SrcList *sqlite3SrcListAppendFromTerm(
  Parse *pParse,          /* Parsing context */
  SrcList *p,             /* The left part of the FROM clause already seen */
  Token *pTable,          /* Name of the table to add to the FROM clause */
  Token *pDatabase,       /* Name of the database containing pTable */
  Token *pAlias,          /* The right-hand side of the AS subexpression */
  Select *pSubquery,      /* A subquery used in place of a table name */

  const OnUsing *pOnUsing /* The ON or USING clause */
){
  struct SrcList_item *pItem;
  sqlite3 *db = pParse->db;
  assert( pOnUsing!=0 );
  if( !p && (pOnUsing->pOn || pOnUsing->pUsing) ){
    sqlite3ErrorMsg(pParse, "a JOIN clause is required before %s", 
      (pOnUsing->pOn ? "ON" : "USING")
    );
    goto append_from_error;
  }
  p = sqlite3SrcListAppend(db, p, pTable, pDatabase);
  if( p==0 ){
    goto append_from_error;
  }
  assert( p->nSrc>0 );
  pItem = &p->a[p->nSrc-1];
  assert( (pTable==0)==(pDatabase==0) );
  assert( pItem->zName==0 || pDatabase!=0 );
  if( IN_RENAME_OBJECT && pItem->zName ){
    Token *pToken = (ALWAYS(pDatabase) && pDatabase->z) ? pDatabase : pTable;
    sqlite3RenameTokenMap(pParse, pItem->zName, pToken);
  }
  assert( pAlias!=0 );
  if( pAlias->n ){
    pItem->zAlias = sqlite3NameFromToken(db, pAlias);
  }
  pItem->pSelect = pSubquery;
  pItem->pOn = pOnUsing->pOn;
  pItem->pUsing = pOnUsing->pUsing;
  return p;

 append_from_error:
  assert( p==0 );
  sqlite3ExprDelete(db, pOnUsing->pOn);
  sqlite3IdListDelete(db, pOnUsing->pUsing);
  sqlite3SelectDelete(db, pSubquery);
  return 0;
}

/*
** Add an INDEXED BY or NOT INDEXED clause to the most recently added 
** element of the source-list passed as the second argument.

selectnowith(A) ::= oneselect(A).
%ifndef SQLITE_OMIT_COMPOUND_SELECT
selectnowith(A) ::= selectnowith(A) multiselect_op(Y) oneselect(Z).  {
  Select *pRhs = Z;
  Select *pLhs = A;
  if( pRhs && pRhs->pPrior ){
    static const OnUsing nullOnUsing = { 0, 0 };
    SrcList *pFrom;
    Token x;
    x.n = 0;
    parserDoubleLinkSelect(pParse, pRhs);
    pFrom = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&x,pRhs,&nullOnUsing);
    pRhs = sqlite3SelectNew(pParse,0,pFrom,0,0,0,0,0,0);
  }
  if( pRhs ){
    pRhs->op = (u8)Y;
    pRhs->pPrior = pLhs;
    if( ALWAYS(pLhs) ) pLhs->selFlags &= ~SF_MultiValue;
    pRhs->selFlags &= ~SF_MultiValue;

