mariadb/sql/sql_lex.cc

/* 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 */


/* A lexical scanner on a temporary buffer with a yacc interface */

#include "mysql_priv.h"
#include "item_create.h"
#include <m_ctype.h>
#include <hash.h>
#include "sp.h"
#include "sp_head.h"

/*
  We are using pointer to this variable for distinguishing between assignment
  to NEW row field (when parsing trigger definition) and structured variable.
*/
sys_var_long_ptr trg_new_row_fake_var(0, 0);

/* Macros to look like lex */

#define yyGet()		*(lex->ptr++)
#define yyGetLast()	lex->ptr[-1]
#define yyPeek()	lex->ptr[0]
#define yyPeek2()	lex->ptr[1]
#define yyUnget()	lex->ptr--
#define yySkip()	lex->ptr++
#define yyLength()	((uint) (lex->ptr - lex->tok_start)-1)

pthread_key(LEX*,THR_LEX);

/* Longest standard keyword name */
#define TOCK_NAME_LENGTH 24

/*
  The following data is based on the latin1 character set, and is only
  used when comparing keywords
*/

static uchar to_upper_lex[]=
{
    0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15,
   16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
   48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
   64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
   96, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,123,124,125,126,127,
  128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
  144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,
  160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,
  176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,
  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
  208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,
  192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,
  208,209,210,211,212,213,214,247,216,217,218,219,220,221,222,255
};


inline int lex_casecmp(const char *s, const char *t, uint len)
{
  while (len-- != 0 &&
	 to_upper_lex[(uchar) *s++] == to_upper_lex[(uchar) *t++]) ;
  return (int) len+1;
}

#include "lex_hash.h"


void lex_init(void)
{
  uint i;
  DBUG_ENTER("lex_init");
  for (i=0 ; i < array_elements(symbols) ; i++)
    symbols[i].length=(uchar) strlen(symbols[i].name);
  for (i=0 ; i < array_elements(sql_functions) ; i++)
    sql_functions[i].length=(uchar) strlen(sql_functions[i].name);

  VOID(pthread_key_create(&THR_LEX,NULL));

  DBUG_VOID_RETURN;
}


void lex_free(void)
{					// Call this when daemon ends
  DBUG_ENTER("lex_free");
  DBUG_VOID_RETURN;
}


/*
  This is called before every query that is to be parsed.
  Because of this, it's critical to not do too much things here.
  (We already do too much here)
*/

void lex_start(THD *thd, uchar *buf,uint length)
{
  LEX *lex= thd->lex;
  DBUG_ENTER("lex_start");

  lex->thd= lex->unit.thd= thd;
  lex->buf= lex->ptr= buf;
  lex->end_of_query= buf+length;

  lex->context_stack.empty();
  lex->unit.init_query();
  lex->unit.init_select();
  /* 'parent_lex' is used in init_query() so it must be before it. */
  lex->select_lex.parent_lex= lex;
  lex->select_lex.init_query();
  lex->value_list.empty();
  lex->update_list.empty();
  lex->param_list.empty();
  lex->view_list.empty();
  lex->unit.next= lex->unit.master=
    lex->unit.link_next= lex->unit.return_to= 0;
  lex->unit.prev= lex->unit.link_prev= 0;
  lex->unit.slave= lex->unit.global_parameters= lex->current_select=
    lex->all_selects_list= &lex->select_lex;
  lex->select_lex.master= &lex->unit;
  lex->select_lex.prev= &lex->unit.slave;
  lex->select_lex.link_next= lex->select_lex.slave= lex->select_lex.next= 0;
  lex->select_lex.link_prev= (st_select_lex_node**)&(lex->all_selects_list);
  lex->select_lex.options= 0;
  lex->select_lex.init_order();
  lex->select_lex.group_list.empty();
  lex->describe= 0;
  lex->subqueries= FALSE;
  lex->view_prepare_mode= FALSE;
  lex->derived_tables= 0;
  lex->lock_option= TL_READ;
  lex->found_semicolon= 0;
  lex->safe_to_cache_query= 1;
  lex->time_zone_tables_used= 0;
  lex->leaf_tables_insert= lex->query_tables= 0;
  lex->query_tables_last= &lex->query_tables;
  lex->variables_used= 0;
  lex->empty_field_list_on_rset= 0;
  lex->select_lex.select_number= 1;
  lex->next_state=MY_LEX_START;
  lex->yylineno = 1;
  lex->in_comment=0;
  lex->length=0;
  lex->select_lex.in_sum_expr=0;
  lex->select_lex.expr_list.empty();
  lex->select_lex.ftfunc_list_alloc.empty();
  lex->select_lex.ftfunc_list= &lex->select_lex.ftfunc_list_alloc;
  lex->select_lex.group_list.empty();
  lex->select_lex.order_list.empty();
  lex->current_select= &lex->select_lex;
  lex->yacc_yyss=lex->yacc_yyvs=0;
  lex->ignore_space=test(thd->variables.sql_mode & MODE_IGNORE_SPACE);
  lex->sql_command= lex->orig_sql_command= SQLCOM_END;
  lex->duplicates= DUP_ERROR;
  lex->ignore= 0;
  lex->sphead= NULL;
  lex->spcont= NULL;
  lex->proc_list.first= 0;
  lex->query_tables_own_last= 0;

  if (lex->sroutines.records)
    my_hash_reset(&lex->sroutines);
  lex->sroutines_list.empty();
  DBUG_VOID_RETURN;
}

void lex_end(LEX *lex)
{
  x_free(lex->yacc_yyss);
  x_free(lex->yacc_yyvs);
}


static int find_keyword(LEX *lex, uint len, bool function)
{
  uchar *tok=lex->tok_start;

  SYMBOL *symbol = get_hash_symbol((const char *)tok,len,function);
  if (symbol)
  {
    lex->yylval->symbol.symbol=symbol;
    lex->yylval->symbol.str= (char*) tok;
    lex->yylval->symbol.length=len;
    
    if ((symbol->tok == NOT_SYM) &&
        (lex->thd->variables.sql_mode & MODE_HIGH_NOT_PRECEDENCE))
      return NOT2_SYM;
    if ((symbol->tok == OR_OR_SYM) &&
	!(lex->thd->variables.sql_mode & MODE_PIPES_AS_CONCAT))
      return OR2_SYM;
    
    return symbol->tok;
  }
  return 0;
}

/*
  Check if name is a keyword

  SYNOPSIS
    is_keyword()
    name      checked name
    len       length of checked name

  RETURN VALUES
    0         name is a keyword
    1         name isn't a keyword
*/

bool is_keyword(const char *name, uint len)
{
  return get_hash_symbol(name,len,0)!=0;
}

/* make a copy of token before ptr and set yytoklen */

static LEX_STRING get_token(LEX *lex,uint length)
{
  LEX_STRING tmp;
  yyUnget();			// ptr points now after last token char
  tmp.length=lex->yytoklen=length;
  tmp.str=(char*) lex->thd->strmake((char*) lex->tok_start,tmp.length);
  return tmp;
}

/* 
 todo: 
   There are no dangerous charsets in mysql for function 
   get_quoted_token yet. But it should be fixed in the 
   future to operate multichar strings (like ucs2)
*/

static LEX_STRING get_quoted_token(LEX *lex,uint length, char quote)
{
  LEX_STRING tmp;
  byte *from, *to, *end;
  yyUnget();			// ptr points now after last token char
  tmp.length=lex->yytoklen=length;
  tmp.str=(char*) lex->thd->alloc(tmp.length+1);
  for (from= (byte*) lex->tok_start, to= (byte*) tmp.str, end= to+length ;
       to != end ;
       )
  {
    if ((*to++= *from++) == quote)
      from++;					// Skip double quotes
  }
  *to= 0;					// End null for safety
  return tmp;
}


