Merge pull request #628 from TomFischer/excludeObjectCopy

Exclude object copy

BaseLib/excludeObjectCopy.h

+/**
+ *
+ * \copyright
+ * Copyright (c) 2012-2015, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#ifndef EXCLUDEOBJECTCOPIER_H_
+#define EXCLUDEOBJECTCOPIER_H_
+
+#include <vector>
+#include <algorithm>
+
+namespace BaseLib
+{
+
+/// excludeObjectCopy copies only those objects that position within the source
+/// vector is not in the exclude_positions vector. The implementation of the
+/// algorithm requires that the given positions in exclude_positions are sorted
+/// in ascending order.
+/// @param src_vec the vector of source objects
+/// @param exclude_positions the positions of objects in the source vector that
+/// do not have to be copied
+/// @return vector that contains the copied objects
+template <typename T>
+std::vector<T> excludeObjectCopy(std::vector<T> const& src_vec,
+	std::vector<std::size_t> const& exclude_positions)
+{
+	std::vector<T> dest_vec;
+	if (exclude_positions.empty()) {
+		dest_vec = src_vec;
+		return dest_vec;
+	}
+
+	assert (exclude_positions.back() < src_vec.size());
+
+	std::copy_n(src_vec.cbegin(), exclude_positions[0], std::back_inserter(dest_vec));
+	for (std::size_t i=1; i<exclude_positions.size(); ++i) {
+		std::copy_n(
+			src_vec.cbegin()+exclude_positions[i-1]+1,
+			exclude_positions[i]-(exclude_positions[i-1]+1),
+			std::back_inserter(dest_vec)
+		);
+	}
+	std::copy(src_vec.cbegin()+exclude_positions.back()+1,
+		src_vec.cend(), std::back_inserter(dest_vec));
+
+	return dest_vec;
+}
+
+template <typename T>
+void excludeObjectCopy(std::vector<T> const& src_vec,
+	std::vector<std::size_t> const& exclude_positions,
+	std::vector<T> & dest_vec)
+{
+	dest_vec = excludeObjectCopy(src_vec, exclude_positions);
+}
+
+
+} // end namespace BaseLib
+
+#endif
+

Tests/BaseLib/excludeObjectCopy.cpp

+/**
+ * \date   2015-03-18
+ * \brief
+ *
+ * \copyright
+ * Copyright (c) 2012-2015, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/project/license
+ *
+ */
+
+#include <algorithm>
+#include <cstddef>
+#include <vector>
+
+#include "gtest/gtest.h"
+
+#include "BaseLib/excludeObjectCopy.h"
+
+TEST(BaseLib, excludeObjectCopy)
+{
+	// create and fill vector
+	std::size_t const size(100);
+	std::vector<std::size_t> v(size);
+	std::iota(v.begin(), v.end(), 0);
+
+	std::vector<std::size_t> ex_positions(size/10);
+	// do not copy first 10 elements
+	std::iota(ex_positions.begin(), ex_positions.end(), 0);
+
+	std::vector<std::size_t> c1(BaseLib::excludeObjectCopy(v,ex_positions));
+	ASSERT_EQ(size-ex_positions.size(), c1.size());
+
+	for (std::size_t i(0); i<c1.size(); i++)
+		ASSERT_EQ(c1[i], v[size/10+i]);
+
+	// do not copy element 0, 2, 4, 6, 8, 10, 12, 14, 16, 18
+	std::transform(ex_positions.begin(), ex_positions.end(),
+		ex_positions.begin(), std::bind1st(std::multiplies<size_t>(),2));
+
+	std::vector<std::size_t> c2(BaseLib::excludeObjectCopy(v,ex_positions));
+	ASSERT_EQ(size-ex_positions.size(), c2.size());
+
+	for (std::size_t i(0); i<ex_positions.size(); i++)
+		ASSERT_EQ(c2[i], v[2*i+1]);
+	for (std::size_t i(ex_positions.size()); i<c2.size(); i++)
+		ASSERT_EQ(c2[i], v[ex_positions.size()+i]);
+
+	// do not copy the last element
+	ex_positions.clear();
+	ex_positions.push_back(99);
+
+	std::vector<std::size_t> c3(BaseLib::excludeObjectCopy(v,ex_positions));
+	ASSERT_EQ(size-ex_positions.size(), c3.size());
+
+	for (std::size_t i(0); i<c3.size(); i++)
+		ASSERT_EQ(c3[i], v[i]);
+}