sql_lex.h

/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/* YACC and LEX Definitions */

/* These may not be declared yet */
class Table_ident;
class sql_exchange;
class LEX_COLUMN;
class sp_head;
class sp_name;
class sp_instr;
class sp_pcontext;

/*
  The following hack is needed because mysql_yacc.cc does not define
  YYSTYPE before including this file
*/

#include "set_var.h"

#ifdef MYSQL_YACC
#define LEX_YYSTYPE void *
#else
#include "lex_symbol.h"
#include "sql_yacc.h"
#define LEX_YYSTYPE YYSTYPE *
#endif

/*
  When a command is added here, be sure it's also added in mysqld.cc
  in "struct show_var_st status_vars[]= {" ...
*/

enum enum_sql_command {
  SQLCOM_SELECT, SQLCOM_CREATE_TABLE, SQLCOM_CREATE_INDEX, SQLCOM_ALTER_TABLE,
  SQLCOM_UPDATE, SQLCOM_INSERT, SQLCOM_INSERT_SELECT,
  SQLCOM_DELETE, SQLCOM_TRUNCATE, SQLCOM_DROP_TABLE, SQLCOM_DROP_INDEX,

  SQLCOM_SHOW_DATABASES, SQLCOM_SHOW_TABLES, SQLCOM_SHOW_FIELDS,
  SQLCOM_SHOW_KEYS, SQLCOM_SHOW_VARIABLES, SQLCOM_SHOW_LOGS, SQLCOM_SHOW_STATUS,
  SQLCOM_SHOW_INNODB_STATUS, SQLCOM_SHOW_MUTEX_STATUS,
  SQLCOM_SHOW_PROCESSLIST, SQLCOM_SHOW_MASTER_STAT, SQLCOM_SHOW_SLAVE_STAT,
  SQLCOM_SHOW_GRANTS, SQLCOM_SHOW_CREATE, SQLCOM_SHOW_CHARSETS,
  SQLCOM_SHOW_COLLATIONS, SQLCOM_SHOW_CREATE_DB, SQLCOM_SHOW_TABLE_STATUS,

  SQLCOM_LOAD,SQLCOM_SET_OPTION,SQLCOM_LOCK_TABLES,SQLCOM_UNLOCK_TABLES,
  SQLCOM_GRANT,
  SQLCOM_CHANGE_DB, SQLCOM_CREATE_DB, SQLCOM_DROP_DB, SQLCOM_ALTER_DB,
  SQLCOM_REPAIR, SQLCOM_REPLACE, SQLCOM_REPLACE_SELECT,
  SQLCOM_CREATE_FUNCTION, SQLCOM_DROP_FUNCTION,
  SQLCOM_REVOKE,SQLCOM_OPTIMIZE, SQLCOM_CHECK,
  SQLCOM_ASSIGN_TO_KEYCACHE, SQLCOM_PRELOAD_KEYS,
  SQLCOM_FLUSH, SQLCOM_KILL, SQLCOM_ANALYZE,
  SQLCOM_ROLLBACK, SQLCOM_ROLLBACK_TO_SAVEPOINT,
  SQLCOM_COMMIT, SQLCOM_SAVEPOINT,
  SQLCOM_SLAVE_START, SQLCOM_SLAVE_STOP,
  SQLCOM_BEGIN, SQLCOM_LOAD_MASTER_TABLE, SQLCOM_CHANGE_MASTER,
  SQLCOM_RENAME_TABLE, SQLCOM_BACKUP_TABLE, SQLCOM_RESTORE_TABLE,
  SQLCOM_RESET, SQLCOM_PURGE, SQLCOM_PURGE_BEFORE, SQLCOM_SHOW_BINLOGS,
  SQLCOM_SHOW_OPEN_TABLES, SQLCOM_LOAD_MASTER_DATA,
  SQLCOM_HA_OPEN, SQLCOM_HA_CLOSE, SQLCOM_HA_READ,
  SQLCOM_SHOW_SLAVE_HOSTS, SQLCOM_DELETE_MULTI, SQLCOM_UPDATE_MULTI,
  SQLCOM_SHOW_BINLOG_EVENTS, SQLCOM_SHOW_NEW_MASTER, SQLCOM_DO,
  SQLCOM_SHOW_WARNS, SQLCOM_EMPTY_QUERY, SQLCOM_SHOW_ERRORS,
  SQLCOM_SHOW_COLUMN_TYPES, SQLCOM_SHOW_STORAGE_ENGINES, SQLCOM_SHOW_PRIVILEGES,
  SQLCOM_HELP, SQLCOM_CREATE_USER, SQLCOM_DROP_USER, SQLCOM_RENAME_USER,
  SQLCOM_REVOKE_ALL, SQLCOM_CHECKSUM,
  SQLCOM_CREATE_PROCEDURE, SQLCOM_CREATE_SPFUNCTION, SQLCOM_CALL,
  SQLCOM_DROP_PROCEDURE, SQLCOM_ALTER_PROCEDURE,SQLCOM_ALTER_FUNCTION,
  SQLCOM_SHOW_CREATE_PROC, SQLCOM_SHOW_CREATE_FUNC,
  SQLCOM_SHOW_STATUS_PROC, SQLCOM_SHOW_STATUS_FUNC,
  SQLCOM_PREPARE, SQLCOM_EXECUTE, SQLCOM_DEALLOCATE_PREPARE,
  SQLCOM_CREATE_VIEW, SQLCOM_DROP_VIEW,
  SQLCOM_CREATE_TRIGGER, SQLCOM_DROP_TRIGGER,
  /* This should be the last !!! */