/*
  Return an unescaped text literal without quotes
  Fix sometimes to do only one scan of the string
*/

static char *get_text(LEX *lex)
{
  reg1 uchar c,sep;
  uint found_escape=0;
  CHARSET_INFO *cs= lex->thd->charset();

  sep= yyGetLast();			// String should end with this
  //lex->tok_start=lex->ptr-1;		// Remember '
  while (lex->ptr != lex->end_of_query)
  {
    c = yyGet();
#ifdef USE_MB
    int l;
    if (use_mb(cs) &&
        (l = my_ismbchar(cs,
                         (const char *)lex->ptr-1,
                         (const char *)lex->end_of_query))) {
	lex->ptr += l-1;
	continue;
    }
#endif
    if (c == '\\' &&
	!(lex->thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES))
    {					// Escaped character
      found_escape=1;
      if (lex->ptr == lex->end_of_query)
	return 0;
#ifdef USE_MB
      int l;
      if (use_mb(cs) &&
          (l = my_ismbchar(cs,
                           (const char *)lex->ptr,
                           (const char *)lex->end_of_query))) {
          lex->ptr += l;
          continue;
      }
      else
#endif
        yySkip();
    }
    else if (c == sep)
    {
      if (c == yyGet())			// Check if two separators in a row
      {
	found_escape=1;			// dupplicate. Remember for delete
	continue;
      }
      else
	yyUnget();

      /* Found end. Unescape and return string */
      uchar *str,*end,*start;

      str=lex->tok_start+1;
      end=lex->ptr-1;
      if (!(start=(uchar*) lex->thd->alloc((uint) (end-str)+1)))
	return (char*) "";		// Sql_alloc has set error flag
      if (!found_escape)
      {
	lex->yytoklen=(uint) (end-str);
	memcpy(start,str,lex->yytoklen);
	start[lex->yytoklen]=0;
      }
      else
      {
	uchar *to;

        /* Re-use found_escape for tracking state of escapes */
        found_escape= 0;

	for (to=start ; str != end ; str++)
	{
#ifdef USE_MB
	  int l;
	  if (use_mb(cs) &&
              (l = my_ismbchar(cs,
                               (const char *)str, (const char *)end))) {
	      while (l--)
		  *to++ = *str++;
	      str--;
	      continue;
	  }
#endif
	  if (!found_escape &&
              !(lex->thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES) &&
              *str == '\\' && str+1 != end)
	  {
	    switch(*++str) {
	    case 'n':
	      *to++='\n';
	      break;
	    case 't':
	      *to++= '\t';
	      break;
	    case 'r':
	      *to++ = '\r';
	      break;
	    case 'b':
	      *to++ = '\b';
	      break;
	    case '0':
	      *to++= 0;			// Ascii null
	      break;
	    case 'Z':			// ^Z must be escaped on Win32
	      *to++='\032';
	      break;
	    case '_':
	    case '%':
	      *to++= '\\';		// remember prefix for wildcard
	      /* Fall through */
	    default:
              found_escape= 1;
              str--;
	      break;
	    }
	  }
	  else if (!found_escape && *str == sep)
          {
            found_escape= 1;
          }
	  else
          {
	    *to++ = *str;
            found_escape= 0;
          }
	}
	*to=0;
	lex->yytoklen=(uint) (to-start);
      }
      return (char*) start;
    }
  }
  return 0;					// unexpected end of query
}


/*
** Calc type of integer; long integer, longlong integer or real.
** Returns smallest type that match the string.
** When using unsigned long long values the result is converted to a real
** because else they will be unexpected sign changes because all calculation
** is done with longlong or double.
*/

static const char *long_str="2147483647";
static const uint long_len=10;
static const char *signed_long_str="-2147483648";
static const char *longlong_str="9223372036854775807";
static const uint longlong_len=19;
static const char *signed_longlong_str="-9223372036854775808";
static const uint signed_longlong_len=19;
static const char *unsigned_longlong_str="18446744073709551615";
static const uint unsigned_longlong_len=20;

static inline uint int_token(const char *str,uint length)
{
  if (length < long_len)			// quick normal case
    return NUM;
  bool neg=0;

  if (*str == '+')				// Remove sign and pre-zeros
  {
    str++; length--;
  }
  else if (*str == '-')
  {
    str++; length--;
    neg=1;
  }
  while (*str == '0' && length)
  {
    str++; length --;
  }
  if (length < long_len)
    return NUM;

  uint smaller,bigger;
  const char *cmp;
  if (neg)
  {
    if (length == long_len)
    {
      cmp= signed_long_str+1;
      smaller=NUM;				// If <= signed_long_str
      bigger=LONG_NUM;				// If >= signed_long_str
    }
    else if (length < signed_longlong_len)
      return LONG_NUM;
    else if (length > signed_longlong_len)
      return DECIMAL_NUM;
    else
    {
      cmp=signed_longlong_str+1;
      smaller=LONG_NUM;				// If <= signed_longlong_str
      bigger=DECIMAL_NUM;
    }
  }
  else
  {
    if (length == long_len)
    {
      cmp= long_str;
      smaller=NUM;
      bigger=LONG_NUM;
    }
    else if (length < longlong_len)
      return LONG_NUM;
    else if (length > longlong_len)
    {
      if (length > unsigned_longlong_len)
        return DECIMAL_NUM;
      cmp=unsigned_longlong_str;
      smaller=ULONGLONG_NUM;
      bigger=DECIMAL_NUM;
    }
    else
    {
      cmp=longlong_str;
      smaller=LONG_NUM;
      bigger= ULONGLONG_NUM;
    }
  }
  while (*cmp && *cmp++ == *str++) ;
  return ((uchar) str[-1] <= (uchar) cmp[-1]) ? smaller : bigger;
}

/*
  yylex remember the following states from the following yylex()

  - MY_LEX_EOQ			Found end of query
  - MY_LEX_OPERATOR_OR_IDENT	Last state was an ident, text or number
				(which can't be followed by a signed number)
*/

int yylex(void *arg, void *yythd)
{
  reg1	uchar c;
  int	tokval, result_state;
  uint length;
  enum my_lex_states state;
  LEX	*lex= ((THD *)yythd)->lex;
  YYSTYPE *yylval=(YYSTYPE*) arg;
  CHARSET_INFO *cs= ((THD *) yythd)->charset();
  uchar *state_map= cs->state_map;
  uchar *ident_map= cs->ident_map;

