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/*=========================================================================
*
* Copyright NumFOCUS
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#include <unordered_set>
#include <unordered_map>
#include <iostream>
#include <cstring>
/**
* Helper function to prevent compiler's unused variable warning.
*/
template <typename T>
void
IgnoreUnusedVariable(const T &)
{}
struct eqstr
{
bool
operator()(const char * s1, const char * s2) const
{
return strcmp(s1, s2) == 0;
}
};
void
lookup(const std::unordered_set<const char *, std::hash<const char *>, eqstr> & Set, const char * word)
{
auto it = Set.find(word);
std::cout << word << ": " << (it != Set.end() ? "present" : "not present") << std::endl;
}
inline void
println(const char * s)
{
std::cout << std::endl << s << std::endl;
}
int
itkHashTableTest(int, char *[])
{
println("Testing std::hash");
std::hash<const char *> H;
std::cout << "foo -> " << H("foo") << std::endl;
std::cout << "bar -> " << H("bar") << std::endl;
std::hash<int> H1;
std::cout << "1 -> " << H1(1) << std::endl;
std::cout << "234 -> " << H1(234) << std::endl;
std::hash<char> H2;
std::cout << "a -> " << H2('a') << std::endl;
std::cout << "Z -> " << H2('Z') << std::endl;
println("Testing std::unordered_set");
using HashSetType = std::unordered_set<const char *, std::hash<const char *>, eqstr>;
HashSetType Set;
Set.insert("kiwi");
Set.insert("plum");
Set.insert("apple");
Set.insert("mango");
Set.insert("apricot");
Set.insert("banana");
lookup(Set, "mango");
lookup(Set, "apple");
lookup(Set, "durian");
// CppCheck gives us a warning if the return value isn't used.
// This is to prevent the user from calling empty() when they mean clear().
if (Set.empty())
{
std::cout << "Set is empty." << std::endl;
}
Set.rehash(50);
Set.insert("the horror");
auto hsh_it = Set.begin();
HashSetType::const_iterator hst_const_it;
hst_const_it = Set.end();
HashSetType SetCopy;
SetCopy = Set;
println("Testing std::unordered_map");
using HashMapType = std::unordered_map<const char *, int, std::hash<const char *>, eqstr>;
HashMapType months;
months["january"] = 31;
months["february"] = 28;
months["march"] = 31;
months["april"] = 30;
months["may"] = 31;
months["june"] = 30;
months["july"] = 31;
months["august"] = 31;
months["september"] = 30;
months["october"] = 31;
months["november"] = 30;
months["december"] = 31;
std::cout << "september -> " << months["september"] << std::endl;
std::cout << "april -> " << months["april"] << std::endl;
std::cout << "june -> " << months["june"] << std::endl;
std::cout << "november -> " << months["november"] << std::endl;
// CppCheck gives us a warning if the return value isn't used.
// This is to prevent the user from calling empty() when they mean clear().
if (months.empty())
{
std::cout << "Set is empty." << std::endl;
}
months.rehash(50);
HashMapType::value_type p("psychotic break", 2);
months.insert(p);
auto map_it = months.begin();
HashMapType::const_iterator map_const_it;
map_const_it = months.end();
HashMapType MapCopy;
MapCopy = months;
IgnoreUnusedVariable(hsh_it);
IgnoreUnusedVariable(map_it);
return EXIT_SUCCESS;
}
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