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authorClifford Wolf <clifford@clifford.at>2014-12-31 03:58:29 +0100
committerClifford Wolf <clifford@clifford.at>2014-12-31 03:58:29 +0100
commitc4bd6cb9d38f445da8db6734411fd7b067c3f499 (patch)
tree9bc24ec9e7326b6bc2a0cd97d08329a5746b87f1 /kernel
parent7d6a7fe2ce8936c7af09ba7661e1159bc403483d (diff)
major rewrite of hashlib::dict<>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/hashlib.h319
1 files changed, 123 insertions, 196 deletions
diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 3164282f..a34d194f 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -140,8 +140,8 @@ struct hash_obj_ops {
inline int hashtable_size(int min_size)
{
- static std::vector<int> primes = {
- 23, 29, 37, 47, 59, 79, 101, 127, 163, 211, 269, 337, 431, 541, 677,
+ static std::vector<int> zero_and_some_primes = {
+ 0, 23, 29, 37, 47, 59, 79, 101, 127, 163, 211, 269, 337, 431, 541, 677,
853, 1069, 1361, 1709, 2137, 2677, 3347, 4201, 5261, 6577, 8231, 10289,
12889, 16127, 20161, 25219, 31531, 39419, 49277, 61603, 77017, 96281,
120371, 150473, 188107, 235159, 293957, 367453, 459317, 574157, 717697,
@@ -151,13 +151,13 @@ inline int hashtable_size(int min_size)
121590311, 151987889, 189984863, 237481091, 296851369, 371064217
};
- for (auto p : primes)
- if (p > min_size) return p;
+ for (auto p : zero_and_some_primes)
+ if (p >= min_size) return p;
if (sizeof(int) == 4)
throw std::length_error("hash table exceeded maximum size. use a ILP64 abi for larger tables.");
- for (auto p : primes)
+ for (auto p : zero_and_some_primes)
if (100129 * p > min_size) return 100129 * p;
throw std::length_error("hash table exceeded maximum size.");
@@ -168,49 +168,26 @@ class dict
{
struct entry_t
{
- int link;
std::pair<K, T> udata;
+ int next;
- entry_t() : link(-1) { }
- entry_t(const std::pair<K, T> &udata) : link(1), udata(udata) { }
-
- bool is_free() const { return link < 0; }
- int get_next() const { return (link > 0 ? link : -link) - 2; }
- bool get_last() const { return get_next() == -1; }
- void set_next_used(int next) { link = next + 2; }
- void set_next_free(int next) { link = -(next + 2); }
+ entry_t() { }
+ entry_t(const std::pair<K, T> &udata, int next) : udata(udata), next(next) { }
};
std::vector<int> hashtable;
std::vector<entry_t> entries;
- int free_list, counter, begin_n;
- int begin_seek_count;
OPS ops;
- void init()
- {
- free_list = -1;
- counter = 0;
- begin_n = -1;
- begin_seek_count = 0;
- }
-
- void init_from(const dict<K, T, OPS> &other)
- {
- hashtable.clear();
- entries.clear();
-
- counter = other.size();
- begin_n = counter - 1;
- entries.reserve(counter);
-
- for (auto &it : other)
- entries.push_back(entry_t(it));
-
- rehash();
+#if 0
+ static inline void do_assert(bool cond) {
+ if (!cond) throw std::runtime_error("dict<> assert failed.");
}
+#else
+ static inline void do_assert(bool) { }
+#endif
- int mkhash(const K &key) const
+ int do_hash(const K &key) const
{
unsigned int hash = 0;
if (!hashtable.empty())
@@ -218,145 +195,108 @@ class dict
return hash;
}
- void upd_begin_n(bool do_refree = true)
+ void do_rehash()
{
- if (begin_n < -1) {
- begin_n = -(begin_n+2);
- while (begin_n >= 0 && entries[begin_n].is_free()) { begin_seek_count++; begin_n--; }
- if (do_refree && begin_seek_count > int(entries.size() / 2)) refree();
+ hashtable.clear();
+ hashtable.resize(hashtable_size(entries.size() * hashtable_size_factor), -1);
+
+ for (int i = 0; i < int(entries.size()); i++) {
+ do_assert(-1 <= entries[i].next && entries[i].next < int(entries.size()));
+ int hash = do_hash(entries[i].udata.first);
+ entries[i].next = hashtable[hash];
+ hashtable[hash] = i;
}
}
- void refree()
+ int do_erase(int index, int hash)
{
- free_list = -1;
- begin_n = -1;
+ do_assert(index < int(entries.size()));
+ if (hashtable.empty() || index < 0)
+ return 0;
- int last_free = -1;
- for (int i = 0; i < int(entries.size()); i++)
- if (entries[i].is_free()) {
- if (last_free != -1)
- entries[last_free].set_next_free(i);
- else
- free_list = i;
- last_free = i;
- } else
- begin_n = i;
-
- if (last_free != -1)
- entries[last_free].set_next_free(-1);
-
- begin_seek_count = 0;
- }
-
- void rehash()
- {
- upd_begin_n(false);
- entries.resize(begin_n + 1);
+ int k = hashtable[hash];
+ if (k == index) {
+ hashtable[hash] = entries[index].next;
+ } else {
+ while (entries[k].next != index) {
+ k = entries[k].next;