  SQLCOM_END
};

// describe/explain types
#define DESCRIBE_NORMAL		1
#define DESCRIBE_EXTENDED	2

enum enum_sp_suid_behaviour
{
  SP_IS_DEFAULT_SUID= 0,
  SP_IS_NOT_SUID,
  SP_IS_SUID
};

enum enum_sp_data_access
{
  SP_DEFAULT_ACCESS= 0,
  SP_CONTAINS_SQL,
  SP_NO_SQL,
  SP_READS_SQL_DATA,
  SP_MODIFIES_SQL_DATA
};


#define DERIVED_SUBQUERY	1
#define DERIVED_VIEW		2

enum enum_view_create_mode
{
  VIEW_CREATE_NEW,		// check that there are not such VIEW/table
  VIEW_ALTER,			// check that VIEW .frm with such name exists
  VIEW_CREATE_OR_REPLACE	// check only that there are not such table
};

enum enum_drop_mode
{
  DROP_DEFAULT, // mode is not specified
  DROP_CASCADE, // CASCADE option
  DROP_RESTRICT // RESTRICT option
};

typedef List<Item> List_item;

typedef struct st_lex_master_info
{
  char *host, *user, *password, *log_file_name;
  uint port, connect_retry;
  ulonglong pos;
  ulong server_id;
  /* 
     Variable for MASTER_SSL option.
     MASTER_SSL=0 in CHANGE MASTER TO corresponds to SSL_DISABLE
     MASTER_SSL=1 corresponds to SSL_ENABLE
  */
  enum {SSL_UNCHANGED=0, SSL_DISABLE, SSL_ENABLE} ssl; 
  char *ssl_key, *ssl_cert, *ssl_ca, *ssl_capath, *ssl_cipher;
  char *relay_log_name;
  ulong relay_log_pos;
} LEX_MASTER_INFO;


enum sub_select_type
{
  UNSPECIFIED_TYPE,UNION_TYPE, INTERSECT_TYPE,
  EXCEPT_TYPE, GLOBAL_OPTIONS_TYPE, DERIVED_TABLE_TYPE, OLAP_TYPE
};

enum olap_type 
{
  UNSPECIFIED_OLAP_TYPE, CUBE_TYPE, ROLLUP_TYPE
};

enum tablespace_op_type
{
  NO_TABLESPACE_OP, DISCARD_TABLESPACE, IMPORT_TABLESPACE
};

