sql_lex.h

/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

   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; version 2 of the License.

   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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef SQL_LEX_INCLUDED
#define SQL_LEX_INCLUDED

#include "violite.h"                            /* SSL_type */
#include "sql_trigger.h"
#include "item.h"               /* From item_subselect.h: subselect_union_engine */
#include "thr_lock.h"                  /* thr_lock_type, TL_UNLOCK */
#include "sql_array.h"
#include "mem_root_array.h"
#include "sql_alter.h"                // Alter_info

/* 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;
class st_alter_tablespace;
class partition_info;
class Event_parse_data;
class set_var_base;
class sys_var;
class Item_func_match;
class File_parser;
class Key_part_spec;
struct sql_digest_state;

#ifdef MYSQL_SERVER
/*
  There are 8 different type of table access so there is no more than
  combinations 2^8 = 256:

  . STMT_READS_TRANS_TABLE

  . STMT_READS_NON_TRANS_TABLE

  . STMT_READS_TEMP_TRANS_TABLE

  . STMT_READS_TEMP_NON_TRANS_TABLE

  . STMT_WRITES_TRANS_TABLE

  . STMT_WRITES_NON_TRANS_TABLE

  . STMT_WRITES_TEMP_TRANS_TABLE

  . STMT_WRITES_TEMP_NON_TRANS_TABLE

  The unsafe conditions for each combination is represented within a byte
  and stores the status of the option --binlog-direct-non-trans-updates,
  whether the trx-cache is empty or not, and whether the isolation level
  is lower than ISO_REPEATABLE_READ:

  . option (OFF/ON)
  . trx-cache (empty/not empty)
  . isolation (>= ISO_REPEATABLE_READ / < ISO_REPEATABLE_READ)

  bits 0 : . OFF, . empty, . >= ISO_REPEATABLE_READ
  bits 1 : . OFF, . empty, . < ISO_REPEATABLE_READ
  bits 2 : . OFF, . not empty, . >= ISO_REPEATABLE_READ
  bits 3 : . OFF, . not empty, . < ISO_REPEATABLE_READ
  bits 4 : . ON, . empty, . >= ISO_REPEATABLE_READ
  bits 5 : . ON, . empty, . < ISO_REPEATABLE_READ
  bits 6 : . ON, . not empty, . >= ISO_REPEATABLE_READ
  bits 7 : . ON, . not empty, . < ISO_REPEATABLE_READ
*/
extern uint binlog_unsafe_map[256];
/*
  Initializes the array with unsafe combinations and its respective
  conditions.
*/
void binlog_unsafe_map_init();
#endif

struct sys_var_with_base
{
  sys_var *var;
  LEX_STRING base_name;
};

#ifdef MYSQL_SERVER
/*
  The following hack is needed because mysql_yacc.cc does not define
  YYSTYPE before including this file
*/
#ifdef MYSQL_YACC
#define LEX_YYSTYPE void *
#else
#include "lex_symbol.h"
#if MYSQL_LEX
#include "item_func.h"            /* Cast_target used in sql_yacc.h */
#include "sql_get_diagnostics.h"  /* Types used in sql_yacc.h */
#include "sql_yacc.h"
#define LEX_YYSTYPE YYSTYPE *
#else
#define LEX_YYSTYPE void *
#endif
#endif
#endif

#include "sql_cmd.h"

// describe/explain types
#define DESCRIBE_NONE           0 // Not explain query
#define DESCRIBE_NORMAL         1
#define DESCRIBE_EXTENDED       2
/*
  This is not within #ifdef because we want "EXPLAIN PARTITIONS ..." to produce
  additional "partitions" column even if partitioning is not compiled in.
*/
#define DESCRIBE_PARTITIONS     4

#ifdef MYSQL_SERVER

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
};

enum enum_sp_type
{
  SP_TYPE_FUNCTION= 1,
  SP_TYPE_PROCEDURE,
  SP_TYPE_TRIGGER
};

/*
  Values for the type enum. This reflects the order of the enum declaration
  in the CREATE TABLE command. These values are used to enumerate object types
  for the ACL statements.

  These values were also used for enumerating stored program types. However, now
  enum_sp_type should be used for that instead of them.
*/
#define TYPE_ENUM_FUNCTION  1
#define TYPE_ENUM_PROCEDURE 2
#define TYPE_ENUM_TRIGGER   3
#define TYPE_ENUM_PROXY     4

const LEX_STRING sp_data_access_name[]=
{
  { C_STRING_WITH_LEN("") },
  { C_STRING_WITH_LEN("CONTAINS SQL") },
  { C_STRING_WITH_LEN("NO SQL") },
  { C_STRING_WITH_LEN("READS SQL DATA") },
  { C_STRING_WITH_LEN("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
};

/* Options to add_table_to_list() */
#define TL_OPTION_UPDATING      1
#define TL_OPTION_FORCE_INDEX   2
#define TL_OPTION_IGNORE_LEAVES 4
#define TL_OPTION_ALIAS         8

typedef List<Item> List_item;
typedef Mem_root_array<ORDER*, true> Group_list_ptrs;

/* SERVERS CACHE CHANGES */
typedef struct st_lex_server_options
{
  long port;
  uint server_name_length;
  char *server_name, *host, *db, *username, *password, *scheme, *socket, *owner;
} LEX_SERVER_OPTIONS;


typedef struct st_lex_master_info
{
  char *host, *user, *password, *log_file_name, *bind_addr;
  uint port, connect_retry;
  float heartbeat_period;
  int sql_delay;
  ulonglong pos;
  ulong server_id, retry_count;
  char *gtid;
  enum {UNTIL_SQL_BEFORE_GTIDS= 0, UNTIL_SQL_AFTER_GTIDS} gtid_until_condition;
  bool until_after_gaps;

  /*
    Enum is used for making it possible to detect if the user
    changed variable or if it should be left at old value
   */
  enum {LEX_MI_UNCHANGED= 0, LEX_MI_DISABLE, LEX_MI_ENABLE}
    ssl, ssl_verify_server_cert, heartbeat_opt, repl_ignore_server_ids_opt, 
    retry_count_opt, auto_position;
  char *ssl_key, *ssl_cert, *ssl_ca, *ssl_capath, *ssl_cipher;
  char *ssl_crl, *ssl_crlpath;
  char *relay_log_name;
  ulong relay_log_pos;
  DYNAMIC_ARRAY repl_ignore_server_ids;
  ulong server_ids_buffer[2];
  void set_unspecified();
} LEX_MASTER_INFO;

typedef struct st_lex_reset_slave
{
  bool all;
} LEX_RESET_SLAVE;

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
};

/* 
  String names used to print a statement with index hints.
  Keep in sync with index_hint_type.
*/
extern const char * index_hint_type_name[];
typedef uchar index_clause_map;

/*
  Bits in index_clause_map : one for each possible FOR clause in
  USE/FORCE/IGNORE INDEX index hint specification
*/
#define INDEX_HINT_MASK_JOIN  (1)
#define INDEX_HINT_MASK_GROUP (1 << 1)
#define INDEX_HINT_MASK_ORDER (1 << 2)

#define INDEX_HINT_MASK_ALL (INDEX_HINT_MASK_JOIN | INDEX_HINT_MASK_GROUP | \
                             INDEX_HINT_MASK_ORDER)

