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Overview
Comment:Factor out the common operation of setting the Expr.x.pSelect field of an Expr object into a subroutine.
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SHA1: 6a5cceee486c5e3625556e4c7076ff90e9d8fa43
User & Date: drh 2016-04-11 01:06:47
Context
2016-04-11
01:26
Small size reduction and performance improvement in the parser. check-in: 16df7128 user: drh tags: trunk
01:06
Factor out the common operation of setting the Expr.x.pSelect field of an Expr object into a subroutine. check-in: 6a5cceee user: drh tags: trunk
2016-04-09
18:04
Fix a problem in the code generator for joins on virtual tables where the outer loop of the join uses the IN operator. check-in: 6c56b3a0 user: drh tags: trunk
Changes
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Changes to src/delete.c.

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  SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
  Select *pSelect = NULL;      /* Complete SELECT tree */

  /* Check that there isn't an ORDER BY without a LIMIT clause.
  */
  if( pOrderBy && (pLimit == 0) ) {
    sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
    goto limit_where_cleanup_2;
  }

  /* We only need to generate a select expression if there
  ** is a limit/offset term to enforce.
  */
  if( pLimit == 0 ) {
    /* if pLimit is null, pOffset will always be null as well. */
................................................................................
  ** becomes:
  **   DELETE FROM table_a WHERE rowid IN ( 
  **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  **   );
  */

  pSelectRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
  if( pSelectRowid == 0 ) goto limit_where_cleanup_2;
  pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid);
  if( pEList == 0 ) goto limit_where_cleanup_2;

  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
  ** and the SELECT subtree. */
  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
  if( pSelectSrc == 0 ) {
    sqlite3ExprListDelete(pParse->db, pEList);
    goto limit_where_cleanup_2;
  }

  /* generate the SELECT expression tree. */
  pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,
                             pOrderBy,0,pLimit,pOffset);
  if( pSelect == 0 ) return 0;

  /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
  pWhereRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
  if( pWhereRowid == 0 ) goto limit_where_cleanup_1;
  pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
  if( pInClause == 0 ) goto limit_where_cleanup_1;

  pInClause->x.pSelect = pSelect;
  pInClause->flags |= EP_xIsSelect;
  sqlite3ExprSetHeightAndFlags(pParse, pInClause);
  return pInClause;

  /* something went wrong. clean up anything allocated. */
limit_where_cleanup_1:
  sqlite3SelectDelete(pParse->db, pSelect);
  return 0;

limit_where_cleanup_2:
  sqlite3ExprDelete(pParse->db, pWhere);
  sqlite3ExprListDelete(pParse->db, pOrderBy);
  sqlite3ExprDelete(pParse->db, pLimit);
  sqlite3ExprDelete(pParse->db, pOffset);
  return 0;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */







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  SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
  Select *pSelect = NULL;      /* Complete SELECT tree */

  /* Check that there isn't an ORDER BY without a LIMIT clause.
  */
  if( pOrderBy && (pLimit == 0) ) {
    sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
    goto limit_where_cleanup;
  }

  /* We only need to generate a select expression if there
  ** is a limit/offset term to enforce.
  */
  if( pLimit == 0 ) {
    /* if pLimit is null, pOffset will always be null as well. */
................................................................................
  ** becomes:
  **   DELETE FROM table_a WHERE rowid IN ( 
  **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  **   );
  */

  pSelectRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
  if( pSelectRowid == 0 ) goto limit_where_cleanup;
  pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid);
  if( pEList == 0 ) goto limit_where_cleanup;

  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
  ** and the SELECT subtree. */
  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
  if( pSelectSrc == 0 ) {
    sqlite3ExprListDelete(pParse->db, pEList);
    goto limit_where_cleanup;
  }

  /* generate the SELECT expression tree. */
  pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,
                             pOrderBy,0,pLimit,pOffset);
  if( pSelect == 0 ) return 0;

  /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
  pWhereRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);

  pInClause = pWhereRowid ? sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0) : 0;




  sqlite3PExprAddSelect(pParse, pInClause, pSelect);
  return pInClause;


limit_where_cleanup:




  sqlite3ExprDelete(pParse->db, pWhere);
  sqlite3ExprListDelete(pParse->db, pOrderBy);
  sqlite3ExprDelete(pParse->db, pLimit);
  sqlite3ExprDelete(pParse->db, pOffset);
  return 0;
}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */

Changes to src/expr.c.