/* 
  The state of the lex parsing for selects 
   
   All select describing structures linked with following pointers:
   - list of neighbors (next/prev) (prev of first element point to slave 
     pointer of upper structure)
     - one level units for unit (union) structure
     - member of one union(unit) for ordinary select_lex
   - pointer to master
     - outer select_lex for unit (union)
     - unit structure for ordinary select_lex
   - pointer to slave
     - first list element of select_lex belonged to this unit for unit
     - first unit in list of units that belong to this select_lex (as
       subselects or derived tables) for ordinary select_lex
   - list of all select_lex (for group operation like correcting list of opened
     tables)
   - if unit contain several selects (union) then it have special 
     select_lex called fake_select_lex. It used for storing global parameters
     and executing union. subqueries of global ORDER BY clause will be
     attached to this fake_select_lex, which will allow them correctly
     resolve fields of 'upper' union and other more outer selects. 

   for example for following query:

   select *
     from table1
     where table1.field IN (select * from table1_1_1 union
                            select * from table1_1_2)
     union
   select *
     from table2
     where table2.field=(select (select f1 from table2_1_1_1_1
                                   where table2_1_1_1_1.f2=table2_1_1.f3)
                           from table2_1_1
                           where table2_1_1.f1=table2.f2)
     union
   select * from table3;

   we will have following structure:


     main unit
     fake0
     select1 select2 select3
     |^^     |^
    s|||     ||master
    l|||     |+---------------------------------+
    a|||     +---------------------------------+|
    v|||master                         slave   ||
    e||+-------------------------+             ||
     V|            neighbor      |             V|
     unit1.1<+==================>unit1.2       unit2.1
     fake1.1
     select1.1.1 select 1.1.2    select1.2.1   select2.1.1
                                               |^
                                               ||
                                               V|
                                               unit2.1.1.1
                                               select2.1.1.1.1


   relation in main unit will be following:
                          
         main unit
         |^^^^|fake_select_lex
         |||||+--------------------------------------------+
         ||||+--------------------------------------------+|
         |||+------------------------------+              ||
         ||+--------------+                |              ||
    slave||master         |                |              ||
         V|      neighbor |       neighbor |        master|V
         select1<========>select2<========>select3        fake0

    list of all select_lex will be following (as it will be constructed by
    parser):

    select1->select2->select3->select2.1.1->select 2.1.2->select2.1.1.1.1-+
                                                                          |
    +---------------------------------------------------------------------+
    |
    +->select1.1.1->select1.1.2

*/

/* 
    Base class for st_select_lex (SELECT_LEX) & 
    st_select_lex_unit (SELECT_LEX_UNIT)
*/
struct st_lex;
class st_select_lex;
class st_select_lex_unit;
class st_select_lex_node {
protected:
  st_select_lex_node *next, **prev,   /* neighbor list */
    *master, *slave,                  /* vertical links */
    *link_next, **link_prev;          /* list of whole SELECT_LEX */
public:

  ulong options;
  /*
    result of this query can't be cached, bit field, can be :
      UNCACHEABLE_DEPENDENT
      UNCACHEABLE_RAND
      UNCACHEABLE_SIDEEFFECT
      UNCACHEABLE_EXPLAIN
  */
  uint8 uncacheable;
  enum sub_select_type linkage;
  bool no_table_names_allowed; /* used for global order by */
  bool no_error; /* suppress error message (convert it to warnings) */

  static void *operator new(size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root)
  { return (void*) alloc_root(mem_root, (uint) size); }
  static void operator delete(void *ptr,size_t size) { TRASH(ptr, size); }
  static void operator delete(void *ptr,size_t size, MEM_ROOT *mem_root)
  { TRASH(ptr, size); }
  st_select_lex_node(): linkage(UNSPECIFIED_TYPE) {}
  virtual ~st_select_lex_node() {}
  inline st_select_lex_node* get_master() { return master; }
  virtual void init_query();
  virtual void init_select();
  void include_down(st_select_lex_node *upper);
  void include_neighbour(st_select_lex_node *before);
  void include_standalone(st_select_lex_node *sel, st_select_lex_node **ref);
  void include_global(st_select_lex_node **plink);
  void exclude();

