HashTableKey Class Reference
[Containers]

Abstract base class for hash table keys. More...

Inheritance diagram for HashTableKey:

List of all members.

Public Member Functions
virtual	~HashTableKey ()
virtual StringId	GetType () const =0
virtual unsigned int	GetHash () const =0
virtual bool	Compare (const HashTableKey *key) const =0

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Detailed Description

Abstract base class for hash table keys.

Author:

Mattias Gustavsson

The HashTable container may store data indexed by any type of key, as long as there's an implementation for it derived from this abstract base class. The HashTable class will accept any object derived from HashTableKey as a valid key value, but will detect if different types of keys are used within the same HashTable instance, and report an error if that is the case.

It is a good idea to create HashTableKeys during initialization or similar, and store them off for later use, as the way they work is to calculate the hash value when they are created, and after that they're quite quick to work with.

Definition at line 28 of file HashTableKey.h.

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Constructor & Destructor Documentation

virtual HashTableKey::~HashTableKey

(

)

[virtual]

Destructor

Definition at line 35 of file HashTableKey.h.

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Member Function Documentation

virtual StringId HashTableKey::GetType

(

)

const [pure virtual]

The hashtable can store data with different types of keys, and doesn't need to know which type it is to perform its functionality. However, things would not work very well if different types of keys were used within the same hash table. Therefore, each type of HashTableKey needs to implement the GetType method, to return a unique string id for that specific key type. It is only used to make sure that all keys used within the same hash table is of the same type. For the actual string it is recommended that the actual class name is used, for example "HashTableKey_Int" or "HashTableKey_String".

Returns:

A pointer to a string id uniquely identifying this type of hash key.

Implemented in HashTableKey_Int, HashTableKey_Pointer, HashTableKey_String, and HashTableKey_StringId.

virtual unsigned int HashTableKey::GetHash

(

)

const [pure virtual]

Gets the hash number for this key

Returns:

The hash number for this key

Implemented in HashTableKey_Int, HashTableKey_Pointer, HashTableKey_String, and HashTableKey_StringId.

virtual bool HashTableKey::Compare

(

const HashTableKey *

key

)

const [pure virtual]

Compares this key with the specified key. This might be a cheap operation if the actual key is simple (like for example the integer key type) or more expensive for complex keys (the string key type will perform a full string compare (case insensitive) when comparing keys).

Note that this method compare the actual key values, not their calculated hash values.

Returns:

True if the two keys are identical, false if they are not

Parameters:

key

Key to compare this key to

Implemented in HashTableKey_Int, HashTableKey_Pointer, HashTableKey_String, and HashTableKey_StringId.