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AK: Consolidate iterators for HashTable and DoublyLinkedList respectively.

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Get rid of the ConstIterator classes for these containers and use templated
FooIterator<T, ...> and FooIterator<const T, ...> helpers.

This makes the HashTable class a lot easier to read.
This commit is contained in:
Andreas Kling 2019-06-27 15:57:49 +02:00
parent 50700c107f
commit 516d736afe
5 changed files with 150 additions and 240 deletions
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76
AK/DoublyLinkedList.h
View file

@ -5,6 +5,30 @@
namespace AK {
template<typename ListType, typename ElementType>
class DoublyLinkedListIterator {
public:
bool operator!=(const DoublyLinkedListIterator& other) const { return m_node != other.m_node; }
bool operator==(const DoublyLinkedListIterator& other) const { return m_node == other.m_node; }
DoublyLinkedListIterator& operator++()
{
m_node = m_node->next;
return *this;
}
ElementType& operator*() { return m_node->value; }
ElementType* operator->() { return &m_node->value; }
bool is_end() const { return !m_node; }
static DoublyLinkedListIterator universal_end() { return DoublyLinkedListIterator(nullptr); }
private:
friend ListType;
explicit DoublyLinkedListIterator(typename ListType::Node* node)
: m_node(node)
{
}
typename ListType::Node* m_node;
};
template<typename T>
class DoublyLinkedList {
private:
@ -79,55 +103,13 @@ public:
return false;
}
class Iterator {
public:
bool operator!=(const Iterator& other) const { return m_node != other.m_node; }
bool operator==(const Iterator& other) const { return m_node == other.m_node; }
Iterator& operator++()
{
m_node = m_node->next;
return *this;
}
T& operator*() { return m_node->value; }
T* operator->() { return &m_node->value; }
bool is_end() const { return !m_node; }
static Iterator universal_end() { return Iterator(nullptr); }
private:
friend class DoublyLinkedList;
explicit Iterator(DoublyLinkedList::Node* node)
: m_node(node)
{
}
DoublyLinkedList::Node* m_node;
};
using Iterator = DoublyLinkedListIterator<DoublyLinkedList, T>;
friend Iterator;
Iterator begin() { return Iterator(m_head); }
Iterator end() { return Iterator::universal_end(); }
class ConstIterator {
public:
bool operator!=(const ConstIterator& other) const { return m_node != other.m_node; }
bool operator==(const ConstIterator& other) const { return m_node == other.m_node; }
ConstIterator& operator++()
{
m_node = m_node->next;
return *this;
}
const T& operator*() const { return m_node->value; }
const T* operator->() const { return &m_node->value; }
bool is_end() const { return !m_node; }
static ConstIterator universal_end() { return ConstIterator(nullptr); }
private:
friend class DoublyLinkedList;
explicit ConstIterator(const DoublyLinkedList::Node* node)
: m_node(node)
{
}
const DoublyLinkedList::Node* m_node;
};
using ConstIterator = DoublyLinkedListIterator<const DoublyLinkedList, const T>;
friend ConstIterator;
ConstIterator begin() const { return ConstIterator(m_head); }
ConstIterator end() const { return ConstIterator::universal_end(); }
@ -171,8 +153,6 @@ public:
}
private:
friend class Iterator;
void append_node(Node* node)
{
if (!m_head) {

