casacore
ScalarQuantColumn.h
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1 //# ScalarQuantColumn.h: Access to a Scalar Quantum Column in a table.
2 //# Copyright (C) 1997,1998,1999,2000,2001
3 //# Associated Universities, Inc. Washington DC, USA.
4 //#
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25 //#
26 //# $Id$
27 
28 #ifndef MEASURES_SCALARQUANTCOLUMN_H
29 #define MEASURES_SCALARQUANTCOLUMN_H
30 
31 //# Includes
32 #include <casacore/casa/aips.h>
33 #include <casacore/casa/Quanta/Quantum.h>
34 
35 namespace casacore { //# NAMESPACE CASACORE - BEGIN
36 
37 //# Forward Declarations
38 class Table;
39 template <class T> class ScalarColumn;
40 class String;
41 class Unit;
42 
43 
44 // <summary>
45 // Provides access to Scalar Quantum Columns in Tables.
46 // </summary>
47 
48 // <use visibility=export>
49 
50 // <reviewed reviewer="Bob Garwood" date="1999/12/23" tests="tTableQuantum.cc">
51 // </reviewed>
52 
53 // <prerequisite>
54 //# Classes you should understand before using this one.
55 // <li> <linkto class=TableQuantumDesc>TableQuantumDesc</linkto>
56 // <li> <linkto class=Table>Table</linkto>
57 // <li> <linkto class=ScalarColumn>ScalarColumn</linkto>
58 // <li> <linkto class=Quantum>Quantum</linkto>
59 // </prerequisite>
60 
61 // <synopsis>
62 // The ScalarQuantColumn class provides read/write access to quanta
63 // stored in a scalar Quantum Table column. The Quantum column should
64 // already exist in the table and would have been defined by means of a
65 // <linkto class=TableQuantumDesc>TableQuantumDesc object</linkto>.
66 // In addition,
67 // for a ScalarQuantColumn object to be useful the column should
68 // contain Quanta.
69 //
70 // A ScalarQuantColumn object is used much in the same way as a
71 // <linkto class=ScalarColumn>ScalarColumn</linkto> object.
72 //
73 // <h3>Quantum Units</h3></A>
74 // Quanta retrieved from the column will normally have the Unit that was
75 // specified when the Quantum column was defined.
76 // However, it is possible to override the default column Unit by
77 // supplying a Unit in the ScalarQuantColumn constructor.
78 // When constructed in this fashion the retrieved Quanta will by
79 // default be retrieved in this unit, i.e. they will by default be
80 // converted to this unit.
81 // <br>
82 // By giving a unit (as a Unit or Quantum object) to a get function,
83 // the data can be retrieved in another unit than the default.
84 // </synopsis>
85 
86 // <example>
87 // <srcblock>
88 // Quantum<Double> q(5.3, "keV");
89 // // "QuantScalar" has previously been defined as a Quantum column
90 // // by means of a TableQuantumDesc. This example assumes the column
91 // // already contains quanta.
92 // ScalarQuantColumn<Double> qCol(qtab, "QuantScalar");
93 // // return and print quanta as stored in the column
94 // for (i = 0; i < qtab.nrow(); i++) {
95 // cout << qCol(i) << endl;
96 // }
97 // // The following retrieves and converts the quanta to GHz. They
98 // // are then divided by the Quantum constant QC::h (Planck).
99 // for (i=0; i < qtab.nrow(); i++) {
100 // cout << (qCol(i, "GHz"))/(QC::h);
101 // }
102 // </srcblock>
103 // </example>
104 
105 // <motivation>
106 // Add support for Quanta in the Tables system.
107 // </motivation>
108 
109 // <thrown>
110 // <li>TableInvOper if the Table column is null.
111 // </thrown>
112 
113 // <todo asof="$DATE:$">
114 //# A List of bugs, limitations, extensions or planned refinements.
115 // <li> Functions like getColumn
116 // </todo>
117 
118 
119 template<class T> class ScalarQuantColumn
120 {
121 public:
122  // The default constructor creates a null object. It is useful for creating
123  // arrays of ScalarQuantColumn objects. Attempting to use a null object
124  // will produce a segmentation fault so care needs to be taken to
125  // initialise the objects by using the attach() member before any attempt
126  // is made to use the object. The isNull() member can be used to test
127  // if a ScalarQuantColumn object is null.
129 
130  // Create the ScalarQuantColumn from the specified table and column name.
131  // The default unit for data retrieved is the unit in which they were stored.
132  ScalarQuantColumn (const Table& tab, const String& columnName);
133 
134  // Create the ScalarQuantColumn from the specified table and column name.
135  // The default unit for data retrieved is the given unit (the data is
136  // converted as needed).
137  ScalarQuantColumn (const Table& tab, const String& columnName,
138  const Unit&);
139 
140  // Copy constructor (copy semantics).
142 
144 
145  // Change the reference to another column.
146  void reference (const ScalarQuantColumn<T>& that);
147 
148  // Attach a column to the object. Optionally supply a default unit
149  // which has the same meaning as the constructor unit argument.
150  // <group name="attach">
151  void attach (const Table& tab, const String& columnName);
152  void attach (const Table& tab, const String& columnName, const Unit&);
153  // </group>
154 
155  // Get the quantum stored in the specified row.
156  // <group name="get">
157  void get (rownr_t rownr, Quantum<T>& q) const;
158  // Get the quantum in the specified row, converted to the given unit.
