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ExprAggrNode.h
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1//# ExprAggrNode.h: TaQL node representing a scalar aggregate function
2//# Copyright (C) 2013
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//# $Id: TaQLNode.h 21051 2011-04-20 11:46:29Z gervandiepen $
27
28#ifndef TABLES_EXPRAGGRNODE_H
29#define TABLES_EXPRAGGRNODE_H
30
31//# Includes
32#include <casacore/casa/aips.h>
33#include <casacore/tables/TaQL/ExprFuncNode.h>
34
35
36namespace casacore { //# NAMESPACE CASACORE - BEGIN
37
38 //# Forward Declarations.
39 class TableExprGroupFuncBase;
40 class TableExprGroupFuncSet;
41
42// <summary>
43// TaQL node representing a scalar aggregate function
44// </summary>
45
46// <use visibility=local>
47
48// <reviewed reviewer="" date="" tests="tTableGram">
49// </reviewed>
50
51// <synopsis>
52// A TableExprAggrNode object is a special TableExprFuncNode object.
53// Instead of operating on a single row, it operates on a group of table
54// rows, usually formed by means of the GROUPBY clause.
55// It aggregates the values in the rows in the group by means of an
56// aggregation function derived from TableExprGroupFuncBase.
57// Several standard aggregation functions (e.g., gmean, gmin, gsum) are
58// defined in TaQL and implemented this way.
59//
60// There are two types of aggregate function implementations:
61// <ul>
62// <li> Immediate aggregate functions calculate the results while the
63// groups are being formed. In this way they step sequentially through
64// the data.
65// This is only possible for functions that do not have to keep
66// to many data in memory.
67// <li> Lazy aggregate functions calculate the results after the groups are
68// formed using the vector of TableExprIds they get per group.
69// In this way only data for a single group might need to be kept in
70// memory. It is used, for instance, to calculate the median.
71// </ul>
72// Note that this class handles operands that are a scalar or array.
73// If array, all values in the array are used as individual values.
74// Class TableExprAggrNodeArray handles aggregate functions giving an
75// array result (e.g., function <src>gaggr</src>).
76//
77// It is also possible to define an aggregate function in a UDF derived
78// from class UDFBase. Such an aggregate function is instantiated as a
79// TableExprUDFNode(Array) object, not as TabeExprAggrNode(Array).
80// These functions are always lazy.
81// </synopsis>
82
84 {
85 public:
86 // Constructor.
88 const TableExprNodeSet& source,
89 const vector<TENShPtr>& nodes,
90 const Block<Int>& dtypeOper);
91
92 // Check the operands of the aggregate function and return the
93 // result's data type.
95 ValueType& resVT, FunctionType ftype,
96 std::vector<TENShPtr>& nodes);
97
98 // Get the nodes representing an aggregate function.
99 virtual void getAggrNodes (std::vector<TableExprNodeRep*>& aggr);
100
101 // Get the operand node.
103 { return (operands().empty() ? TENShPtr() : operands()[0]); }
104
105 // Create the correct aggregate function object.
106 // It is also kept in case it is a lazy aggregate function.
108
109 // Is the aggregate function a lazy or an immediate one?
110 virtual Bool isLazyAggregate() const;
111
112 // Functions to get the result of an aggregate function.
113 // <group>
114 virtual Bool getBool (const TableExprId& id);
115 virtual Int64 getInt (const TableExprId& id);
116 virtual Double getDouble (const TableExprId& id);
117 virtual DComplex getDComplex (const TableExprId& id);
118 virtual String getString (const TableExprId& id);
119 virtual MVTime getDate (const TableExprId& id);
120 // </group>
121
122 private:
123 // Do the actual creation of the correct aggregate function object.
125
126 //# Data members.
128 };
129
130
131} //# NAMESPACE CASACORE - END
132
133#endif
simple 1-D array
Definition Block.h:200
String: the storage and methods of handling collections of characters.
Definition String.h:225
virtual Double getDouble(const TableExprId &id)
TENShPtr operand()
Get the operand node.
virtual Bool getBool(const TableExprId &id)
Functions to get the result of an aggregate function.
TableExprGroupFuncBase * doMakeGroupAggrFunc()
Do the actual creation of the correct aggregate function object.
virtual Int64 getInt(const TableExprId &id)
TableExprAggrNode(FunctionType, NodeDataType, ValueType, const TableExprNodeSet &source, const vector< TENShPtr > &nodes, const Block< Int > &dtypeOper)
Constructor.
CountedPtr< TableExprGroupFuncBase > itsFunc
virtual String getString(const TableExprId &id)
virtual CountedPtr< TableExprGroupFuncBase > makeGroupAggrFunc()
Create the correct aggregate function object.
virtual MVTime getDate(const TableExprId &id)
virtual DComplex getDComplex(const TableExprId &id)
static NodeDataType checkOperands(Block< Int > &dtypeOper, ValueType &resVT, FunctionType ftype, std::vector< TENShPtr > &nodes)
Check the operands of the aggregate function and return the result's data type.
virtual void getAggrNodes(std::vector< TableExprNodeRep * > &aggr)
Get the nodes representing an aggregate function.
virtual Bool isLazyAggregate() const
Is the aggregate function a lazy or an immediate one?
const std::vector< TENShPtr > & operands() const
Some functions to be used by TableExprNodeFuncArray.
Abstract base class for classes calculating an aggregated group result.
Definition ExprGroup.h:202
NodeDataType
Define the data types of a node.
ValueType
Define the value types.
Class to hold multiple table expression nodes.
this file contains all the compiler specific defines
Definition mainpage.dox:28
long long Int64
Define the extra non-standard types used by Casacore (like proposed uSize, Size)
Definition aipsxtype.h:38
CountedPtr< TableExprNodeRep > TENShPtr
Definition ExprNodeRep.h:57
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:42
double Double
Definition aipstype.h:55