276
AK/HashTable.h
View file

@ -6,19 +6,76 @@
#include "Traits.h"
#include "kstdio.h"
//#define HASHTABLE_DEBUG
namespace AK {
template<typename T, typename = Traits<T>>
class HashTable;
template<typename HashTableType, typename ElementType, typename BucketIteratorType>
class HashTableIterator {
public:
bool operator!=(const HashTableIterator& other) const
{
if (m_is_end && other.m_is_end)
return false;
return &m_table != &other.m_table
|| m_is_end != other.m_is_end
|| m_bucket_index != other.m_bucket_index
|| m_bucket_iterator != other.m_bucket_iterator;
}
bool operator==(const HashTableIterator& other) const { return !(*this != other); }
ElementType& operator*() { return *m_bucket_iterator; }
ElementType* operator->() { return m_bucket_iterator.operator->(); }
HashTableIterator& operator++()
{
skip_to_next();
return *this;
}
void skip_to_next()
{
while (!m_is_end) {
if (m_bucket_iterator.is_end()) {
++m_bucket_index;
if (m_bucket_index >= m_table.capacity()) {
m_is_end = true;
return;
}
m_bucket_iterator = m_table.bucket(m_bucket_index).begin();
} else {
++m_bucket_iterator;
}
if (!m_bucket_iterator.is_end())
return;
}
}
private:
friend HashTableType;
explicit HashTableIterator(HashTableType& table, bool is_end, BucketIteratorType bucket_iterator = BucketIteratorType::universal_end(), int bucket_index = 0)
: m_table(table)
, m_bucket_index(bucket_index)
, m_is_end(is_end)
, m_bucket_iterator(bucket_iterator)
{
if (!is_end && !m_table.is_empty() && !(m_bucket_iterator != BucketIteratorType::universal_end())) {
m_bucket_iterator = m_table.bucket(0).begin();
if (m_bucket_iterator.is_end())
skip_to_next();
}
}
HashTableType& m_table;
int m_bucket_index { 0 };
bool m_is_end { false };
BucketIteratorType m_bucket_iterator;
};
template<typename T, typename TraitsForT>
class HashTable {
private:
struct Bucket {
DoublyLinkedList<T> chain;
};
using Bucket = DoublyLinkedList<T>;
public:
HashTable() {}
@ -79,161 +136,13 @@ public:
void dump() const;
class Iterator {
public:
bool operator!=(const Iterator& other) const
{
if (m_is_end && other.m_is_end)
return false;
return &m_table != &other.m_table
|| m_is_end != other.m_is_end
|| m_bucket_index != other.m_bucket_index
|| m_bucket_iterator != other.m_bucket_iterator;
}
bool operator==(const Iterator& other) const { return !(*this != other); }
T& operator*()
{
#ifdef HASHTABLE_DEBUG
kprintf("retrieve { bucket_index: %u, is_end: %u }\n", m_bucket_index, m_is_end);
#endif
return *m_bucket_iterator;
}
T* operator->() { return m_bucket_iterator.operator->(); }
Iterator& operator++()
{
skip_to_next();
return *this;
}
void skip_to_next()
{
#ifdef HASHTABLE_DEBUG
unsigned pass = 0;
#endif
while (!m_is_end) {
#ifdef HASHTABLE_DEBUG
++pass;
kprintf("skip_to_next pass %u, m_bucket_index=%u\n", pass, m_bucket_index);
#endif
if (m_bucket_iterator.is_end()) {
++m_bucket_index;
if (m_bucket_index >= m_table.capacity()) {
m_is_end = true;
return;
}
m_bucket_iterator = m_table.m_buckets[m_bucket_index].chain.begin();
} else {
++m_bucket_iterator;
}
if (!m_bucket_iterator.is_end())
return;
}
}
private:
friend class HashTable;
explicit Iterator(HashTable& table, bool is_end, typename DoublyLinkedList<T>::Iterator bucket_iterator = DoublyLinkedList<T>::Iterator::universal_end(), int bucket_index = 0)
: m_table(table)
, m_bucket_index(bucket_index)
, m_is_end(is_end)
, m_bucket_iterator(bucket_iterator)
{
if (!is_end && !m_table.is_empty() && !(m_bucket_iterator != DoublyLinkedList<T>::Iterator::universal_end())) {
#ifdef HASHTABLE_DEBUG
kprintf("bucket iterator init!\n");
#endif
m_bucket_iterator = m_table.m_buckets[0].chain.begin();
if (m_bucket_iterator.is_end())
skip_to_next();
}
}
HashTable& m_table;
int m_bucket_index { 0 };
bool m_is_end { false };
typename DoublyLinkedList<T>::Iterator m_bucket_iterator;
};
using Iterator = HashTableIterator<HashTable, T, typename DoublyLinkedList<T>::Iterator>;
friend Iterator;
Iterator begin() { return Iterator(*this, is_empty()); }
Iterator end() { return Iterator(*this, true); }
class ConstIterator {
public:
bool operator!=(const ConstIterator& other) const
{
if (m_is_end && other.m_is_end)
return false;
return &m_table != &other.m_table
|| m_is_end != other.m_is_end
|| m_bucket_index != other.m_bucket_index
|| m_bucket_iterator != other.m_bucket_iterator;
}
bool operator==(const ConstIterator& other) const { return !(*this != other); }
const T& operator*() const
{
#ifdef HASHTABLE_DEBUG
kprintf("retrieve { bucket_index: %u, is_end: %u }\n", m_bucket_index, m_is_end);
#endif
return *m_bucket_iterator;
}
const T* operator->() const { return m_bucket_iterator.operator->(); }
ConstIterator& operator++()
{
skip_to_next();
return *this;
}
void skip_to_next()
{
#ifdef HASHTABLE_DEBUG
unsigned pass = 0;
#endif
while (!m_is_end) {
#ifdef HASHTABLE_DEBUG
++pass;
kprintf("skip_to_next pass %u, m_bucket_index=%u\n", pass, m_bucket_index);
#endif
if (m_bucket_iterator.is_end()) {
++m_bucket_index;
if (m_bucket_index >= m_table.capacity()) {
m_is_end = true;
return;
}
const DoublyLinkedList<T>& chain = m_table.m_buckets[m_bucket_index].chain;
m_bucket_iterator = chain.begin();
} else {
++m_bucket_iterator;
}
if (!m_bucket_iterator.is_end())
return;
}
}
private:
friend class HashTable;
ConstIterator(const HashTable& table, bool is_end, typename DoublyLinkedList<T>::ConstIterator bucket_iterator = DoublyLinkedList<T>::ConstIterator::universal_end(), int bucket_index = 0)
: m_table(table)
, m_bucket_index(bucket_index)
, m_is_end(is_end)
, m_bucket_iterator(bucket_iterator)
