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ezEngine
Release 25.03
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ezEngine
Release 25.03
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This class is optimized to take nearly no memory (sizeof(void*)) and to allow very fast checks whether two strings are identical. More...
#include <HashedString.h>
Classes | |
| struct | HashedData |
Public Types | |
| using | StringStorage = ezMap< ezUInt64, HashedData, ezCompareHelper< ezUInt64 >, ezStaticsAllocatorWrapper > |
| using | HashedType = StringStorage::Iterator |
Public Member Functions | |
| EZ_DECLARE_MEM_RELOCATABLE_TYPE () | |
| ezHashedString () | |
| Initializes this string to the empty string. | |
| ezHashedString (const ezHashedString &rhs) | |
| Copies the given ezHashedString. | |
| ezHashedString (ezHashedString &&rhs) | |
| Moves the given ezHashedString. | |
| void | operator= (const ezHashedString &rhs) |
| Copies the given ezHashedString. | |
| void | operator= (ezHashedString &&rhs) |
| Moves the given ezHashedString. | |
| template<size_t N> | |
| void | Assign (const char(&string)[N]) |
| Assigning a new string from a string constant is a slow operation, but the hash computation can happen at compile time. More... | |
| template<size_t N> | |
| void | Assign (char(&string)[N])=delete |
| void | Assign (ezStringView sString) |
| Assigning a new string from a non-hashed string is a very slow operation, this should be used rarely. More... | |
| bool | operator== (const ezHashedString &rhs) const |
| Comparing whether two hashed strings are identical is just a pointer comparison. This operation is what ezHashedString is optimized for. More... | |
| EZ_ADD_DEFAULT_OPERATOR_NOTEQUAL (const ezHashedString &) | |
| bool | operator== (const ezTempHashedString &rhs) const |
| Compares this string object to an ezTempHashedString object. This should be used whenever some object needs to be found and the string to compare against is not yet an ezHashedString object. | |
| bool | operator!= (const ezTempHashedString &rhs) const |
| bool | operator< (const ezHashedString &rhs) const |
| This operator allows sorting objects by hash value, not by alphabetical order. | |
| bool | operator< (const ezTempHashedString &rhs) const |
| This operator allows sorting objects by hash value, not by alphabetical order. | |
| const ezString & | GetString () const |
| Gives access to the actual string data, so you can do all the typical (read-only) string operations on it. | |
| const char * | GetData () const |
| Gives access to the actual string data, so you can do all the typical (read-only) string operations on it. | |
| ezUInt64 | GetHash () const |
| Returns the hash of the stored string. | |
| bool | IsEmpty () const |
| Returns whether the string is empty. | |
| void | Clear () |
| Resets the string to the empty string. | |
| EZ_ALWAYS_INLINE | operator ezStringView () const |
| Returns a string view to this string's data. | |
| EZ_ALWAYS_INLINE ezStringView | GetView () const |
| Returns a string view to this string's data. | |
| EZ_ALWAYS_INLINE | operator const char * () const |
| Returns a pointer to the internal Utf8 string. | |
| EZ_ALWAYS_INLINE bool | operator== (const char *szString) const |
| EZ_ADD_DEFAULT_OPERATOR_NOTEQUAL (const char *) | |
| template<size_t N> | |
| EZ_FORCE_INLINE void | Assign (const char(&string)[N]) |
Static Public Member Functions | |
| static ezResult | LookupStringHash (ezUInt64 uiHash, ezStringView &out_sResult) |
| Attempts to find a known string for the given hash value. More... | |
This class is optimized to take nearly no memory (sizeof(void*)) and to allow very fast checks whether two strings are identical.
Internally only a reference to the string data is stored. The data itself is stored in a central location, where no duplicates are possible. Thus two identical strings will result in identical ezHashedString objects, which makes equality comparisons very easy (it's a pointer comparison).
Copying ezHashedString objects around and assigning between them is very fast as well.
Assigning from some other string type is rather slow though, as it requires thread synchronization.
You can also get access to the actual string data via GetString().
You should use ezHashedString whenever the size of the encapsulating object is important and when changes to the string itself are rare, but checks for equality might be frequent (e.g. in a system where objects are identified via their name).
At runtime when you need to compare ezHashedString objects with some temporary string object, used ezTempHashedString, as it will only use the string's hash value for comparison, but will not store the actual string anywhere.
| void ezHashedString::Assign | ( | const char(&) | string[N] | ) |
Assigning a new string from a string constant is a slow operation, but the hash computation can happen at compile time.
If you need to create an object to compare ezHashedString objects against, prefer to use ezTempHashedString. It will only compute the strings hash value, but does not require any thread synchronization.
| EZ_FORCE_INLINE void ezHashedString::Assign | ( | ezStringView | sString | ) |
Assigning a new string from a non-hashed string is a very slow operation, this should be used rarely.
If you need to create an object to compare ezHashedString objects against, prefer to use ezTempHashedString. It will only compute the strings hash value, but does not require any thread synchronization.
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static |
Attempts to find a known string for the given hash value.
Careful, this is a slow operation (involving a mutex). It is only meant for debug output purposes. The string hash may not be known, if the value was never assigned to any ezHashedString, in which case EZ_FAILURE is returned.
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inline |
Comparing whether two hashed strings are identical is just a pointer comparison. This operation is what ezHashedString is optimized for.
1.8.17