Hash

PHP version: 5

Required modules: standard, spl, simplexml, dom

Required packages: all.php, errors.php, autoload.php, AutoloadException.php, cast.php, Types.php, ArrayBothType.php, TypeInterface.php, Printable.php, ArrayIntType.php, ArrayStringType.php, BooleanType.php, ClassType.php, FloatType.php, IntType.php, NullType.php, ObjectType.php, ResourceType.php, StringType.php, CastException.php, Hashable.php, Comparable.php

class it\icosaedro\containers\Hash

Hashing functions

Version: $Date: 2012/04/02 09:11:36 $

Author: Umberto Salsi <salsi@icosaedro.it>

For every type T on which one may want to calculate an hash, a function named hashOfT() is provided. Classes that implement the it\icosaedro\containers\Hashable interface may then easily implement the getHash() method by "xoring" the properties that univocally identify the object:

	class MyClass implements Hashable {
		function getHash()
		{
			return Hash::hashOfInt($this->int_property)
			^ Hash::hashOfString($this->string_property)
			^ $this->hashable_object_propery->getHash();
		}
	}
	

Note that the same properties should appear in the implementation of the equals() method.

static int hashOfBoolean(
        boolean $b)

Hash of a boolean value

Parameters:

$b	The value.

Return: Hash of the value. Implementation note: merely returns 1 if true, 0 if false, so you may want to save time simply avoiding to call this function at all :-)

static int hashOfInt(
        int $i)

Hash of an integer value

Parameters:

$i	The value.

Return: Hash of the value. Implementation note: merely returns the value itself, so you may want to save time simply avoiding to call this function at all :-)

static int hashOfString(
        string $s)

Hash of a string value

Parameters:

$s	The value.

Return: Hash of the value, or zero if NULL. Implementation note: if the string is not NULL, returns the CRC32 of its bytes.

static int hashOfObject(
        object $obj)

Hash of an object

Parameters:

$obj	The value.

Return: If the object implements the it\icosaedro\containers\Hashable::getHash() method, then returns the value from that method. Otherwise, returns the CRC32 of the has given by the spl_object_hash() function.

static int hashOf(
        mixed $x)

Returns the hash of the expression passed, typically a key

The value is calculated applying the methods hashOfT() of this class according to the actual type of the value.

Parameters:

$x	Any value of type null, boolean, int, string or object. Types float, array and resource are not supported and give exception.

Return: The hash of the value.

Throws:

• unchecked RuntimeException    Type not supported float, array or resource.

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