{
if (!is_end && !m_table.is_empty() && !(m_bucket_iterator != DoublyLinkedList<T>::ConstIterator::universal_end())) {
#ifdef HASHTABLE_DEBUG
kprintf("const bucket iterator init!\n");
#endif
const DoublyLinkedList<T>& chain = m_table.m_buckets[0].chain;
m_bucket_iterator = chain.begin();
if (m_bucket_iterator.is_end())
skip_to_next();
}
}
const HashTable& m_table;
int m_bucket_index { 0 };
bool m_is_end { false };
typename DoublyLinkedList<T>::ConstIterator m_bucket_iterator;
};
using ConstIterator = HashTableIterator<const HashTable, const T, typename DoublyLinkedList<T>::ConstIterator>;
friend ConstIterator;
ConstIterator begin() const { return ConstIterator(*this, is_empty()); }
ConstIterator end() const { return ConstIterator(*this, true); }
@ -256,6 +165,9 @@ private:
void insert(const T&);
void insert(T&&);
Bucket& bucket(int index) { return m_buckets[index]; }
const Bucket& bucket(int index) const { return m_buckets[index]; }
Bucket* m_buckets { nullptr };
int m_size { 0 };
@ -268,7 +180,7 @@ void HashTable<T, TraitsForT>::set(T&& value)
if (!m_capacity)
rehash(1);
auto& bucket = lookup(value);
for (auto& e : bucket.chain) {
for (auto& e : bucket) {
if (e == value) {
e = move(value);
return;
@ -278,7 +190,7 @@ void HashTable<T, TraitsForT>::set(T&& value)
rehash(size() + 1);
insert(move(value));
} else {
bucket.chain.append(move(value));
bucket.append(move(value));
}
m_size++;
}
@ -289,7 +201,7 @@ void HashTable<T, TraitsForT>::set(const T& value)
if (!m_capacity)
rehash(1);
auto& bucket = lookup(value);
for (auto& e : bucket.chain) {
for (auto& e : bucket) {
if (e == value) {
e = move(value);
return;
@ -299,7 +211,7 @@ void HashTable<T, TraitsForT>::set(const T& value)
rehash(size() + 1);
insert(value);
} else {
bucket.chain.append(value);
bucket.append(value);
}
m_size++;
}
@ -308,20 +220,14 @@ template<typename T, typename TraitsForT>
void HashTable<T, TraitsForT>::rehash(int new_capacity)
{
new_capacity *= 2;
#ifdef HASHTABLE_DEBUG
kprintf("rehash to %u buckets\n", new_capacity);
#endif
auto* new_buckets = new Bucket[new_capacity];
auto* old_buckets = m_buckets;
int old_capacity = m_capacity;
m_buckets = new_buckets;
m_capacity = new_capacity;
#ifdef HASHTABLE_DEBUG
kprintf("reinsert %u buckets\n", old_capacity);
#endif
for (int i = 0; i < old_capacity; ++i) {
for (auto& value : old_buckets[i].chain) {
for (auto& value : old_buckets[i]) {
insert(move(value));
}
}
@ -344,14 +250,14 @@ template<typename T, typename TraitsForT>
void HashTable<T, TraitsForT>::insert(T&& value)
{
auto& bucket = lookup(value);
bucket.chain.append(move(value));
bucket.append(move(value));
}
template<typename T, typename TraitsForT>
void HashTable<T, TraitsForT>::insert(const T& value)
{
auto& bucket = lookup(value);
bucket.chain.append(value);
bucket.append(value);
}
template<typename T, typename TraitsForT>
@ -360,7 +266,7 @@ bool HashTable<T, TraitsForT>::contains(const T& value) const
if (is_empty())
return false;
auto& bucket = lookup(value);
for (auto& e : bucket.chain) {
for (auto& e : bucket) {
if (e == value)
return true;
}
@ -374,8 +280,8 @@ auto HashTable<T, TraitsForT>::find(const T& value) -> Iterator
return end();
int bucket_index;
auto& bucket = lookup(value, &bucket_index);
auto bucket_iterator = bucket.chain.find(value);
if (bucket_iterator != bucket.chain.end())
auto bucket_iterator = bucket.find(value);
if (bucket_iterator != bucket.end())
return Iterator(*this, false, bucket_iterator, bucket_index);
return end();
}
@ -386,9 +292,9 @@ auto HashTable<T, TraitsForT>::find(const T& value) const -> ConstIterator
if (is_empty())
return end();
int bucket_index;
auto& bucket = lookup(value, &bucket_index);
auto bucket_iterator = bucket.chain.find(value);
if (bucket_iterator != bucket.chain.end())
const auto& bucket = lookup(value, &bucket_index);
auto bucket_iterator = bucket.find(value);
if (bucket_iterator != bucket.end())
return ConstIterator(*this, false, bucket_iterator, bucket_index);
return end();
}
@ -397,33 +303,23 @@ template<typename T, typename TraitsForT>
void HashTable<T, TraitsForT>::remove(Iterator it)
{
ASSERT(!is_empty());
m_buckets[it.m_bucket_index].chain.remove(it.m_bucket_iterator);
m_buckets[it.m_bucket_index].remove(it.m_bucket_iterator);
--m_size;
}
template<typename T, typename TraitsForT>
typename HashTable<T, TraitsForT>::Bucket& HashTable<T, TraitsForT>::lookup(const T& value, int* bucket_index)
auto HashTable<T, TraitsForT>::lookup(const T& value, int* bucket_index) -> Bucket&
{
unsigned hash = TraitsForT::hash(value);
#ifdef HASHTABLE_DEBUG
kprintf("hash for ");
TraitsForT::dump(value);
kprintf(" is %u\n", hash);
#endif
if (bucket_index)
*bucket_index = hash % m_capacity;
return m_buckets[hash % m_capacity];
}
template<typename T, typename TraitsForT>
const typename HashTable<T, TraitsForT>::Bucket& HashTable<T, TraitsForT>::lookup(const T& value, int* bucket_index) const
auto HashTable<T, TraitsForT>::lookup(const T& value, int* bucket_index) const -> const Bucket&
{
unsigned hash = TraitsForT::hash(value);
#ifdef HASHTABLE_DEBUG
kprintf("hash for ");
TraitsForT::dump(value);
kprintf(" is %u\n", hash);
#endif
if (bucket_index)
*bucket_index = hash % m_capacity;
return m_buckets[hash % m_capacity];
@ -436,7 +332,7 @@ void HashTable<T, TraitsForT>::dump() const
for (int i = 0; i < m_capacity; ++i) {
auto& bucket = m_buckets[i];
kprintf("Bucket %u\n", i);
for (auto& e : bucket.chain) {
for (auto& e : bucket) {
kprintf(" > ");
TraitsForT::dump(e);
kprintf("\n");

