resolve.c

最新的sqlite3.6.2源代码

    return 1;
  }
}

/*
** This routine is callback for sqlite3WalkExpr().
**
** Resolve symbolic names into TK_COLUMN operators for the current
** node in the expression tree.  Return 0 to continue the search down
** the tree or 2 to abort the tree walk.
**
** This routine also does error checking and name resolution for
** function names.  The operator for aggregate functions is changed
** to TK_AGG_FUNCTION.
*/
static int resolveExprStep(Walker *pWalker, Expr *pExpr){
  NameContext *pNC;
  Parse *pParse;

  pNC = pWalker->u.pNC;
  assert( pNC!=0 );
  pParse = pNC->pParse;
  assert( pParse==pWalker->pParse );

  if( ExprHasAnyProperty(pExpr, EP_Resolved) ) return WRC_Prune;
  ExprSetProperty(pExpr, EP_Resolved);
#ifndef NDEBUG
  if( pNC->pSrcList && pNC->pSrcList->nAlloc>0 ){
    SrcList *pSrcList = pNC->pSrcList;
    int i;
    for(i=0; i<pNC->pSrcList->nSrc; i++){
      assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab);
    }
  }
#endif
  switch( pExpr->op ){
    /* A lone identifier is the name of a column.
    */
    case TK_ID: {
      lookupName(pParse, 0, 0, &pExpr->token, pNC, pExpr);
      return WRC_Prune;
    }
  
    /* A table name and column name:     ID.ID
    ** Or a database, table and column:  ID.ID.ID
    */
    case TK_DOT: {
      Token *pColumn;
      Token *pTable;
      Token *pDb;
      Expr *pRight;

      /* if( pSrcList==0 ) break; */
      pRight = pExpr->pRight;
      if( pRight->op==TK_ID ){
        pDb = 0;
        pTable = &pExpr->pLeft->token;
        pColumn = &pRight->token;
      }else{
        assert( pRight->op==TK_DOT );
        pDb = &pExpr->pLeft->token;
        pTable = &pRight->pLeft->token;
        pColumn = &pRight->pRight->token;
      }
      lookupName(pParse, pDb, pTable, pColumn, pNC, pExpr);
      return WRC_Prune;
    }

    /* Resolve function names
    */
    case TK_CONST_FUNC:
    case TK_FUNCTION: {
      ExprList *pList = pExpr->pList;    /* The argument list */
      int n = pList ? pList->nExpr : 0;  /* Number of arguments */
      int no_such_func = 0;       /* True if no such function exists */
      int wrong_num_args = 0;     /* True if wrong number of arguments */
      int is_agg = 0;             /* True if is an aggregate function */
      int auth;                   /* Authorization to use the function */
      int nId;                    /* Number of characters in function name */
      const char *zId;            /* The function name. */
      FuncDef *pDef;              /* Information about the function */
      int enc = ENC(pParse->db);  /* The database encoding */

      zId = (char*)pExpr->token.z;
      nId = pExpr->token.n;
      pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
      if( pDef==0 ){
        pDef = sqlite3FindFunction(pParse->db, zId, nId, -1, enc, 0);
        if( pDef==0 ){
          no_such_func = 1;
        }else{
          wrong_num_args = 1;
        }
      }else{
        is_agg = pDef->xFunc==0;
      }
#ifndef SQLITE_OMIT_AUTHORIZATION
      if( pDef ){
        auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
        if( auth!=SQLITE_OK ){
          if( auth==SQLITE_DENY ){
            sqlite3ErrorMsg(pParse, "not authorized to use function: %s",
                                    pDef->zName);
            pNC->nErr++;
          }
          pExpr->op = TK_NULL;
          return WRC_Prune;
        }
      }
#endif
      if( is_agg && !pNC->allowAgg ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
        pNC->nErr++;
        is_agg = 0;
      }else if( no_such_func ){
        sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);
        pNC->nErr++;
      }else if( wrong_num_args ){
        sqlite3ErrorMsg(pParse,"wrong number of arguments to function %.*s()",
             nId, zId);
        pNC->nErr++;
      }
      if( is_agg ){
        pExpr->op = TK_AGG_FUNCTION;
        pNC->hasAgg = 1;
      }
      if( is_agg ) pNC->allowAgg = 0;
      sqlite3WalkExprList(pWalker, pList);
      if( is_agg ) pNC->allowAgg = 1;
      /* FIX ME:  Compute pExpr->affinity based on the expected return
      ** type of the function 
      */
      return WRC_Prune;
    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_SELECT:
    case TK_EXISTS:
#endif
    case TK_IN: {
      if( pExpr->pSelect ){
        int nRef = pNC->nRef;
#ifndef SQLITE_OMIT_CHECK
        if( pNC->isCheck ){
          sqlite3ErrorMsg(pParse,"subqueries prohibited in CHECK constraints");
        }
#endif
        sqlite3WalkSelect(pWalker, pExpr->pSelect);
        assert( pNC->nRef>=nRef );
        if( nRef!=pNC->nRef ){
          ExprSetProperty(pExpr, EP_VarSelect);
        }
      }
      break;
    }
#ifndef SQLITE_OMIT_CHECK
    case TK_VARIABLE: {
      if( pNC->isCheck ){
        sqlite3ErrorMsg(pParse,"parameters prohibited in CHECK constraints");
      }
      break;
    }
#endif
  }
  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
}

