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xo-arena: reorg: move DArenaHashMapIterator to dedicated file

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This commit is contained in:
Roland Conybeare 2026-01-08 18:50:04 -05:00
commit fcc29411c8
2 changed files with 83 additions and 68 deletions
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69
include/xo/arena/DArenaHashMap.hpp
View file

@ -8,6 +8,7 @@
#include "DArenaVector.hpp" #include "DArenaVector.hpp"
#include "hashmap/verify_policy.hpp" #include "hashmap/verify_policy.hpp"
#include "hashmap/HashMapStore.hpp" #include "hashmap/HashMapStore.hpp"
#include "hashmap/DArenaHashMapIterator.hpp"
#include <xo/indentlog/scope.hpp> #include <xo/indentlog/scope.hpp>
#include <algorithm> #include <algorithm>
#include <array> #include <array>
@ -25,74 +26,6 @@ namespace xo {
}; };
#endif #endif
namespace detail {
template <typename Key,
typename Value>
struct DArenaHashMapIterator : public DArenaHashMapUtil {
using value_type = std::pair<const Key, Value>;
public:
DArenaHashMapIterator(uint8_t * c, value_type * p)
: ctrl_{c}, pos_{p} {}
value_type & operator*() const { return *pos_; }
value_type * operator->() const { return pos_; }
/** true iff iterator at sentinel position (not dereferencable state !) **/
bool _at_slot_sentinel() const { return is_sentinel(*ctrl_) && (*ctrl_ != c_iterator_bookend); }
bool operator==(const DArenaHashMapIterator & x) const {
return this->pos_ == x.pos_;
}
bool operator!=(const DArenaHashMapIterator & x) const {
return this->pos_ != x.pos_;
}
DArenaHashMapIterator & operator++() {
do {
++ctrl_;
++pos_;
/** end condition: iterator ends at last non-wrapped position.
* relyin on bookend sentinel values at known offset from 'wrap' section
*
* ctrl_ ctrl_ + c_group_size
* | |
* v v
* <----------------- control_size(n_slot) ---------------->
* <-stub-> <----------- n_slot ----------> <group> <-stub->
* +--------+-------------------------------+-------+--------+
* | 0xF0 | empty / data / tombstone | wrap | 0xF0 |
* +--------+-------------------------------+-------+--------+
**/
} while (is_sentinel(*ctrl_)
&& (*(ctrl_ + c_group_size) != c_iterator_bookend));
return *this;
}
DArenaHashMapIterator & operator--() {
/* simpler than forward iteration, since bookend immediately
* precedes control byte for first slot
*/
do {
--ctrl_;
--pos_;
} while (is_sentinel(*ctrl_)
&& (*ctrl_ != c_iterator_bookend));
return *this;
}
private:
uint8_t * ctrl_ = nullptr;
value_type * pos_ = nullptr;
};
}
/** @brief flat hash map of key-value pairs using dedicated DArenas for storage /** @brief flat hash map of key-value pairs using dedicated DArenas for storage
* *
* Replicates (to the extent feasible) std::unordered_map<K,V> * Replicates (to the extent feasible) std::unordered_map<K,V>

82
include/xo/arena/hashmap/DArenaHashMapIterator.hpp Normal file
View file

@ -0,0 +1,82 @@
/** @file DArenaHashMapIterator.hpp
*
* @author Roland Conybeare, Jan 2026
**/
#pragma once
#include "hashmap/DArenaHashMapUtil.hpp"
namespace xo {
namespace mm {
namespace detail {
template <typename Key,
typename Value>
struct DArenaHashMapIterator : public DArenaHashMapUtil {
using value_type = std::pair<const Key, Value>;
public:
DArenaHashMapIterator(uint8_t * c, value_type * p)
: ctrl_{c}, pos_{p} {}
value_type & operator*() const { return *pos_; }
value_type * operator->() const { return pos_; }
/** true iff iterator at sentinel position (not dereferencable state !) **/
bool _at_slot_sentinel() const { return is_sentinel(*ctrl_) && (*ctrl_ != c_iterator_bookend); }
bool operator==(const DArenaHashMapIterator & x) const {
return this->pos_ == x.pos_;
}
bool operator!=(const DArenaHashMapIterator & x) const {
return this->pos_ != x.pos_;
}
DArenaHashMapIterator & operator++() {
do {
++ctrl_;
++pos_;
/** end condition: iterator ends at last non-wrapped position.
* relyin on bookend sentinel values at known offset from 'wrap' section
*
* ctrl_ ctrl_ + c_group_size
* | |
* v v
* <----------------- control_size(n_slot) ---------------->
* <-stub-> <----------- n_slot ----------> <group> <-stub->
* +--------+-------------------------------+-------+--------+
* | 0xF0 | empty / data / tombstone | wrap | 0xF0 |
* +--------+-------------------------------+-------+--------+
**/
} while (is_sentinel(*ctrl_)
&& (*(ctrl_ + c_group_size) != c_iterator_bookend));
return *this;
}
DArenaHashMapIterator & operator--() {
/* simpler than forward iteration, since bookend immediately
* precedes control byte for first slot
*/
do {
--ctrl_;
--pos_;
} while (is_sentinel(*ctrl_)
&& (*ctrl_ != c_iterator_bookend));
return *this;
}
private:
uint8_t * ctrl_ = nullptr;
value_type * pos_ = nullptr;
};
}
} /*namespace mm*/
} /*namespace xo*/
/* end DArenaHashMapIterator.hpp */