Filter Library

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Interface Physics

CHashBuilder Class Reference
[Dialog Related]

#include <ToolHashBuilder.h>

List of all members.

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Detailed Description

This class can incrementally build a hash value from fundamental types. It is used to determine if settings on a dialog changed or have remained as they where with respect to a previously taken snapshot.

Example.

 char   character = 'a';
 int    integer   =  0;
 char*  string    = "";

 typedef CHashBuilder::ValueType HashType;

 HashType LastHash = 0;

 HashType ComputeHash()
 {
    CHashBuilder NewHash;

    return NewHash = character, integer, string;
 }

 bool SomethingChanged()
 {
    return ComputeHash() != LastHash;
 }

 void MyInitialize()
 {
    LastHash = ComputeHash();
 }

 void MyAction()
 {
    if ( SomethingChanged() )
    {
       // act on changes and save new hash value

       LastHash = ComputeHash();
    }
    else
    {
       ; // no action required
    }
 }

Class CHashBuilder was inspired on the article "A Checksum Algorithm" by Joseph M. Newcomer [CHECKSUM].

Class CHashBuilder uses the hash function by P.J. Weinberger from the dragon book [Aho et al., 1986].

Definition at line 85 of file ToolHashBuilder.h.

Public Types
typedef CHashBuilder	Self
	this type.
typedef unsigned char	uchar
	unsigned character type;
typedef unsigned int	uint
	unsigned integer type.
typedef unsigned long	ulong
	unsigned long integer type.
typedef ulong	ValueType
	the hash type.
Public Member Functions
Operators
Self &	operator= (char c)
	assign a character.
Self &	operator= (int i)
	assign an integer.
Self &	operator= (long int i)
	assign a long integer.
Self &	operator= (unsigned char c)
	assign an unsigned character.
Self &	operator= (uint i)
	assign an unsigned integer.
Self &	operator= (ulong i)
	assign an unsigned long integer.
Self &	operator= (float f)
	assign a float.
Self &	operator= (double d)
	assign a double.
Self &	operator= (const char *s)
	assign a C-string.
Self &	operator, (char chr)
	add a character.
Self &	operator, (uchar chr)
	add a unsigned character.
Self &	operator, (int i)
	add an integer.
Self &	operator, (uint i)
	add an unsigned integer.
Self &	operator, (long i)
	add a long integer.
Self &	operator, (ulong i)
	add an unsigned long integer.
Self &	operator, (float f)
	add a float.
Self &	operator, (double d)
	add a double.
Self &	operator, (const char *s)
	add a C-string.
	operator ValueType () const
	convert to ValueType, return hash value; alias for GetHash().
Accessors
ValueType	GetHash () const
	the current hash value.
Mutators
void	Clear ()
	clear the hash value.
Self &	Add (unsigned char chr)
	add an unsigned character to the hash (P.J.
Self &	Add (char chr)
	add a character to the hash.
Self &	Add (int i)
	add an integer to the hash.
Self &	Add (uint i)
	add an unsigned integer to the hash.
Self &	Add (long i)
	add a long to the hash.
Self &	Add (ulong i)
	add an unsigned long to the hash.
Self &	Add (float f)
	add a float to the hash.
Self &	Add (double d)
	add a float to the hash.
Self &	Add (const char *string)
	add a C-string to the hash.
Private Attributes
ValueType	m_hash

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Member Function Documentation

Self& CHashBuilder::Add

(

unsigned char

chr

)

[inline]

Weinberger's hash, hash_pjw).

Definition at line 390 of file ToolHashBuilder.h.

References m_hash.

Referenced by Add(), CHashBuilder(), operator,(), and operator=().

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The documentation for this class was generated from the following file:

• ToolHashBuilder.h

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