  virtual st_select_lex_unit* master_unit()= 0;
  virtual st_select_lex* outer_select()= 0;
  virtual st_select_lex* return_after_parsing()= 0;

  virtual bool set_braces(bool value);
  virtual bool inc_in_sum_expr();
  virtual uint get_in_sum_expr();
  virtual TABLE_LIST* get_table_list();
  virtual List<Item>* get_item_list();
  virtual List<String>* get_use_index();
  virtual List<String>* get_ignore_index();
  virtual ulong get_table_join_options();
  virtual TABLE_LIST *add_table_to_list(THD *thd, Table_ident *table,
					LEX_STRING *alias,
					ulong table_options,
					thr_lock_type flags= TL_UNLOCK,
					List<String> *use_index= 0,
					List<String> *ignore_index= 0,
                                        LEX_STRING *option= 0);
  virtual void set_lock_for_tables(thr_lock_type lock_type) {}

  friend class st_select_lex_unit;
  friend bool mysql_new_select(struct st_lex *lex, bool move_down);
  friend my_bool mysql_make_view (File_parser *parser,
				  TABLE_LIST *table);
private:
  void fast_exclude();
};
typedef class st_select_lex_node SELECT_LEX_NODE;

/* 
   SELECT_LEX_UNIT - unit of selects (UNION, INTERSECT, ...) group 
   SELECT_LEXs
*/
struct st_lex;
class THD;
class select_result;
class JOIN;
class select_union;
class Procedure;
class st_select_lex_unit: public st_select_lex_node {
protected:
  TABLE_LIST result_table_list;
  select_union *union_result;
  TABLE *table; /* temporary table using for appending UNION results */

  select_result *result;
  ulong found_rows_for_union;
  bool res;
  bool  prepared, // prepare phase already performed for UNION (unit)
    optimized, // optimize phase already performed for UNION (unit)
    executed, // already executed
    cleaned;

public:
  // list of fields which points to temporary table for union
  List<Item> item_list;
  /*
    list of types of items inside union (used for union & derived tables)
    
    Item_type_holders from which this list consist may have pointers to Field,
    pointers is valid only after preparing SELECTS of this unit and before
    any SELECT of this unit execution
  */
  List<Item> types;
  /*
    Pointer to 'last' select or pointer to unit where stored
    global parameters for union
  */
  st_select_lex *global_parameters;
  //node on wich we should return current_select pointer after parsing subquery
  st_select_lex *return_to;
  /* LIMIT clause runtime counters */
  ha_rows select_limit_cnt, offset_limit_cnt;
  /* not NULL if unit used in subselect, point to subselect item */
  Item_subselect *item;
  /* thread handler */
  THD *thd;
  /*
    SELECT_LEX for hidden SELECT in onion which process global
    ORDER BY and LIMIT
  */
  st_select_lex *fake_select_lex;

  st_select_lex *union_distinct; /* pointer to the last UNION DISTINCT */
  bool describe; /* union exec() called for EXPLAIN */
  Procedure *last_procedure;	 /* Pointer to procedure, if such exists */

  void init_query();
  st_select_lex_unit* master_unit();
  st_select_lex* outer_select();
  st_select_lex* first_select()
  {
    return my_reinterpret_cast(st_select_lex*)(slave);
  }
  st_select_lex* first_select_in_union() 
  { 
    return my_reinterpret_cast(st_select_lex*)(slave);
  }
  st_select_lex_unit* next_unit()
  {
    return my_reinterpret_cast(st_select_lex_unit*)(next);
  }
  st_select_lex* return_after_parsing() { return return_to; }
  void exclude_level();
  void exclude_tree();

