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BaseEngine.h
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1//# BaseEngine.h: Base class for the TaQL UDF conversion engines
2//# Copyright (C) 2018
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//# $Id$
27
28#ifndef MEAS_BASEENGINE_H
29#define MEAS_BASEENGINE_H
30
31//# Includes
32#include <casacore/casa/aips.h>
33#include <casacore/tables/TaQL/ExprNode.h>
34#include <casacore/measures/TableMeasures/ScalarMeasColumn.h>
35#include <casacore/measures/TableMeasures/ArrayMeasColumn.h>
36#include <casacore/casa/Arrays/Array.h>
37
38namespace casacore {
39
40 // <summary>
41 // Abstract base class for the TaQL UDF conversion engines
42 // </summary>
43
44 // <use visibility=export>
45
46 // <reviewed reviewer="" date="" tests="tMeas.cc">
47 // </reviewed>
48
49 // <prerequisite>
50 //# Classes you should understand before using this one.
51 // <li> EngineBase
52 // </prerequisite>
53
54 // <synopsis>
55 // DopplerEngine defines Engines (user defined functions) that can be used
56 // in TaQL to convert Measures for dopplers.
57 // In this way such derived values appear to be ordinary TaQL functions.
58 //
59 // Doppler conversions require a MeasFrame containing sky direction,
60 // epoch and position on earth.
61 // In TaQL these functions can be called like:
62 // <srcblock>
63 // meas.rv ('TOPO', 1 'm/s', 'LSRK', 'CasA', date(),
64 // [1e6m,1e6m,1e6m], 'WGS84')
65 // </srcblock>
66 // which converts the dopplers from LSRK to TOPO.
67 // <ul>
68 // <li>
69 // <src>toref</src> is a single constant string.
70 // <li>
71 // <src>pos</src> can have various value types. A single numeric array is
72 // a series of RA,DEC in J2000. If given as a set, the last argument of the
73 // set can be the reference types of the values in the set. The values can
74 // be strings (indicating planetary objects) or value pairs giving lon,lat.
75 // The default reference type is J2000.
76 // </ul>
77 // All such functions return data with type double and unit Hz.
78 //
79 // Dopplers can be given like:
80 // [v1,v2,...], fromRef
81 // where fromRef is the reference type.
82 //
83 // A doppler can also be a table column which usually knows its type.
84 // It can also be an expression (e.g. DOPPLER[0,]) which also knows the type.
85 // </synopsis>
86
87 // <motivation>
88 // It makes it possible to handle measures in TaQL.
89 // </motivation>
90
92 {
93 public:
95 : itsIsConst (False),
96 itsNDim (-1)
97 {}
98
99 virtual ~BaseEngine();
100
101 // Adapt the output shape and dimensionality for possible constant values.
102 // It also sets the itsIsConst flag.
103 // If the given shape is not empty the shape is set to it and an extra axis
104 // is added if nvalues>0 (for e.g. LONLAT).
105 // If nvalues=1, the first axis is removed from the shape.
106 // Note that the shape might have been set to the column's shape if a
107 // measure column is used.
108 void adaptForConstant (const IPosition& shapeConstant, uInt nvalues=0);
109
110 // Extend the shape (if not empty) with the engine's shape.
111 // If the engine is not const, itsIsConst is cleared.
112 void extendBase (const BaseEngine&, Bool removeFirstAxis=False);
113
114 // Get the output shape.
115 const IPosition& shape() const
116 { return itsShape; }
117
118 // Get the output dimensionality.
119 Int ndim() const
120 { return itsNDim; }
121
122 // Get the unit of the function's result.
123 const Unit& unit() const
124 { return itsOutUnit; }
125
126 // Get the unit of the expression.
127 const Unit& inUnit() const
128 { return itsInUnit; }
129
130 // Tell if the expression is constant.
132 { return itsIsConst; }
133
134 protected:
135 // Let a derived class derive its attributes.
136 // The default implementation does nothing.
137 virtual void deriveAttr (const Unit& unit, Int nval);
138
139 // Let a derived class set its value type.
140 // By default is does nothing.
141 virtual void setValueType (Int valueType);
142
143 // Let a derived class strip part of the reference type.
144 // The default implementation returns the full type string.
145 virtual String stripMeasType (const String& type);
146
147
148 //# Data members.
151 Int itsNDim; // <0 unknown shape, 0 scalar, >0 known shape
155 };
156
157} //end namespace
158
159#endif
Bool isConstant() const
Tell if the expression is constant.
Definition BaseEngine.h:131
virtual void deriveAttr(const Unit &unit, Int nval)
Let a derived class derive its attributes.
void adaptForConstant(const IPosition &shapeConstant, uInt nvalues=0)
Adapt the output shape and dimensionality for possible constant values.
const Unit & inUnit() const
Get the unit of the expression.
Definition BaseEngine.h:127
const Unit & unit() const
Get the unit of the function's result.
Definition BaseEngine.h:123
virtual void setValueType(Int valueType)
Let a derived class set its value type.
void extendBase(const BaseEngine &, Bool removeFirstAxis=False)
Extend the shape (if not empty) with the engine's shape.
Int ndim() const
Get the output dimensionality.
Definition BaseEngine.h:119
const IPosition & shape() const
Get the output shape.
Definition BaseEngine.h:115
TableExprNode itsExprNode
Definition BaseEngine.h:154
virtual String stripMeasType(const String &type)
Let a derived class strip part of the reference type.
String: the storage and methods of handling collections of characters.
Definition String.h:225
this file contains all the compiler specific defines
Definition mainpage.dox:28
const Bool False
Definition aipstype.h:44
unsigned int uInt
Definition aipstype.h:51
int Int
Definition aipstype.h:50
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:42