expr.c

sqlite数据库管理系统开放源码

){
  char *zDb = 0;       /* Name of the database.  The "X" in X.Y.Z */
  char *zTab = 0;      /* Name of the table.  The "Y" in X.Y.Z or Y.Z */
  char *zCol = 0;      /* Name of the column.  The "Z" */
  int i, j;            /* Loop counters */
  int cnt = 0;         /* Number of matching column names */
  int cntTab = 0;      /* Number of matching table names */
  sqlite *db = pParse->db;  /* The database */

  assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */
  if( pDbToken && pDbToken->z ){
    zDb = sqliteStrNDup(pDbToken->z, pDbToken->n);
    sqliteDequote(zDb);
  }else{
    zDb = 0;
  }
  if( pTableToken && pTableToken->z ){
    zTab = sqliteStrNDup(pTableToken->z, pTableToken->n);
    sqliteDequote(zTab);
  }else{
    assert( zDb==0 );
    zTab = 0;
  }
  zCol = sqliteStrNDup(pColumnToken->z, pColumnToken->n);
  sqliteDequote(zCol);
  if( sqlite_malloc_failed ){
    return 1;  /* Leak memory (zDb and zTab) if malloc fails */
  }
  assert( zTab==0 || pEList==0 );

  pExpr->iTable = -1;
  for(i=0; i<pSrcList->nSrc; i++){
    struct SrcList_item *pItem = &pSrcList->a[i];
    Table *pTab = pItem->pTab;
    Column *pCol;

    if( pTab==0 ) continue;
    assert( pTab->nCol>0 );
    if( zTab ){
      if( pItem->zAlias ){
        char *zTabName = pItem->zAlias;
        if( sqliteStrICmp(zTabName, zTab)!=0 ) continue;
      }else{
        char *zTabName = pTab->zName;
        if( zTabName==0 || sqliteStrICmp(zTabName, zTab)!=0 ) continue;
        if( zDb!=0 && sqliteStrICmp(db->aDb[pTab->iDb].zName, zDb)!=0 ){
          continue;
        }
      }
    }
    if( 0==(cntTab++) ){
      pExpr->iTable = pItem->iCursor;
      pExpr->iDb = pTab->iDb;
    }
    for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
      if( sqliteStrICmp(pCol->zName, zCol)==0 ){
        cnt++;
        pExpr->iTable = pItem->iCursor;
        pExpr->iDb = pTab->iDb;
        /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
        pExpr->iColumn = j==pTab->iPKey ? -1 : j;
        pExpr->dataType = pCol->sortOrder & SQLITE_SO_TYPEMASK;
        break;
      }
    }
  }

  /* If we have not already resolved the name, then maybe 
  ** it is a new.* or old.* trigger argument reference
  */
  if( zDb==0 && zTab!=0 && cnt==0 && pParse->trigStack!=0 ){
    TriggerStack *pTriggerStack = pParse->trigStack;
    Table *pTab = 0;
    if( pTriggerStack->newIdx != -1 && sqliteStrICmp("new", zTab) == 0 ){
      pExpr->iTable = pTriggerStack->newIdx;
      assert( pTriggerStack->pTab );
      pTab = pTriggerStack->pTab;
    }else if( pTriggerStack->oldIdx != -1 && sqliteStrICmp("old", zTab) == 0 ){
      pExpr->iTable = pTriggerStack->oldIdx;
      assert( pTriggerStack->pTab );
      pTab = pTriggerStack->pTab;
    }

    if( pTab ){ 
      int j;
      Column *pCol = pTab->aCol;
      
      pExpr->iDb = pTab->iDb;
      cntTab++;
      for(j=0; j < pTab->nCol; j++, pCol++) {
        if( sqliteStrICmp(pCol->zName, zCol)==0 ){
          cnt++;
          pExpr->iColumn = j==pTab->iPKey ? -1 : j;
          pExpr->dataType = pCol->sortOrder & SQLITE_SO_TYPEMASK;
          break;
        }
      }
    }
  }

  /*
  ** Perhaps the name is a reference to the ROWID
  */
  if( cnt==0 && cntTab==1 && sqliteIsRowid(zCol) ){
    cnt = 1;
    pExpr->iColumn = -1;
    pExpr->dataType = SQLITE_SO_NUM;
  }