  /* UNION methods */
  bool prepare(THD *thd, select_result *result, ulong additional_options);
  bool exec();
  bool cleanup();
  inline void unclean() { cleaned= 0; }
  void reinit_exec_mechanism();

  bool check_updateable(char *db, char *table);
  void print(String *str);

  ulong init_prepare_fake_select_lex(THD *thd);
  bool change_result(select_subselect *result, select_subselect *old_result);
  void set_limit(st_select_lex *values, st_select_lex *sl);

  friend void lex_start(THD *thd, uchar *buf, uint length);
  friend int subselect_union_engine::exec();
};
typedef class st_select_lex_unit SELECT_LEX_UNIT;

/*
  SELECT_LEX - store information of parsed SELECT_LEX statment
*/
class st_select_lex: public st_select_lex_node
{
public:
  char *db, *db1, *table1, *db2, *table2;      	/* For outer join using .. */
  Item *where, *having;                         /* WHERE & HAVING clauses */
  Item *prep_where; /* saved WHERE clause for prepared statement processing */
  /* point on lex in which it was created, used in view subquery detection */
  st_lex *parent_lex;
  enum olap_type olap;
  SQL_LIST	      table_list, group_list;   /* FROM & GROUP BY clauses */
  List<Item>          item_list; /* list of fields & expressions */
  List<String>        interval_list, use_index, *use_index_ptr,
		      ignore_index, *ignore_index_ptr;
  /* 
    Usualy it is pointer to ftfunc_list_alloc, but in union used to create fake
    select_lex for calling mysql_select under results of union
  */
  List<Item_func_match> *ftfunc_list;
  List<Item_func_match> ftfunc_list_alloc;
  JOIN *join; /* after JOIN::prepare it is pointer to corresponding JOIN */
  List<TABLE_LIST> top_join_list; /* join list of the top level          */
  List<TABLE_LIST> *join_list;    /* list for the currently parsed join  */
  TABLE_LIST *embedding;          /* table embedding to the above list   */
  TABLE_LIST *leaf_tables;        /* list of leaves in join table tree   */
  const char *type;               /* type of select for EXPLAIN          */

  SQL_LIST order_list;                /* ORDER clause */
  List<List_item>     expr_list;
  List<List_item>     when_list;      /* WHEN clause (expression) */
  SQL_LIST *gorder_list;
  ha_rows select_limit, offset_limit; /* LIMIT clause parameters */
  // Arrays of pointers to top elements of all_fields list
  Item **ref_pointer_array;

  /*
    number of items in select_list and HAVING clause used to get number
    bigger then can be number of entries that will be added to all item
    list during split_sum_func
  */
  uint select_n_having_items;
  uint cond_count;      /* number of arguments of and/or/xor in where/having */
  enum_parsing_place parsing_place; /* where we are parsing expression */
  bool with_sum_func;   /* sum function indicator */
  /* 
    PS or SP cond natural joins was alredy processed with permanent
    arena and all additional items which we need alredy stored in it
  */
  bool conds_processed_with_permanent_arena;

  ulong table_join_options;
  uint in_sum_expr;
  uint select_number; /* number of select (used for EXPLAIN) */
  uint with_wild; /* item list contain '*' */
  bool  braces;   	/* SELECT ... UNION (SELECT ... ) <- this braces */
  /* TRUE when having fix field called in processing of this SELECT */
  bool having_fix_field;
  /* explicit LIMIT clause was used */
  bool explicit_limit;
  /*
    there are subquery in HAVING clause => we can't close tables before
    query processing end even if we use temporary table
  */
  bool subquery_in_having;
  bool first_execution; /* first execution in SP or PS */
  bool first_cond_optimization;
  /* do not wrap view fields with Item_ref */
  bool no_wrap_view_item;

  /* 
     SELECT for SELECT command st_select_lex. Used to privent scaning
     item_list of non-SELECT st_select_lex (no sense find to finding
     reference in it (all should be in tables, it is dangerouse due
     to order of fix_fields calling for non-SELECTs commands (item list
     can be not fix_fieldsd)). This value will be assigned for
     primary select (sql_yac.yy) and for any subquery and
     UNION SELECT (sql_parse.cc mysql_new_select())