/* Single element of an USE/FORCE/IGNORE INDEX list specified as a SQL hint  */
class Index_hint : public Sql_alloc
{
public:
  /* The type of the hint : USE/FORCE/IGNORE */
  enum index_hint_type type;
  /* Where the hit applies to. A bitmask of INDEX_HINT_MASK_<place> values */
  index_clause_map clause;
  /* 
    The index name. Empty (str=NULL) name represents an empty list 
    USE INDEX () clause 
  */ 
  LEX_STRING key_name;

  Index_hint (enum index_hint_type type_arg, index_clause_map clause_arg,
              char *str, uint length) :
    type(type_arg), clause(clause_arg)
  {
    key_name.str= str;
    key_name.length= length;
  }

  void print(THD *thd, String *str);
}; 

/* 
  The state of the lex parsing for selects 
   
   master and slaves are pointers to select_lex.
   master is pointer to upper level node.
   slave is pointer to lower level node
   select_lex is a SELECT without union
   unit is container of either
     - One SELECT
     - UNION of selects
   select_lex and unit are both inherited form select_lex_node
   neighbors are two select_lex or units on the same level

   All select describing structures linked with following pointers:
   - list of neighbors (next/prev) (prev of first element point to slave
     pointer of upper structure)
     - For select this is a list of UNION's (or one element list)
     - For units this is a list of sub queries for the upper level select

   - pointer to master (master), which is
     If this is a unit
       - pointer to outer select_lex
     If this is a select_lex
       - pointer to outer unit structure for select

   - pointer to slave (slave), which is either:
     If this is a unit:
       - first SELECT that belong to this unit
     If this is a select_lex
       - first unit that belong to this SELECT (subquries or derived tables)

   - list of all select_lex (link_next/link_prev)
     This is to be used for things like derived tables creation, where we
     go through this list and create the derived tables.

   If unit contain several selects (UNION now, INTERSECT etc later)
   then it have special select_lex called fake_select_lex. It used for
   storing global parameters (like ORDER BY, LIMIT) and executing union.
   Subqueries used in global ORDER BY clause will be attached to this
   fake_select_lex, which will allow them correctly resolve fields of
   'upper' UNION and 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:

   select1: (select * from table1 ...)
   select2: (select * from table2 ...)
   select3: (select * from table3)
   select1.1.1: (select * from table1_1_1)
   ...

     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:
   (bigger picture for:
      main unit
      fake0
      select1 select2 select3
   in the above picture)

         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 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:

  ulonglong options;

  /*
    In sql_cache we store SQL_CACHE flag as specified by user to be
    able to restore SELECT statement from internal structures.
  */
  enum e_sql_cache { SQL_CACHE_UNSPECIFIED, SQL_NO_CACHE, SQL_CACHE };
  e_sql_cache sql_cache;

  /*
    result of this query can't be cached, bit field, can be :
      UNCACHEABLE_DEPENDENT
      UNCACHEABLE_RAND
      UNCACHEABLE_SIDEEFFECT
      UNCACHEABLE_EXPLAIN
      UNCACHEABLE_PREPARE
  */
  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) throw ()
  {
    return sql_alloc(size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root) throw ()
  { 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, MEM_ROOT *mem_root) {}

  // Ensures that at least all members used during cleanup() are initialized.
  st_select_lex_node()
    : next(NULL), prev(NULL),
      master(NULL), slave(NULL),
      link_next(NULL), link_prev(NULL),
      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 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 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,
                                        enum_mdl_type mdl_type= MDL_SHARED_READ,
                                        List<Index_hint> *hints= 0,
                                        List<String> *partition_names= 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(LEX *lex, bool move_down);
  friend bool mysql_make_view(THD *thd, TABLE_SHARE *share, TABLE_LIST *table,
                              bool open_view_no_parse);
private:
  void fast_exclude();
};
typedef class st_select_lex_node SELECT_LEX_NODE;

/* 
   SELECT_LEX_UNIT - unit of selects (UNION, INTERSECT, ...) group 
   SELECT_LEXs
*/
class THD;
class select_result;
class JOIN;
class select_union;


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;
  ulonglong found_rows_for_union;
  bool saved_error;

public:
  // Ensures that at least all members used during cleanup() are initialized.
  st_select_lex_unit()
    : union_result(NULL), table(NULL), result(NULL),
      cleaned(false),
      fake_select_lex(NULL),
      explain_marker(0)
  {
  }

  bool  prepared, // prepare phase already performed for UNION (unit)
    optimized, // optimize phase already performed for UNION (unit)
    executed, // already executed
    cleaned;

  // 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

    TODO:
    Possibly this member should be protected, and its direct use replaced
    by get_unit_column_types(). Check the places where it is used.
  */
  List<Item> types;
  /*
    Pointer to 'last' select or pointer to unit where stored
    global parameters for union
  */
  st_select_lex *global_parameters;
  /* 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 */

  int explain_marker;

  void init_query();
  st_select_lex_unit* master_unit();
  st_select_lex* outer_select();
  st_select_lex* first_select()
  {
    return reinterpret_cast<st_select_lex*>(slave);
  }
  st_select_lex_unit* next_unit()
  {
    return reinterpret_cast<st_select_lex_unit*>(next);
  }
  void exclude_level();
  void exclude_tree();
  inline select_result *get_result() { return result; }

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

  void print(String *str, enum_query_type query_type);

  bool add_fake_select_lex(THD *thd);
  bool init_prepare_fake_select_lex(THD *thd, bool no_const_tables);
  inline bool is_prepared() { return prepared; }
  bool change_result(select_result_interceptor *result,
                     select_result_interceptor *old_result);
  void set_limit(st_select_lex *values);
  void set_thd(THD *thd_arg) { thd= thd_arg; }
  inline bool is_union (); 

  friend void lex_start(THD *thd);
  friend bool subselect_union_engine::exec();

  List<Item> *get_unit_column_types();
  List<Item> *get_field_list();
private:
  void invalidate();
};

typedef class st_select_lex_unit SELECT_LEX_UNIT;
typedef Bounds_checked_array<Item*> Ref_ptr_array;

/*
  SELECT_LEX - store information of parsed SELECT statment
*/
class st_select_lex: public st_select_lex_node
{
public:
  Name_resolution_context context;
  /*
    Two fields used by semi-join transformations to know when semi-join is
    possible, and in which condition tree the subquery predicate is located.
  */
  enum Resolve_place { RESOLVE_NONE, RESOLVE_JOIN_NEST, RESOLVE_CONDITION,
                       RESOLVE_HAVING };
  Resolve_place resolve_place; // Indicates part of query being resolved
  TABLE_LIST *resolve_nest;    // Used when resolving outer join condition
  char *db;
  Item *where, *having;                         /* WHERE & HAVING clauses */
  Item *prep_where; /* saved WHERE clause for prepared statement processing */
  Item *prep_having;/* saved HAVING clause for prepared statement processing */
  Item::cond_result cond_value, having_value;
  /* point on lex in which it was created, used in view subquery detection */
  LEX *parent_lex;
  enum olap_type olap;
  /* FROM clause - points to the beginning of the TABLE_LIST::next_local list. */
  SQL_I_List<TABLE_LIST>  table_list;

  /*
    GROUP BY clause.
    This list may be mutated during optimization (by remove_const()),
    so for prepared statements, we keep a copy of the ORDER.next pointers in
    group_list_ptrs, and re-establish the original list before each execution.
  */
  SQL_I_List<ORDER>       group_list;
  Group_list_ptrs        *group_list_ptrs;