/*
** pEList is a list of expressions which are really the result set of the
** a SELECT statement.  pE is a term in an ORDER BY or GROUP BY clause.
** This routine checks to see if pE is a simple identifier which corresponds
** to the AS-name of one of the terms of the expression list.  If it is,
** this routine return an integer between 1 and N where N is the number of
** elements in pEList, corresponding to the matching entry.  If there is
** no match, or if pE is not a simple identifier, then this routine
** return 0.
**
** pEList has been resolved.  pE has not.
*/
static int resolveAsName(
  Parse *pParse,     /* Parsing context for error messages */
  ExprList *pEList,  /* List of expressions to scan */
  Expr *pE           /* Expression we are trying to match */
){
  int i;             /* Loop counter */

  if( pE->op==TK_ID || (pE->op==TK_STRING && pE->token.z[0]!='\'') ){
    sqlite3 *db = pParse->db;
    char *zCol = sqlite3NameFromToken(db, &pE->token);
    if( zCol==0 ){
      return -1;
    }
    for(i=0; i<pEList->nExpr; i++){
      char *zAs = pEList->a[i].zName;
      if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
        sqlite3DbFree(db, zCol);
        return i+1;
      }
    }
    sqlite3DbFree(db, zCol);
  }
  return 0;
}

/*
** pE is a pointer to an expression which is a single term in the
** ORDER BY of a compound SELECT.  The expression has not been
** name resolved.
**
** At the point this routine is called, we already know that the
** ORDER BY term is not an integer index into the result set.  That
** case is handled by the calling routine.
**
** Attempt to match pE against result set columns in the left-most
** SELECT statement.  Return the index i of the matching column,
** as an indication to the caller that it should sort by the i-th column.
** The left-most column is 1.  In other words, the value returned is the
** same integer value that would be used in the SQL statement to indicate
** the column.
**
** If there is no match, return 0.  Return -1 if an error occurs.
*/
static int resolveOrderByTermToExprList(
  Parse *pParse,     /* Parsing context for error messages */
  Select *pSelect,   /* The SELECT statement with the ORDER BY clause */
  Expr *pE           /* The specific ORDER BY term */
){
  int i;             /* Loop counter */
  ExprList *pEList;  /* The columns of the result set */
  NameContext nc;    /* Name context for resolving pE */

  assert( sqlite3ExprIsInteger(pE, &i)==0 );
  pEList = pSelect->pEList;

  /* Resolve all names in the ORDER BY term expression
  */
  memset(&nc, 0, sizeof(nc));
  nc.pParse = pParse;
  nc.pSrcList = pSelect->pSrc;
  nc.pEList = pEList;
  nc.allowAgg = 1;
  nc.nErr = 0;
  if( sqlite3ResolveExprNames(&nc, pE) ){
    sqlite3ErrorClear(pParse);
    return 0;
  }

  /* Try to match the ORDER BY expression against an expression
  ** in the result set.  Return an 1-based index of the matching
  ** result-set entry.
  */
  for(i=0; i<pEList->nExpr; i++){
    if( sqlite3ExprCompare(pEList->a[i].pExpr, pE) ){
      return i+1;
    }
  }