  lex->yylval=yylval;			// The global state
  lex->tok_start=lex->tok_end=lex->ptr;
  state=lex->next_state;
  lex->next_state=MY_LEX_OPERATOR_OR_IDENT;
  LINT_INIT(c);
  for (;;)
  {
    switch (state) {
    case MY_LEX_OPERATOR_OR_IDENT:	// Next is operator or keyword
    case MY_LEX_START:			// Start of token
      // Skip startspace
      for (c=yyGet() ; (state_map[c] == MY_LEX_SKIP) ; c= yyGet())
      {
	if (c == '\n')
	  lex->yylineno++;
      }
      lex->tok_start=lex->ptr-1;	// Start of real token
      state= (enum my_lex_states) state_map[c];
      break;
    case MY_LEX_ESCAPE:
      if (yyGet() == 'N')
      {					// Allow \N as shortcut for NULL
	yylval->lex_str.str=(char*) "\\N";
	yylval->lex_str.length=2;
	return NULL_SYM;
      }
    case MY_LEX_CHAR:			// Unknown or single char token
    case MY_LEX_SKIP:			// This should not happen
      if (c == '-' && yyPeek() == '-' &&
          (my_isspace(cs,yyPeek2()) || 
           my_iscntrl(cs,yyPeek2())))
      {
        state=MY_LEX_COMMENT;
        break;
      }
      yylval->lex_str.str=(char*) (lex->ptr=lex->tok_start);// Set to first chr
      yylval->lex_str.length=1;
      c=yyGet();
      if (c != ')')
	lex->next_state= MY_LEX_START;	// Allow signed numbers
      if (c == ',')
	lex->tok_start=lex->ptr;	// Let tok_start point at next item
      /*
        Check for a placeholder: it should not precede a possible identifier
        because of binlogging: when a placeholder is replaced with
        its value in a query for the binlog, the query must stay
        grammatically correct.
      */
      else if (c == '?' && ((THD*) yythd)->command == COM_STMT_PREPARE &&
               !ident_map[yyPeek()])
        return(PARAM_MARKER);
      return((int) c);

    case MY_LEX_IDENT_OR_NCHAR:
      if (yyPeek() != '\'')
      {					// Found x'hex-number'
	state= MY_LEX_IDENT;
	break;
      }
      yyGet();				// Skip '
      while ((c = yyGet()) && (c !='\'')) ;
      length=(lex->ptr - lex->tok_start);	// Length of hexnum+3
      if (c != '\'')
      {
	return(ABORT_SYM);		// Illegal hex constant
      }
      yyGet();				// get_token makes an unget
      yylval->lex_str=get_token(lex,length);
      yylval->lex_str.str+=2;		// Skip x'
      yylval->lex_str.length-=3;	// Don't count x' and last '
      lex->yytoklen-=3;
      return (NCHAR_STRING);

    case MY_LEX_IDENT_OR_HEX:
      if (yyPeek() == '\'')
      {					// Found x'hex-number'
	state= MY_LEX_HEX_NUMBER;
	break;
      }
    case MY_LEX_IDENT_OR_BIN:
      if (yyPeek() == '\'')
      {                                 // Found b'bin-number'
        state= MY_LEX_BIN_NUMBER;
        break;
      }
    case MY_LEX_IDENT:
      uchar *start;
#if defined(USE_MB) && defined(USE_MB_IDENT)
      if (use_mb(cs))
      {
	result_state= IDENT_QUOTED;
        if (my_mbcharlen(cs, yyGetLast()) > 1)
        {
          int l = my_ismbchar(cs,
                              (const char *)lex->ptr-1,
                              (const char *)lex->end_of_query);
          if (l == 0) {
            state = MY_LEX_CHAR;
            continue;
          }
          lex->ptr += l - 1;
        }
        while (ident_map[c=yyGet()])
        {
          if (my_mbcharlen(cs, c) > 1)
          {
            int l;
            if ((l = my_ismbchar(cs,
                              (const char *)lex->ptr-1,
                              (const char *)lex->end_of_query)) == 0)
              break;
            lex->ptr += l-1;
          }
        }
      }
      else
#endif
      {
        for (result_state= c; ident_map[c= yyGet()]; result_state|= c);
        /* If there were non-ASCII characters, mark that we must convert */
        result_state= result_state & 0x80 ? IDENT_QUOTED : IDENT;
      }
      length= (uint) (lex->ptr - lex->tok_start)-1;
      start= lex->ptr;
      if (lex->ignore_space)
      {
        /*
          If we find a space then this can't be an identifier. We notice this
          below by checking start != lex->ptr.
        */
        for (; state_map[c] == MY_LEX_SKIP ; c= yyGet());
      }
      if (start == lex->ptr && c == '.' && ident_map[yyPeek()])
	lex->next_state=MY_LEX_IDENT_SEP;
      else
      {					// '(' must follow directly if function
	yyUnget();
	if ((tokval = find_keyword(lex,length,c == '(')))
	{
	  lex->next_state= MY_LEX_START;	// Allow signed numbers
	  return(tokval);		// Was keyword
	}
	yySkip();			// next state does a unget
      }
      yylval->lex_str=get_token(lex,length);

      /* 
         Note: "SELECT _bla AS 'alias'"
         _bla should be considered as a IDENT if charset haven't been found.
         So we don't use MYF(MY_WME) with get_charset_by_csname to avoid 
         producing an error.
      */

      if ((yylval->lex_str.str[0]=='_') && 
          (lex->charset=get_charset_by_csname(yylval->lex_str.str+1,
					      MY_CS_PRIMARY,MYF(0))))
        return(UNDERSCORE_CHARSET);
      return(result_state);			// IDENT or IDENT_QUOTED

    case MY_LEX_IDENT_SEP:		// Found ident and now '.'
      yylval->lex_str.str=(char*) lex->ptr;
      yylval->lex_str.length=1;
      c=yyGet();			// should be '.'
      lex->next_state= MY_LEX_IDENT_START;// Next is an ident (not a keyword)
      if (!ident_map[yyPeek()])		// Probably ` or "
	lex->next_state= MY_LEX_START;
      return((int) c);

    case MY_LEX_NUMBER_IDENT:		// number or ident which num-start
      while (my_isdigit(cs,(c = yyGet()))) ;
      if (!ident_map[c])
      {					// Can't be identifier
	state=MY_LEX_INT_OR_REAL;
	break;
      }
      if (c == 'e' || c == 'E')
      {
	// The following test is written this way to allow numbers of type 1e1
	if (my_isdigit(cs,yyPeek()) || 
            (c=(yyGet())) == '+' || c == '-')
	{				// Allow 1E+10
	  if (my_isdigit(cs,yyPeek()))	// Number must have digit after sign
	  {
	    yySkip();
	    while (my_isdigit(cs,yyGet())) ;
	    yylval->lex_str=get_token(lex,yyLength());
	    return(FLOAT_NUM);
	  }
	}
	yyUnget(); /* purecov: inspected */
      }
      else if (c == 'x' && (lex->ptr - lex->tok_start) == 2 &&
	  lex->tok_start[0] == '0' )
      {						// Varbinary
	while (my_isxdigit(cs,(c = yyGet()))) ;
	if ((lex->ptr - lex->tok_start) >= 4 && !ident_map[c])
	{
	  yylval->lex_str=get_token(lex,yyLength());
	  yylval->lex_str.str+=2;		// Skip 0x
	  yylval->lex_str.length-=2;
	  lex->yytoklen-=2;
	  return (HEX_NUM);
	}
	yyUnget();
      }
      else if (c == 'b' && (lex->ptr - lex->tok_start) == 2 &&
               lex->tok_start[0] == '0' )
      {						// b'bin-number'
	while (my_isxdigit(cs,(c = yyGet()))) ;
	if ((lex->ptr - lex->tok_start) >= 4 && !ident_map[c])
	{
	  yylval->lex_str= get_token(lex, yyLength());
	  yylval->lex_str.str+= 2;		// Skip 0x
	  yylval->lex_str.length-= 2;
	  lex->yytoklen-= 2;
	  return (BIN_NUM);
	}
	yyUnget();
      }
      // fall through
    case MY_LEX_IDENT_START:			// We come here after '.'
      result_state= IDENT;
#if defined(USE_MB) && defined(USE_MB_IDENT)
      if (use_mb(cs))
      {
	result_state= IDENT_QUOTED;
        while (ident_map[c=yyGet()])
        {
          if (my_mbcharlen(cs, c) > 1)
          {
            int l;
            if ((l = my_ismbchar(cs,
                                 (const char *)lex->ptr-1,
                                 (const char *)lex->end_of_query)) == 0)
              break;
            lex->ptr += l-1;
          }
        }
      }
      else
#endif
      {
        for (result_state=0; ident_map[c= yyGet()]; result_state|= c);
        /* If there were non-ASCII characters, mark that we must convert */
        result_state= result_state & 0x80 ? IDENT_QUOTED : IDENT;
      }
      if (c == '.' && ident_map[yyPeek()])
	lex->next_state=MY_LEX_IDENT_SEP;// Next is '.'

