Improved hashlib iterator implementation

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index a8d320865e57b2f371bf4f0abdaa6a31390470c5..d363d68b5cb5014a329543e40bcc6ef3c70a7717 100644 (file)
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -145,13 +145,14 @@ class dict
 
        std::vector<int> hashtable;
        std::vector<entry_t> entries;
-       int free_list, counter;
+       int free_list, counter, begin_n;
        OPS ops;
 
        void init()
        {
                free_list = -1;
                counter = 0;
+               begin_n = -1;
        }
 
        void init_from(const dict<K, T, OPS> &other)
@@ -182,6 +183,7 @@ class dict
        void rehash()
        {
                free_list = -1;
+               begin_n = -1;
 
                for (auto &h : hashtable)
                        h = -1;
@@ -194,6 +196,7 @@ class dict
                                int hash = mkhash(entries[i].udata.first);
                                entries[i].set_next_used(hashtable[hash]);
                                hashtable[hash] = i;
+                               begin_n = i;
                        }
        }
 
@@ -213,7 +216,9 @@ class dict
                                entries[index].set_next_free(free_list);
                                free_list = index;
                                if (--counter == 0)
-                                       init();
+                                       clear();
+                               else if (index == begin_n)
+                                       do begin_n--; while (begin_n >= 0 && entries[begin_n].is_free());
                                return;
                        }
                        last_index = index;
@@ -253,6 +258,8 @@ class dict
                entries[i].udata = value;
                entries[i].set_next_used(hashtable[hash]);
                hashtable[hash] = i;
+               if (begin_n < i)
+                       begin_n = i;
                counter++;
                return i;
        }
@@ -265,8 +272,7 @@ public:
        public:
                iterator() { }
                iterator(dict<K, T, OPS> *ptr, int index) : ptr(ptr), index(index) { }
-               iterator operator++() { do index++; while (index != int(ptr->entries.size()) && ptr->entries[index].is_free()); return *this; }
-               iterator operator--() { do index--; while (index != 0 && ptr->entries[index].is_free()); return *this; }
+               iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); 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; }
@@ -282,8 +288,7 @@ public:
        public:
                const_iterator() { }
                const_iterator(const dict<K, T, OPS> *ptr, int index) : ptr(ptr), index(index) { }
-               const_iterator operator++() { do index++; while (index != int(ptr->entries.size()) && ptr->entries[index].is_free()); return *this; }
-               const_iterator operator--() { do index--; while (index != 0 && ptr->entries[index].is_free()); return *this; }
+               const_iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); 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; }
@@ -308,8 +313,8 @@ public:
        }
 
        dict<K, T, OPS> &operator=(const dict<K, T, OPS> &other) {
-               clear();
-               init_from(other);
+               if (this != &other)
+                       init_from(other);
                return *this;
        }
 
@@ -420,6 +425,7 @@ public:
                entries.swap(other.entries);
                std::swap(free_list, other.free_list);
                std::swap(counter, other.counter);
+               std::swap(begin_n, other.begin_n);
        }
 
        bool operator==(const dict<K, T, OPS> &other) const {
@@ -450,11 +456,11 @@ public:
        bool empty() const { return counter == 0; }
        void clear() { hashtable.clear(); entries.clear(); init(); }
 
-       iterator begin() { int index = 0; while (index != int(entries.size()) && entries[index].is_free()) index++; return iterator(this, index); }
-       iterator end() { return iterator(this, entries.size()); }
+       iterator begin() { return iterator(this, begin_n); }
+       iterator end() { return iterator(this, -1); }
 
