internal static Expression <Func <IDataRecord, T> > Optimize(ReadOnlyCollection <string> fieldNames, Expression <Func <IDataRecord, T> > shaper)
{
EnitityUtility.CheckArgumentNotNull(fieldNames, "fieldNames");
EnitityUtility.CheckArgumentNotNull(shaper, "shaper");
OptimizingExpressionVisitor visitor = new OptimizingExpressionVisitor(fieldNames, shaper.Parameters.Single());
return((Expression <Func <IDataRecord, T> >)visitor.Visit(shaper));
}
private void InitializeShaper(IDataRecord record)
{
// Determine the layout of the record.
if (null != fieldNames)
{
// If a record layout has already been established, make sure the current
// record is compatible with it.
ValidateFieldNames(record);
}
else
{
// Initialize a new shaper delegate within a lock (first one wins).
lock (syncLock)
{
if (null != fieldNames)
{
// another thread beat us to it...
ValidateFieldNames(record);
}
else
{
// if the user didn't provide an explicit shaper, generate a default shaper
// based on the element type and the record layout.
ReadOnlyCollection <string> recordFieldNames = GetFieldNames(record);
Expression <Func <IDataRecord, T> > shaper = userSuppliedShaper ??
GetDefaultShaper(recordFieldNames);
// optimize the expression
Func <IDataRecord, T> compiledShaper = OptimizingExpressionVisitor
.Optimize(recordFieldNames, shaper)
.Compile();
// lock down the Materializer instance to use the (first encountered) field information and delegate
fieldNames = recordFieldNames;
shaperDelegate = compiledShaper;
}
}
}
}
