Item_func_xor Class Reference

#include <item_cmpfunc.h>

Inheritance diagram for Item_func_xor:

List of all members.

Public Member Functions
	Item_func_xor (Item *i1, Item *i2)
enum Functype	functype () const
const char *	func_name () const
longlong	val_int ()
void	top_level_item ()
Item *	neg_transformer (THD *thd)

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Detailed Description

XOR inherits from Item_bool_func2 because it is not optimized yet. Later, when XOR is optimized, it needs to inherit from Item_cond instead. See WL#5800.

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Member Function Documentation

Item * Item_func_xor::neg_transformer

(

THD *

thd

)

[virtual]

XOR can be negated by negating one of the operands:

NOT (a XOR b) => (NOT a) XOR b => a XOR (NOT b)

Parameters:

thd	Thread handle

Returns:

New negated item

Reimplemented from Item.

longlong Item_func_xor::val_int

(

void

)

[virtual]

Make a logical XOR of the arguments.

If either operator is NULL, return NULL.

Todo:

(low priority) Change this to be optimized as:
A XOR B -> (A) == 1 AND (B) <> 1) OR (A <> 1 AND (B) == 1)
To be able to do this, we would however first have to extend the MySQL range optimizer to handle OR better.

Note:

As we don't do any index optimization on XOR this is not going to be very fast to use.

Implements Item.

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

• item_cmpfunc.h
• item_cmpfunc.cc