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    sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
  }
  if( p ) {
    sqlite3ExprCheckHeight(pParse, p->nHeight);
  }
  return p;
}

















/*
** If the expression is always either TRUE or FALSE (respectively),
** then return 1.  If one cannot determine the truth value of the
** expression at compile-time return 0.
**
** This is an optimization.  If is OK to return 0 here even if







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    sqlite3ExprAttachSubtrees(pParse->db, p, pLeft, pRight);
  }
  if( p ) {
    sqlite3ExprCheckHeight(pParse, p->nHeight);
  }
  return p;
}

/*
** Add pSelect to the Expr.x.pSelect field.  Or, if pExpr is NULL (due
** do a memory allocation failure) then delete the pSelect object.
*/
void sqlite3PExprAddSelect(Parse *pParse, Expr *pExpr, Select *pSelect){
  if( pExpr ){
    pExpr->x.pSelect = pSelect;
    ExprSetProperty(pExpr, EP_xIsSelect|EP_Subquery);
    sqlite3ExprSetHeightAndFlags(pParse, pExpr);
  }else{
    assert( pParse->db->mallocFailed );
    sqlite3SelectDelete(pParse->db, pSelect);
  }
}


/*
** If the expression is always either TRUE or FALSE (respectively),
** then return 1.  If one cannot determine the truth value of the
** expression at compile-time return 0.
**
** This is an optimization.  If is OK to return 0 here even if

Changes to src/parse.y.

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      exprNot(pParse, N, &A);
    }
    A.zEnd = &E.z[E.n];
  }
  expr(A) ::= LP(B) select(X) RP(E). {
    spanSet(&A,&B,&E); /*A-overwrites-B*/
    A.pExpr = sqlite3PExpr(pParse, TK_SELECT, 0, 0, 0);
    if( A.pExpr ){
      A.pExpr->x.pSelect = X;
      ExprSetProperty(A.pExpr, EP_xIsSelect|EP_Subquery);
      sqlite3ExprSetHeightAndFlags(pParse, A.pExpr);
    }else{
      sqlite3SelectDelete(pParse->db, X);
    }
  }
  expr(A) ::= expr(A) in_op(N) LP select(Y) RP(E).  [IN] {
    A.pExpr = sqlite3PExpr(pParse, TK_IN, A.pExpr, 0, 0);
    if( A.pExpr ){
      A.pExpr->x.pSelect = Y;
      ExprSetProperty(A.pExpr, EP_xIsSelect|EP_Subquery);
      sqlite3ExprSetHeightAndFlags(pParse, A.pExpr);
    }else{
      sqlite3SelectDelete(pParse->db, Y);
    }
    exprNot(pParse, N, &A);
    A.zEnd = &E.z[E.n];
  }
  expr(A) ::= expr(A) in_op(N) nm(Y) dbnm(Z). [IN] {
    SrcList *pSrc = sqlite3SrcListAppend(pParse->db, 0,&Y,&Z);

    A.pExpr = sqlite3PExpr(pParse, TK_IN, A.pExpr, 0, 0);
    if( A.pExpr ){
      A.pExpr->x.pSelect = sqlite3SelectNew(pParse, 0,pSrc,0,0,0,0,0,0,0);
      ExprSetProperty(A.pExpr, EP_xIsSelect|EP_Subquery);
      sqlite3ExprSetHeightAndFlags(pParse, A.pExpr);
    }else{
      sqlite3SrcListDelete(pParse->db, pSrc);
    }
    exprNot(pParse, N, &A);
    A.zEnd = Z.z ? &Z.z[Z.n] : &Y.z[Y.n];
  }
  expr(A) ::= EXISTS(B) LP select(Y) RP(E). {
    Expr *p;
    spanSet(&A,&B,&E); /*A-overwrites-B*/
    p = A.pExpr = sqlite3PExpr(pParse, TK_EXISTS, 0, 0, 0);
    if( p ){
      p->x.pSelect = Y;
      ExprSetProperty(p, EP_xIsSelect|EP_Subquery);
      sqlite3ExprSetHeightAndFlags(pParse, p);
    }else{
      sqlite3SelectDelete(pParse->db, Y);
    }
  }
%endif SQLITE_OMIT_SUBQUERY

