casa::HashClass< key > Class Template Reference

   Hash function with state

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#include <HashMap.h>

List of all members.

Public Member Functions
virtual uInt	hash (const key &)=0
	This function maps elements of key type to any integer.
virtual HashClass< key > *	clone () const =0
	This function is used to make a deep copy.
	HashClass ()
virtual	~HashClass ()

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Detailed Description

template<class key>
class casa::HashClass< key >

   Hash function with state

Intended use:

Public interface

Review Status

Date Reviewed:

yyyy/mm/dd

Etymology

This is basically a way of specifying a hash function, but it is implemented as a class. Thus it is called HashClass, similar to "hash function".

Synopsis

This class is used to specify a hash function. Sometimes a hash function may require state, it may be useful to create a hierarchy of hash functions, or it may be useful to create a class which provides for hashing as well as other functionality. This class can be used as a base class for any of these purposed. This class is intended for parameterization of HashMap .

The hash function maps the key type to any integer. This integer is then used by HashMap to select a bucket in the hash table.

Example

If one wished to make a HashClass for integers, something like the following might be done:

        class IntHash : public HashClass<Int> {
        public:
          uInt hash(const Int &v) const { return (uInt) v; }
          uInt hash(const Int &v) { return (uInt) v; }
          HashClass<Int> *clone() const { return new IntHash; }
          IntHash() : HashClass<Int>() { }
        };

Motivation

There may be occasions when it is more convenient to use a class instead of a single function. This base class provides a starting point plus, and HashMap<k,v> has the necessary hooks to make use of classes derived from this class.

Definition at line 135 of file HashMap.h.

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Constructor & Destructor Documentation

template<class key>

casa::HashClass< key >::HashClass

(

)

template<class key>

virtual casa::HashClass< key >::~HashClass

(

)

[virtual]

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Member Function Documentation

template<class key>

virtual HashClass<key>* casa::HashClass< key >::clone

(

)

const [pure virtual]

This function is used to make a deep copy.

This means that the copy, which this function returns, contains all derived information.

template<class key>

virtual uInt casa::HashClass< key >::hash

(

const key &

)

[pure virtual]

This function maps elements of key type to any integer.

This integer is then used by HashMap to select a bucket in the hash table.

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

• casacore/casa/Containers/HashMap.h