Hashtable

Namespace: Hashtable Language: C++ Type: Defold C++ File: hashtable.h Source: engine/dlib/src/dmsdk/dlib/hashtable.h Include: dmsdk/dlib/hashtable.h

Hash table

API

Capacity

Type: FUNCTION Hashtable capacity. Maximum number of entries possible to store in table

Returns

• return (uint32_t) - the capacity of the table

Clear

Type: FUNCTION Removes all the entries from the table.

dmHashTable

Type: CLASS Hashtable with chaining for collision resolution, memcpy-copy semantics (POD types) and 32-bit indicies instead of pointers. (NUMA-friendly)

Notes

• The key type needs to support == and % operators

Template Parameters

• KEY
• T

dmHashTable

Type: FUNCTION Constructor. Create an empty hashtable with zero capacity and zero hashtable (buckets)

dmHashTable

Type: FUNCTION Creates a hashtable array with user allocated memory.

Notes

• User allocated arrays can not change capacity.

Parameters

• user_allocated (void*) - Pointer to user allocated continous data-block ((table_sizesizeof(uint32_t)) + (capacitysizeof(dmHashTable::Entry))
• table_size (uint32_t) - Hashtable size, ie number of buckets. table_size < 0xffffffff
• capacity (uint32_t) - Capacity. capacity < 0xffffffff

dmHashTable16

Type: CLASS Specialized hash table with uint16_t as keys

dmHashTable32

Type: CLASS Specialized hash table with uint32_t as keys

dmHashTable64

Type: CLASS Specialized hash table with uint64_t as keys

Empty

Type: FUNCTION Check if the table is empty

Returns

• true - if the table is empty

Erase

Type: FUNCTION Remove key/value pair.

Notes

• Only valid if key exists in table

Parameters

• key (KEY) - Key to remove

Full

Type: FUNCTION Check if the table is full

Returns

• true - if the table is full

Get

Type: FUNCTION Get pointer to value from key

Parameters

• key (KEY) - Key

Returns

• value (T*) - Pointer to value. NULL if the key/value pair doesn’t exist.

GetIterator

Type: FUNCTION Get an iterator for the key/value pairs

Returns

• iterator (dmHashTable::Iterator) - the iterator

Examples

dmHashTable::Iterator iter = ht.GetIterator();
while(iter.Next())
{
    printf("%s: %d\n", dmHashReverseSafe64(iter.GetKey()), iter.GetValue());
}

Iterate

Type: FUNCTION Iterate over all entries in table

Template Parameters

• CONTEXT

Parameters

• call_back (void*) - Call-back called for every entry
• context (CONTEXT*) - Context

Iterator

Type: STRUCT Iterator to the key/value pairs of a hash table

Members

• GetKey()
• GetValue()

OffsetCapacity

Type: FUNCTION Relative change of capacity Equivalent to SetCapacity(Capacity() + offset). Only allowed for auto-allocated hash tables and will result in a new dynamic allocation

Parameters

• offset (uint32_t) - relative amount of elements to change the capacity

Put

Type: FUNCTION Put key/value pair in hash table. NOTE: The method will “assert” if the hashtable is full.

Parameters

• key (KEY) - Key
• value (const T&) - Value

SetCapacity

Type: FUNCTION Set hashtable capacity. New capacity must be greater or equal to current capacity

Parameters

• table_size (uint32_t) - Hashtable size, ie number of buckets. table_size < 0xffffffff
• capacity (uint32_t) - Capacity. capacity < 0xffffffff

Size

Type: FUNCTION Number of entries stored in table. (not the actual hashtable size)

Returns

• Number - of entries.

Swap

Type: FUNCTION Swaps the contents of two hash tables

Parameters

• other (dmHashTable<KEY, T>&) - the other table