add dereferencing iterator

alib2std/src/extensions/iterator.hpp

@@ -34,6 +34,125 @@ reverser<T> make_reverse(T& container) {
 	return reverser<T>(container);
 }
+template < class Iterator >
+class dereferencing_iterator {
+	Iterator m_base;
+
+public:
+	using pointer = typename std::iterator_traits < Iterator >::value_type;
+	using value_type = typename std::remove_pointer < pointer >::type;
+	using difference_type = std::ptrdiff_t;
+	using reference = value_type &;
+	using iterator_category = typename std::iterator_traits < Iterator >::iterator_category;
+
+	explicit dereferencing_iterator ( Iterator base ) : m_base ( base ) {
+	}
+
+	template < class Iter >
+	dereferencing_iterator ( const dereferencing_iterator < Iter > & iter ) : m_base ( iter.base ( ) ) {
+	}
+
+	// Dereferencable.
+	reference operator * ( ) const {
+		return * * m_base;
+	}
+
+	pointer operator -> ( ) const {
+		return * m_base;
+	}
+
+	// Pre- and post-incrementable.
+	dereferencing_iterator < Iterator > & operator ++ ( ) {
+		++ m_base;
+		return * this;
+	}
+
+	dereferencing_iterator < Iterator > operator ++ ( int ) {
+		auto tmp = * this;
+		++ m_base;
+		return tmp;
+	}
+
+	// Pre- and post-decrementable.
+	dereferencing_iterator < Iterator > & operator -- ( ) {
+		++ m_base;
+		return * this;
+	}
+
+	dereferencing_iterator < Iterator > operator -- ( int ) {
+		auto tmp = * this;
+		++ m_base;
+		return tmp;
+	}
+
+	// Add and substract.
+	dereferencing_iterator < Iterator > & operator += ( int distance ) {
+		m_base += distance;
+		return *this;
+	}
+
+	dereferencing_iterator < Iterator > operator + ( int distance ) const {
+		auto res = * this;
+		res += distance;
+		return res;
+	}
+
+	dereferencing_iterator < Iterator > & operator -= ( int distance ) {
+		m_base -= distance;
+		return *this;
+	}
+
+	dereferencing_iterator < Iterator > operator - ( int distance ) const {
+		auto res = * this;
+		res -= distance;
+		return res;
+	}
+
+	//Array subscript
+	reference operator [ ] ( int index ) const {
+		return * ( m_base [ index ] );
+	}
+
+	difference_type operator - ( const dereferencing_iterator < Iterator > & other ) {
+		return m_base - other.m_base;
+	}
+
+	// Equality / inequality.
+	bool operator == ( const dereferencing_iterator < Iterator > & other ) const {
+		return this->m_base == other.m_base;
+	}
+
+	bool operator != ( const dereferencing_iterator < Iterator > & other ) const {
+		return ! ( * this == other );
+	}
+
+	bool operator < ( const dereferencing_iterator < Iterator > & other ) const {
+		return this->m_base < other.m_base;
+	}
+
+	bool operator > ( const dereferencing_iterator < Iterator > & other ) const {
+		return other < * this;
+	}
+
+	bool operator <= ( const dereferencing_iterator < Iterator > & other ) const {
+		return ! ( * this > other );
+	}
+
+	bool operator >= ( const dereferencing_iterator < Iterator > & other ) const {
+		return ! ( * this < other );
+	}
+
+	Iterator base ( ) const {
+		return m_base;
+	}
+
+};
+
+template < class Iterator >
+dereferencing_iterator < Iterator > dereferencer ( Iterator iter ) {
+	return dereferencing_iterator < Iterator > ( iter );
+}
+
 template < typename T >
 struct is_iterator : std::false_type {};

alib2std/test-src/extensions/IteratorTest.cpp

+#include "IteratorTest.h"
+#include <alib/set>
+#include <alib/vector>
+#include <alib/pair>
+#include <sstream>
+#include <alib/istream>
+#include <alib/string>
+#include <alib/iterator>
+
+CPPUNIT_TEST_SUITE_NAMED_REGISTRATION( IteratorTest, "bits" );
+CPPUNIT_TEST_SUITE_REGISTRATION( IteratorTest );
+
+void IteratorTest::setUp() {
+}
+
+void IteratorTest::tearDown() {
+}
+
+void IteratorTest::testIterator() {
+	std::vector < int * > data;
+
+	data.push_back ( new int ( 1 ) );
+	data.push_back ( new int ( 2 ) );
+	data.push_back ( new int ( 3 ) );
+	data.push_back ( new int ( 4 ) );
+	data.push_back ( new int ( 5 ) );
+
+	std::vector < int > ref { 1, 2, 3, 4, 5 };
+
+	bool res = std::equal ( ext::dereferencer ( data.begin ( ) ), ext::dereferencer ( data.end ( ) ), ref.begin ( ), ref.end ( ) );
+	CPPUNIT_ASSERT ( res );
+
+	for ( int * elem : data ) {
+		delete elem;
+	}
+}
+

alib2std/test-src/extensions/IteratorTest.h

+#ifndef ITERATOR_TEST_H_
+#define ITERATOR_TEST_H_
+
+#include <cppunit/extensions/HelperMacros.h>
+
+class IteratorTest : public CppUnit::TestFixture
+{
+  CPPUNIT_TEST_SUITE( IteratorTest );
+  CPPUNIT_TEST( testIterator );
+  CPPUNIT_TEST_SUITE_END();
+
+public:
+  void setUp();
+  void tearDown();
+
+  void testIterator();
+};
+
+#endif  // ITERATOR_TEST_H_