  List<Item>          item_list;
  List<String>        interval_list;
  bool                is_item_list_lookup;
  /* 
    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   */
  List<TABLE_LIST> sj_nests;
  //Dynamic_array<TABLE_LIST*> sj_nests; psergey-5:
  /*
    Beginning of the list of leaves in a FROM clause, where the leaves
    inlcude all base tables including view tables. The tables are connected
    by TABLE_LIST::next_leaf, so leaf_tables points to the left-most leaf.
  */
  TABLE_LIST *leaf_tables;
  enum type_enum {
    SLT_NONE= 0,
    SLT_PRIMARY,
    SLT_SIMPLE,
    SLT_DERIVED,
    SLT_SUBQUERY,
    SLT_UNION,
    SLT_UNION_RESULT,
    SLT_MATERIALIZED,
  // Total:
    SLT_total 
  // Don't insert new types below this line!
  };

  /*
    ORDER BY clause.
    This list may be mutated during optimization (by remove_const()),
    so for prepared statements, we keep a copy of the ORDER.next pointers in
    order_list_ptrs, and re-establish the original list before each execution.
  */
  SQL_I_List<ORDER> order_list;
  Group_list_ptrs *order_list_ptrs;

  SQL_I_List<ORDER> gorder_list;
  Item *select_limit, *offset_limit;  /* LIMIT clause parameters */

  Ref_ptr_array ref_pointer_array;

  uint derived_table_count;
  uint materialized_table_count;
  uint partitioned_table_count;
  /*
    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/on */
  uint between_count; /* number of between predicates in where/having/on      */
  uint max_equal_elems; /* maximal number of elements in multiple equalities  */
  /*
    Number of fields used in select list or where clause of current select
    and all inner subselects.
  */
  uint select_n_where_fields;
  enum_parsing_place parsing_place; /* where we are parsing expression */
  bool with_sum_func;   /* sum function indicator */

  ulong table_join_options;
  uint in_sum_expr;
  uint select_number; /* number of select (used for EXPLAIN) */
  int nest_level;
  /* Circularly linked list of sum func in nested selects */
  Item_sum *inner_sum_func_list;
  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;
  /* TRUE when GROUP BY fix field called in processing of this SELECT */
  bool group_fix_field;
  /* List of references to fields referenced from inner selects */
  List<Item_outer_ref> inner_refs_list;
  /* Number of Item_sum-derived objects in this SELECT */
  uint n_sum_items;
  /* Number of Item_sum-derived objects in children and descendant SELECTs */
  uint n_child_sum_items;

  /* 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;
  /*
    This variable is required to ensure proper work of subqueries and
    stored procedures. Generally, one should use the states of
    Query_arena to determine if it's a statement prepare or first
    execution of a stored procedure. However, in case when there was an
    error during the first execution of a stored procedure, the SP body
    is not expelled from the SP cache. Therefore, a deeply nested
    subquery might be left unoptimized. So we need this per-subquery
    variable to inidicate the optimization/execution state of every
    subquery. Prepared statements work OK in that regard, as in
    case of an error during prepare the PS is not created.
  */
  bool first_execution;
  bool first_natural_join_processing;
  bool first_cond_optimization;
  /* do not wrap view fields with Item_ref */
  bool no_wrap_view_item;
  /* exclude this select from check of unique_table() */
  bool exclude_from_table_unique_test;
  /* List of table columns which are not under an aggregate function */
  List<Item_field> non_agg_fields;

  static const int ALL_FIELDS_UNDEF_POS= INT_MIN;

  int cur_pos_in_all_fields;

  List<udf_func>     udf_list;                  /* udf function calls stack */

  /* 
    This is a copy of the original JOIN USING list that comes from
    the parser. The parser :
      1. Sets the natural_join of the second TABLE_LIST in the join
         and the st_select_lex::prev_join_using.
      2. Makes a parent TABLE_LIST and sets its is_natural_join/
       join_using_fields members.
      3. Uses the wrapper TABLE_LIST as a table in the upper level.
    We cannot assign directly to join_using_fields in the parser because
    at stage (1.) the parent TABLE_LIST is not constructed yet and
    the assignment will override the JOIN USING fields of the lower level
    joins on the right.
  */
  List<String> *prev_join_using;
  table_map select_list_tables;
  st_select_lex *removed_select;

  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* last_select() 
  { 
    st_select_lex* mylast= this;
    for (; mylast->next_select(); mylast= mylast->next_select())
    {}
    return mylast; 
  }

  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;
  }
  void invalidate();
  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);
  bool add_gorder_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,
                                enum_mdl_type mdl_type= MDL_SHARED_READ,
                                List<Index_hint> *hints= 0,
                                List<String> *partition_names= 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 add_joined_table(TABLE_LIST *table);
  TABLE_LIST *convert_right_join();
  List<Item>* get_item_list();
  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= &order_list.first;
  }
  /*
    This method created for reiniting LEX in mysql_admin_table() and can be
    used only if you are going remove all SELECT_LEX & units except belonger
    to LEX (LEX::unit & LEX::select, for other purposes there are
    SELECT_LEX_UNIT::exclude_level & SELECT_LEX_UNIT::exclude_tree
  */
  void cut_subtree() { slave= 0; }
  bool test_limit();

  friend void lex_start(THD *thd);
  st_select_lex() : group_list_ptrs(NULL), order_list_ptrs(NULL),
    n_sum_items(0), n_child_sum_items(0),
    cur_pos_in_all_fields(ALL_FIELDS_UNDEF_POS)
  {}
  void make_empty_select()
  {
    init_query();
    init_select();
  }
  bool setup_ref_array(THD *thd, uint order_group_num);
  void print(THD *thd, String *str, enum_query_type query_type);
  static void print_order(String *str,
                          ORDER *order,
                          enum_query_type query_type);
  void print_limit(THD *thd, String *str, enum_query_type query_type);
  void fix_prepare_information(THD *thd, Item **conds, Item **having_conds);
  /*
    Destroy the used execution plan (JOIN) of this subtree (this
    SELECT_LEX and all nested SELECT_LEXes and SELECT_LEX_UNITs).
  */
  bool cleanup();
  bool cleanup_level();
  /*
    Recursively cleanup the join of this select lex and of all nested
    select lexes.
  */
  void cleanup_all_joins(bool full);

  void set_index_hint_type(enum index_hint_type type, index_clause_map clause);

  /* 
   Add a index hint to the tagged list of hints. The type and clause of the
   hint will be the current ones (set by set_index_hint()) 
  */
  bool add_index_hint (THD *thd, char *str, uint length);

  /* make a list to hold index hints */
  void alloc_index_hints (THD *thd);
  /* read and clear the index hints */
  List<Index_hint>* pop_index_hints(void) 
  {
    List<Index_hint> *hints= index_hints;
    index_hints= NULL;
    return hints;
  }

  void clear_index_hints(void) { index_hints= NULL; }
  bool handle_derived(LEX *lex, bool (*processor)(THD*, LEX*, TABLE_LIST*));
  bool is_part_of_union() { return master_unit()->is_union(); }

  /*
    For MODE_ONLY_FULL_GROUP_BY we need to maintain two flags:
     - Non-aggregated fields are used in this select.
     - Aggregate functions are used in this select.
    In MODE_ONLY_FULL_GROUP_BY only one of these may be true.
  */
  bool non_agg_field_used() const { return m_non_agg_field_used; }
  bool agg_func_used()      const { return m_agg_func_used; }

  void set_non_agg_field_used(bool val) { m_non_agg_field_used= val; }
  void set_agg_func_used(bool val)      { m_agg_func_used= val; }

  type_enum type(const THD *thd);

  const char *get_type_str(const THD *thd) { return type_str[type(thd)]; }
  static const char *get_type_str(type_enum type) { return type_str[type]; }

  bool is_dependent() const { return uncacheable & UNCACHEABLE_DEPENDENT; }
  bool is_cacheable() const
  {
    // drop UNCACHEABLE_EXPLAIN, because it is for internal usage only
    return !(uncacheable & ~UNCACHEABLE_EXPLAIN);
  }
  
private:
  bool m_non_agg_field_used;
  bool m_agg_func_used;

