use the first element in the table

before 0 was used as a sentinel for checking if an element
was used, so table[0] could not be used.
This commit is contained in:
Sébastien Loriot 2022-04-06 12:02:12 +02:00
parent 157658848b
commit e059d68e94
1 changed files with 6 additions and 8 deletions

View File

@ -37,8 +37,7 @@ class chained_map_elem
template <typename T, typename Allocator>
class chained_map
{
static constexpr std::size_t nullptrKEY = 0;
static constexpr std::size_t NONnullptrKEY = 1;
static constexpr std::size_t nullptrKEY = (std::numeric_limits<std::size_t>::max)();
chained_map_elem<T>* table;
chained_map_elem<T>* table_end;
@ -146,7 +145,6 @@ void chained_map<T, Allocator>::init_table(std::size_t n)
{ p->succ = nullptr;
p->k = nullptrKEY;
}
table->k = NONnullptrKEY;
}
@ -178,7 +176,7 @@ void chained_map<T, Allocator>::rehash()
chained_map_item p;
for(p = old_table + 1; p < old_table_mid; p++) // the first element is never used (nullptrKEY vs NONnullptrKEY)
for(p = old_table; p < old_table_mid; p++)
{ std::size_t x = p->k;
if ( x != nullptrKEY ) // list p is non-empty
{ chained_map_item q = HASH(x);
@ -243,7 +241,7 @@ chained_map<T, Allocator>::chained_map(const chained_map<T, Allocator>& D)
{
init_table(D.table_size);
for(chained_map_item p = D.table + 1; p < D.free; p++)
for(chained_map_item p = D.table; p < D.free; p++)
{ if (p->k != nullptrKEY || p >= D.table + D.table_size)
{ insert(p->k,p->i);
//D.copy_inf(p->i); // see chapter Implementation
@ -263,7 +261,7 @@ chained_map<T, Allocator>& chained_map<T, Allocator>::operator=(const chained_ma
init_table(D.table_size);
for(chained_map_item p = D.table + 1; p < D.free; p++)
for(chained_map_item p = D.table; p < D.free; p++)
{ if (p->k != nullptrKEY || p >= D.table + D.table_size)
{ insert(p->k,p->i);
//copy_inf(p->i); // see chapter Implementation
@ -285,7 +283,7 @@ void chained_map<T, Allocator>::clear_entries()
if(!table)
return;
for(chained_map_item p = table + 1; p < free; p++)
for(chained_map_item p = table; p < free; p++)
if (p->k != nullptrKEY || p >= table + table_size)
p->i = T();
}
@ -322,7 +320,7 @@ template <typename T, typename Allocator>
void chained_map<T, Allocator>::statistics() const
{ std::cout << "table_size: " << table_size <<"\n";
std::size_t n = 0;
for (chained_map_item p = table + 1; p < table + table_size; p++)
for (chained_map_item p = table; p < table + table_size; p++)
if (p ->k != nullptrKEY) n++;
std::size_t used_in_overflow = free - (table + table_size );
n += used_in_overflow;