private DbExpression RewriteRow(DbExpression expression, RowType rowType)
{
DbLambdaExpression lambdaExpression = expression as DbLambdaExpression;
DbNewInstanceExpression newRow;
if (lambdaExpression != null)
{
// NOTE: We rely on the fact that today span cannot be done over queries containing DbLambdaExpressions
// created by users, because user-created expressions cannot be used for querying in O-space.
// If that were to change, pushing span beyond a LambdaExpression could cause variable name
// collisions between the variable names used in the Lambda and the names generated by the
// RelationshipNavigationVisitor.
newRow = lambdaExpression.Lambda.Body as DbNewInstanceExpression;
}
else
{
newRow = expression as DbNewInstanceExpression;
}
Dictionary <int, DbExpression> unmodifiedColumns = null;
Dictionary <int, DbExpression> spannedColumns = null;
for (int idx = 0; idx < rowType.Properties.Count; idx++)
{
// Retrieve the property that represents the current column
EdmProperty columnProp = rowType.Properties[idx];
// Construct an expression that defines the current column.
DbExpression columnExpr = null;
if (newRow != null)
{
// For a row-constructing NewInstance expression, the corresponding argument can simply be used
columnExpr = newRow.Arguments[idx];
}
else
{
// For all other expressions the property corresponding to the column name must be retrieved
// from the row-typed expression
columnExpr = expression.Property(columnProp.Name);
}
DbExpression spannedColumn = this.Rewrite(columnExpr);
if (!object.ReferenceEquals(spannedColumn, columnExpr))
{
// If so, then update the dictionary of column index to span information
if (null == spannedColumns)
{
spannedColumns = new Dictionary <int, DbExpression>();
}
spannedColumns[idx] = spannedColumn;
}
else
{
// Otherwise, update the dictionary of column index to unmodified expression
if (null == unmodifiedColumns)
{
unmodifiedColumns = new Dictionary <int, DbExpression>();
}
unmodifiedColumns[idx] = columnExpr;
}
}
// A new expression need only be built if at least one column was spanned
if (null == spannedColumns)
{
// No columns were spanned, indicate that the original expression should remain.
return(expression);
}
else
{
// At least one column was spanned, so build a new row constructor that defines the new row, including spanned columns.
List <DbExpression> columnArguments = new List <DbExpression>(rowType.Properties.Count);
List <EdmProperty> properties = new List <EdmProperty>(rowType.Properties.Count);
for (int idx = 0; idx < rowType.Properties.Count; idx++)
{
EdmProperty columnProp = rowType.Properties[idx];
DbExpression columnDef = null;
if (!spannedColumns.TryGetValue(idx, out columnDef))
{
columnDef = unmodifiedColumns[idx];
}
columnArguments.Add(columnDef);
properties.Add(new EdmProperty(columnProp.Name, columnDef.ResultType));
}
// Copy over any eLinq initializer metadata (if present, or null if not).
// Note that this initializer metadata does not strictly match the new row type
// that includes spanned columns, but will be correct once the object materializer
// has interpreted the query results to produce the correct value for each colum.
RowType rewrittenRow = new RowType(properties, rowType.InitializerMetadata);
TypeUsage rewrittenRowTypeUsage = TypeUsage.Create(rewrittenRow);
DbExpression rewritten = rewrittenRowTypeUsage.New(columnArguments);
// SQLBUDT #554182: If we insert a new projection we should should make sure to
// not interfere with the nullability of the input.
// In particular, if the input row is null and we construct a new row as a projection over its columns
// we would get a row consisting of nulls, instead of a null row.
// Thus, given an input X, we rewritte it as: if (X is null) then NULL else rewritten.
if (newRow == null)
{
DbExpression condition = DbExpressionBuilder.CreateIsNullExpressionAllowingRowTypeArgument(expression);
DbExpression nullExpression = DbExpressionBuilder.Null(rewrittenRowTypeUsage);
rewritten = DbExpressionBuilder.Case(
new List <DbExpression>(new DbExpression[] { condition }),
new List <DbExpression>(new DbExpression[] { nullExpression }),
rewritten);
}
// Add an entry to the spanned row type => original row type map for the new row type.
AddSpannedRowType(rewrittenRow, expression.ResultType);
if (lambdaExpression != null && newRow != null)
{
rewritten = DbLambda.Create(rewritten, lambdaExpression.Lambda.Variables).Invoke(lambdaExpression.Arguments);
}
return(rewritten);
}
}
private DbExpression RewriteRow(DbExpression expression, RowType rowType)
{
DbLambdaExpression lambdaExpression = expression as DbLambdaExpression;
DbNewInstanceExpression instanceExpression = lambdaExpression == null ? expression as DbNewInstanceExpression : lambdaExpression.Lambda.Body as DbNewInstanceExpression;
Dictionary <int, DbExpression> dictionary1 = (Dictionary <int, DbExpression>)null;
Dictionary <int, DbExpression> dictionary2 = (Dictionary <int, DbExpression>)null;
for (int index = 0; index < rowType.Properties.Count; ++index)
{
EdmProperty property = rowType.Properties[index];
DbExpression expression1 = instanceExpression == null ? (DbExpression)expression.Property(property.Name) : instanceExpression.Arguments[index];
DbExpression dbExpression = this.Rewrite(expression1);
if (!object.ReferenceEquals((object)dbExpression, (object)expression1))
{
if (dictionary2 == null)
{
dictionary2 = new Dictionary <int, DbExpression>();
}
dictionary2[index] = dbExpression;
}
else
{
if (dictionary1 == null)
{
dictionary1 = new Dictionary <int, DbExpression>();
}
dictionary1[index] = expression1;
}
}
if (dictionary2 == null)
{
return(expression);
}
List <DbExpression> dbExpressionList = new List <DbExpression>(rowType.Properties.Count);
List <EdmProperty> edmPropertyList = new List <EdmProperty>(rowType.Properties.Count);
for (int key = 0; key < rowType.Properties.Count; ++key)
{
EdmProperty property = rowType.Properties[key];
DbExpression dbExpression = (DbExpression)null;
if (!dictionary2.TryGetValue(key, out dbExpression))
{
dbExpression = dictionary1[key];
}
dbExpressionList.Add(dbExpression);
edmPropertyList.Add(new EdmProperty(property.Name, dbExpression.ResultType));
}
RowType spannedType = new RowType((IEnumerable <EdmProperty>)edmPropertyList, rowType.InitializerMetadata);
TypeUsage typeUsage = TypeUsage.Create((EdmType)spannedType);
DbExpression dbExpression1 = (DbExpression)typeUsage.New((IEnumerable <DbExpression>)dbExpressionList);
if (instanceExpression == null)
{
dbExpression1 = (DbExpression)DbExpressionBuilder.Case((IEnumerable <DbExpression>) new List <DbExpression>((IEnumerable <DbExpression>) new DbExpression[1]
{
(DbExpression)expression.IsNull()
}), (IEnumerable <DbExpression>) new List <DbExpression>((IEnumerable <DbExpression>) new DbExpression[1]
{
(DbExpression)typeUsage.Null()
}), dbExpression1);
}
this.AddSpannedRowType(spannedType, expression.ResultType);
if (lambdaExpression != null && instanceExpression != null)
{
dbExpression1 = (DbExpression)DbLambda.Create(dbExpression1, (IEnumerable <DbVariableReferenceExpression>)lambdaExpression.Lambda.Variables).Invoke((IEnumerable <DbExpression>)lambdaExpression.Arguments);
}
return(dbExpression1);
}