source: branches/alma/src/IndexedCompare.h@ 1849

Last change on this file since 1849 was 1757, checked in by Kana Sugimoto, 14 years ago

New Development: Yes

JIRA Issue: Yes (CAS-2211)

Ready for Test: Yes

Interface Changes: Yes

What Interface Changed: ASAP 3.0.0 interface changes

Test Programs:

Put in Release Notes: Yes

Module(s): all the CASA sd tools and tasks are affected.

Description: Merged ATNF-ASAP 3.0.0 developments to CASA (alma) branch.

Note you also need to update casa/code/atnf.


File size: 5.1 KB
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1/// @file
2///
3/// @brief A binary predicate to compare two numbers referred by indices
4/// @details While sorting a vector, it is often necessary to track
5/// permutations. One way of doing this is to write a std::pair-like class
6/// with comparison operators using one element of the pair only and store
7/// both value and its index. This is done in the PairOrderedFirst class
8/// in AIPS++, which I wrote some time ago. However, there exists a more elegant
9/// solution using a version of std::sort with a user-suppled binary predicate.
10/// This file defines such binary predicate class comparing two values
11/// stored in a container defined by its random access iterator of the origin
12/// each time it is asked to compare two indicies. Each instance of the class
13/// holds a copy of the rangom access iterator.
14///
15/// @copyright (c) 2007 CSIRO
16/// Australia Telescope National Facility (ATNF)
17/// Commonwealth Scientific and Industrial Research Organisation (CSIRO)
18/// PO Box 76, Epping NSW 1710, Australia
19/// atnf-enquiries@csiro.au
20///
21/// This file was originally written as a part of the ASKAP software
22/// distribution and then adapted and reused in the ASAP project.
23///
24/// The ASKAP software distribution is free software: you can redistribute it
25/// and/or modify it under the terms of the GNU General Public License as
26/// published by the Free Software Foundation; either version 2 of the License,
27/// or (at your option) any later version.
28///
29/// This program is distributed in the hope that it will be useful,
30/// but WITHOUT ANY WARRANTY; without even the implied warranty of
31/// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
32/// GNU General Public License for more details.
33///
34/// You should have received a copy of the GNU General Public License
35/// along with this program; if not, write to the Free Software
36/// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
37///
38/// @author Max Voronkov <maxim.voronkov@csiro.au>
39
40#ifndef INDEXED_COMPARE_H
41#define INDEXED_COMPARE_H
42
43#include <functional>
44
45namespace asap {
46
47/// @brief A binary predicate to compare two numbers referred by indices
48/// @details While sorting a vector, it is often necessary to track
49/// permutations. One way of doing this is to write a std::pair-like class
50/// with comparison operators using one element of the pair only and store
51/// both value and its index. This is done in the PairOrderedFirst class
52/// in AIPS++, which I wrote some time ago. However, there exists a more elegant
53/// solution using a version of std::sort with a user-suppled binary predicate.
54/// This is such binary predicate class comparing two values
55/// stored in a container defined by its random access iterator of the origin
56/// each time it is asked to compare two indicies. Each instance of the class
57/// holds a copy of the rangom access iterator.
58template<typename IndexType, typename Iter,
59 typename Cmp = std::less<typename Iter::value_type> >
60struct IndexedCompare : public std::binary_function<IndexType,IndexType,bool> {
61 /// @brief constructor with a default comparator initialization
62 /// @details
63 /// A comparator (which type is a template parameter) is set up with its
64 /// default constructor.
65 /// @param[in] iter random access iterator to work with
66 IndexedCompare(const Iter &iter) : itsIter(iter) {}
67
68 /// @brief constructor with a user-specified comparator initialization
69 /// @details
70 /// A comparator (which type is a template parameter) is set up using a
71 /// a copy constructor
72 /// @param[in] iter random access iterator to work with
73 IndexedCompare(const Iter &iter, const Cmp &cmp) : itsIter(iter),
74 itsComparator(cmp) {}
75
76
77 /// @brief main operator of the predicate
78 /// @details Returns result of comparison of the value referred to by the
79 /// first and the second indices
80 /// @param[in] index1 index of the first value
81 /// @param[in] index2 index of the second value
82 /// @return result of comparison
83 bool operator()(const IndexType &index1, const IndexType &index2) const
84 {
85 return itsComparator(*(itsIter+index1), *(itsIter+index2));
86 }
87
88
89private:
90 /// random access iterator to work with
91 Iter itsIter;
92 /// underlying binary predicate to do the comparison
93 Cmp itsComparator;
94};
95
96/// @brief helper function to construct IndexedCompare object
97/// @details It is handy to have a helper method to avoid
98/// writing type names all the time. This function can extract the
99/// template parameter from the argument type, i.e. automatically
100/// @param[in] iter random access iterator to work with
101/// @param[in] cmp an object which does the actual comparison
102template<typename IndexType, typename Iter, typename Cmp>
103IndexedCompare<IndexType,Iter,Cmp> indexedCompare(const Iter &iter, const Cmp &cmp =
104 std::less<typename Iter::value_type>())
105{
106 return IndexedCompare<IndexType,Iter,Cmp>(iter,cmp);
107}
108
109template<typename IndexType, typename Iter>
110IndexedCompare<IndexType,Iter> indexedCompare(const Iter &iter)
111{
112 return IndexedCompare<IndexType,Iter>(iter);
113}
114
115} // namespace asap
116
117#endif // #define INDEXED_COMPARE_H
118
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