  /* If no match, return 0. */
  return 0;
}

/*
** Generate an ORDER BY or GROUP BY term out-of-range error.
*/
static void resolveOutOfRangeError(
  Parse *pParse,         /* The error context into which to write the error */
  const char *zType,     /* "ORDER" or "GROUP" */
  int i,                 /* The index (1-based) of the term out of range */
  int mx                 /* Largest permissible value of i */
){
  sqlite3ErrorMsg(pParse, 
    "%r %s BY term out of range - should be "
    "between 1 and %d", i, zType, mx);
}

/*
** Analyze the ORDER BY clause in a compound SELECT statement.   Modify
** each term of the ORDER BY clause is a constant integer between 1
** and N where N is the number of columns in the compound SELECT.
**
** ORDER BY terms that are already an integer between 1 and N are
** unmodified.  ORDER BY terms that are integers outside the range of
** 1 through N generate an error.  ORDER BY terms that are expressions
** are matched against result set expressions of compound SELECT
** beginning with the left-most SELECT and working toward the right.
** At the first match, the ORDER BY expression is transformed into
** the integer column number.
**
** Return the number of errors seen.
*/
static int resolveCompoundOrderBy(
  Parse *pParse,        /* Parsing context.  Leave error messages here */
  Select *pSelect       /* The SELECT statement containing the ORDER BY */
){
  int i;
  ExprList *pOrderBy;
  ExprList *pEList;
  sqlite3 *db;
  int moreToDo = 1;

  pOrderBy = pSelect->pOrderBy;
  if( pOrderBy==0 ) return 0;
  db = pParse->db;
#if SQLITE_MAX_COLUMN
  if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
    sqlite3ErrorMsg(pParse, "too many terms in ORDER BY clause");
    return 1;
  }
#endif
  for(i=0; i<pOrderBy->nExpr; i++){
    pOrderBy->a[i].done = 0;
  }
  pSelect->pNext = 0;
  while( pSelect->pPrior ){
    pSelect->pPrior->pNext = pSelect;
    pSelect = pSelect->pPrior;
  }
  while( pSelect && moreToDo ){
    struct ExprList_item *pItem;
    moreToDo = 0;
    pEList = pSelect->pEList;
    assert( pEList!=0 );
    for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
      int iCol = -1;
      Expr *pE, *pDup;
      if( pItem->done ) continue;
      pE = pItem->pExpr;
      if( sqlite3ExprIsInteger(pE, &iCol) ){
        if( iCol<0 || iCol>pEList->nExpr ){
          resolveOutOfRangeError(pParse, "ORDER", i+1, pEList->nExpr);
          return 1;
        }
      }else{
        iCol = resolveAsName(pParse, pEList, pE);
        if( iCol==0 ){
          pDup = sqlite3ExprDup(db, pE);
          if( !db->mallocFailed ){
            assert(pDup);
            iCol = resolveOrderByTermToExprList(pParse, pSelect, pDup);
          }
          sqlite3ExprDelete(db, pDup);
        }
        if( iCol<0 ){
          return 1;
        }
      }
      if( iCol>0 ){
        CollSeq *pColl = pE->pColl;
        int flags = pE->flags & EP_ExpCollate;
        sqlite3ExprDelete(db, pE);
        pItem->pExpr = pE = sqlite3Expr(db, TK_INTEGER, 0, 0, 0);
        if( pE==0 ) return 1;
        pE->pColl = pColl;
        pE->flags |= EP_IntValue | flags;
        pE->iTable = iCol;
        pItem->iCol = iCol;
        pItem->done = 1;
      }else{
        moreToDo = 1;
      }
    }
    pSelect = pSelect->pNext;
  }
  for(i=0; i<pOrderBy->nExpr; i++){
    if( pOrderBy->a[i].done==0 ){
      sqlite3ErrorMsg(pParse, "%r ORDER BY term does not match any "
            "column in the result set", i+1);
      return 1;
    }
  }
  return 0;
}

/*
** Check every term in the ORDER BY or GROUP BY clause pOrderBy of
** the SELECT statement pSelect.  If any term is reference to a
** result set expression (as determined by the ExprList.a.iCol field)
** then convert that term into a copy of the corresponding result set
** column.
**
** If any errors are detected, add an error message to pParse and
** return non-zero.  Return zero if no errors are seen.
*/
int sqlite3ResolveOrderGroupBy(
  Parse *pParse,        /* Parsing context.  Leave error messages here */