casacore
Loading...
Searching...
No Matches
BaseEngine.h
Go to the documentation of this file.
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: casa-feedback@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#ifndef MEAS_BASEENGINE_H
27#define MEAS_BASEENGINE_H
28
29//# Includes
30#include <casacore/casa/aips.h>
31#include <casacore/tables/TaQL/ExprNode.h>
32#include <casacore/measures/TableMeasures/ScalarMeasColumn.h>
33#include <casacore/measures/TableMeasures/ArrayMeasColumn.h>
34#include <casacore/casa/Arrays/Array.h>
35
36namespace casacore {
37
38 // <summary>
39 // Abstract base class for the TaQL UDF conversion engines
40 // </summary>
41
42 // <use visibility=export>
43
44 // <reviewed reviewer="" date="" tests="tMeas.cc">
45 // </reviewed>
46
47 // <prerequisite>
48 //# Classes you should understand before using this one.
49 // <li> EngineBase
50 // </prerequisite>
51
52 // <synopsis>
53 // DopplerEngine defines Engines (user defined functions) that can be used
54 // in TaQL to convert Measures for dopplers.
55 // In this way such derived values appear to be ordinary TaQL functions.
56 //
57 // Doppler conversions require a MeasFrame containing sky direction,
58 // epoch and position on earth.
59 // In TaQL these functions can be called like:
60 // <srcblock>
61 // meas.rv ('TOPO', 1 'm/s', 'LSRK', 'CasA', date(),
62 // [1e6m,1e6m,1e6m], 'WGS84')
63 // </srcblock>
64 // which converts the dopplers from LSRK to TOPO.
65 // <ul>
66 // <li>
67 // <src>toref</src> is a single constant string.
68 // <li>
69 // <src>pos</src> can have various value types. A single numeric array is
70 // a series of RA,DEC in J2000. If given as a set, the last argument of the
71 // set can be the reference types of the values in the set. The values can
72 // be strings (indicating planetary objects) or value pairs giving lon,lat.
73 // The default reference type is J2000.
74 // </ul>
75 // All such functions return data with type double and unit Hz.
76 //
77 // Dopplers can be given like:
78 // [v1,v2,...], fromRef
79 // where fromRef is the reference type.
80 //
81 // A doppler can also be a table column which usually knows its type.
82 // It can also be an expression (e.g. DOPPLER[0,]) which also knows the type.
83 // </synopsis>
84
85 // <motivation>
86 // It makes it possible to handle measures in TaQL.
87 // </motivation>
88
90 {
91 public:
93 : itsIsConst (False),
94 itsNDim (-1)
95 {}
96
97 virtual ~BaseEngine();
98
99 // Adapt the output shape and dimensionality for possible constant values.
100 // It also sets the itsIsConst flag.
101 // If the given shape is not empty the shape is set to it and an extra axis
102 // is added if nvalues>0 (for e.g. LONLAT).
103 // If nvalues=1, the first axis is removed from the shape.
104 // Note that the shape might have been set to the column's shape if a
105 // measure column is used.
106 void adaptForConstant (const IPosition& shapeConstant, uInt nvalues=0);
107
108 // Extend the shape (if not empty) with the engine's shape.
109 // If the engine is not const, itsIsConst is cleared.
110 void extendBase (const BaseEngine&, Bool removeFirstAxis=False);
111
112 // Get the output shape.
113 const IPosition& shape() const
114 { return itsShape; }
115
116 // Get the output dimensionality.
117 Int ndim() const
118 { return itsNDim; }
119
120 // Get the unit of the function's result.
121 const Unit& unit() const
122 { return itsOutUnit; }
123
124 // Get the unit of the expression.
125 const Unit& inUnit() const
126 { return itsInUnit; }
127
128 // Tell if the expression is constant.
130 { return itsIsConst; }
131
132 protected:
133 // Let a derived class derive its attributes.
134 // The default implementation does nothing.
135 virtual void deriveAttr (const Unit& unit, Int nval);
136
137 // Let a derived class set its value type.
138 // By default is does nothing.
139 virtual void setValueType (Int valueType);
140
141 // Let a derived class strip part of the reference type.
142 // The default implementation returns the full type string.
143 virtual String stripMeasType (const String& type);
144
145
146 //# Data members.
149 Int itsNDim; // <0 unknown shape, 0 scalar, >0 known shape
153 };
154
155} //end namespace
156
157#endif
Bool isConstant() const
Tell if the expression is constant.
Definition BaseEngine.h:129
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:125
const Unit & unit() const
Get the unit of the function's result.
Definition BaseEngine.h:121
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:117
const IPosition & shape() const
Get the output shape.
Definition BaseEngine.h:113
TableExprNode itsExprNode
Definition BaseEngine.h:152
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:223
this file contains all the compiler specific defines
Definition mainpage.dox:28
const Bool False
Definition aipstype.h:42
unsigned int uInt
Definition aipstype.h:49
int Int
Definition aipstype.h:48
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:40