  /*
  ** If the input is of the form Z (not Y.Z or X.Y.Z) then the name Z
  ** might refer to an result-set alias.  This happens, for example, when
  ** we are resolving names in the WHERE clause of the following command:
  **
  **     SELECT a+b AS x FROM table WHERE x<10;
  **
  ** In cases like this, replace pExpr with a copy of the expression that
  ** forms the result set entry ("a+b" in the example) and return immediately.
  ** Note that the expression in the result set should have already been
  ** resolved by the time the WHERE clause is resolved.
  */
  if( cnt==0 && pEList!=0 ){
    for(j=0; j<pEList->nExpr; j++){
      char *zAs = pEList->a[j].zName;
      if( zAs!=0 && sqliteStrICmp(zAs, zCol)==0 ){
        assert( pExpr->pLeft==0 && pExpr->pRight==0 );
        pExpr->op = TK_AS;
        pExpr->iColumn = j;
        pExpr->pLeft = sqliteExprDup(pEList->a[j].pExpr);
        sqliteFree(zCol);
        assert( zTab==0 && zDb==0 );
        return 0;
      }
    } 
  }

  /*
  ** If X and Y are NULL (in other words if only the column name Z is
  ** supplied) and the value of Z is enclosed in double-quotes, then
  ** Z is a string literal if it doesn't match any column names.  In that
  ** case, we need to return right away and not make any changes to
  ** pExpr.
  */
  if( cnt==0 && zTab==0 && pColumnToken->z[0]=='"' ){
    sqliteFree(zCol);
    return 0;
  }

  /*
  ** cnt==0 means there was not match.  cnt>1 means there were two or
  ** more matches.  Either way, we have an error.
  */
  if( cnt!=1 ){
    char *z = 0;
    char *zErr;
    zErr = cnt==0 ? "no such column: %s" : "ambiguous column name: %s";
    if( zDb ){
      sqliteSetString(&z, zDb, ".", zTab, ".", zCol, 0);
    }else if( zTab ){
      sqliteSetString(&z, zTab, ".", zCol, 0);
    }else{
      z = sqliteStrDup(zCol);
    }
    sqliteErrorMsg(pParse, zErr, z);
    sqliteFree(z);
  }

  /* Clean up and return
  */
  sqliteFree(zDb);
  sqliteFree(zTab);
  sqliteFree(zCol);
  sqliteExprDelete(pExpr->pLeft);
  pExpr->pLeft = 0;
  sqliteExprDelete(pExpr->pRight);
  pExpr->pRight = 0;
  pExpr->op = TK_COLUMN;
  sqliteAuthRead(pParse, pExpr, pSrcList);
  return cnt!=1;
}

/*
** This routine walks an expression tree and resolves references to
** table columns.  Nodes of the form ID.ID or ID resolve into an
** index to the table in the table list and a column offset.  The 
** Expr.opcode for such nodes is changed to TK_COLUMN.  The Expr.iTable
** value is changed to the index of the referenced table in pTabList
** plus the "base" value.  The base value will ultimately become the
** VDBE cursor number for a cursor that is pointing into the referenced
** table.  The Expr.iColumn value is changed to the index of the column 
** of the referenced table.  The Expr.iColumn value for the special
** ROWID column is -1.  Any INTEGER PRIMARY KEY column is tried as an
** alias for ROWID.
**
** We also check for instances of the IN operator.  IN comes in two
** forms:
**
**           expr IN (exprlist)
** and
**           expr IN (SELECT ...)
**
** The first form is handled by creating a set holding the list
** of allowed values.  The second form causes the SELECT to generate 
** a temporary table.
**
** This routine also looks for scalar SELECTs that are part of an expression.
** If it finds any, it generates code to write the value of that select
** into a memory cell.
**
** Unknown columns or tables provoke an error.  The function returns
** the number of errors seen and leaves an error message on pParse->zErrMsg.
*/
int sqliteExprResolveIds(
  Parse *pParse,     /* The parser context */
  SrcList *pSrcList, /* List of tables used to resolve column names */
  ExprList *pEList,  /* List of expressions used to resolve "AS" */
  Expr *pExpr        /* The expression to be analyzed. */
){
  int i;

  if( pExpr==0 || pSrcList==0 ) return 0;
  for(i=0; i<pSrcList->nSrc; i++){
    assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab );
  }
  switch( pExpr->op ){
    /* Double-quoted strings (ex: "abc") are used as identifiers if
    ** possible.  Otherwise they remain as strings.  Single-quoted
    ** strings (ex: 'abc') are always string literals.
    */
    case TK_STRING: {
      if( pExpr->token.z[0]=='\'' ) break;
      /* Fall thru into the TK_ID case if this is a double-quoted string */
    }
    /* A lone identifier is the name of a columnd.
    */
    case TK_ID: {
      if( lookupName(pParse, 0, 0, &pExpr->token, pSrcList, pEList, pExpr) ){
        return 1;
      }
      break; 
    }
  