     INSERT for primary st_select_lex structure of simple INSERT/REPLACE
     (used for name resolution, see Item_fiels & Item_ref fix_fields,
     FALSE for INSERT/REPLACE ... SELECT, because it's
     st_select_lex->table_list will be preprocessed (first table removed)
     before passing to handle_select)

     NOMATTER for other
  */
  enum {NOMATTER_MODE, SELECT_MODE, INSERT_MODE} resolve_mode;


  void init_query();
  void init_select();
  st_select_lex_unit* master_unit();
  st_select_lex_unit* first_inner_unit() 
  { 
    return (st_select_lex_unit*) slave; 
  }
  st_select_lex* outer_select();
  st_select_lex* next_select() { return (st_select_lex*) next; }
  st_select_lex* next_select_in_list() 
  {
    return (st_select_lex*) link_next;
  }
  st_select_lex_node** next_select_in_list_addr()
  {
    return &link_next;
  }
  st_select_lex* return_after_parsing()
  {
    return master_unit()->return_after_parsing();
  }

  void mark_as_dependent(st_select_lex *last);

  bool set_braces(bool value);
  bool inc_in_sum_expr();
  uint get_in_sum_expr();

  bool add_item_to_list(THD *thd, Item *item);
  bool add_group_to_list(THD *thd, Item *item, bool asc);
  bool add_ftfunc_to_list(Item_func_match *func);
  bool add_order_to_list(THD *thd, Item *item, bool asc);
  TABLE_LIST* add_table_to_list(THD *thd, Table_ident *table,
				LEX_STRING *alias,
				ulong table_options,
				thr_lock_type flags= TL_UNLOCK,
				List<String> *use_index= 0,
				List<String> *ignore_index= 0,
                                LEX_STRING *option= 0);
  TABLE_LIST* get_table_list();
  bool init_nested_join(THD *thd);
  TABLE_LIST *end_nested_join(THD *thd);
  TABLE_LIST *nest_last_join(THD *thd);
  void save_names_for_using_list(TABLE_LIST *tab1, TABLE_LIST *tab2);
  void add_joined_table(TABLE_LIST *table);
  TABLE_LIST *convert_right_join();
  List<Item>* get_item_list();
  List<String>* get_use_index();
  List<String>* get_ignore_index();
  ulong get_table_join_options();
  void set_lock_for_tables(thr_lock_type lock_type);
  inline void init_order()
  {
    order_list.elements= 0;
    order_list.first= 0;
    order_list.next= (byte**) &order_list.first;
  }
  
  bool test_limit();

  friend void lex_start(THD *thd, uchar *buf, uint length);
  st_select_lex() {}
  void make_empty_select()
  {
    init_query();
    init_select();
  }
  bool setup_ref_array(THD *thd, uint order_group_num);
  bool check_updateable(char *db, char *table);
  bool check_updateable_in_subqueries(char *db, char *table);
  void print(THD *thd, String *str);
  static void print_order(String *str, ORDER *order);
  void print_limit(THD *thd, String *str);
  void fix_prepare_information(THD *thd, Item **conds);
};
typedef class st_select_lex SELECT_LEX;

#define ALTER_ADD_COLUMN	1
#define ALTER_DROP_COLUMN	2
#define ALTER_CHANGE_COLUMN	4
#define ALTER_ADD_INDEX		8
#define ALTER_DROP_INDEX	16
#define ALTER_RENAME		32
#define ALTER_ORDER		64
#define ALTER_OPTIONS		128
#define ALTER_CHANGE_COLUMN_DEFAULT 256
#define ALTER_KEYS_ONOFF        512
#define ALTER_CONVERT          1024

typedef struct st_alter_info
{
  List<Alter_drop>            drop_list;
  List<Alter_column>          alter_list;
  uint                        flags;
  enum enum_enable_or_disable keys_onoff;
  enum tablespace_op_type     tablespace_op;

  st_alter_info(){clear();}
  void clear(){keys_onoff= LEAVE_AS_IS;tablespace_op= NO_TABLESPACE_OP;}
  void reset(){drop_list.empty();alter_list.empty();clear();}
} ALTER_INFO;

struct st_sp_chistics
{
  LEX_STRING comment;
  enum enum_sp_suid_behaviour suid;
  bool detistic;
  enum enum_sp_data_access daccess;
};


struct st_trg_chistics
{
  enum trg_action_time_type action_time;
  enum trg_event_type event;
};

extern sys_var_long_ptr trg_new_row_fake_var;

