qep_row::mem_root_str Struct Reference

#include <opt_explain_format.h>

Collaboration diagram for qep_row::mem_root_str:

Public Member Functions
void	cleanup ()
bool	is_empty ()
bool	set (const char *str_arg)
bool	set (const String &s)
bool	set (const char *str_arg, size_t length_arg)
void	set (Lazy *x)
void	set_const (const char *str_arg)
void	set_const (const char *str_arg, size_t length_arg)

Static Public Member Functions
static char *	strndup_root (MEM_ROOT *root, const char *str, size_t len)

Public Attributes
const char *	str
size_t	length
Lazy *	deferred

Detailed Description

Helper class to keep string data in MEM_ROOT before passing to Item_string

Since Item_string constructors doesn't copy input string parameter data in the most cases, those input strings must have the same lifetime as Item_string objects, i.e. lifetime of MEM_ROOT. This class allocates input parameters for Item_string objects in MEM_ROOT.

Note

Call to is_empty() is necessary before the access to "str" and "length" fields, since is_empty() may trigger an evaluation of an associated expression that updates these fields.

Definition at line 201 of file opt_explain_format.h.

Member Function Documentation

bool qep_row::mem_root_str::set ( const char *  str_arg, size_t  length_arg  )

inline

Make a copy of the string in MEM_ROOT

Parameters

str_arg	string to copy
length_arg	input string length

Returns

false if success, true if error

Definition at line 244 of file opt_explain_format.h.

void qep_row::mem_root_str::set ( Lazy *  x )

inline

Save expression for further evaluation

Parameters

x	Expression

Definition at line 257 of file opt_explain_format.h.

void qep_row::mem_root_str::set_const ( const char *  str_arg )

inline

Make a copy of string constant

Variant of set() usable when the str_arg argument lives longer than the mem_root_str instance.

Definition at line 269 of file opt_explain_format.h.

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

• sql/opt_explain_format.h