  /* current index hint kind. used in filling up index_hints */
  enum index_hint_type current_index_hint_type;
  index_clause_map current_index_hint_clause;
  /* a list of USE/FORCE/IGNORE INDEX */
  List<Index_hint> *index_hints;

  static const char *type_str[SLT_total];
};
typedef class st_select_lex SELECT_LEX;

inline bool st_select_lex_unit::is_union ()
{ 
  return first_select()->next_select() && 
    first_select()->next_select()->linkage == UNION_TYPE;
}

class Switch_resolve_place
{
public:
  Switch_resolve_place(SELECT_LEX::Resolve_place *rp_ptr,
                       SELECT_LEX::Resolve_place new_rp,
                       bool apply)
    : rp(NULL), saved_rp()
  {
    if (apply)
    {
      rp= rp_ptr;
      saved_rp= *rp;
      *rp= new_rp;
    }
  }
  ~Switch_resolve_place()
  {
    if (rp)
      *rp= saved_rp;
  }
private:
  SELECT_LEX::Resolve_place *rp;
  SELECT_LEX::Resolve_place saved_rp;
};


typedef struct struct_slave_connection
{
  char *user;
  char *password;
  char *plugin_auth;
  char *plugin_dir;

  void reset();
} LEX_SLAVE_CONNECTION;

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

extern const LEX_STRING null_lex_str;
extern const LEX_STRING empty_lex_str;

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

extern sys_var *trg_new_row_fake_var;

enum xa_option_words {XA_NONE, XA_JOIN, XA_RESUME, XA_ONE_PHASE,
                      XA_SUSPEND, XA_FOR_MIGRATE};

extern const LEX_STRING null_lex_str;

class Sroutine_hash_entry;

/*
  Class representing list of all tables used by statement and other
  information which is necessary for opening and locking its tables,
  like SQL command for this statement.

  Also contains information about stored functions used by statement
  since during its execution we may have to add all tables used by its
  stored functions/triggers to this list in order to pre-open and lock
  them.

  Also used by LEX::reset_n_backup/restore_backup_query_tables_list()
  methods to save and restore this information.
*/

class Query_tables_list
{
public:
  enum_sql_command sql_command;
  /* Global list of all tables used by this statement */
  TABLE_LIST *query_tables;
  /* Pointer to next_global member of last element in the previous list. */
  TABLE_LIST **query_tables_last;
  /*
    If non-0 then indicates that query requires prelocking and points to
    next_global member of last own element in query table list (i.e. last
    table which was not added to it as part of preparation to prelocking).
    0 - indicates that this query does not need prelocking.
  */
  TABLE_LIST **query_tables_own_last;
  /*
    Set of stored routines called by statement.
    (Note that we use lazy-initialization for this hash).
  */
  enum { START_SROUTINES_HASH_SIZE= 16 };
  HASH sroutines;
  /*
    List linking elements of 'sroutines' set. Allows you to add new elements
    to this set as you iterate through the list of existing elements.
    'sroutines_list_own_last' is pointer to ::next member of last element of
    this list which represents routine which is explicitly used by query.
    'sroutines_list_own_elements' number of explicitly used routines.
    We use these two members for restoring of 'sroutines_list' to the state
    in which it was right after query parsing.
  */
  SQL_I_List<Sroutine_hash_entry> sroutines_list;
  Sroutine_hash_entry **sroutines_list_own_last;
  uint sroutines_list_own_elements;

  enum enum_lock_tables_state {
    LTS_NOT_LOCKED = 0,
    LTS_LOCKED
  };
  enum_lock_tables_state lock_tables_state;
  bool is_query_tables_locked()
  {
    return (lock_tables_state == LTS_LOCKED);
  }

  uint table_count;

  /*
    These constructor and destructor serve for creation/destruction
    of Query_tables_list instances which are used as backup storage.
  */
  Query_tables_list() {}
  ~Query_tables_list() {}

  /* Initializes (or resets) Query_tables_list object for "real" use. */
  void reset_query_tables_list(bool init);
  void destroy_query_tables_list();
  void set_query_tables_list(Query_tables_list *state)
  {
    *this= *state;
  }

  /*
    Direct addition to the list of query tables.
    If you are using this function, you must ensure that the table
    object, in particular table->db member, is initialized.
  */
  void add_to_query_tables(TABLE_LIST *table)
  {
    *(table->prev_global= query_tables_last)= table;
    query_tables_last= &table->next_global;
  }
  bool requires_prelocking()
  {
    return MY_TEST(query_tables_own_last);
  }
  void mark_as_requiring_prelocking(TABLE_LIST **tables_own_last)
  {
    query_tables_own_last= tables_own_last;
  }
  /* Return pointer to first not-own table in query-tables or 0 */
  TABLE_LIST* first_not_own_table()
  {
    return ( query_tables_own_last ? *query_tables_own_last : 0);
  }
  void chop_off_not_own_tables()
  {
    if (query_tables_own_last)
    {
      *query_tables_own_last= 0;
      query_tables_last= query_tables_own_last;
      query_tables_own_last= 0;
    }
  }

  TABLE_LIST *last_table()
  {
    /* Don't use offsetof() macro in order to avoid warnings. */
    return query_tables ?
           (TABLE_LIST*) ((char*) query_tables_last -
                          ((char*) &(query_tables->next_global) -
                           (char*) query_tables)) :
           0;
  }

  enum enum_binlog_stmt_unsafe {
    BINLOG_STMT_UNSAFE_LIMIT= 0,
    BINLOG_STMT_UNSAFE_INSERT_DELAYED,
    BINLOG_STMT_UNSAFE_SYSTEM_TABLE,
    BINLOG_STMT_UNSAFE_AUTOINC_COLUMNS,
    BINLOG_STMT_UNSAFE_UDF,
    BINLOG_STMT_UNSAFE_SYSTEM_VARIABLE,
    BINLOG_STMT_UNSAFE_SYSTEM_FUNCTION,

    BINLOG_STMT_UNSAFE_NONTRANS_AFTER_TRANS,

    BINLOG_STMT_UNSAFE_MULTIPLE_ENGINES_AND_SELF_LOGGING_ENGINE,

    BINLOG_STMT_UNSAFE_MIXED_STATEMENT,

    BINLOG_STMT_UNSAFE_INSERT_IGNORE_SELECT,

    BINLOG_STMT_UNSAFE_INSERT_SELECT_UPDATE,

    BINLOG_STMT_UNSAFE_WRITE_AUTOINC_SELECT,

    BINLOG_STMT_UNSAFE_REPLACE_SELECT,

    BINLOG_STMT_UNSAFE_CREATE_IGNORE_SELECT,

    BINLOG_STMT_UNSAFE_CREATE_REPLACE_SELECT,

    BINLOG_STMT_UNSAFE_CREATE_SELECT_AUTOINC,

    BINLOG_STMT_UNSAFE_UPDATE_IGNORE,

    BINLOG_STMT_UNSAFE_INSERT_TWO_KEYS,

    BINLOG_STMT_UNSAFE_AUTOINC_NOT_FIRST,

    /* The last element of this enumeration type. */
    BINLOG_STMT_UNSAFE_COUNT
  };
  static const int BINLOG_STMT_UNSAFE_ALL_FLAGS=
    ((1 << BINLOG_STMT_UNSAFE_COUNT) - 1);