      yylval->lex_str= get_token(lex,yyLength());
      return(result_state);

    case MY_LEX_USER_VARIABLE_DELIMITER:	// Found quote char
    {
      uint double_quotes= 0;
      char quote_char= c;                       // Used char
      lex->tok_start=lex->ptr;			// Skip first `
      while ((c=yyGet()))
      {
	int length;
	if ((length= my_mbcharlen(cs, c)) == 1)
	{
	  if (c == (uchar) NAMES_SEP_CHAR)
	    break; /* Old .frm format can't handle this char */
	  if (c == quote_char)
	  {
	    if (yyPeek() != quote_char)
	      break;
	    c=yyGet();
	    double_quotes++;
	    continue;
	  }
	}
#ifdef USE_MB
	else if (length < 1)
	  break;				// Error
	lex->ptr+= length-1;
#endif
      }
      if (double_quotes)
	yylval->lex_str=get_quoted_token(lex,yyLength() - double_quotes,
					 quote_char);
      else
	yylval->lex_str=get_token(lex,yyLength());
      if (c == quote_char)
	yySkip();			// Skip end `
      lex->next_state= MY_LEX_START;
      return(IDENT_QUOTED);
    }
    case MY_LEX_INT_OR_REAL:		// Compleat int or incompleat real
      if (c != '.')
      {					// Found complete integer number.
	yylval->lex_str=get_token(lex,yyLength());
	return int_token(yylval->lex_str.str,yylval->lex_str.length);
      }
      // fall through
    case MY_LEX_REAL:			// Incomplete real number
      while (my_isdigit(cs,c = yyGet())) ;

      if (c == 'e' || c == 'E')
      {
	c = yyGet();
	if (c == '-' || c == '+')
	  c = yyGet();			// Skip sign
	if (!my_isdigit(cs,c))
	{				// No digit after sign
	  state= MY_LEX_CHAR;
	  break;
	}
	while (my_isdigit(cs,yyGet())) ;
	yylval->lex_str=get_token(lex,yyLength());
	return(FLOAT_NUM);
      }
      yylval->lex_str=get_token(lex,yyLength());
      return(DECIMAL_NUM);

    case MY_LEX_HEX_NUMBER:		// Found x'hexstring'
      yyGet();				// Skip '
      while (my_isxdigit(cs,(c = yyGet()))) ;
      length=(lex->ptr - lex->tok_start);	// Length of hexnum+3
      if (!(length & 1) || c != '\'')
      {
	return(ABORT_SYM);		// Illegal hex constant
      }
      yyGet();				// get_token makes an unget
      yylval->lex_str=get_token(lex,length);
      yylval->lex_str.str+=2;		// Skip x'
      yylval->lex_str.length-=3;	// Don't count x' and last '
      lex->yytoklen-=3;
      return (HEX_NUM);

    case MY_LEX_BIN_NUMBER:           // Found b'bin-string'
      yyGet();                                // Skip '
      while ((c= yyGet()) == '0' || c == '1');
      length= (lex->ptr - lex->tok_start);    // Length of bin-num + 3
      if (c != '\'')
      return(ABORT_SYM);              // Illegal hex constant
      yyGet();                        // get_token makes an unget
      yylval->lex_str= get_token(lex, length);
      yylval->lex_str.str+= 2;        // Skip b'
      yylval->lex_str.length-= 3;     // Don't count b' and last '
      lex->yytoklen-= 3;
      return (BIN_NUM); 

    case MY_LEX_CMP_OP:			// Incomplete comparison operator
      if (state_map[yyPeek()] == MY_LEX_CMP_OP ||
	  state_map[yyPeek()] == MY_LEX_LONG_CMP_OP)
	yySkip();
      if ((tokval = find_keyword(lex,(uint) (lex->ptr - lex->tok_start),0)))
      {
	lex->next_state= MY_LEX_START;	// Allow signed numbers
	return(tokval);
      }
      state = MY_LEX_CHAR;		// Something fishy found
      break;

    case MY_LEX_LONG_CMP_OP:		// Incomplete comparison operator
      if (state_map[yyPeek()] == MY_LEX_CMP_OP ||
	  state_map[yyPeek()] == MY_LEX_LONG_CMP_OP)
      {
	yySkip();
	if (state_map[yyPeek()] == MY_LEX_CMP_OP)
	  yySkip();
      }
      if ((tokval = find_keyword(lex,(uint) (lex->ptr - lex->tok_start),0)))
      {
	lex->next_state= MY_LEX_START;	// Found long op
	return(tokval);
      }
      state = MY_LEX_CHAR;		// Something fishy found
      break;

    case MY_LEX_BOOL:
      if (c != yyPeek())
      {
	state=MY_LEX_CHAR;
	break;
      }
      yySkip();
      tokval = find_keyword(lex,2,0);	// Is a bool operator
      lex->next_state= MY_LEX_START;	// Allow signed numbers
      return(tokval);

    case MY_LEX_STRING_OR_DELIMITER:
      if (((THD *) yythd)->variables.sql_mode & MODE_ANSI_QUOTES)
      {
	state= MY_LEX_USER_VARIABLE_DELIMITER;
	break;
      }
      /* " used for strings */
    case MY_LEX_STRING:			// Incomplete text string
      if (!(yylval->lex_str.str = get_text(lex)))
      {
	state= MY_LEX_CHAR;		// Read char by char
	break;
      }
      yylval->lex_str.length=lex->yytoklen;
      return(TEXT_STRING);