/* The state of the lex parsing. This is saved in the THD struct */

typedef struct st_lex
{
  uint	 yylineno,yytoklen;			/* Simulate lex */
  LEX_YYSTYPE yylval;
  SELECT_LEX_UNIT unit;                         /* most upper unit */
  SELECT_LEX select_lex;                        /* first SELECT_LEX */
  /* current SELECT_LEX in parsing */
  SELECT_LEX *current_select;
  /* list of all SELECT_LEX */
  SELECT_LEX *all_selects_list;
  uchar *buf;			/* The beginning of string, used by SPs */
  uchar *ptr,*tok_start,*tok_end,*end_of_query;
  char *length,*dec,*change,*name;
  char *help_arg;
  char *backup_dir;				/* For RESTORE/BACKUP */
  char* to_log;                                 /* For PURGE MASTER LOGS TO */
  char* x509_subject,*x509_issuer,*ssl_cipher;
  char* found_colon;                            /* For multi queries - next query */
  String *wild;
  sql_exchange *exchange;
  select_result *result;
  Item *default_value, *on_update_value;
  LEX_STRING *comment, name_and_length;
  LEX_USER *grant_user;
  gptr yacc_yyss,yacc_yyvs;
  THD *thd;
  CHARSET_INFO *charset;
  TABLE_LIST *query_tables;	/* global list of all tables in this query */
  /*
    last element next_global of previous list (used only for list building
    during parsing and VIEW processing. This pointer is not valid in
    mysql_execute_command
  */
  TABLE_LIST **query_tables_last;
  TABLE_LIST *proc_table; /* refer to mysql.proc if it was opened by VIEW */
  /* store original leaf_tables for INSERT SELECT and PS/SP */
  TABLE_LIST *leaf_tables_insert;