  static const int binlog_stmt_unsafe_errcode[BINLOG_STMT_UNSAFE_COUNT];

  inline bool is_stmt_unsafe() const {
    return get_stmt_unsafe_flags() != 0;
  }

  inline void set_stmt_unsafe(enum_binlog_stmt_unsafe unsafe_type) {
    DBUG_ENTER("set_stmt_unsafe");
    DBUG_ASSERT(unsafe_type >= 0 && unsafe_type < BINLOG_STMT_UNSAFE_COUNT);
    binlog_stmt_flags|= (1U << unsafe_type);
    DBUG_VOID_RETURN;
  }

  inline void set_stmt_unsafe_flags(uint32 flags) {
    DBUG_ENTER("set_stmt_unsafe_flags");
    DBUG_ASSERT((flags & ~BINLOG_STMT_UNSAFE_ALL_FLAGS) == 0);
    binlog_stmt_flags|= flags;
    DBUG_VOID_RETURN;
  }

  inline uint32 get_stmt_unsafe_flags() const {
    DBUG_ENTER("get_stmt_unsafe_flags");
    DBUG_RETURN(binlog_stmt_flags & BINLOG_STMT_UNSAFE_ALL_FLAGS);
  }

  inline void clear_stmt_unsafe() {
    DBUG_ENTER("clear_stmt_unsafe");
    binlog_stmt_flags&= ~BINLOG_STMT_UNSAFE_ALL_FLAGS;
    DBUG_VOID_RETURN;
  }

  inline bool is_stmt_row_injection() const {
    return binlog_stmt_flags &
      (1U << (BINLOG_STMT_UNSAFE_COUNT + BINLOG_STMT_TYPE_ROW_INJECTION));
  }

  inline void set_stmt_row_injection() {
    DBUG_ENTER("set_stmt_row_injection");
    binlog_stmt_flags|=
      (1U << (BINLOG_STMT_UNSAFE_COUNT + BINLOG_STMT_TYPE_ROW_INJECTION));
    DBUG_VOID_RETURN;
  }

  enum enum_stmt_accessed_table
  {
    /*
       If a transactional table is about to be read. Note that
       a write implies a read.
    */
    STMT_READS_TRANS_TABLE= 0,
    /*
       If a non-transactional table is about to be read. Note that
       a write implies a read.
    */
    STMT_READS_NON_TRANS_TABLE,
    /*
       If a temporary transactional table is about to be read. Note
       that a write implies a read.
    */
    STMT_READS_TEMP_TRANS_TABLE,
    /*
       If a temporary non-transactional table is about to be read. Note
      that a write implies a read.
    */
    STMT_READS_TEMP_NON_TRANS_TABLE,
    /*
       If a transactional table is about to be updated.
    */
    STMT_WRITES_TRANS_TABLE,
    /*
       If a non-transactional table is about to be updated.
    */
    STMT_WRITES_NON_TRANS_TABLE,
    /*
       If a temporary transactional table is about to be updated.
    */
    STMT_WRITES_TEMP_TRANS_TABLE,
    /*
       If a temporary non-transactional table is about to be updated.
    */
    STMT_WRITES_TEMP_NON_TRANS_TABLE,
    /*
      The last element of the enumeration. Please, if necessary add
      anything before this.
    */
    STMT_ACCESS_TABLE_COUNT
  };

#ifndef DBUG_OFF
  static inline const char *stmt_accessed_table_string(enum_stmt_accessed_table accessed_table)
  {
    switch (accessed_table)
    {
      case STMT_READS_TRANS_TABLE:
         return "STMT_READS_TRANS_TABLE";
      break;
      case STMT_READS_NON_TRANS_TABLE:
        return "STMT_READS_NON_TRANS_TABLE";
      break;
      case STMT_READS_TEMP_TRANS_TABLE:
        return "STMT_READS_TEMP_TRANS_TABLE";
      break;
      case STMT_READS_TEMP_NON_TRANS_TABLE:
        return "STMT_READS_TEMP_NON_TRANS_TABLE";
      break;  
      case STMT_WRITES_TRANS_TABLE:
        return "STMT_WRITES_TRANS_TABLE";
      break;
      case STMT_WRITES_NON_TRANS_TABLE:
        return "STMT_WRITES_NON_TRANS_TABLE";
      break;
      case STMT_WRITES_TEMP_TRANS_TABLE:
        return "STMT_WRITES_TEMP_TRANS_TABLE";
      break;
      case STMT_WRITES_TEMP_NON_TRANS_TABLE:
        return "STMT_WRITES_TEMP_NON_TRANS_TABLE";
      break;
      case STMT_ACCESS_TABLE_COUNT:
      default:
        DBUG_ASSERT(0);
      break;
    }
    MY_ASSERT_UNREACHABLE();
    return "";
  }
#endif  /* DBUG */
               
  #define BINLOG_DIRECT_ON 0xF0    /* unsafe when
                                      --binlog-direct-non-trans-updates
                                      is ON */

  #define BINLOG_DIRECT_OFF 0xF    /* unsafe when
                                      --binlog-direct-non-trans-updates
                                      is OFF */

  #define TRX_CACHE_EMPTY 0x33     /* unsafe when trx-cache is empty */

  #define TRX_CACHE_NOT_EMPTY 0xCC /* unsafe when trx-cache is not empty */

  #define IL_LT_REPEATABLE 0xAA    /* unsafe when < ISO_REPEATABLE_READ */

  #define IL_GTE_REPEATABLE 0x55   /* unsafe when >= ISO_REPEATABLE_READ */
  
  inline void set_stmt_accessed_table(enum_stmt_accessed_table accessed_table)
  {
    DBUG_ENTER("LEX::set_stmt_accessed_table");

    DBUG_ASSERT(accessed_table >= 0 && accessed_table < STMT_ACCESS_TABLE_COUNT);
    stmt_accessed_table_flag |= (1U << accessed_table);

    DBUG_VOID_RETURN;
  }

  inline bool stmt_accessed_table(enum_stmt_accessed_table accessed_table)
  {
    DBUG_ENTER("LEX::stmt_accessed_table");

    DBUG_ASSERT(accessed_table >= 0 && accessed_table < STMT_ACCESS_TABLE_COUNT);

    DBUG_RETURN((stmt_accessed_table_flag & (1U << accessed_table)) != 0);
  }

  /*
    Checks if a mixed statement is unsafe.

    
    @param in_multi_stmt_transaction_mode defines if there is an on-going
           multi-transactional statement.
    @param binlog_direct defines if --binlog-direct-non-trans-updates is
           active.
    @param trx_cache_is_not_empty defines if the trx-cache is empty or not.
    @param trx_isolation defines the isolation level.
 