1
AK/Tests/.gitignore vendored
View file

@ -1,5 +1,6 @@
TestString
TestQueue
TestVector
TestHashMap
*.d
*.o

9
AK/Tests/Makefile
View file

@ -1,4 +1,6 @@
all: TestString TestQueue TestVector
PROGRAMS = TestString TestQueue TestVector TestHashMap
all: $(PROGRAMS)
CXXFLAGS = -std=c++17 -Wall -Wextra
@ -11,5 +13,8 @@ TestQueue: TestQueue.cpp ../String.cpp ../StringImpl.cpp ../StringBuilder.cpp ..
TestVector: TestVector.cpp ../String.cpp ../StringImpl.cpp ../StringBuilder.cpp ../StringView.cpp TestHelpers.h
$(CXX) $(CXXFLAGS) -I../ -I../../ -o $@ TestVector.cpp ../String.cpp ../StringImpl.cpp ../StringBuilder.cpp ../StringView.cpp
TestHashMap: TestHashMap.cpp ../String.cpp ../StringImpl.cpp ../StringBuilder.cpp ../StringView.cpp TestHelpers.h
$(CXX) $(CXXFLAGS) -I../ -I../../ -o $@ TestHashMap.cpp ../String.cpp ../StringImpl.cpp ../StringBuilder.cpp ../StringView.cpp
clean:
rm -f TestString TestQueue
rm -f $(PROGRAMS)

28
AK/Tests/TestHashMap.cpp Normal file
View file

@ -0,0 +1,28 @@
#include "TestHelpers.h"
#include <AK/AKString.h>
#include <AK/HashMap.h>
typedef HashMap<int, int> IntIntMap;
int main()
{
EXPECT(IntIntMap().is_empty());
EXPECT(IntIntMap().size() == 0);
HashMap<int, String> number_to_string;
number_to_string.set(1, "One");
number_to_string.set(2, "Two");
number_to_string.set(3, "Three");
EXPECT_EQ(number_to_string.is_empty(), false);
EXPECT_EQ(number_to_string.size(), 3);
int loop_counter = 0;
for (auto& it : number_to_string) {
EXPECT(!it.value.is_null());
++loop_counter;
}
EXPECT_EQ(loop_counter, 3);
return 0;
}