    case MY_LEX_COMMENT:			//  Comment
      lex->select_lex.options|= OPTION_FOUND_COMMENT;
      while ((c = yyGet()) != '\n' && c) ;
      yyUnget();			// Safety against eof
      state = MY_LEX_START;		// Try again
      break;
    case MY_LEX_LONG_COMMENT:		/* Long C comment? */
      if (yyPeek() != '*')
      {
	state=MY_LEX_CHAR;		// Probable division
	break;
      }
      yySkip();				// Skip '*'
      lex->select_lex.options|= OPTION_FOUND_COMMENT;
      if (yyPeek() == '!')		// MySQL command in comment
      {
	ulong version=MYSQL_VERSION_ID;
	yySkip();
	state=MY_LEX_START;
	if (my_isdigit(cs,yyPeek()))
	{				// Version number
	  version=strtol((char*) lex->ptr,(char**) &lex->ptr,10);
	}
	if (version <= MYSQL_VERSION_ID)
	{
	  lex->in_comment=1;
	  break;
	}
      }
      while (lex->ptr != lex->end_of_query &&
	     ((c=yyGet()) != '*' || yyPeek() != '/'))
      {
	if (c == '\n')
	  lex->yylineno++;
      }
      if (lex->ptr != lex->end_of_query)
	yySkip();			// remove last '/'
      state = MY_LEX_START;		// Try again
      break;
    case MY_LEX_END_LONG_COMMENT:
      if (lex->in_comment && yyPeek() == '/')
      {
	yySkip();
	lex->in_comment=0;
	state=MY_LEX_START;
      }
      else
	state=MY_LEX_CHAR;		// Return '*'
      break;
    case MY_LEX_SET_VAR:		// Check if ':='
      if (yyPeek() != '=')
      {
	state=MY_LEX_CHAR;		// Return ':'
	break;
      }
      yySkip();
      return (SET_VAR);
    case MY_LEX_SEMICOLON:			// optional line terminator
      if (yyPeek())
      {
        THD* thd= (THD*)yythd;
        if ((thd->client_capabilities & CLIENT_MULTI_STATEMENTS) && 
            (thd->command != COM_STMT_PREPARE))
        {
	  lex->safe_to_cache_query= 0;
          lex->found_semicolon=(char*) lex->ptr;
          thd->server_status|= SERVER_MORE_RESULTS_EXISTS;
          lex->next_state=     MY_LEX_END;
          return (END_OF_INPUT);
        }
        state= MY_LEX_CHAR;		// Return ';'
	break;
      }
      /* fall true */
    case MY_LEX_EOL:
      if (lex->ptr >= lex->end_of_query)
      {
	lex->next_state=MY_LEX_END;	// Mark for next loop
	return(END_OF_INPUT);
      }
      state=MY_LEX_CHAR;
      break;
    case MY_LEX_END:
      lex->next_state=MY_LEX_END;
      return(0);			// We found end of input last time
      
      /* Actually real shouldn't start with . but allow them anyhow */
    case MY_LEX_REAL_OR_POINT:
      if (my_isdigit(cs,yyPeek()))
	state = MY_LEX_REAL;		// Real
      else
      {
	state= MY_LEX_IDENT_SEP;	// return '.'
	yyUnget();			// Put back '.'
      }
      break;
    case MY_LEX_USER_END:		// end '@' of user@hostname
      switch (state_map[yyPeek()]) {
      case MY_LEX_STRING:
      case MY_LEX_USER_VARIABLE_DELIMITER:
      case MY_LEX_STRING_OR_DELIMITER:
	break;
      case MY_LEX_USER_END:
	lex->next_state=MY_LEX_SYSTEM_VAR;
	break;
      default:
	lex->next_state=MY_LEX_HOSTNAME;
	break;
      }
      yylval->lex_str.str=(char*) lex->ptr;
      yylval->lex_str.length=1;
      return((int) '@');
    case MY_LEX_HOSTNAME:		// end '@' of user@hostname
      for (c=yyGet() ; 
	   my_isalnum(cs,c) || c == '.' || c == '_' ||  c == '$';
	   c= yyGet()) ;
      yylval->lex_str=get_token(lex,yyLength());
      return(LEX_HOSTNAME);
    case MY_LEX_SYSTEM_VAR:
      yylval->lex_str.str=(char*) lex->ptr;
      yylval->lex_str.length=1;
      yySkip();					// Skip '@'
      lex->next_state= (state_map[yyPeek()] ==
			MY_LEX_USER_VARIABLE_DELIMITER ?
			MY_LEX_OPERATOR_OR_IDENT :
			MY_LEX_IDENT_OR_KEYWORD);
      return((int) '@');
    case MY_LEX_IDENT_OR_KEYWORD:
      /*
	We come here when we have found two '@' in a row.
	We should now be able to handle:
	[(global | local | session) .]variable_name
      */
      
      for (result_state= 0; ident_map[c= yyGet()]; result_state|= c);
      /* If there were non-ASCII characters, mark that we must convert */
      result_state= result_state & 0x80 ? IDENT_QUOTED : IDENT;
      
      if (c == '.')
	lex->next_state=MY_LEX_IDENT_SEP;
      length= (uint) (lex->ptr - lex->tok_start)-1;
      if ((tokval= find_keyword(lex,length,0)))
      {
	yyUnget();				// Put back 'c'
	return(tokval);				// Was keyword
      }
      yylval->lex_str=get_token(lex,length);
      return(result_state);
    }
  }
}

/*
  st_select_lex structures initialisations
*/

void st_select_lex_node::init_query()
{
  options= 0;
  linkage= UNSPECIFIED_TYPE;
  no_error= no_table_names_allowed= 0;
  uncacheable= 0;
}

void st_select_lex_node::init_select()
{
}

void st_select_lex_unit::init_query()
{
  st_select_lex_node::init_query();
  linkage= GLOBAL_OPTIONS_TYPE;
  global_parameters= first_select();
  select_limit_cnt= HA_POS_ERROR;
  offset_limit_cnt= 0;
  union_distinct= 0;
  prepared= optimized= executed= 0;
  item= 0;
  union_result= 0;
  table= 0;
  fake_select_lex= 0;
  cleaned= 0;
  item_list.empty();
  describe= 0;
  found_rows_for_union= 0;
}

void st_select_lex::init_query()
{
  st_select_lex_node::init_query();
  table_list.empty();
  top_join_list.empty();
  join_list= &top_join_list;
  embedding= leaf_tables= 0;
  item_list.empty();
  join= 0;
  having= where= prep_where= 0;
  olap= UNSPECIFIED_OLAP_TYPE;
  having_fix_field= 0;
  context.select_lex= this;
  context.init();
  /*
    Add the name resolution context of the current (sub)query to the
    stack of contexts for the whole query.
  */
  parent_lex->push_context(&context);
  cond_count= with_wild= 0;
  conds_processed_with_permanent_arena= 0;
  ref_pointer_array= 0;
  select_n_having_items= 0;
  subquery_in_having= explicit_limit= 0;
  first_execution= 1;
  first_cond_optimization= 1;
  parsing_place= NO_MATTER;
  exclude_from_table_unique_test= no_wrap_view_item= FALSE;
  link_next= 0;
}

void st_select_lex::init_select()
{
  st_select_lex_node::init_select();
  group_list.empty();
  type= db= 0;
  having= 0;
  use_index_ptr= ignore_index_ptr= 0;
  table_join_options= 0;
  in_sum_expr= with_wild= 0;
  options= 0;
  braces= 0;
  when_list.empty();
  expr_list.empty();
  interval_list.empty();
  use_index.empty();
  ftfunc_list_alloc.empty();
  ftfunc_list= &ftfunc_list_alloc;
  linkage= UNSPECIFIED_TYPE;
  order_list.elements= 0;
  order_list.first= 0;
  order_list.next= (byte**) &order_list.first;
  /* Set limit and offset to default values */
  select_limit= 0;      /* denotes the default limit = HA_POS_ERROR */
  offset_limit= 0;      /* denotes the default offset = 0 */
  with_sum_func= 0;
}

/*
  st_select_lex structures linking
*/

/* include on level down */
void st_select_lex_node::include_down(st_select_lex_node *upper)
{
  if ((next= upper->slave))
    next->prev= &next;
  prev= &upper->slave;
  upper->slave= this;
  master= upper;
  slave= 0;
}

/*
  include on level down (but do not link)

  SYNOPSYS
    st_select_lex_node::include_standalone()
    upper - reference on node underr which this node should be included
    ref - references on reference on this node
*/
void st_select_lex_node::include_standalone(st_select_lex_node *upper,
					    st_select_lex_node **ref)
{
  next= 0;
  prev= ref;
  master= upper;
  slave= 0;
}

