpression(ordering.OrderType, expr));
}
}
return(new BindResult(existingColumns, newOrderings));
}
protected AliasedExpression(DbExpressionType nodeType, Type type, TableAlias alias)
: base(nodeType, type)
{
this.alias = alias;
}
public bool Equals(TableAlias other)
{
return(other.hashCode == hashCode);
}
public TableExpression(TableAlias alias, IEntityMapping entity)
: base(DbExpressionType.Table, typeof(void), alias)
{
this.entity = entity;
}
public static Expression Map(Expression expression, TableAlias newAlias, params TableAlias[] oldAliases)
{
return(Map(expression, newAlias, (IEnumerable <TableAlias>)oldAliases));
}
public static Expression Map(Expression expression, TableAlias newAlias, IEnumerable <TableAlias> oldAliases)
{
return(new ColumnMapper(oldAliases, newAlias).Visit(expression));
}
private ColumnMapper(IEnumerable <TableAlias> oldAliases, TableAlias newAlias)
{
this.oldAliases = new HashSet <TableAlias>(oldAliases, TableAlias.Comparer);
this.newAlias = newAlias;
}
private void ClearColumnsUsed(TableAlias alias)
{
this.allColumnsUsed[alias] = new HashSet <string>();
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
SelectExpression save = this.currentSelect;
this.currentSelect = proj.Select;
try
{
if (!this.isTopLevel)
{
if (this.CanJoinOnClient(this.currentSelect))
{
// make a query that combines all the constraints from the outer queries into a single select
SelectExpression newOuterSelect = (SelectExpression)QueryDuplicator.Duplicate(save);
// remap any references to the outer select to the new alias;
SelectExpression newInnerSelect = (SelectExpression)ColumnMapper.Map(proj.Select, newOuterSelect.Alias, save.Alias);
// add outer-join test
ProjectionExpression newInnerProjection = this.dbExpressionBuilder.AddOuterJoinTest(new ProjectionExpression(newInnerSelect, proj.Projector));
newInnerSelect = newInnerProjection.Select;
Expression newProjector = newInnerProjection.Projector;
TableAlias newAlias = new TableAlias();
var pc = ColumnProjector.ProjectColumns(newProjector, null, newAlias, newOuterSelect.Alias, newInnerSelect.Alias);
JoinExpression join = new JoinExpression(JoinType.OuterApply, newOuterSelect, newInnerSelect, null);
SelectExpression joinedSelect = new SelectExpression(newAlias, pc.Columns, join, null, null, null, proj.IsSingleton, null, null, false);
// apply client-join treatment recursively
this.currentSelect = joinedSelect;
newProjector = this.Visit(pc.Projector);
// compute keys (this only works if join condition was a single column comparison)
List <Expression> outerKeys = new List <Expression>();
List <Expression> innerKeys = new List <Expression>();
if (this.GetEquiJoinKeyExpressions(newInnerSelect.Where, newOuterSelect.Alias, outerKeys, innerKeys))
{
// outerKey needs to refer to the outer-scope's alias
var outerKey = outerKeys.Select(k => ColumnMapper.Map(k, save.Alias, newOuterSelect.Alias));
// innerKey needs to refer to the new alias for the select with the new join
var innerKey = innerKeys.Select(k => ColumnMapper.Map(k, joinedSelect.Alias, ((ColumnExpression)k).Alias));
ProjectionExpression newProjection = new ProjectionExpression(joinedSelect, newProjector, proj.Aggregator);
return(new ClientJoinExpression(newProjection, outerKey, innerKey));
}
}
else
{
bool saveJoin = this.canJoinOnClient;
this.canJoinOnClient = false;
var result = base.VisitProjection(proj);
this.canJoinOnClient = saveJoin;
return(result);
}
}
else
{
this.isTopLevel = false;
}
return(base.VisitProjection(proj));
}
finally
{
this.currentSelect = save;
}
}
