/usr/include/casacore/tables/TaQL/TableExprData.h is in casacore-dev 2.2.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 | //# TableExprData.h: Abstract base class for data object in a TaQL expression
//# Copyright (C) 2000,2001
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: aips2-request@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
//#
//#
//# $Id$
#ifndef TABLES_TABLEEXPRDATA_H
#define TABLES_TABLEEXPRDATA_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Utilities/DataType.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
//# Forward Declarations
class String;
class IPosition;
template<class T> class Array;
template<class T> class Block;
// <summary>
// Abstract base class for data object in a TaQL expression.
// </summary>
// <use visibility=export>
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="">
// </reviewed>
// <prerequisite>
// <li> <linkto class="TableExprNode">TableExprNode</linkto>.
// </prerequisite>
// <synopsis>
// The Table Query Language (TaQL) is implemented by means of the
// <src>TableExprNode</src> classes. It is primarily meant to do
// selection on tables. However, it is also possible to use it for
// selection on any other set of data resembling tabular data.
// <br>An example of such a data set is a set of
// <linkto class=Record>Record</linkto> objects. TaQL can be used
// to select some of those records based on the contents of one or more
// fields in the records. Note that this example is already directly
// supported by TaQL.
// <br>Another example is when a user has several equally long vectors
// with data. The vectors can be seen as fields and TaQL can be used
// to select entries from the vectors. This example requires that
// this class TableExprData is used.
// <p>
// The <linkto class=TableExprNodeRecordField>TableExprNodeRecordField</linkto>
// and <linkto class=TableExprId>TableExprId</linkto> classes form
// the means by which TaQL can deal with any set of data.
// <br>First the TaQL expression has to be setup. This is done by
// constructing a <src>TableExprNodeRecordField</src> object for each
// 'field' to be used in the expression. <src>TableExprNodeRecordField</src>
// uses a <linkto class=RecordInterface>RecordInterface</linkto> object
// to make the data type of a field in the data set known and to
// map a field name to a field index (the index is the sequence number
// of the field in the record description).
// <br>When evaluating the expression for each member in the data set,
// a <src>TableExprData></src> needs to be passed (which is automatically
// converted to <linkto class=TableExprId>TableExprId</linkto>).
// So a class needs to be written to access the data in the data set.
// It needs to be derived from the abstract base class <src>TableExprData</src>
// defined in this file. An example is given below.
// <p>
// It is also possible that the data set contains records and that
// the selection is based on fields in those records. In such a case
// the record passed to <src>TableExprNodeRecordField</src> should contain
// subrecords representing those records. The field index in the various
// functions as passed as a <src>Block<Int></src> to denote the fields
// in the subrecords (and possibly subsubrecords, etc..
// However, normally records won't be used and <src>fieldNrs[0]</src>
// gives the field index.
// </synopsis>
// <example>
// This example shows how a data set consisting of two vectors
// of scalars can be used.
// <srcblock>
// // Write a class derived from TableExprData to handle the vectors.
// class MyTestClass : public TableExprData
// {
// public:
// // Constructor checks if both vectors have equal length.
// MyTestClass (const Vector<Int>& fld1, const Vector<String>& fld2)
// : itsFld1(fld1), itsFld2(fld2), itsEntry(0)
// { AlwaysAssert (fld1.nelements() == fld2.nelements(), AipsError); }
// virtual ~MyTestClass()
// {}
// void next()
// { itsEntry++; }
// // Note that only the get functions for the possible types are needed.
// // Also note that all numeric types are handled by TaQL as Double.
// // The exception should never be thrown unless things are screwed up.
// virtual Double getDouble (const Block<Int>& fieldNrs) const
// { switch (fieldNrs[0]) {
// case 0:
// return itsFld1(itsEntry);
// default:
// throw AipsError();
// }
// }
// virtual String getString (const Block<Int>& fieldNrs) const
// { switch (fieldNrs[0]) {
// case 1:
// return itsFld2(itsEntry);
// default:
// throw AipsError();
// }
// }
// virtual DataType dataType (const Block<Int>& fieldNrs) const
// { switch (fieldNrs[0]) {
// case 0:
// return TpInt;
// case 1:
// return TpString;
// default:
// throw AipsError();
// }
// }
// // Make a Record to give to vectors a name.