+ do_assert(0 <= k && k < int(entries.size()));
+ }
+ entries[k].next = entries[index].next;
+ }
- free_list = -1;
- begin_n = -1;
+ int back_idx = entries.size()-1;
- hashtable.clear();
- hashtable.resize(hashtable_size(entries.size() * hashtable_size_factor), -1);
+ if (index != back_idx)
+ {
+ int back_hash = do_hash(entries[back_idx].udata.first);
- int last_free = -1;
- for (int i = 0; i < int(entries.size()); i++)
- if (entries[i].is_free()) {
- if (last_free != -1)
- entries[last_free].set_next_free(i);
- else
- free_list = i;
- last_free = i;
+ k = hashtable[back_hash];
+ if (k == back_idx) {
+ hashtable[back_hash] = index;
} else {
- int hash = mkhash(entries[i].udata.first);
- entries[i].set_next_used(hashtable[hash]);
- hashtable[hash] = i;
- begin_n = i;
+ while (entries[k].next != back_idx) {
+ k = entries[k].next;
+ do_assert(0 <= k && k < int(entries.size()));
+ }
+ entries[k].next = index;
}
- if (last_free != -1)
- entries[last_free].set_next_free(-1);
+ entries[index] = std::move(entries[back_idx]);
+ }
- begin_seek_count = 0;
+ entries.pop_back();
+
+ if (entries.empty())
+ hashtable.clear();
+
+ return 1;
}
- int do_erase(const K &key, int hash)
+ int do_lookup(const K &key, int &hash) const
{
- int last_index = -1;
- int index = hashtable.empty() ? -1 : hashtable[hash];
- while (1) {
- if (index < 0)
- return 0;
- if (ops.cmp(entries[index].udata.first, key)) {
- if (last_index < 0)
- hashtable[hash] = entries[index].get_next();
- else
- entries[last_index].set_next_used(entries[index].get_next());
- entries[index].udata = std::pair<K, T>();
- entries[index].set_next_free(free_list);
- free_list = index;
- if (--counter == 0)
- clear();
- else if (index == begin_n)
- begin_n = -(begin_n+2);
- return 1;
- }
- last_index = index;
- index = entries[index].get_next();
+ if (hashtable.empty())
+ return -1;
+
+ if (entries.size() * hashtable_size_trigger > hashtable.size()) {
+ ((dict*)this)->do_rehash();
+ hash = do_hash(key);
}
- }
- int lookup_index(const K &key, int hash) const
- {
- int index = hashtable.empty() ? -1 : hashtable[hash];
- while (1) {
- if (index < 0)
- return -1;
- if (ops.cmp(entries[index].udata.first, key))
- return index;
- index = entries[index].get_next();
+ int index = hashtable[hash];
+
+ while (index >= 0 && !ops.cmp(entries[index].udata.first, key)) {
+ index = entries[index].next;
+ do_assert(-1 <= index && index < int(entries.size()));
}
+
+ return index;
}
- int insert_at(const std::pair<K, T> &value, int hash)
+ int do_insert(const std::pair<K, T> &value, int &hash)
{
- if (free_list < 0)
- {
- free_list = entries.size();
- entries.push_back(entry_t());
-
- if (entries.size() * hashtable_size_trigger > hashtable.size()) {
- int i = free_list;
- entries[i].udata = value;
- entries[i].set_next_used(0);
- begin_n = i;
- counter++;
- rehash();
- return i;
- }
+ if (hashtable.empty()) {
+ entries.push_back(entry_t(value, -1));
+ do_rehash();
+ hash = do_hash(value.first);
+ } else {
+ entries.push_back(entry_t(value, hashtable[hash]));
+ hashtable[hash] = entries.size() - 1;
}
-
- int i = free_list;
- free_list = entries[i].get_next();
- entries[i].udata = value;
- entries[i].set_next_used(hashtable[hash]);
- hashtable[hash] = i;
- if ((begin_n < -1 && -(begin_n+2) <= i) || (begin_n >= -1 && begin_n <= i))
- begin_n = i;
- counter++;
- return i;
+ return entries.size() - 1;
}
public:
class iterator
{
+ friend dict<K, T, OPS>;
+ protected:
dict<K, T, OPS> *ptr;
int index;
public:
iterator() { }
iterator(dict<K, T, OPS> *ptr, int index) : ptr(ptr), index(index) { }
- iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); return *this; }
+ iterator operator++() { index--; return *this; }
bool operator==(const iterator &other) const { return index == other.index; }
bool operator!=(const iterator &other) const { return index != other.index; }
std::pair<K, T> &operator*() { return ptr->entries[index].udata; }
@@ -367,12 +307,14 @@ public:
class const_iterator
{
+ friend dict<K, T, OPS>;
+ protected:
const dict<K, T, OPS> *ptr;
int index;
public:
const_iterator() { }
const_iterator(const dict<K, T, OPS> *ptr, int index) : ptr(ptr), index(index) { }
- const_iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); return *this; }
+ const_iterator operator++() { index--; return *this; }
bool operator==(const const_iterator &other) const { return index == other.index; }