/* CASE expressions */
expr(A) ::= CASE(C) case_operand(X) case_exprlist(Y) case_else(Z) END(E). {
  spanSet(&A,&C,&E);  /*A-overwrites-C*/
  A.pExpr = sqlite3PExpr(pParse, TK_CASE, X, 0, 0);







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      exprNot(pParse, N, &A);
    }
    A.zEnd = &E.z[E.n];
  }
  expr(A) ::= LP(B) select(X) RP(E). {
    spanSet(&A,&B,&E); /*A-overwrites-B*/
    A.pExpr = sqlite3PExpr(pParse, TK_SELECT, 0, 0, 0);



    sqlite3PExprAddSelect(pParse, A.pExpr, X);



  }
  expr(A) ::= expr(A) in_op(N) LP select(Y) RP(E).  [IN] {
    A.pExpr = sqlite3PExpr(pParse, TK_IN, A.pExpr, 0, 0);



    sqlite3PExprAddSelect(pParse, A.pExpr, Y);



    exprNot(pParse, N, &A);
    A.zEnd = &E.z[E.n];
  }
  expr(A) ::= expr(A) in_op(N) nm(Y) dbnm(Z). [IN] {
    SrcList *pSrc = sqlite3SrcListAppend(pParse->db, 0,&Y,&Z);
    Select *pSelect = sqlite3SelectNew(pParse, 0,pSrc,0,0,0,0,0,0,0);
    A.pExpr = sqlite3PExpr(pParse, TK_IN, A.pExpr, 0, 0);

    sqlite3PExprAddSelect(pParse, A.pExpr, pSelect);





    exprNot(pParse, N, &A);
    A.zEnd = Z.z ? &Z.z[Z.n] : &Y.z[Y.n];
  }
  expr(A) ::= EXISTS(B) LP select(Y) RP(E). {
    Expr *p;
    spanSet(&A,&B,&E); /*A-overwrites-B*/
    p = A.pExpr = sqlite3PExpr(pParse, TK_EXISTS, 0, 0, 0);
    sqlite3PExprAddSelect(pParse, p, Y);






  }
%endif SQLITE_OMIT_SUBQUERY

/* CASE expressions */
expr(A) ::= CASE(C) case_operand(X) case_exprlist(Y) case_else(Z) END(E). {
  spanSet(&A,&C,&E);  /*A-overwrites-C*/
  A.pExpr = sqlite3PExpr(pParse, TK_CASE, X, 0, 0);

Changes to src/sqliteInt.h.

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#ifdef SQLITE_DEBUG
int sqlite3NoTempsInRange(Parse*,int,int);
#endif
Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
Expr *sqlite3Expr(sqlite3*,int,const char*);
void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*, const Token*);

Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*);
void sqlite3ExprAssignVarNumber(Parse*, Expr*);
void sqlite3ExprDelete(sqlite3*, Expr*);
ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
void sqlite3ExprListSetSortOrder(ExprList*,int);
void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);







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#ifdef SQLITE_DEBUG
int sqlite3NoTempsInRange(Parse*,int,int);
#endif
Expr *sqlite3ExprAlloc(sqlite3*,int,const Token*,int);
Expr *sqlite3Expr(sqlite3*,int,const char*);
void sqlite3ExprAttachSubtrees(sqlite3*,Expr*,Expr*,Expr*);
Expr *sqlite3PExpr(Parse*, int, Expr*, Expr*, const Token*);
void sqlite3PExprAddSelect(Parse*, Expr*, Select*);
Expr *sqlite3ExprAnd(sqlite3*,Expr*, Expr*);
Expr *sqlite3ExprFunction(Parse*,ExprList*, Token*);
void sqlite3ExprAssignVarNumber(Parse*, Expr*);
void sqlite3ExprDelete(sqlite3*, Expr*);
ExprList *sqlite3ExprListAppend(Parse*,ExprList*,Expr*);
void sqlite3ExprListSetSortOrder(ExprList*,int);
void sqlite3ExprListSetName(Parse*,ExprList*,Token*,int);