159  void get (rownr_t rownr, Quantum<T>& q, const Unit&) const;
160  // Get the quantum in the specified row, converted to the unit in other.
161  void get (rownr_t rownr, Quantum<T>& q, const Quantum<T>& other) const;
162  // </group>
163 
164  // Return the quantum stored in the specified row.
165  // <group>
167  // Return the quantum stored in the specified row, converted to the
168  // given unit.
169  Quantum<T> operator() (rownr_t rownr, const Unit&) const;
170  // Return the quantum in the specified row, converted to the unit in
171  // other.
172  Quantum<T> operator() (rownr_t rownr, const Quantum<T>& other) const;
173  // </group>
174 
175  // Put a quantum into the table. If the column supports variable units
176  // the q's unit is stored into the unit column defined in the
177  // TableQuantumDesc object. If units are fixed for the column, the
178  // quantum is converted as needed.
179  void put (rownr_t rownr, const Quantum<T>& q);
180 
181  // Test whether the Quantum column has variable units
183  { return (itsUnitsCol != 0); }
184 
185  // Returns the column's value for Units as a string.
186  // An empty string is returned if the column has variable units.
187  const String& getUnits() const
188  { return itsUnit.getName(); }
189 
190  // Test if the object is null.
191  Bool isNull() const
192  { return (itsDataCol == 0); }
193 
194  // Throw an exception if the object is null.
195  void throwIfNull() const;
196 
197  // Get the column as a Quantum<Vector<T> >. If <src>unit</src> is
198  // not empty, the returned Quantum will have that unit. Else if
199  // the units are variable, the values in the returned Vector
200  // have been converted to the unit of the 0th row entry. Otherwise,
201  // the units of the returned Quantum are the units specified in
202  // the column descriptor.
203  std::shared_ptr<Quantum<Vector<T> > > getColumn(const Unit& unit="") const;
204 
205 protected:
206  //# Quantum column's units (if units not variable)
208 
209  // Get access to itsUnitsCol.
211  { return itsUnitsCol; }
212 
213 private:
214  //# The underlying data column stores the quantum column's data.
216  //# Variable units column if applicable.
218  //# Unit to retrieve the data in.
220  //# Convert unit when getting data?
222 
223 
224  // Assignment makes no sense in a read only class.
225  // Declaring this operator private makes it unusable.
227 
228  // Comparison is not defined, since its semantics are unclear.
230 
231  // Initialize the ScalarQuantColumn from the specified table and column.
232  void init (const Table& tab, const String& columnName);
233 
234  // Deletes allocated memory etc. Called by destructor and any member
235  // which needs to reallocate data.
236  void cleanUp();
237 
238  // Get the data without possible conversion.
239  void getData (rownr_t rownr, Quantum<T>& q) const;
240 };
241 
242 } //# NAMESPACE CASACORE - END
243 
244 
245 //# Make old name ROScalarMeasColumn still available.
246 #define ROScalarQuantColumn ScalarQuantColumn
247 
248 
249 #ifndef CASACORE_NO_AUTO_TEMPLATES
250 #include <casacore/measures/TableMeasures/ScalarQuantColumn.tcc>
251 #endif //# CASACORE_NO_AUTO_TEMPLATES
252 #endif
ScalarQuantColumn & operator=(const ScalarQuantColumn< T > &that)
Assignment makes no sense in a read only class.
const ScalarColumn< String > * unitsCol() const
Get access to itsUnitsCol.
void get(rownr_t rownr, Quantum< T > &q) const
Get the quantum stored in the specified row.
std::shared_ptr< Quantum< Vector< T > > > getColumn(const Unit &unit="") const
Get the column as a Quantum<Vector<T> >.
Bool operator==(const ScalarQuantColumn< T > &that)
Comparison is not defined, since its semantics are unclear.
Bool isUnitVariable() const
Test whether the Quantum column has variable units.
ScalarColumn< String > * itsUnitsCol
void getData(rownr_t rownr, Quantum< T > &q) const
Get the data without possible conversion.
ScalarQuantColumn()
The default constructor creates a null object.
ScalarQuantColumn(const ScalarQuantColumn< T > &that)
Copy constructor (copy semantics).
ScalarQuantColumn(const Table &tab, const String &columnName)
Create the ScalarQuantColumn from the specified table and column name.
const String & getUnits() const
Returns the column's value for Units as a string.
void cleanUp()
Deletes allocated memory etc.
void attach(const Table &tab, const String &columnName)
Attach a column to the object.
Quantum< T > operator()(rownr_t rownr) const
Return the quantum stored in the specified row.
Bool isNull() const
Test if the object is null.
ScalarColumn< T > * itsDataCol
ScalarQuantColumn(const Table &tab, const String &columnName, const Unit &)
Create the ScalarQuantColumn from the specified table and column name.
void throwIfNull() const
Throw an exception if the object is null.
void reference(const ScalarQuantColumn< T > &that)
Change the reference to another column.
void put(rownr_t rownr, const Quantum< T > &q)
Put a quantum into the table.
void init(const Table &tab, const String &columnName)
Initialize the ScalarQuantColumn from the specified table and column.
String: the storage and methods of handling collections of characters.
Definition: String.h:225
const String & getName() const
Get the unit name.
this file contains all the compiler specific defines
Definition: mainpage.dox:28
bool Bool
Define the standard types used by Casacore.
Definition: aipstype.h:42
uInt64 rownr_t
Define the type of a row number in a table.
Definition: aipsxtype.h:46