bool operator!=(const const_iterator &other) const { return index != other.index; }
const std::pair<K, T> &operator*() const { return ptr->entries[index].udata; }
@@ -381,23 +323,22 @@ public:
dict()
{
- init();
}
dict(const dict<K, T, OPS> &other)
{
- init_from(other);
+ entries = other.entries;
+ do_rehash();
}
dict(dict<K, T, OPS> &&other)
{
- init();
swap(other);
}
dict<K, T, OPS> &operator=(const dict<K, T, OPS> &other) {
- if (this != &other)
- init_from(other);
+ entries = other.entries;
+ do_rehash();
return *this;
}
@@ -409,7 +350,6 @@ public:
dict(const std::initializer_list<std::pair<K, T>> &list)
{
- init();
for (auto &it : list)
insert(it);
}
@@ -417,7 +357,6 @@ public:
template<class InputIterator>
dict(InputIterator first, InputIterator last)
{
- init();
insert(first, last);
}
@@ -430,38 +369,39 @@ public:
std::pair<iterator, bool> insert(const std::pair<K, T> &value)
{
- int hash = mkhash(value.first);
- int i = lookup_index(value.first, hash);
+ int hash = do_hash(value.first);
+ int i = do_lookup(value.first, hash);
if (i >= 0)
return std::pair<iterator, bool>(iterator(this, i), false);
- i = insert_at(value, hash);
+ i = do_insert(value, hash);
return std::pair<iterator, bool>(iterator(this, i), true);
}
int erase(const K &key)
{
- int hash = mkhash(key);
- return do_erase(key, hash);
+ int hash = do_hash(key);
+ int index = do_lookup(key, hash);
+ return do_erase(index, hash);
}
iterator erase(iterator it)
{
- int hash = mkhash(it->first);
- do_erase(it->first, hash);
+ int hash = do_hash(it->first);
+ do_erase(it.index, hash);
return ++it;
}
int count(const K &key) const
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
return i < 0 ? 0 : 1;
}
iterator find(const K &key)
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
if (i < 0)
return end();
return iterator(this, i);
@@ -469,8 +409,8 @@ public:
const_iterator find(const K &key) const
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
if (i < 0)
return end();
return const_iterator(this, i);
@@ -478,8 +418,8 @@ public:
T& at(const K &key)
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
if (i < 0)
throw std::out_of_range("dict::at()");
return entries[i].udata.second;
@@ -487,8 +427,8 @@ public:
const T& at(const K &key) const
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
if (i < 0)
throw std::out_of_range("dict::at()");
return entries[i].udata.second;
@@ -496,10 +436,10 @@ public:
T& operator[](const K &key)
{
- int hash = mkhash(key);
- int i = lookup_index(key, hash);
+ int hash = do_hash(key);
+ int i = do_lookup(key, hash);
if (i < 0)
- i = insert_at(std::pair<K, T>(key, T()), hash);
+ i = do_insert(std::pair<K, T>(key, T()), hash);
return entries[i].udata.second;
}
@@ -507,29 +447,16 @@ public:
{
hashtable.swap(other.hashtable);
entries.swap(other.entries);
- std::swap(free_list, other.free_list);
- std::swap(counter, other.counter);
- std::swap(begin_n, other.begin_n);
- std::swap(begin_seek_count, other.begin_seek_count);
}
bool operator==(const dict<K, T, OPS> &other) const {
- if (counter != other.counter)
+ if (size() != other.size())
return false;
- if (counter == 0)
- return true;
- if (entries.size() < other.entries.size())
- for (auto &it : *this) {
- auto oit = other.find(it.first);
- if (oit == other.end() || oit->second != it.second)
- return false;
- }
- else
- for (auto &oit : other) {
- auto it = find(oit.first);
- if (it == end() || it->second != oit.second)
- return false;
- }
+ for (auto &it : entries) {
+ auto oit = other.find(it.udata.first);
+ if (oit == other.end() || oit->second != it.udata.second)
+ return false;
+ }
return true;
}
@@ -537,14 +464,14 @@ public:
return !(*this == other);
}
- size_t size() const { return counter; }
- bool empty() const { return counter == 0; }
- void clear() { hashtable.clear(); entries.clear(); init(); }
+ size_t size() const { return entries.size(); }
+ bool empty() const { return entries.empty(); }
+ void clear() { hashtable.clear(); entries.clear(); }
- iterator begin() { upd_begin_n(); return iterator(this, begin_n); }
+ iterator begin() { return iterator(this, int(entries.size())-1); }
iterator end() { return iterator(nullptr, -1); }
- const_iterator begin() const { ((dict*)this)->upd_begin_n(); return const_iterator(this, begin_n); }
+ const_iterator begin() const { return const_iterator(this, int(entries.size())-1); }
const_iterator end() const { return const_iterator(nullptr, -1); }
};