// in a SELECT statement.  "stl_prefix" is a prefix of this list.
//
stl_prefix(A) ::= seltablist(A) joinop(Y).    {
   if( ALWAYS(A && A->nSrc>0) ) A->a[A->nSrc-1].fg.jointype = (u8)Y;
}
stl_prefix(A) ::= .                           {A = 0;}
seltablist(A) ::= stl_prefix(A) nm(Y) dbnm(D) as(Z) indexed_opt(I)
                  onusing(U). {
  A = sqlite3SrcListAppendFromTerm(pParse,A,&Y,&D,&Z,0,&U);
  sqlite3SrcListIndexedBy(pParse, A, &I);
}
seltablist(A) ::= stl_prefix(A) nm(Y) dbnm(D) LP exprlist(E) RP as(Z)
                  onusing(U). {
  A = sqlite3SrcListAppendFromTerm(pParse,A,&Y,&D,&Z,0,&U);
  sqlite3SrcListFuncArgs(pParse, A, E);
}
%ifndef SQLITE_OMIT_SUBQUERY
  seltablist(A) ::= stl_prefix(A) LP select(S) RP
                    as(Z) onusing(U). {
    A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,S,&U);
  }
  seltablist(A) ::= stl_prefix(A) LP seltablist(F) RP
                    as(Z) onusing(U). {
    if( A==0 && Z.n==0 && U.pOn==0 && U.pUsing==0 ){
      A = F;
    }else if( F->nSrc==1 ){
      A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,0,&U);
      if( A ){
        struct SrcList_item *pNew = &A->a[A->nSrc-1];
        struct SrcList_item *pOld = F->a;
        pNew->zName = pOld->zName;
        pNew->zDatabase = pOld->zDatabase;
        pNew->pSelect = pOld->pSelect;
        if( pOld->fg.isTabFunc ){
          pNew->u1.pFuncArg = pOld->u1.pFuncArg;
          pOld->u1.pFuncArg = 0;
          pOld->fg.isTabFunc = 0;
          pNew->fg.isTabFunc = 1;
        }
        pOld->zName = pOld->zDatabase = 0;
        pOld->pSelect = 0;
      }
      sqlite3SrcListDelete(pParse->db, F);
    }else{
      Select *pSubquery;
      sqlite3SrcListShiftJoinType(F);
      pSubquery = sqlite3SelectNew(pParse,0,F,0,0,0,0,SF_NestedFrom,0);
      A = sqlite3SrcListAppendFromTerm(pParse,A,0,0,&Z,pSubquery,&U);
    }
  }
%endif  SQLITE_OMIT_SUBQUERY

%type dbnm {Token}
dbnm(A) ::= .          {A.z=0; A.n=0;}
dbnm(A) ::= DOT nm(X). {A = X;}

// WHERE clause in between, like this:
//
//      INSERT INTO tab SELECT * FROM aaa JOIN bbb WHERE true ON CONFLICT ...
//
// The [AND] and [OR] precedence marks in the rules for on_opt cause the
// ON in this context to always be interpreted as belonging to the JOIN.
//
%type onusing {OnUsing}
%destructor onusing {
  sqlite3ExprDelete(pParse->db, $$.pOn);
  sqlite3IdListDelete(pParse->db, $$.pUsing);
}
onusing(A) ::= .    [OR]   {A.pOn = 0; A.pUsing = 0;}
onusing(A) ::= ON expr(E). {A.pOn = E; A.pUsing = 0;}
onusing(A) ::= USING LP idlist(L) RP.  {A.pOn = 0; A.pUsing=L;}

// Note that this block abuses the Token type just a little. If there is
// no "INDEXED BY" clause, the returned token is empty (z==0 && n==0). If
// there is an INDEXED BY clause, then the token is populated as per normal,
// with z pointing to the token data and n containing the number of bytes
// in the token.
//
// If there is a "NOT INDEXED" clause, then (z==0 && n==1), which is 
// normally illegal. The sqlite3SrcListIndexedBy() function 
// recognizes and interprets this as a special case.
//
%type indexed_opt {Token}
indexed_opt(A) ::= .                 {A.z=0; A.n=0;}
indexed_opt(A) ::= INDEXED BY nm(X). {A = X;}
indexed_opt(A) ::= NOT INDEXED.      {A.z=0; A.n=1;}







%type orderby_opt {ExprList*}
%destructor orderby_opt {sqlite3ExprListDelete(pParse->db, $$);}

// the sortlist non-terminal stores a list of expression where each
// expression is optionally followed by ASC or DESC to indicate the
// sort order.

        if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){
          addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
                       isOuter, &p->pWhere);
        }
      }
    }

    /* Cannot both ON and USING clauses in the same join.  The parser
    ** does not allow this.
    */
    assert( pRight->pOn==0 || pRight->pUsing==0 );