-       const_iterator begin() const { int index = 0; while (index != int(entries.size()) && entries[index].is_free()) index++; return const_iterator(this, index); }
-       const_iterator end() const { return const_iterator(this, entries.size()); }
+       const_iterator begin() const { return const_iterator(this, begin_n); }
+       const_iterator end() const { return const_iterator(this, -1); }
 };
 
 template<typename K, typename OPS = hash_ops<K>>
@@ -477,13 +483,14 @@ class pool
 
        std::vector<int> hashtable;
        std::vector<entry_t> entries;
-       int free_list, counter;
+       int free_list, counter, begin_n;
        OPS ops;
 
        void init()
        {
                free_list = -1;
                counter = 0;
+               begin_n = -1;
        }
 
        void init_from(const pool<K, OPS> &other)
@@ -514,6 +521,7 @@ class pool
        void rehash()
        {
                free_list = -1;
+               begin_n = -1;
 
                for (auto &h : hashtable)
                        h = -1;
@@ -526,6 +534,7 @@ class pool
                                int hash = mkhash(entries[i].key);
                                entries[i].set_next_used(hashtable[hash]);
                                hashtable[hash] = i;
+                               begin_n = i;
                        }
        }
 
@@ -545,7 +554,9 @@ class pool
                                entries[index].set_next_free(free_list);
                                free_list = index;
                                if (--counter == 0)
-                                       init();
+                                       clear();
+                               else if (index == begin_n)
+                                       do begin_n--; while (begin_n >= 0 && entries[begin_n].is_free());
                                return;
                        }
                        last_index = index;
@@ -585,6 +596,8 @@ class pool
                entries[i].key = key;
                entries[i].set_next_used(hashtable[hash]);
                hashtable[hash] = i;
+               if (begin_n < i)
+                       begin_n = i;
                counter++;
                return i;
        }
@@ -597,8 +610,7 @@ public:
        public:
                iterator() { }
                iterator(pool<K, OPS> *ptr, int index) : ptr(ptr), index(index) { }
-               iterator operator++() { do index++; while (index != int(ptr->entries.size()) && ptr->entries[index].is_free()); return *this; }
-               iterator operator--() { do index--; while (index != 0 && ptr->entries[index].is_free()); return *this; }
+               iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); return *this; }
                bool operator==(const iterator &other) const { return index == other.index; }
                bool operator!=(const iterator &other) const { return index != other.index; }
                K &operator*() { return ptr->entries[index].key; }
@@ -614,8 +626,7 @@ public:
        public:
                const_iterator() { }
                const_iterator(const pool<K, OPS> *ptr, int index) : ptr(ptr), index(index) { }
-               const_iterator operator++() { do index++; while (index != int(ptr->entries.size()) && ptr->entries[index].is_free()); return *this; }
-               const_iterator operator--() { do index--; while (index != 0 && ptr->entries[index].is_free()); return *this; }
+               const_iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); 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 K &operator*() const { return ptr->entries[index].key; }
@@ -640,8 +651,8 @@ public:
        }
 
        pool<K, OPS> &operator=(const pool<K, OPS> &other) {
-               clear();
-               init_from(other);
+               if (this != &other)
+                       init_from(other);
                return *this;
        }
 
@@ -732,6 +743,7 @@ public:
                entries.swap(other.entries);
                std::swap(free_list, other.free_list);
                std::swap(counter, other.counter);
+               std::swap(begin_n, other.begin_n);
        }
 
        bool operator==(const pool<K, OPS> &other) const {
@@ -762,11 +774,11 @@ public:
        bool empty() const { return counter == 0; }
        void clear() { hashtable.clear(); entries.clear(); init(); }
 
-       iterator begin() { int index = 0; while (index != int(entries.size()) && entries[index].is_free()) index++; return iterator(this, index); }
-       iterator end() { return iterator(this, entries.size()); }
+       iterator begin() { return iterator(this, begin_n); }
+       iterator end() { return iterator(this, -1); }
 
-       const_iterator begin() const { int index = 0; while (index != int(entries.size()) && entries[index].is_free()) index++; return const_iterator(this, index); }
-       const_iterator end() const { return const_iterator(this, entries.size()); }
+       const_iterator begin() const { return const_iterator(this, begin_n); }
+       const_iterator end() const { return const_iterator(this, -1); }
 };
 
 } /* namespace hashlib */