/* include neighbour (on same level) */
void st_select_lex_node::include_neighbour(st_select_lex_node *before)
{
  if ((next= before->next))
    next->prev= &next;
  prev= &before->next;
  before->next= this;
  master= before->master;
  slave= 0;
}

/* including in global SELECT_LEX list */
void st_select_lex_node::include_global(st_select_lex_node **plink)
{
  if ((link_next= *plink))
    link_next->link_prev= &link_next;
  link_prev= plink;
  *plink= this;
}

//excluding from global list (internal function)
void st_select_lex_node::fast_exclude()
{
  if (link_prev)
  {
    if ((*link_prev= link_next))
      link_next->link_prev= link_prev;
  }
  // Remove slave structure
  for (; slave; slave= slave->next)
    slave->fast_exclude();
  
}

/*
  excluding select_lex structure (except first (first select can't be
  deleted, because it is most upper select))
*/
void st_select_lex_node::exclude()
{
  //exclude from global list
  fast_exclude();
  //exclude from other structures
  if ((*prev= next))
    next->prev= prev;
  /* 
     We do not need following statements, because prev pointer of first 
     list element point to master->slave
     if (master->slave == this)
       master->slave= next;
  */
}


/*
  Exclude level of current unit from tree of SELECTs

  SYNOPSYS
    st_select_lex_unit::exclude_level()

  NOTE: units which belong to current will be brought up on level of
  currernt unit 
*/
void st_select_lex_unit::exclude_level()
{
  SELECT_LEX_UNIT *units= 0, **units_last= &units;
  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
  {
    // unlink current level from global SELECTs list
    if (sl->link_prev && (*sl->link_prev= sl->link_next))
      sl->link_next->link_prev= sl->link_prev;

    // bring up underlay levels
    SELECT_LEX_UNIT **last= 0;
    for (SELECT_LEX_UNIT *u= sl->first_inner_unit(); u; u= u->next_unit())
    {
      u->master= master;
      last= (SELECT_LEX_UNIT**)&(u->next);
    }
    if (last)
    {
      (*units_last)= sl->first_inner_unit();
      units_last= last;
    }
  }
  if (units)
  {
    // include brought up levels in place of current
    (*prev)= units;
    (*units_last)= (SELECT_LEX_UNIT*)next;
    if (next)
      next->prev= (SELECT_LEX_NODE**)units_last;
    units->prev= prev;
  }
  else
  {
    // exclude currect unit from list of nodes
    (*prev)= next;
    if (next)
      next->prev= prev;
  }
}


/*
  Exclude subtree of current unit from tree of SELECTs

  SYNOPSYS
    st_select_lex_unit::exclude_tree()
*/
void st_select_lex_unit::exclude_tree()
{
  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
  {
    // unlink current level from global SELECTs list
    if (sl->link_prev && (*sl->link_prev= sl->link_next))
      sl->link_next->link_prev= sl->link_prev;

    // unlink underlay levels
    for (SELECT_LEX_UNIT *u= sl->first_inner_unit(); u; u= u->next_unit())
    {
      u->exclude_level();
    }
  }
  // exclude currect unit from list of nodes
  (*prev)= next;
  if (next)
    next->prev= prev;
}


/*
  st_select_lex_node::mark_as_dependent mark all st_select_lex struct from 
  this to 'last' as dependent

  SYNOPSIS
    last - pointer to last st_select_lex struct, before wich all 
           st_select_lex have to be marked as dependent

  NOTE
    'last' should be reachable from this st_select_lex_node
*/

void st_select_lex::mark_as_dependent(SELECT_LEX *last)
{
  /*
    Mark all selects from resolved to 1 before select where was
    found table as depended (of select where was found table)
  */
  for (SELECT_LEX *s= this;
       s && s != last;
       s= s->outer_select())
    if (!(s->uncacheable & UNCACHEABLE_DEPENDENT))
    {
      // Select is dependent of outer select
      s->uncacheable|= UNCACHEABLE_DEPENDENT;
      SELECT_LEX_UNIT *munit= s->master_unit();
      munit->uncacheable|= UNCACHEABLE_DEPENDENT;
    }
}

bool st_select_lex_node::set_braces(bool value)      { return 1; }
bool st_select_lex_node::inc_in_sum_expr()           { return 1; }
uint st_select_lex_node::get_in_sum_expr()           { return 0; }
TABLE_LIST* st_select_lex_node::get_table_list()     { return 0; }
List<Item>* st_select_lex_node::get_item_list()      { return 0; }
List<String>* st_select_lex_node::get_use_index()    { return 0; }
List<String>* st_select_lex_node::get_ignore_index() { return 0; }
TABLE_LIST *st_select_lex_node::add_table_to_list(THD *thd, Table_ident *table,
						  LEX_STRING *alias,
						  ulong table_join_options,
						  thr_lock_type flags,
						  List<String> *use_index,
						  List<String> *ignore_index,
                                                  LEX_STRING *option)
{
  return 0;
}
ulong st_select_lex_node::get_table_join_options()
{
  return 0;
}

/*
  prohibit using LIMIT clause
*/
bool st_select_lex::test_limit()
{
  if (select_limit != 0)
  {
    my_error(ER_NOT_SUPPORTED_YET, MYF(0),
             "LIMIT & IN/ALL/ANY/SOME subquery");
    return(1);
  }
  // no sense in ORDER BY without LIMIT
  order_list.empty();
  return(0);
}


st_select_lex_unit* st_select_lex_unit::master_unit()
{
    return this;
}


st_select_lex* st_select_lex_unit::outer_select()
{
  return (st_select_lex*) master;
}


bool st_select_lex::add_order_to_list(THD *thd, Item *item, bool asc)
{
  return add_to_list(thd, order_list, item, asc);
}


bool st_select_lex::add_item_to_list(THD *thd, Item *item)
{
  DBUG_ENTER("st_select_lex::add_item_to_list");
  DBUG_PRINT("info", ("Item: %p", item));
  DBUG_RETURN(item_list.push_back(item));
}


bool st_select_lex::add_group_to_list(THD *thd, Item *item, bool asc)
{
  return add_to_list(thd, group_list, item, asc);
}


bool st_select_lex::add_ftfunc_to_list(Item_func_match *func)
{
  return !func || ftfunc_list->push_back(func); // end of memory?
}


st_select_lex_unit* st_select_lex::master_unit()
{
  return (st_select_lex_unit*) master;
}


st_select_lex* st_select_lex::outer_select()
{
  return (st_select_lex*) master->get_master();
}


bool st_select_lex::set_braces(bool value)
{
  braces= value;
  return 0; 
}


bool st_select_lex::inc_in_sum_expr()
{
  in_sum_expr++;
  return 0;
}


uint st_select_lex::get_in_sum_expr()
{
  return in_sum_expr;
}


TABLE_LIST* st_select_lex::get_table_list()
{
  return (TABLE_LIST*) table_list.first;
}

List<Item>* st_select_lex::get_item_list()
{
  return &item_list;
}


List<String>* st_select_lex::get_use_index()
{
  return use_index_ptr;
}


List<String>* st_select_lex::get_ignore_index()
{
  return ignore_index_ptr;
}


ulong st_select_lex::get_table_join_options()
{
  return table_join_options;
}


bool st_select_lex::setup_ref_array(THD *thd, uint order_group_num)
{
  if (ref_pointer_array)
    return 0;

