mirror of
https://hub.njuu.cf/TheAlgorithms/C-Plus-Plus.git
synced 2023-10-11 13:05:55 +08:00
Tests:
1) Add unit tests for SkipList class with a view to refactoring the code, 2) Added a base class for objects that generate uniformly distributed random numbers between 0 and 1. This means we can mock this interface and choose the sequence of "random" numbers. It allows us to choose the level of a key we want to add to the SkipList for testing purposes.
This commit is contained in:
Mog
parent
6376bf46af
commit
48d179adb5
@ -13,18 +13,28 @@
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* @author [Krishna Vedala](https://github.com/kvedala)
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*/
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#include <algorithm>
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#include <array>
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#include <cmath>
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#include <cstring>
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#include <ctime>
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#include <iostream>
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#include <memory>
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#include <regex>
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#include <sstream>
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#include <string>
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#include <vector>
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template <typename T, typename... Args>
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std::unique_ptr<T> make_unique(Args&&... args) {
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return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
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}
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/** \namespace data_structures
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* \brief Data-structure algorithms
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*/
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namespace data_structures {
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constexpr int MAX_LEVEL = 2; ///< Maximum level of skip list
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constexpr int MAX_LEVEL = 6; ///< Maximum level of skip list
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constexpr float PROBABILITY = 0.5; ///< Current probability for "coin toss"
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/**
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@ -49,23 +59,51 @@ struct Node {
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}
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};
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/*
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A base class for generator that generate uniformly distributed random numbers in
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[0, 1).
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This is introduced mainly because we want to mock insertion of items.
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*/
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class BaseRandomNumberGenerator {
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public:
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virtual float operator()() = 0;
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};
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class CRandBasedGenerator : public BaseRandomNumberGenerator {
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public:
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float operator()() { return static_cast<float>(std::rand()) / RAND_MAX; }
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};
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/*
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This mock allows us to control the random numbers generated so we can
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ensure the new key is added to the required number of levels.
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*/
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class MockRandomNumberGenerator : public BaseRandomNumberGenerator {
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std::vector<float> randos;
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int idx;
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public:
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MockRandomNumberGenerator(const int level) : idx(0) {
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randos = std::vector<float>(level - 1, 0.1);
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randos.push_back(0.65);
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}
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float operator()() {
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// We want to control the skip list level for an item we are adding.
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if (idx < randos.size())
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return randos[idx++];
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else
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return randos[randos.size() - 1];
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}
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};
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/**
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* SkipList class implementation with basic methods
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*/
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class SkipList {
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// const int MAX_LEVEL; ///< Maximum level of skip list
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int level; ///< Maximum level of the skiplist
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std::shared_ptr<Node> header; ///< Pointer to the header node
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public:
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/**
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* Skip List constructor. Initializes header, start
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* Node for searching in the list
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*/
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SkipList() {
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level = 0;
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// Header initialization
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header = std::make_shared<Node>(-1, MAX_LEVEL);
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}
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std::unique_ptr<BaseRandomNumberGenerator> uniformRealNumberGenerator;
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/**
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* Returns random level of the skip list.
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@ -74,13 +112,30 @@ class SkipList {
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*/
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int randomLevel() {
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int lvl = 0;
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while (static_cast<float>(std::rand()) / RAND_MAX < PROBABILITY &&
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while ((*uniformRealNumberGenerator)() < PROBABILITY &&
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lvl < MAX_LEVEL) {
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lvl++;
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}
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return lvl;
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}
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public:
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/**
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* Skip List constructor. Initializes header, start
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* Node for searching in the list
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*/
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SkipList(std::unique_ptr<BaseRandomNumberGenerator> generator) {
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level = 0;
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// Header initialization
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header = std::make_shared<Node>(-1, MAX_LEVEL);
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uniformRealNumberGenerator = std::move(generator);
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}
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void setNumberGenerator(
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std::unique_ptr<BaseRandomNumberGenerator> generator) {
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uniformRealNumberGenerator = std::move(generator);
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}
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/**
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* Inserts elements with given key and value;
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* It's level is computed by randomLevel() function.
