// Reads //
public static StagedReadName RenderStagedReadPlan(Workspace Home, HScriptParser.Crudam_readContext context)
{
// Get the data source //
DataSet data = VisitorHelper.GetData(Home, context.full_table_name());
string alias =
(context.K_AS() != null)
? context.IDENTIFIER().GetText()
: data.Name;
// Create a local heap to work off of //
MemoryStruct local_heap = new MemoryStruct(true);
// Create a record register //
StreamRegister memory = new StreamRegister(null);
// Create expression visitor //
ExpressionVisitor exp_vis = new ExpressionVisitor(local_heap, Home, alias, data.Columns, memory);
// Where clause //
Predicate where = VisitorHelper.GetWhere(exp_vis, context.where_clause());
// Create a reader //
RecordReader reader = data.OpenReader(where);
// Attach the reader to the register //
memory.BaseStream = reader;
// Create the action visitor //
ActionVisitor act_vis = new ActionVisitor(Home, local_heap, exp_vis);
// Get the declarations //
if (context.crudam_declare_many() != null)
{
VisitorHelper.AllocateMemory(Home, local_heap, exp_vis, context.crudam_declare_many());
}
// Get the initial actionset //
TNode pre_run =
(context.init_action() != null)
? act_vis.ToNode(context.init_action().query_action())
: new TNodeNothing(null);
// Get the main actionset //
TNode run = act_vis.ToNode(context.main_action().query_action());
// Get the final actionset //
TNode post_run =
(context.final_action() != null)
? act_vis.ToNode(context.final_action().query_action())
: new TNodeNothing(null);
return new StagedReadName(reader, pre_run, run, post_run);
}
public static long Update(DataSet Data, Key K, FNodeSet Fields, Predicate BaseDataFilter)
{
// Check that the field indicies and the maps have the same length //
if (K.Count != Fields.Count)
throw new Exception(string.Format("Field collection passed [{0}] has fewer elements than the map collection passed [{0}]", K.Count, Fields.Count));
// Create the total append count //
long CountOf = 0;
// Loop through each extent //
foreach (RecordSet rs in Data.Extents)
{
// Open a stream //
RecordReader rr = new RecordReader(rs, BaseDataFilter);
// Create a register //
Register mem = new StreamRegister(rr);
// Assign the register to the fields //
Fields.AssignRegister(mem);
// Update the data //
while (!rr.EndOfData)
{
Update(rr.Read(), K, Fields);
CountOf++;
rr.Advance();
}
//
if (rs.IsAttached)
BinarySerializer.Flush(rs);
}
// No need to flush the data set //
return CountOf;
}
// Constructor //
public RecordReader(RecordSet From, Predicate Where)
{
this._ptrRecord = DEFAULT_POINTER;
this._Data = From;
this._Where = Where;
// Assign the where to a register pointing to 'this' //
StreamRegister reg = new StreamRegister(this);
this._Where.Node.AssignRegister(reg);
// Fix the default //
if (!Where.Default)
{
this._IsFiltered = true;
while (!this.CheckFilter && !this.EndOfData)
this.Advance();
}
// This is used to handle the writer class that inherits the reader //
if (From != null)
this._columns = From.Columns;
}
public static FastReadPlan RenderFastReadPlan(Workspace Home, HScriptParser.Crudam_read_fastContext context)
{
// Get the data source //
DataSet data = VisitorHelper.GetData(Home, context.full_table_name());
string alias =
(context.K_AS() != null)
? context.IDENTIFIER().GetText()
: data.Name;
// Create a record register //
StreamRegister memory = new StreamRegister(null);
// Create expression visitor //
ExpressionVisitor exp_vis = new ExpressionVisitor(new MemoryStruct(true), Home, alias, data.Columns, memory);
// Where clause //
Predicate where = VisitorHelper.GetWhere(exp_vis, context.where_clause());
// Create a reader //
RecordReader reader = data.OpenReader(where);
// Attach the reader to the register //
memory.BaseStream = reader;
// Get the fields being returned //
FNodeSet nodes = VisitorHelper.GetReturnStatement(exp_vis, context.return_action().expression_or_wildcard_set());
// Get the output cursor from the return statement //
RecordWriter writer = VisitorHelper.GetWriter(Home, nodes.Columns, context.return_action());
return new FastReadPlan(data, where, nodes, writer);
}