  /*
    We have to create array in prepared statement memory if it is
    prepared statement
  */
  Query_arena *arena= thd->current_arena;
  return (ref_pointer_array=
          (Item **)arena->alloc(sizeof(Item*) *
                                (item_list.elements +
                                 select_n_having_items +
                                 order_group_num)* 5)) == 0;
}


void st_select_lex_unit::print(String *str)
{
  bool union_all= !union_distinct;
  for (SELECT_LEX *sl= first_select(); sl; sl= sl->next_select())
  {
    if (sl != first_select())
    {
      str->append(" union ", 7);
      if (union_all)
	str->append("all ", 4);
      else if (union_distinct == sl)
        union_all= true;
    }
    if (sl->braces)
      str->append('(');
    sl->print(thd, str);
    if (sl->braces)
      str->append(')');
  }
  if (fake_select_lex == global_parameters)
  {
    if (fake_select_lex->order_list.elements)
    {
      str->append(" order by ", 10);
      fake_select_lex->print_order(str,
				   (ORDER *) fake_select_lex->
				   order_list.first);
    }
    fake_select_lex->print_limit(thd, str);
  }
}


void st_select_lex::print_order(String *str, ORDER *order)
{
  for (; order; order= order->next)
  {
    if (order->counter_used)
    {
      char buffer[20];
      uint length= my_snprintf(buffer, 20, "%d", order->counter);
      str->append(buffer, length);
    }
    else
      (*order->item)->print(str);
    if (!order->asc)
      str->append(" desc", 5);
    if (order->next)
      str->append(',');
  }
}
 

void st_select_lex::print_limit(THD *thd, String *str)
{
  SELECT_LEX_UNIT *unit= master_unit();
  Item_subselect *item= unit->item;
  if (item && unit->global_parameters == this &&
      (item->substype() == Item_subselect::EXISTS_SUBS ||
       item->substype() == Item_subselect::IN_SUBS ||
       item->substype() == Item_subselect::ALL_SUBS))
  {
    DBUG_ASSERT(!item->fixed ||
                select_limit->val_int() == LL(1) && offset_limit == 0);
    return;
  }

  if (explicit_limit)
  {
    str->append(" limit ", 7);
    if (offset_limit)
    {
      offset_limit->print(str);
      str->append(',');
    }
    select_limit->print(str);
  }
}


/*
  Initialize LEX object.

  SYNOPSIS
    st_lex::st_lex()

  NOTE
    LEX object initialized with this constructor can be used as part of
    THD object for which one can safely call open_tables(), lock_tables()
    and close_thread_tables() functions. But it is not yet ready for
    statement parsing. On should use lex_start() function to prepare LEX
    for this.
*/

st_lex::st_lex()
  :result(0), sql_command(SQLCOM_END), query_tables_own_last(0)
{
  hash_init(&sroutines, system_charset_info, 0, 0, 0, sp_sroutine_key, 0, 0);
  sroutines_list.empty();
}


/*
  Check whether the merging algorithm can be used on this VIEW

  SYNOPSIS
    st_lex::can_be_merged()

  DESCRIPTION
    We can apply merge algorithm if it is single SELECT view  with
    subqueries only in WHERE clause (we do not count SELECTs of underlying
    views, and second level subqueries) and we have not grpouping, ordering,
    HAVING clause, aggregate functions, DISTINCT clause, LIMIT clause and
    several underlying tables.

  RETURN
    FALSE - only temporary table algorithm can be used
    TRUE  - merge algorithm can be used
*/

bool st_lex::can_be_merged()
{
  // TODO: do not forget implement case when select_lex.table_list.elements==0

  /* find non VIEW subqueries/unions */
  bool selects_allow_merge= select_lex.next_select() == 0;
  if (selects_allow_merge)
  {
    for (SELECT_LEX_UNIT *unit= select_lex.first_inner_unit();
         unit;
         unit= unit->next_unit())
    {
      if (unit->first_select()->parent_lex == this &&
          (unit->item == 0 || unit->item->place() != IN_WHERE))
      {
        selects_allow_merge= 0;
        break;
      }
    }
  }

  return (selects_allow_merge &&
	  select_lex.order_list.elements == 0 &&
	  select_lex.group_list.elements == 0 &&
	  select_lex.having == 0 &&
          select_lex.with_sum_func == 0 &&
	  select_lex.table_list.elements >= 1 &&
	  !(select_lex.options & SELECT_DISTINCT) &&
          select_lex.select_limit == 0);
}


/*
  check if command can use VIEW with MERGE algorithm (for top VIEWs)

  SYNOPSIS
    st_lex::can_use_merged()

  DESCRIPTION
    Only listed here commands can use merge algorithm in top level
    SELECT_LEX (for subqueries will be used merge algorithm if
    st_lex::can_not_use_merged() is not TRUE).

  RETURN
    FALSE - command can't use merged VIEWs
    TRUE  - VIEWs with MERGE algorithms can be used
*/

bool st_lex::can_use_merged()
{
  switch (sql_command)
  {
  case SQLCOM_SELECT:
  case SQLCOM_CREATE_TABLE:
  case SQLCOM_UPDATE:
  case SQLCOM_UPDATE_MULTI:
  case SQLCOM_DELETE:
  case SQLCOM_DELETE_MULTI:
  case SQLCOM_INSERT:
  case SQLCOM_INSERT_SELECT:
  case SQLCOM_REPLACE:
  case SQLCOM_REPLACE_SELECT:
  case SQLCOM_LOAD:
    return TRUE;
  default:
    return FALSE;
  }
}

/*
  Check if command can't use merged views in any part of command

  SYNOPSIS
    st_lex::can_not_use_merged()

  DESCRIPTION
    Temporary table algorithm will be used on all SELECT levels for queries
    listed here (see also st_lex::can_use_merged()).

  RETURN
    FALSE - command can't use merged VIEWs
    TRUE  - VIEWs with MERGE algorithms can be used
*/

bool st_lex::can_not_use_merged()
{
  switch (sql_command)
  {
  case SQLCOM_CREATE_VIEW:
  case SQLCOM_SHOW_CREATE:
  /*
    SQLCOM_SHOW_FIELDS is necessary to make 
    information schema tables working correctly with views.
    see get_schema_tables_result function
  */
  case SQLCOM_SHOW_FIELDS:
    return TRUE;
  default:
    return FALSE;
  }
}

/*
  Detect that we need only table structure of derived table/view

  SYNOPSIS
    only_view_structure()

  RETURN
    TRUE yes, we need only structure
    FALSE no, we need data
*/

bool st_lex::only_view_structure()
{
  switch (sql_command) {
  case SQLCOM_SHOW_CREATE:
  case SQLCOM_SHOW_TABLES:
  case SQLCOM_SHOW_FIELDS:
  case SQLCOM_REVOKE_ALL:
  case SQLCOM_REVOKE:
  case SQLCOM_GRANT:
  case SQLCOM_CREATE_VIEW:
    return TRUE;
  default:
    return FALSE;
  }
}


/*
  Should Items_ident be printed correctly

  SYNOPSIS
    need_correct_ident()

  RETURN
    TRUE yes, we need only structure
    FALSE no, we need data
*/


bool st_lex::need_correct_ident()
{
  switch(sql_command)
  {
  case SQLCOM_SHOW_CREATE:
  case SQLCOM_SHOW_TABLES:
  case SQLCOM_CREATE_VIEW:
    return TRUE;
  default:
    return FALSE;
  }
}

/*
  Get effective type of CHECK OPTION for given view

  SYNOPSIS
    get_effective_with_check()
    view    given view

  NOTE
    It have not sense to set CHECK OPTION for SELECT satement or subqueries,
    so we do not.