    @return
      @retval TRUE if the mixed statement is unsafe
      @retval FALSE otherwise
  */
  inline bool is_mixed_stmt_unsafe(bool in_multi_stmt_transaction_mode,
                                   bool binlog_direct,
                                   bool trx_cache_is_not_empty,
                                   uint tx_isolation)
  {
    bool unsafe= FALSE;

    if (in_multi_stmt_transaction_mode)
    {
       uint condition=
         (binlog_direct ? BINLOG_DIRECT_ON : BINLOG_DIRECT_OFF) &
         (trx_cache_is_not_empty ? TRX_CACHE_NOT_EMPTY : TRX_CACHE_EMPTY) &
         (tx_isolation >= ISO_REPEATABLE_READ ? IL_GTE_REPEATABLE : IL_LT_REPEATABLE);

      unsafe= (binlog_unsafe_map[stmt_accessed_table_flag] & condition);

#if !defined(DBUG_OFF)
      DBUG_PRINT("LEX::is_mixed_stmt_unsafe", ("RESULT %02X %02X %02X\n", condition,
              binlog_unsafe_map[stmt_accessed_table_flag],
              (binlog_unsafe_map[stmt_accessed_table_flag] & condition)));
 
      int type_in= 0;
      for (; type_in < STMT_ACCESS_TABLE_COUNT; type_in++)
      {
        if (stmt_accessed_table((enum_stmt_accessed_table) type_in))
          DBUG_PRINT("LEX::is_mixed_stmt_unsafe", ("ACCESSED %s ",
                  stmt_accessed_table_string((enum_stmt_accessed_table) type_in)));
      }
#endif
    }

    if (stmt_accessed_table(STMT_WRITES_NON_TRANS_TABLE) &&
      stmt_accessed_table(STMT_READS_TRANS_TABLE) &&
      tx_isolation < ISO_REPEATABLE_READ)
      unsafe= TRUE;
    else if (stmt_accessed_table(STMT_WRITES_TEMP_NON_TRANS_TABLE) &&
      stmt_accessed_table(STMT_READS_TRANS_TABLE) &&
      tx_isolation < ISO_REPEATABLE_READ)
      unsafe= TRUE;

    return(unsafe);
  }

  bool uses_stored_routines() const
  { return sroutines_list.elements != 0; }

private:

  enum enum_binlog_stmt_type {
    BINLOG_STMT_TYPE_ROW_INJECTION = 0,

    BINLOG_STMT_TYPE_COUNT
  };

  uint32 binlog_stmt_flags;

  uint32 stmt_accessed_table_flag;
};


/*
  st_parsing_options contains the flags for constructions that are
  allowed in the current statement.
*/

struct st_parsing_options
{
  bool allows_variable;
  bool allows_select_into;
  bool allows_select_procedure;
  bool allows_derived;

  st_parsing_options() { reset(); }
  void reset();
};


enum enum_comment_state
{
  NO_COMMENT,
  PRESERVE_COMMENT,
  DISCARD_COMMENT
};


class Lex_input_stream
{
public:
  Lex_input_stream()
  {
  }

  ~Lex_input_stream()
  {
  }

  bool init(THD *thd, char *buff, unsigned int length);

  void reset(char *buff, unsigned int length);

  void set_echo(bool echo)
  {
    m_echo= echo;
  }

  void save_in_comment_state()
  {
    m_echo_saved= m_echo;
    in_comment_saved= in_comment;
  }

  void restore_in_comment_state()
  {
    m_echo= m_echo_saved;
    in_comment= in_comment_saved;
  }

  void skip_binary(int n)
  {
    if (m_echo)
    {
      memcpy(m_cpp_ptr, m_ptr, n);
      m_cpp_ptr += n;
    }
    m_ptr += n;
  }

  unsigned char yyGet()
  {
    char c= *m_ptr++;
    if (m_echo)
      *m_cpp_ptr++ = c;
    return c;
  }

  unsigned char yyGetLast()
  {
    return m_ptr[-1];
  }

  unsigned char yyPeek()
  {
    return m_ptr[0];
  }

  unsigned char yyPeekn(int n)
  {
    return m_ptr[n];
  }

  void yyUnget()
  {
    m_ptr--;
    if (m_echo)
      m_cpp_ptr--;
  }

  void yySkip()
  {
    if (m_echo)
      *m_cpp_ptr++ = *m_ptr++;
    else
      m_ptr++;
  }

  void yySkipn(int n)
  {
    if (m_echo)
    {
      memcpy(m_cpp_ptr, m_ptr, n);
      m_cpp_ptr += n;
    }
    m_ptr += n;
  }

  char *yyUnput(char ch)
  {
    *--m_ptr= ch;
    if (m_echo)
      m_cpp_ptr--;
    return m_ptr;
  }

  char *cpp_inject(char ch)
  {
    *m_cpp_ptr= ch;
    return ++m_cpp_ptr;
  }

  bool eof()
  {
    return (m_ptr >= m_end_of_query);
  }

  bool eof(int n)
  {
    return ((m_ptr + n) >= m_end_of_query);
  }

  const char *get_buf()
  {
    return m_buf;
  }

  const char *get_cpp_buf()
  {
    return m_cpp_buf;
  }

  const char *get_end_of_query()
  {
    return m_end_of_query;
  }

  void start_token()
  {
    m_tok_start_prev= m_tok_start;
    m_tok_start= m_ptr;
    m_tok_end= m_ptr;

    m_cpp_tok_start_prev= m_cpp_tok_start;
    m_cpp_tok_start= m_cpp_ptr;
    m_cpp_tok_end= m_cpp_ptr;
  }

  void restart_token()
  {
    m_tok_start= m_ptr;
    m_cpp_tok_start= m_cpp_ptr;
  }

  const char *get_tok_start()
  {
    return m_tok_start;
  }

  const char *get_cpp_tok_start()
  {
    return m_cpp_tok_start;
  }

  const char *get_tok_end()
  {
    return m_tok_end;
  }

  const char *get_cpp_tok_end()
  {
    return m_cpp_tok_end;
  }

  const char *get_tok_start_prev()
  {
    return m_tok_start_prev;
  }

  const char *get_ptr()
  {
    return m_ptr;
  }

  const char *get_cpp_ptr()
  {
    return m_cpp_ptr;
  }

  uint yyLength()
  {
    /*
      The assumption is that the lexical analyser is always 1 character ahead,
      which the -1 account for.
    */
    DBUG_ASSERT(m_ptr > m_tok_start);
    return (uint) ((m_ptr - m_tok_start) - 1);
  }
   
  const char *get_body_utf8_str()
  {
    return m_body_utf8;
  }

  uint get_body_utf8_length()
  {
    return (uint) (m_body_utf8_ptr - m_body_utf8);
  }

  void body_utf8_start(THD *thd, const char *begin_ptr);
  void body_utf8_append(const char *ptr);
  void body_utf8_append(const char *ptr, const char *end_ptr);
  void body_utf8_append_literal(THD *thd,
                                const LEX_STRING *txt,
                                const CHARSET_INFO *txt_cs,
                                const char *end_ptr);

  THD *m_thd;

  uint yylineno;

  uint yytoklen;

  LEX_YYSTYPE yylval;

  int lookahead_token;

  LEX_YYSTYPE lookahead_yylval;

  void add_digest_token(uint token, LEX_YYSTYPE yylval);

  void reduce_digest_token(uint token_left, uint token_right);

private:
  char *m_ptr;

  const char *m_tok_start;

  const char *m_tok_end;

  const char *m_end_of_query;

  const char *m_tok_start_prev;

  const char *m_buf;

  uint m_buf_length;

  bool m_echo;
  bool m_echo_saved;

  char *m_cpp_buf;

  char *m_cpp_ptr;

  const char *m_cpp_tok_start;

  const char *m_cpp_tok_start_prev;

  const char *m_cpp_tok_end;

  char *m_body_utf8;

  char *m_body_utf8_ptr;

  const char *m_cpp_utf8_processed_ptr;

public:

  enum my_lex_states next_state;

  const char *found_semicolon;

  uchar tok_bitmap;

  bool ignore_space;

  bool stmt_prepare_mode;
  bool multi_statements;

  enum_comment_state in_comment;
  enum_comment_state in_comment_saved;

  const char *m_cpp_text_start;

  const char *m_cpp_text_end;