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@ -88,7 +143,6 @@ class SkipList {
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* @param value pointer to a value, that can be any type
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*/
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void insertElement(int key, void* value) {
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std::cout << "Inserting" << key << "...";
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std::shared_ptr<Node> x = header;
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std::array<std::shared_ptr<Node>, MAX_LEVEL + 1> update;
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update.fill(nullptr);
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@ -119,10 +173,6 @@ class SkipList {
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n->forward[i] = update[i]->forward[i];
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update[i]->forward[i] = n;
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}
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std::cout << "Inserted" << std::endl;
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} else {
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std::cout << "Exists" << std::endl;
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}
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}
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@ -156,9 +206,6 @@ class SkipList {
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}
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/* Remove empty levels*/
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while (level > 0 && header->forward[level] == nullptr) level--;
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std::cout << "Deleted" << std::endl;
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} else {
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std::cout << "Doesn't exist" << std::endl;
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}
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}
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@ -169,7 +216,6 @@ class SkipList {
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*/
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void* searchElement(int key) {
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std::shared_ptr<Node> x = header;
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std::cout << "Searching for " << key << std::endl;
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for (int i = level; i >= 0; i--) {
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while (x->forward[i] && x->forward[i]->key < key) x = x->forward[i];
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@ -177,10 +223,8 @@ class SkipList {
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x = x->forward[0];
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if (x && x->key == key) {
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std::cout << "Found" << std::endl;
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return x->value;
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} else {
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std::cout << "Not Found" << std::endl;
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return nullptr;
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}
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}
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@ -188,38 +232,308 @@ class SkipList {
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/**
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* Display skip list level
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*/
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void displayList() {
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std::cout << "Displaying list:\n";
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void displayList(std::ostream& out, std::string end = " ") {
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for (int i = 0; i <= level; i++) {
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std::shared_ptr<Node> node = header->forward[i];
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std::cout << "Level " << (i) << ": ";
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// out << /*"Level " << (i) << ": "; */
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while (node != nullptr) {
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std::cout << node->key << " ";
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out << node->key << " ";
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node = node->forward[i];
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}
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std::cout << std::endl;
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out << end;
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}
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}
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};
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} // namespace data_structures
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// Testing helper functions
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std::string removeItem(std::string input, int key) {
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std::stringstream ss(input);
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std::stringstream out;
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int val;
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while (ss >> val) {
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if (val != key) {
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out << val << " ";
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}
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}
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std::string out_str = out.str();
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// Replace consecutive occurance of 2 or more spaces with one space.
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std::regex regex("(\\s{2,})");
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return std::regex_replace(out.str(), regex, std::string(" "));
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}
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std::string insertItem(const std::string input, int key, const int level) {
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std::stringstream out;
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int val;
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int count = 0;
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size_t start = 0;
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size_t end = 0;
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// Split levels as marked with ;
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do {
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end = input.find(';', start);
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std::stringstream in(input.substr(start, end - start));
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bool keyInserted = false;
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bool foundFirstLarger = false;
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while (in >> val) {
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if (val == key) {
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return input;
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} else if (foundFirstLarger == false && key < val) {
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foundFirstLarger = true;
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keyInserted = true;
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out << key << " " << val << " ";
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} else {
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out << val << " ";
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}
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}
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if (keyInserted == false) {
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out << key << " ";
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}
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start = end + 1;
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count++;
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} while (end != std::string::npos && count < level);
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while (count < level) {
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out << key << " ";
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count++;
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}
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if (end != std::string::npos) {
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std::regex regex("(;)");
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out << std::regex_replace(input.substr(start), regex, std::string(" "));
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}
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// Replace consecutive occurance of 2 or more spaces with one space.
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std::regex regex("(\\s{2,})");
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return std::regex_replace(out.str(), regex, std::string(" "));
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}
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data_structures::SkipList createSkipListTestInstance() {
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data_structures::SkipList lst(
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make_unique<data_structures::CRandBasedGenerator>());
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int count = 0;
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for (int j = 0; j < 100; j++) {
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int k = (std::rand() % 512 + 1);
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lst.insertElement(k, &j);
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count++;
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}
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return lst;
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}
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void isTrue(bool isEqual, std::string failure_msg, std::string success_msg) {
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if (isEqual)
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std::cout << success_msg << std::endl;
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else
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std::cout << failure_msg << std::endl;
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}
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void testInsertNewKey() {
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data_structures::SkipList lst = createSkipListTestInstance();
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// Add 200 to the skip list
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int key = 200;
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int level = 4;
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// Generate ground truth for the insertion
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std::stringstream ss_insertion_target;
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lst.displayList(ss_insertion_target, " ; ");
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std::string target = insertItem(ss_insertion_target.str(), key, level);
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// This mock allows us to control the random numbers generated so we can
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// ensure the new key is added to the required number of levels.