  List<key_part_spec> col_list;
  List<key_part_spec> ref_list;
  List<String>	      interval_list;
  List<LEX_USER>      users_list;
  List<LEX_COLUMN>    columns;
  List<Key>	      key_list;
  List<create_field>  create_list;
  List<Item>	      *insert_list,field_list,value_list,update_list;
  List<List_item>     many_values;
  List<set_var_base>  var_list;
  List<Item_param>    param_list;
  List<LEX_STRING>    view_list; // view list (list of field names in view)
  SQL_LIST	      proc_list, auxilliary_table_list, save_list;
  create_field	      *last_field;
  char		      *savepoint_name;		// Transaction savepoint id
  udf_func udf;
  HA_CHECK_OPT   check_opt;			// check/repair options
  HA_CREATE_INFO create_info;
  LEX_MASTER_INFO mi;				// used by CHANGE MASTER
  USER_RESOURCES mqh;
  ulong type;
  enum_sql_command sql_command, orig_sql_command;
  thr_lock_type lock_option, multi_lock_option;
  enum SSL_type ssl_type;			/* defined in violite.h */
  enum my_lex_states next_state;
  enum enum_duplicates duplicates;
  enum enum_tx_isolation tx_isolation;
  enum enum_ha_read_modes ha_read_mode;
  enum ha_rkey_function ha_rkey_mode;
  enum enum_var_type option_type;
  enum enum_view_create_mode create_view_mode;
  enum enum_drop_mode drop_mode;
  uint uint_geom_type;
  uint grant, grant_tot_col, which_columns;
  uint fk_delete_opt, fk_update_opt, fk_match_option;
  uint slave_thd_opt, start_transaction_opt;
  uint table_count; /* used when usual update transformed in multiupdate */
  uint8 describe;
  uint8 derived_tables;
  uint8 create_view_algorithm;
  uint8 create_view_check;
  bool drop_if_exists, drop_temporary, local_file, one_shot_set;
  bool in_comment, ignore_space, verbose, no_write_to_binlog;
  /* special JOIN::prepare mode: changing of query is prohibited */
  bool view_prepare_mode;
  bool safe_to_cache_query;
  bool subqueries, ignore;
  bool variables_used;
  ALTER_INFO alter_info;
  /* Prepared statements SQL syntax:*/
  LEX_STRING prepared_stmt_name; /* Statement name (in all queries) */
  /* 
    Prepared statement query text or name of variable that holds the
    prepared statement (in PREPARE ... queries)
  */
  LEX_STRING prepared_stmt_code; 
  /* If true, prepared_stmt_code is a name of variable that holds the query */
  bool prepared_stmt_code_is_varref;
  /* Names of user variables holding parameters (in EXECUTE) */
  List<LEX_STRING> prepared_stmt_params; 
  /*
    Points to part of global table list which contains time zone tables
    implicitly used by the statement.
  */
  TABLE_LIST *time_zone_tables_used;
  sp_head *sphead;
  sp_name *spname;
  bool sp_lex_in_use;	/* Keep track on lex usage in SPs for error handling */
  bool all_privileges;
  sp_pcontext *spcont;
  HASH spfuns;		/* Called functions */
  st_sp_chistics sp_chistics;
  bool only_view;       /* used for SHOW CREATE TABLE/VIEW */
  /*
    field_list was created for view and should be removed before PS/SP
    rexecuton
  */
  bool empty_field_list_on_rset;
  /* Characterstics of trigger being created */
  st_trg_chistics trg_chistics;
  /*
    List of all items (Item_trigger_field objects) representing fields in
    old/new version of row in trigger. We use this list for checking whenever
    all such fields are valid at trigger creation time and for binding these
    fields to TABLE object at table open (altough for latter pointer to table
    being opened is probably enough).
  */
  SQL_LIST trg_table_fields;

  st_lex() :result(0), sql_command(SQLCOM_END)
  {
    extern byte *sp_lex_spfuns_key(const byte *ptr, uint *plen, my_bool first);
    hash_init(&spfuns, system_charset_info, 0, 0, 0, sp_lex_spfuns_key, 0, 0);
  }
  
  ~st_lex()
  {
    if (spfuns.array.buffer)
      hash_free(&spfuns);
  }

  inline void uncacheable(uint8 cause)
  {
    safe_to_cache_query= 0;

    /*
      There are no sense to mark select_lex and union fields of LEX,
      but we should merk all subselects as uncacheable from current till
      most upper
    */
    SELECT_LEX *sl;
    SELECT_LEX_UNIT *un;
    for (sl= current_select, un= sl->master_unit();
	 un != &unit;
	 sl= sl->outer_select(), un= sl->master_unit())
    {
      sl->uncacheable|= cause;
      un->uncacheable|= cause;
    }
  }
  TABLE_LIST *unlink_first_table(bool *link_to_local);
  void link_first_table_back(TABLE_LIST *first, bool link_to_local);
  void first_lists_tables_same();
  inline void add_to_query_tables(TABLE_LIST *table)
  {
    *(table->prev_global= query_tables_last)= table;
    query_tables_last= &table->next_global;
  }
  bool add_time_zone_tables_to_query_tables(THD *thd);

  bool can_be_merged();
  bool can_use_merged();
  bool can_not_use_merged();
  bool only_view_structure();
  bool need_correct_ident();
} LEX;

struct st_lex_local: public st_lex
{
  static void *operator new(size_t size)
  {
    return (void*) sql_alloc((uint) size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root)
  {
    return (void*) alloc_root(mem_root, (uint) size);
  }
  static void operator delete(void *ptr,size_t size)
  { TRASH(ptr, size); }
};

void lex_init(void);
void lex_free(void);
void lex_start(THD *thd, uchar *buf,uint length);
void lex_end(LEX *lex);

extern pthread_key(LEX*,THR_LEX);

#define current_lex (current_thd->lex)