Add new algorithm 'gather'

[SVN r82584]

test/gather_test1.cpp

@@ -0,0 +1,139 @@
+/* 
+   Copyright (c) Marshall Clow 2011-2012.
+
+   Distributed under the Boost Software License, Version 1.0. (See accompanying
+   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+    For more information, see http://www.boost.org
+*/
+
+#include <iostream>
+
+#include <boost/config.hpp>
+#include <boost/algorithm/gather.hpp>
+#include <boost/test/included/test_exec_monitor.hpp>
+
+#include <string>
+#include <vector>
+#include <list>
+
+#include "iterator_test.hpp"
+
+namespace ba = boost::algorithm;
+
+template <typename Container>
+void print ( const char *prompt, const Container &c ) {
+    std::cout << prompt << " { ";
+    std::copy ( c.begin (), c.end (), std::ostream_iterator<typename Container::value_type>(std::cout, " "));
+    std::cout << std::endl;
+    }
+
+template <typename Iterator, typename Predicate>
+void test_iterators ( Iterator first, Iterator last, Predicate comp, std::size_t offset ) {
+//  Create the pivot point
+    Iterator off = first;
+    std::advance(off, offset);
+        
+//  Gather the elements
+    std::pair<Iterator, Iterator> res = ba::gather ( first, last, off, comp );
+
+//  We should now have three sequences, any of which may be empty:
+//      * [begin .. result.first)         - items that do not satisfy the predicate
+//      * [result.first .. result.second) - items that do satisfy the predicate
+//      * [result.second .. end)          - items that do not satisfy the predicate
+    Iterator iter = first;
+    for ( ; iter != res.first; ++iter )
+        BOOST_CHECK ( !comp ( *iter ));
+    for ( ; iter != res.second; ++iter)
+        BOOST_CHECK ( comp ( *iter ));
+    for ( ; iter != last; ++iter )
+        BOOST_CHECK ( !comp ( *iter ));
+    }
+
+template <typename Container, typename Predicate>
+void test_iterator_types ( const Container &c, Predicate comp, std::size_t offset ) {
+    typedef std::vector<typename Container::value_type> vec;
+    typedef forward_iterator<typename vec::iterator> FI;
+    typedef bidirectional_iterator<typename vec::iterator> BDI;
+    typedef random_access_iterator<typename vec::iterator> RAI;
+    
+    vec v;
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( FI  ( v.begin ()), FI  ( v.end ()), comp, offset );
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( BDI ( v.begin ()), BDI ( v.end ()), comp, offset );
+    v.assign ( c.begin (), c.end ());
+    test_iterators ( RAI ( v.begin ()), RAI ( v.end ()), comp, offset );
+    }
+
+
+template <typename T>
+struct less_than {
+public:
+//    typedef T argument_type;
+//    typedef bool result_type;
+
+    less_than ( T foo ) : val ( foo ) {}
+    less_than ( const less_than &rhs ) : val ( rhs.val ) {}
+
+    bool operator () ( const T &v ) const { return v < val; }
+private:
+    less_than ();
+    less_than operator = ( const less_than &rhs );
+    T val;
+    };
+
+bool is_even ( int i ) { return i % 2 == 0; }
+bool is_ten  ( int i ) { return i == 10; }
+
+void test_sequence1 () {
+    std::vector<int> v;
+    
+    for ( int i = 5; i < 15; ++i )
+        v.push_back ( i );
+    test_iterator_types ( v, less_than<int>(10),  0 );                  // at beginning
+    test_iterator_types ( v, less_than<int>(10),  5 );
+    test_iterator_types ( v, less_than<int>(10), v.size () - 1 );       // at end
+
+    test_iterator_types ( v, is_even, 0 );
+    test_iterator_types ( v, is_even, 5 );
+    test_iterator_types ( v, is_even, v.size () - 1 );
+
+//  Exactly one element in the sequence matches
+    test_iterator_types ( v, is_ten, 0 );
+    test_iterator_types ( v, is_ten, 5 );
+    test_iterator_types ( v, is_ten, v.size () - 1 );
+
+//  Everything in the sequence matches
+    test_iterator_types ( v, less_than<int>(99),  0 );
+    test_iterator_types ( v, less_than<int>(99),  5 );
+    test_iterator_types ( v, less_than<int>(99), v.size () - 1 );
+    
+//  Nothing in the sequence matches
+    test_iterator_types ( v, less_than<int>(0),  0 );
+    test_iterator_types ( v, less_than<int>(0),  5 );
+    test_iterator_types ( v, less_than<int>(0), v.size () - 1 );
+    
+//  All the elements in the sequence are the same
+    v.clear ();
+    for ( int i = 0; i < 11; ++i )
+        v.push_back ( 10 );
+    
+//  Everything in the sequence matches
+    test_iterator_types ( v, is_ten, 0 );
+    test_iterator_types ( v, is_ten, 5 );
+    test_iterator_types ( v, is_ten, v.size () - 1 );
+
+//  Nothing in the sequence matches
+    test_iterator_types ( v, less_than<int>(5),  0 );
+    test_iterator_types ( v, less_than<int>(5),  5 );
+    test_iterator_types ( v, less_than<int>(5), v.size () - 1 );
+
+    }
+
+
+int test_main( int , char* [] )
+{
+  test_sequence1 ();
+  return 0;
+}