protected virtual Expression VisitBatch(DbBatchExpression batch)
{
var operation = this.Visit(batch.Operation) as LambdaExpression;
var batchSize = this.Visit(batch.BatchSize);
var stream = this.Visit(batch.Stream);
return(this.UpdateBatch(batch, batch.Input, operation, batchSize, stream));
}
protected virtual Expression BuildExecuteBatch(DbBatchExpression batch)
{
var operation = this.Parameterize(batch.Operation.Body);
var commandText = this.linguist.Format(operation);
var namedValues = DbNamedValueGatherer.Gather(operation);
var command = new QueryCommand(commandText, namedValues.Select(v => new QueryParameter(v.Name, v.Type, v.QueryType)));
var values = namedValues.Select(v => Expression.Convert(this.Visit(v.Value), typeof(object))).ToArray() as Expression[];
var paramSets = Expression.Call
(
typeof(Enumerable), nameof(Enumerable.Select), new Type[] { batch.Operation.Parameters[1].Type, typeof(object[]) },
batch.Input,
Expression.Lambda(Expression.NewArrayInit(typeof(object), values), new[] { batch.Operation.Parameters[1] })
);
var plan = null as Expression;
var projection = ProjectionFinder.FindProjection(operation);
if (projection != null)
{
var saveScope = this.scope;
var reader = Expression.Parameter(typeof(FieldReader), "r" + nReaders++);
this.scope = new Scope(this.scope, reader, projection.Select.Alias, projection.Select.Columns);
var projector = Expression.Lambda(this.Visit(projection.Projector), reader);
this.scope = saveScope;
var entity = EntityFinder.Find(projection.Projector);
command = new QueryCommand(command.CommandText, command.Parameters);
plan = Expression.Call
(
this.executor, nameof(QueryExecutor.ExecuteBatch), new Type[] { projector.Body.Type },
Expression.Constant(command),
paramSets,
projector,
Expression.Constant(entity, typeof(MappingEntity)),
batch.BatchSize,
batch.Stream
);
}
else
{
plan = Expression.Call
(
this.executor, nameof(QueryExecutor.ExecuteBatch), null,
Expression.Constant(command),
paramSets,
batch.BatchSize,
batch.Stream
);
}
return(plan);
}
protected DbBatchExpression UpdateBatch(DbBatchExpression batch, Expression input, LambdaExpression operation, Expression batchSize, Expression stream)
{
if (input != batch.Input || operation != batch.Operation || batchSize != batch.BatchSize || stream != batch.Stream)
{
return(new DbBatchExpression(input, operation, batchSize, stream));
}
return(batch);
}
protected virtual bool CompareBatch(DbBatchExpression x, DbBatchExpression y)
{
return
(
this.Compare(x.Input, y.Input) &&
this.Compare(x.Operation, y.Operation) &&
this.Compare(x.BatchSize, y.BatchSize) &&
this.Compare(x.Stream, y.Stream)
);
}
protected override Expression VisitBatch(DbBatchExpression batch)
{
if (this.linguist.Language.AllowsMultipleCommands || !IsMultipleCommands(batch.Operation.Body as DbCommandExpression))
{
return(this.BuildExecuteBatch(batch));
}
var source = this.Visit(batch.Input);
var op = this.Visit(batch.Operation.Body);
var fn = Expression.Lambda(op, batch.Operation.Parameters[1]);
return(Expression.Call(typeof(DbExecutionBuilder), nameof(DbExecutionBuilder.Batch), new Type[] { TypeHelper.GetElementType(source.Type), batch.Operation.Body.Type }, source, fn, batch.Stream));
}
protected virtual Expression VisitBatch(DbBatchExpression batch)
{
this.Write("Batch(");
this.WriteLine(Indentation.Inner);
this.Visit(batch.Input);
this.Write(",");
this.WriteLine(Indentation.Same);
this.Visit(batch.Operation);
this.Write(",");
this.WriteLine(Indentation.Same);
this.Visit(batch.BatchSize);
this.Write(", ");
this.Visit(batch.Stream);
this.WriteLine(Indentation.Outer);
this.Write(")");
return(batch);
}