  CHARSET_INFO *m_underscore_cs;

  sql_digest_state* m_digest;
};


struct Proc_analyse_params: public Sql_alloc
{
  uint max_tree_elements; //< maximum number of distinct values per column
  uint max_treemem; //< maximum amount of memory to allocate per column

  Proc_analyse_params()
    : max_tree_elements(256),
      max_treemem(8192)
  {}
};


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

struct LEX: public Query_tables_list
{
  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;

  char *length,*dec,*change;
  LEX_STRING name;
  char *help_arg;
  char* to_log;                                 /* For PURGE MASTER LOGS TO */
  char* x509_subject,*x509_issuer,*ssl_cipher;
  String *wild;
  sql_exchange *exchange;
  select_result *result;
  Item *default_value, *on_update_value;
  LEX_STRING comment, ident;
  LEX_USER *grant_user;
  XID *xid;
  THD *thd;

  /* maintain a list of used plugins for this LEX */
  DYNAMIC_ARRAY plugins;
  plugin_ref plugins_static_buffer[INITIAL_LEX_PLUGIN_LIST_SIZE];

  const CHARSET_INFO *charset;
  bool text_string_is_7bit;
  /* store original leaf_tables for INSERT SELECT and PS/SP */
  TABLE_LIST *leaf_tables_insert;

  LEX_STRING create_view_select;

  const char* raw_trg_on_table_name_begin;
  const char* raw_trg_on_table_name_end;

  /* Partition info structure filled in by PARTITION BY parse part */
  partition_info *part_info;

  /*
    The definer of the object being created (view, trigger, stored routine).
    I.e. the value of DEFINER clause.
  */
  LEX_USER *definer;

  List<Key_part_spec> col_list;
  List<Key_part_spec> ref_list;
  /*
    A list of strings is maintained to store the SET clause command user strings
    which are specified in load data operation.  This list will be used
    during the reconstruction of "load data" statement at the time of writing
    to binary log.
   */
  List<String>        load_set_str_list;
  List<String>        interval_list;
  List<LEX_USER>      users_list;
  List<LEX_COLUMN>    columns;
  List<Item>          *insert_list,field_list,value_list,update_list;
  List<List_item>     many_values;
  List<set_var_base>  var_list;
  List<Item_func_set_user_var> set_var_list; // in-query assignment list
  List<Item_param>    param_list;
  List<LEX_STRING>    view_list; // view list (list of field names in view)
  /*
    A stack of name resolution contexts for the query. This stack is used
    at parse time to set local name resolution contexts for various parts
    of a query. For example, in a JOIN ... ON (some_condition) clause the
    Items in 'some_condition' must be resolved only against the operands
    of the the join, and not against the whole clause. Similarly, Items in
    subqueries should be resolved against the subqueries (and outer queries).
    The stack is used in the following way: when the parser detects that
    all Items in some clause need a local context, it creates a new context
    and pushes it on the stack. All newly created Items always store the
    top-most context in the stack. Once the parser leaves the clause that
    required a local context, the parser pops the top-most context.
  */
  List<Name_resolution_context> context_stack;

  Proc_analyse_params *proc_analyse;
  SQL_I_List<TABLE_LIST> auxiliary_table_list, save_list;
  Create_field        *last_field;
  Item_sum *in_sum_func;
  udf_func udf;
  HA_CHECK_OPT   check_opt;                     // check/repair options
  HA_CREATE_INFO create_info;
  KEY_CREATE_INFO key_create_info;
  LEX_MASTER_INFO mi;                           // used by CHANGE MASTER
  LEX_SLAVE_CONNECTION slave_connection;
  LEX_SERVER_OPTIONS server_options;
  USER_RESOURCES mqh;
  LEX_RESET_SLAVE reset_slave_info;
  ulong type;
  /*
    This variable is used in post-parse stage to declare that sum-functions,
    or functions which have sense only if GROUP BY is present, are allowed.
    For example in a query
    SELECT ... FROM ...WHERE MIN(i) == 1 GROUP BY ... HAVING MIN(i) > 2
    MIN(i) in the WHERE clause is not allowed in the opposite to MIN(i)
    in the HAVING clause. Due to possible nesting of select construct
    the variable can contain 0 or 1 for each nest level.
  */
  nesting_map allow_sum_func;

  Sql_cmd *m_sql_cmd;

  /*
    Usually `expr` rule of yacc is quite reused but some commands better
    not support subqueries which comes standard with this rule, like
    KILL, HA_READ, CREATE/ALTER EVENT etc. Set this to `false` to get
    syntax error back.
  */
  bool expr_allows_subselect;

  enum SSL_type ssl_type;                       /* defined in violite.h */
  enum enum_duplicates duplicates;
  enum enum_tx_isolation tx_isolation;
  enum xa_option_words xa_opt;
  enum enum_var_type option_type;
  enum enum_view_create_mode create_view_mode;
  enum enum_drop_mode drop_mode;

  uint profile_query_id;
  uint profile_options;
  uint uint_geom_type;
  uint grant, grant_tot_col, which_columns;
  enum Foreign_key::fk_match_opt fk_match_option;
  enum Foreign_key::fk_option fk_update_opt;
  enum Foreign_key::fk_option fk_delete_opt;
  uint slave_thd_opt, start_transaction_opt;
  int nest_level;
  uint8 describe;
  /*
    A flag that indicates what kinds of derived tables are present in the
    query (0 if no derived tables, otherwise a combination of flags
    DERIVED_SUBQUERY and DERIVED_VIEW).
  */
  uint8 derived_tables;
  uint8 create_view_algorithm;
  uint8 create_view_check;
  uint8 context_analysis_only;
  bool drop_if_exists, drop_temporary, local_file, one_shot_set;
  bool autocommit;
  bool verbose, no_write_to_binlog;

  enum enum_yes_no_unknown tx_chain, tx_release;
  bool safe_to_cache_query;
  bool subqueries, ignore;
  st_parsing_options parsing_options;
  Alter_info alter_info;
  /*
    For CREATE TABLE statement last element of table list which is not
    part of SELECT or LIKE part (i.e. either element for table we are
    creating or last of tables referenced by foreign keys).
  */
  TABLE_LIST *create_last_non_select_table;
  /* 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;
  sp_head *sphead;
  sp_name *spname;
  bool sp_lex_in_use;   /* Keep track on lex usage in SPs for error handling */
  bool all_privileges;
  bool proxy_priv;
  bool is_change_password;
  /*
    Temporary variable to distinguish SET PASSWORD command from others
    SQLCOM_SET_OPTION commands. Should be removed when WL#6409 is
    introduced.
  */
  bool is_set_password_sql;
  bool contains_plaintext_password;

private:
  bool m_broken; 


  sp_pcontext *sp_current_parsing_ctx;

public:

  bool is_broken() const { return m_broken; }
  void mark_broken(bool broken= true)
  {
    if (broken)
    {
      /*
        "OPEN <cursor>" cannot be re-prepared if the cursor uses no tables
        ("SELECT FROM DUAL"). Indeed in that case cursor_query is left empty
        in constructions of sp_instr_cpush, and thus
        sp_lex_instr::parse_expr() cannot re-prepare. So we mark the statement
        as broken only if tables are used.
      */
      if (is_metadata_used())
        m_broken= true;
    }
    else
      m_broken= false;
  }

  sp_pcontext *get_sp_current_parsing_ctx()
  { return sp_current_parsing_ctx; }

  void set_sp_current_parsing_ctx(sp_pcontext *ctx)
  { sp_current_parsing_ctx= ctx; }

  bool is_metadata_used() const
  { return query_tables != NULL || sroutines.records > 0; }

public:
  st_sp_chistics sp_chistics;