  RETURN
    VIEW_CHECK_NONE      no need CHECK OPTION
    VIEW_CHECK_LOCAL     CHECK OPTION LOCAL
    VIEW_CHECK_CASCADED  CHECK OPTION CASCADED
*/

uint8 st_lex::get_effective_with_check(st_table_list *view)
{
  if (view->select_lex->master_unit() == &unit &&
      which_check_option_applicable())
    return (uint8)view->with_check;
  return VIEW_CHECK_NONE;
}


/*
  initialize limit counters

  SYNOPSIS
    st_select_lex_unit::set_limit()
    values	- SELECT_LEX with initial values for counters
*/

void st_select_lex_unit::set_limit(SELECT_LEX *sl)
{
  ha_rows select_limit_val;

  DBUG_ASSERT(! thd->current_arena->is_stmt_prepare());
  select_limit_val= (ha_rows)(sl->select_limit ? sl->select_limit->val_uint() :
                                                 HA_POS_ERROR);
  offset_limit_cnt= (ha_rows)(sl->offset_limit ? sl->offset_limit->val_uint() :
                                                 ULL(0));
  select_limit_cnt= select_limit_val + offset_limit_cnt;
  if (select_limit_cnt < select_limit_val)
    select_limit_cnt= HA_POS_ERROR;		// no limit
}


/*
  Unlink the first table from the global table list and the first table from
  outer select (lex->select_lex) local list

  SYNOPSIS
    unlink_first_table()
    link_to_local	Set to 1 if caller should link this table to local list

  NOTES
    We assume that first tables in both lists is the same table or the local
    list is empty.

  RETURN
    0	If 'query_tables' == 0
    unlinked table
      In this case link_to_local is set.

*/
TABLE_LIST *st_lex::unlink_first_table(bool *link_to_local)
{
  TABLE_LIST *first;
  if ((first= query_tables))
  {
    /*
      Exclude from global table list
    */
    if ((query_tables= query_tables->next_global))
      query_tables->prev_global= &query_tables;
    else
      query_tables_last= &query_tables;
    first->next_global= 0;

    /*
      and from local list if it is not empty
    */
    if ((*link_to_local= test(select_lex.table_list.first)))
    {
      select_lex.context.table_list= 
        select_lex.context.first_name_resolution_table= first->next_local;
      select_lex.table_list.first= (byte*) (first->next_local);
      select_lex.table_list.elements--;	//safety
      first->next_local= 0;
      /*
        Ensure that the global list has the same first table as the local
        list.
      */
      first_lists_tables_same();
    }
  }
  return first;
}


/*
  Bring first local table of first most outer select to first place in global
  table list

  SYNOPSYS
     st_lex::first_lists_tables_same()

  NOTES
    In many cases (for example, usual INSERT/DELETE/...) the first table of
    main SELECT_LEX have special meaning => check that it is the first table
    in global list and re-link to be first in the global list if it is
    necessary.  We need such re-linking only for queries with sub-queries in
    the select list, as only in this case tables of sub-queries will go to
    the global list first.
*/

void st_lex::first_lists_tables_same()
{
  TABLE_LIST *first_table= (TABLE_LIST*) select_lex.table_list.first;
  if (query_tables != first_table && first_table != 0)
  {
    TABLE_LIST *next;
    if (query_tables_last == &first_table->next_global)
      query_tables_last= first_table->prev_global;

    if ((next= *first_table->prev_global= first_table->next_global))
      next->prev_global= first_table->prev_global;
    /* include in new place */
    first_table->next_global= query_tables;
    /*
       We are sure that query_tables is not 0, because first_table was not
       first table in the global list => we can use
       query_tables->prev_global without check of query_tables
    */
    query_tables->prev_global= &first_table->next_global;
    first_table->prev_global= &query_tables;
    query_tables= first_table;
  }
}


/*
  Add implicitly used time zone description tables to global table list
  (if needed).

  SYNOPSYS
    st_lex::add_time_zone_tables_to_query_tables()
      thd - pointer to current thread context

  RETURN VALUE
   TRUE  - error
   FALSE - success
*/

bool st_lex::add_time_zone_tables_to_query_tables(THD *thd)
{
  /* We should not add these tables twice */
  if (!time_zone_tables_used)
  {
    time_zone_tables_used= my_tz_get_table_list(thd, &query_tables_last);
    if (time_zone_tables_used == &fake_time_zone_tables_list)
      return TRUE;
  }
  return FALSE;
}

/*
  Link table back that was unlinked with unlink_first_table()

  SYNOPSIS
    link_first_table_back()
    link_to_local	do we need link this table to local

  RETURN
    global list
*/

void st_lex::link_first_table_back(TABLE_LIST *first,
				   bool link_to_local)
{
  if (first)
  {
    if ((first->next_global= query_tables))
      query_tables->prev_global= &first->next_global;
    else
      query_tables_last= &first->next_global;
    query_tables= first;

    if (link_to_local)
    {
      first->next_local= (TABLE_LIST*) select_lex.table_list.first;
      select_lex.context.table_list= first;
      select_lex.table_list.first= (byte*) first;
      select_lex.table_list.elements++;	//safety
    }
  }
}



/*
  cleanup lex for case when we open table by table for processing

  SYNOPSIS
    st_lex::cleanup_after_one_table_open()
*/

void st_lex::cleanup_after_one_table_open()
{
  /*
    thd->lex->derived_tables & additional units may be set if we open
    a view. It is necessary to clear thd->lex->derived_tables flag
    to prevent processing of derived tables during next open_and_lock_tables
    if next table is a real table and cleanup & remove underlying units
    NOTE: all units will be connected to thd->lex->select_lex, because we
    have not UNION on most upper level.
    */
  if (all_selects_list != &select_lex)
  {
    derived_tables= 0;
    /* cleunup underlying units (units of VIEW) */
    for (SELECT_LEX_UNIT *un= select_lex.first_inner_unit();
         un;
         un= un->next_unit())
      un->cleanup();
    /* reduce all selects list to default state */
    all_selects_list= &select_lex;
    /* remove underlying units (units of VIEW) subtree */
    select_lex.cut_subtree();
  }
  time_zone_tables_used= 0;
  if (sroutines.records)
    my_hash_reset(&sroutines);
  sroutines_list.empty();
}


/*
  fix some structures at the end of preparation

  SYNOPSIS
    st_select_lex::fix_prepare_information
    thd   thread handler
    conds pointer on conditions which will be used for execution statement
*/

void st_select_lex::fix_prepare_information(THD *thd, Item **conds)
{
  if (!thd->current_arena->is_conventional() && first_execution)
  {
    first_execution= 0;
    if (*conds)
    {
      prep_where= *conds;
      *conds= where= prep_where->copy_andor_structure(thd);
    }
    for (TABLE_LIST *tbl= (TABLE_LIST *)table_list.first;
         tbl;
         tbl= tbl->next_local)
    {
      if (tbl->on_expr)
      {
        tbl->prep_on_expr= tbl->on_expr;
        tbl->on_expr= tbl->on_expr->copy_andor_structure(thd);
      }
    }
  }
}

/*
  There are st_select_lex::add_table_to_list &
  st_select_lex::set_lock_for_tables are in sql_parse.cc

  st_select_lex::print is in sql_select.cc

  st_select_lex_unit::prepare, st_select_lex_unit::exec,
  st_select_lex_unit::cleanup, st_select_lex_unit::reinit_exec_mechanism,
  st_select_lex_unit::change_result
  are in sql_union.cc
*/