    /* Add the ON clause to the end of the WHERE clause, connected by
    ** an AND operator.
    */
    if( pRight->pOn ){
      if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
      p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);

  Select *pNew;
  Select *pX;
  sqlite3 *db;
  struct ExprList_item *a;
  SrcList *pNewSrc;
  Parse *pParse;
  Token dummy;
  static const OnUsing nullOnUsing = { 0, 0 };

  if( p->pPrior==0 ) return WRC_Continue;
  if( p->pOrderBy==0 ) return WRC_Continue;
  for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){}
  if( pX==0 ) return WRC_Continue;
  a = p->pOrderBy->a;
  for(i=p->pOrderBy->nExpr-1; i>=0; i--){
    if( a[i].pExpr->flags & EP_Collate ) break;
  }
  if( i<0 ) return WRC_Continue;

  /* If we reach this point, that means the transformation is required. */

  pParse = pWalker->pParse;
  db = pParse->db;
  pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
  if( pNew==0 ) return WRC_Abort;
  memset(&dummy, 0, sizeof(dummy));
  pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,&nullOnUsing);
  if( pNewSrc==0 ) return WRC_Abort;
  *pNew = *p;
  p->pSrc = pNewSrc;
  p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ASTERISK, 0));
  p->op = TK_SELECT;
  p->pWhere = 0;
  pNew->pGroupBy = 0;

typedef struct IndexSample IndexSample;
typedef struct KeyClass KeyClass;
typedef struct KeyInfo KeyInfo;
typedef struct Lookaside Lookaside;
typedef struct LookasideSlot LookasideSlot;
typedef struct Module Module;
typedef struct NameContext NameContext;
typedef struct OnUsing OnUsing;
typedef struct Parse Parse;
typedef struct PreUpdate PreUpdate;
typedef struct PrintfArguments PrintfArguments;
typedef struct RenameToken RenameToken;
typedef struct RowSet RowSet;
typedef struct Savepoint Savepoint;
typedef struct Select Select;

  struct IdList_item {
    char *zName;      /* Name of the identifier */
    int idx;          /* Index in some Table.aCol[] of a column named zName */
  } *a;
  int nId;         /* Number of identifiers on the list */
};

/*
** An instance of the following structure records the ON and USING clauses
** as part of a join.
**
**          ON expr USING exprlist
**
** The parser uses a single instance of this object to hold both elements
** as a performance optimization - to reduce the number of "reduce" actions
** required in the parser automaton.
*/
struct OnUsing {
  Expr *pOn;
  IdList *pUsing;
};

/*
** The following structure describes the FROM clause of a SELECT statement.
** Each table or subquery in the FROM clause is a separate element of
** the SrcList.a[] array.
**
** With the addition of multiple database support, the following structure
** can also be used to describe a particular table such as the table that

void sqlite3Insert(Parse*, SrcList*, Select*, IdList*, int, Upsert*);
void *sqlite3ArrayAllocate(sqlite3*,void*,int,int*,int*);
IdList *sqlite3IdListAppend(Parse*, IdList*, Token*);
int sqlite3IdListIndex(IdList*,const char*);
SrcList *sqlite3SrcListEnlarge(sqlite3*, SrcList*, int, int);
SrcList *sqlite3SrcListAppend(sqlite3*, SrcList*, Token*, Token*);
SrcList *sqlite3SrcListAppendFromTerm(Parse*, SrcList*, Token*, Token*,
                                      Token*, Select*, const OnUsing*);
void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *);
void sqlite3SrcListFuncArgs(Parse*, SrcList*, ExprList*);
int sqlite3IndexedByLookup(Parse *, struct SrcList_item *);
void sqlite3SrcListShiftJoinType(SrcList*);
void sqlite3SrcListAssignCursors(Parse*, SrcList*);
void sqlite3IdListDelete(sqlite3*, IdList*);
void sqlite3SrcListDelete(sqlite3*, SrcList*);