  Event_parse_data *event_parse_data;

  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;
  /*
    view created to be run from definer (standard behaviour)
  */
  uint8 create_view_suid;

  /*
    stmt_definition_begin is intended to point to the next word after
    DEFINER-clause in the following statements:
      - CREATE TRIGGER (points to "TRIGGER");
      - CREATE PROCEDURE (points to "PROCEDURE");
      - CREATE FUNCTION (points to "FUNCTION" or "AGGREGATE");
      - CREATE EVENT (points to "EVENT")

    This pointer is required to add possibly omitted DEFINER-clause to the
    DDL-statement before dumping it to the binlog.

    keyword_delayed_begin_offset is the offset to the beginning of the DELAYED
    keyword in INSERT DELAYED statement. keyword_delayed_end_offset is the
    offset to the character right after the DELAYED keyword.
  */
  union {
    const char *stmt_definition_begin;
    uint keyword_delayed_begin_offset;
  };

  union {
    const char *stmt_definition_end;
    uint keyword_delayed_end_offset;
  };

  bool use_only_table_context;

  /*
    Reference to a struct that contains information in various commands
    to add/create/drop/change table spaces.
  */
  st_alter_tablespace *alter_tablespace_info;
  
  bool escape_used;
  bool is_lex_started; /* If lex_start() did run. For debugging. */

  /*
    The set of those tables whose fields are referenced in all subqueries
    of the query.
    TODO: possibly this it is incorrect to have used tables in LEX because
    with subquery, it is not clear what does the field mean. To fix this
    we should aggregate used tables information for selected expressions
    into the select_lex.
  */
  table_map  used_tables;

  class Explain_format *explain_format;

  LEX();

  virtual ~LEX()
  {
    destroy_query_tables_list();
    plugin_unlock_list(NULL, (plugin_ref *)plugins.buffer, plugins.elements);
    delete_dynamic(&plugins);
  }

  inline bool is_ps_or_view_context_analysis()
  {
    return (context_analysis_only &
            (CONTEXT_ANALYSIS_ONLY_PREPARE |
             CONTEXT_ANALYSIS_ONLY_VIEW));
  }

  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;
    }
  }
  void set_trg_event_type_for_tables();

  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();

  bool can_be_merged();
  bool can_use_merged();
  bool can_not_use_merged();
  bool only_view_structure();
  bool need_correct_ident();
  uint8 get_effective_with_check(TABLE_LIST *view);
  /*
    Is this update command where 'WHITH CHECK OPTION' clause is important

    SYNOPSIS
      LEX::which_check_option_applicable()

    RETURN
      TRUE   have to take 'WHITH CHECK OPTION' clause into account
      FALSE  'WHITH CHECK OPTION' clause do not need
  */
  inline bool which_check_option_applicable()
  {
    switch (sql_command) {
    case SQLCOM_UPDATE:
    case SQLCOM_UPDATE_MULTI:
    case SQLCOM_INSERT:
    case SQLCOM_INSERT_SELECT:
    case SQLCOM_REPLACE:
    case SQLCOM_REPLACE_SELECT:
    case SQLCOM_LOAD:
      return TRUE;
    default:
      return FALSE;
    }
  }

  void cleanup_after_one_table_open();

  bool push_context(Name_resolution_context *context)
  {
    return context_stack.push_front(context);
  }

  void pop_context()
  {
    context_stack.pop();
  }

  bool copy_db_to(char **p_db, size_t *p_db_length) const;

  Name_resolution_context *current_context()
  {
    return context_stack.head();
  }
  /*
    Restore the LEX and THD in case of a parse error.
  */
  static void cleanup_lex_after_parse_error(THD *thd);

  void reset_n_backup_query_tables_list(Query_tables_list *backup);
  void restore_backup_query_tables_list(Query_tables_list *backup);

  bool table_or_sp_used();
  bool is_partition_management() const;

  bool is_single_level_stmt() 
  { 
    /* 
      This check exploits the fact that the last added to all_select_list is
      on its top. So select_lex (as the first added) will be at the tail 
      of the list.
    */ 
    if (&select_lex == all_selects_list && !sroutines.records)
    {
      DBUG_ASSERT(!all_selects_list->next_select_in_list());
      return TRUE;
    }
    return FALSE;
  }
};


class Set_signal_information
{
public:
 Set_signal_information() {} 

  Set_signal_information(const Set_signal_information& set);

  ~Set_signal_information()
  {}

  void clear();

  Item *m_item[LAST_DIAG_SET_PROPERTY+1];
};


class Yacc_state
{
public:
  Yacc_state()
  {
    reset();
  }

  void reset()
  {
    yacc_yyss= NULL;
    yacc_yyvs= NULL;
    m_set_signal_info.clear();
    m_lock_type= TL_READ_DEFAULT;
    m_mdl_type= MDL_SHARED_READ;
    m_ha_rkey_mode= HA_READ_KEY_EXACT;
  }

  ~Yacc_state();

  void reset_before_substatement()
  {
    m_lock_type= TL_READ_DEFAULT;
    m_mdl_type= MDL_SHARED_READ;
    m_ha_rkey_mode= HA_READ_KEY_EXACT; /* Let us be future-proof. */
  }

  uchar *yacc_yyss;

  uchar *yacc_yyvs;

  Set_signal_information m_set_signal_info;

  thr_lock_type m_lock_type;

  enum_mdl_type m_mdl_type;

  enum ha_rkey_function m_ha_rkey_mode;

  /*
    TODO: move more attributes from the LEX structure here.
  */
};

struct Parser_input
{
  bool m_compute_digest;

  Parser_input()
    : m_compute_digest(false)
  {}
};

class Parser_state
{
public:
  Parser_state()
    : m_yacc()
  {}

  bool init(THD *thd, char *buff, unsigned int length)
  {
    return m_lip.init(thd, buff, length);
  }

  ~Parser_state()
  {}

  Parser_input m_input;
  Lex_input_stream m_lip;
  Yacc_state m_yacc;

  PSI_digest_locker* m_digest_psi;

  void reset(char *found_semicolon, unsigned int length)
  {
    m_lip.reset(found_semicolon, length);
    m_yacc.reset();
  }
};

extern sql_digest_state *
digest_add_token(sql_digest_state *state, uint token, LEX_YYSTYPE yylval);

extern sql_digest_state *
digest_reduce_token(sql_digest_state *state, uint token_left, uint token_right);

struct st_lex_local: public LEX
{
  static void *operator new(size_t size) throw()
  {
    return sql_alloc(size);
  }
  static void *operator new(size_t size, MEM_ROOT *mem_root) throw()
  {
    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, MEM_ROOT *mem_root)
  { /* Never called */ }
};

extern void lex_init(void);
extern void lex_free(void);
extern void lex_start(THD *thd);
extern void lex_end(LEX *lex);
extern int MYSQLlex(union YYSTYPE *yylval, class THD *thd);

extern void trim_whitespace(const CHARSET_INFO *cs, LEX_STRING *str);

extern bool is_lex_native_function(const LEX_STRING *name);

void my_missing_function_error(const LEX_STRING &token, const char *name);
bool is_keyword(const char *name, uint len);
bool db_is_default_db(const char *db, size_t db_len, const THD *thd);

#endif /* MYSQL_SERVER */
#endif /* SQL_LEX_INCLUDED */