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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// Actually insert into the skip list
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lst.insertElement(key, NULL);
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std::stringstream ss_insertion;
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lst.displayList(ss_insertion, "");
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isTrue(ss_insertion.str() == target, "FAILURE: test_insert_key",
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"SUCCESS: test_insert_key");
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}
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// TEST: Insert a key that is already in the skip list
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void testInsertExistingKey() {
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data_structures::SkipList lst = createSkipListTestInstance();
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// Add 200 to the skip list
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int key = 390;
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int level = 5;
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// Inserting a key that is already there should leave the skip list
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// unchanged. Record the current state of the skip list
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std::stringstream ss_insertion_gt;
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lst.displayList(ss_insertion_gt, "");
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// Actually insert into the skip list
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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lst.insertElement(key, NULL);
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std::stringstream ss_insertion;
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lst.displayList(ss_insertion, "");
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isTrue(ss_insertion.str() == ss_insertion_gt.str(),
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"FAILURE: test_insert_existing_key",
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"SUCCESS: test_insert_existing_key");
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}
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void testInsertLargestKey() { // TEST: Insert the largest key
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data_structures::SkipList lst = createSkipListTestInstance();
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int key = 10000;
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int level = data_structures::MAX_LEVEL;
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// We will use string processing to insert a key into this string and
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// use the result as a target
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std::stringstream ss_insertion_target;
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lst.displayList(ss_insertion_target, " ; ");
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std::string target = insertItem(ss_insertion_target.str(), key, level);
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// Actually insert into the skip list
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// This mock allows us to control the random numbers generated so we can
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// ensure the new key is added to the required number of levels.
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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lst.insertElement(key, NULL);
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std::stringstream ss_insertion;
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lst.displayList(ss_insertion, "");
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isTrue(ss_insertion.str() == target, "FAILURE: test_insert_largest_key",
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"SUCCESS: test_insert_largest_key");
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}
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// TEST: Insert what would be the smallest key in the skip list
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void testInsertSmallestKey() {
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data_structures::SkipList lst = createSkipListTestInstance();
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int key = -10000;
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int level = 1;
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// We will use string processing to insert a key into this string and
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// use the result as a target
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std::stringstream ss_insertion_target;
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lst.displayList(ss_insertion_target, " ; ");
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std::string target = insertItem(ss_insertion_target.str(), key, level);
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// Actually insert into the skip list
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// This mock allows us to control the random numbers generated so we can
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// ensure the new key is added to the required number of levels.
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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lst.insertElement(key, NULL);
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std::stringstream ss_insertion;
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lst.displayList(ss_insertion, "");
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isTrue(ss_insertion.str() == target, "FAILURE: test_insert_smallest_key",
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"SUCCESS: test_insert_smallest_key");
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}
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void testDeleteExistingKey() { // TEST: Delete an existing key
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data_structures::SkipList lst = createSkipListTestInstance();
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int key = 119;
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int level = 1;
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// We will use string processing to insert a key into this string and
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// use the result as a target
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std::stringstream ss_deletion_target;
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lst.displayList(ss_deletion_target, " ");
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std::string target = removeItem(ss_deletion_target.str(), key);
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// Actually insert into the skip list
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// This mock allows us to control the random numbers generated so we can
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// ensure the new key is added to the required number of levels.
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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lst.deleteElement(key);
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std::stringstream ss_deletion;
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lst.displayList(ss_deletion, "");
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isTrue(ss_deletion.str() == target, "FAILURE: test_delete_existing_key",
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"SUCCESS: test_delete_existing_key");
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}
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// TEST: Delete a key that is not in the skip list
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void testDeleteKeyNotInSkipList() {
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data_structures::SkipList lst = createSkipListTestInstance();
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int key = 299;
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int level = 1;
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// We will use string processing to insert a key into this string and
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// use the result as a target
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std::stringstream ss_deletion_target;
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lst.displayList(ss_deletion_target, " ");
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std::string target = removeItem(ss_deletion_target.str(), key);
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// Actually insert into the skip list
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// This mock allows us to control the random numbers generated so we can
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// ensure the new key is added to the required number of levels.
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lst.setNumberGenerator(
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make_unique<data_structures::MockRandomNumberGenerator>(level));
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lst.deleteElement(key);
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std::stringstream ss_deletion;
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lst.displayList(ss_deletion, "");
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isTrue(ss_deletion.str() == target,
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"FAILURE: test_delete_key_not_in_skip_list",
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"SUCCESS: test_delete_key_not_in_skip_list");
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}
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/**
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* Main function:
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* Creates and inserts random 2^[number of levels]
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* elements into the skip lists and than displays it
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*/
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int main() {
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std::srand(std::time(nullptr));
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std::srand(0);
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data_structures::SkipList lst;
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data_structures::SkipList lst(
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make_unique<data_structures::CRandBasedGenerator>());
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for (int j = 0; j < (1 << (data_structures::MAX_LEVEL + 1)); j++) {
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int k = (std::rand() % (1 << (data_structures::MAX_LEVEL + 2)) + 1);
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int count = 0;
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for (int j = 0; j < 100; j++) {
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int k = (std::rand() % 512 + 1);
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lst.insertElement(k, &j);
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count++;
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}
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std::cout << "Number of nodes: " << count << " "
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<< (2 << (data_structures::MAX_LEVEL + 2)) << "\n";
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lst.displayList();
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lst.displayList(std::cout, "\n");
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testInsertNewKey();
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testInsertExistingKey();
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testInsertLargestKey();
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testInsertSmallestKey();
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testDeleteExistingKey();
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testDeleteKeyNotInSkipList();
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return 0;
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}
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