// // The order in which the fields are defined determines the fieldnrs
// // passed to the get functions.
// static Record makeRecord()
// { RecordDesc desc;
// desc.addField ("fld1", TpInt);
// desc.addField ("fld2", TpString);
// return Record(desc);
// }
// private:
// Vector<Int> itsFld1;
// Vector<String> itsFld2;
// uInt itsEntry;
// };
//
// Vector<uInt> findMatches (const Vector<Int>& fld1,
// const Vector<String>& fld2)
// {
// // Make some expression.
// // First create a Record to make the names and types known.
// Record rec(MyTestClass::makeRecord());
// TableExprNode expr (makeRecordExpr(rec,"fld1") > 10 &&
// makeRecordExpr(rec,"fld2") != pattern("*xxx*"));
// // Now evaluate the expression for each entry in the vector.
// // Make a MyTestClass object to handle the vectors and put it in
// // a TableExprId object for the TaQL evaluator.
// // Note that TableExprId holds a pointer to the original MyTestClass
// // object, so the TaQL evaluator 'sees' the changes we make by
// // using the its next() function.
// MyTestClass subj(fld1, fld2);
// TableExprId eid(subj);
// // The matching entry numbers are stored in a vector.
// Vector<uInt> result(fld1.nelements());
// uInt nr=0;
// Bool valb;
// for (uInt i=0; i<fld1.nelements(); i++) {
// expr.get (eid, valb);
// if (valb) {
// result(nr++) = i;
// }
// subj.next(); // Next time the next entry must be used
// }
// result.resize (nr, True);
// return result;
// }
// </srcBlock>
// </example>
// <motivation>
// This class makes it possible that TaQL can be used in a very versatile way.
// </motivation>
//# <todo asof="1996/03/12">
//# </todo>
class TableExprData
{
public:
// Construct it from a row number.
TableExprData()
{;}
virtual ~TableExprData();
// Get the shape of the given field.
// Need only be implemented if there are arrays in the data.
// The default implementation returns an empty IPosition.
virtual IPosition shape (const Block<Int>& fieldNrs) const;
// Get the data type of the given field.
// Note that TpArray types have to be returned for arrays.
// If the field is unknown, TpOther should be returned.
// It is used for the isdefined function to check if the field
// is really defined.
virtual DataType dataType (const Block<Int>& fieldNrs) const = 0;
// Get a scalar in the given type.
// This might involve converting for Double and DComplex.
// Most default implementations throws an "not possible" exception.
// The default <src>getDouble</src> invokes <src>getInt</src>.
// The default <src>getDComplex</src> invokes <src>getDouble</src>.
// <group>
virtual Bool getBool (const Block<Int>& fieldNrs) const;
virtual Int64 getInt (const Block<Int>& fieldNrs) const;
virtual Double getDouble (const Block<Int>& fieldNrs) const;
virtual DComplex getDComplex (const Block<Int>& fieldNrs) const;
virtual String getString (const Block<Int>& fieldNrs) const;
// </group>
// Get an array in the given type.
// This might involve converting for Double and DComplex.
// Most default implementations throws an "not possible" exception.
// The default <src>getArrayDComplex</src> invokes
// <src>getArrayDouble</src>.
// <group>
virtual Array<Bool> getArrayBool (const Block<Int>& fieldNrs) const;
virtual Array<Int64> getArrayInt (const Block<Int>& fieldNrs) const;
virtual Array<Double> getArrayDouble (const Block<Int>& fieldNrs) const;
virtual Array<DComplex> getArrayDComplex (const Block<Int>& fieldNrs) const;
virtual Array<String> getArrayString (const Block<Int>& fieldNrs) const;
// </group>
};
} //# NAMESPACE CASACORE - END
#endif
|