    /* 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;

      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;
      }
      if( lookupName(pParse, pDb, pTable, pColumn, pSrcList, 0, pExpr) ){
        return 1;
      }
      break;
    }

    case TK_IN: {
      Vdbe *v = sqliteGetVdbe(pParse);
      if( v==0 ) return 1;
      if( sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pLeft) ){
        return 1;
      }
      if( pExpr->pSelect ){
        /* Case 1:     expr IN (SELECT ...)
        **
        ** Generate code to write the results of the select into a temporary
        ** table.  The cursor number of the temporary table has already
        ** been put in iTable by sqliteExprResolveInSelect().
        */
        pExpr->iTable = pParse->nTab++;
        sqliteVdbeAddOp(v, OP_OpenTemp, pExpr->iTable, 1);
        sqliteSelect(pParse, pExpr->pSelect, SRT_Set, pExpr->iTable, 0,0,0);
      }else if( pExpr->pList ){
        /* Case 2:     expr IN (exprlist)
        **
        ** Create a set to put the exprlist values in.  The Set id is stored
        ** in iTable.
        */
        int i, iSet;
        for(i=0; i<pExpr->pList->nExpr; i++){
          Expr *pE2 = pExpr->pList->a[i].pExpr;
          if( !sqliteExprIsConstant(pE2) ){
            sqliteErrorMsg(pParse,
              "right-hand side of IN operator must be constant");
            return 1;
          }
          if( sqliteExprCheck(pParse, pE2, 0, 0) ){
            return 1;
          }
        }
        iSet = pExpr->iTable = pParse->nSet++;
        for(i=0; i<pExpr->pList->nExpr; i++){
          Expr *pE2 = pExpr->pList->a[i].pExpr;
          switch( pE2->op ){
            case TK_FLOAT:
            case TK_INTEGER:
            case TK_STRING: {
              int addr;
              assert( pE2->token.z );
              addr = sqliteVdbeOp3(v, OP_SetInsert, iSet, 0,
                                  pE2->token.z, pE2->token.n);
              sqliteVdbeDequoteP3(v, addr);
              break;
            }
            default: {
              sqliteExprCode(pParse, pE2);
              sqliteVdbeAddOp(v, OP_SetInsert, iSet, 0);
              break;
            }
          }
        }
      }
      break;
    }

    case TK_SELECT: {
      /* This has to be a scalar SELECT.  Generate code to put the
      ** value of this select in a memory cell and record the number
      ** of the memory cell in iColumn.
      */
      pExpr->iColumn = pParse->nMem++;
      if( sqliteSelect(pParse, pExpr->pSelect, SRT_Mem, pExpr->iColumn,0,0,0) ){
        return 1;
      }
      break;
    }

    /* For all else, just recursively walk the tree */
    default: {
      if( pExpr->pLeft
      && sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pLeft) ){
        return 1;
      }
      if( pExpr->pRight 
      && sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pRight) ){
        return 1;
      }
      if( pExpr->pList ){
        int i;
        ExprList *pList = pExpr->pList;
        for(i=0; i<pList->nExpr; i++){
          Expr *pArg = pList->a[i].pExpr;
          if( sqliteExprResolveIds(pParse, pSrcList, pEList, pArg) ){
            return 1;
          }
        }
      }
    }
  }
  return 0;
}

/*
** pExpr is a node that defines a function of some kind.  It might
** be a syntactic function like "count(x)" or it might be a function
** that implements an operator, like "a LIKE b".  
**
** This routine makes *pzName point to the name of the function and 
** *pnName hold the number of characters in the function name.
*/
static void getFunctionName(Expr *pExpr, const char **pzName, int *pnName){
  switch( pExpr->op ){
    case TK_FUNCTION: {
      *pzName = pExpr->token.z;
      *pnName = pExpr->token.n;
      break;
    }
    case TK_LIKE: {
      *pzName = "like";
      *pnName = 4;
      break;
    }
    case TK_GLOB: {
      *pzName = "glob";
      *pnName = 4;
      break;
    }
    default: {
      *pzName = "can't happen";
      *pnName = 12;
      break;
    }
  }
}

/*
** Error check the functions in an expression.  Make sure all
** function names are recognized and all functions have the correct
** number of arguments.  Leave an error message in pParse->zErrMsg
** if anything is amiss.  Return the number of errors.
**
** if pIsAgg is not null and this expression is an aggregate function
** (like count(*) or max(value)) then write a 1 into *pIsAgg.
*/
int sqliteExprCheck(Parse *pParse, Expr *pExpr, int allowAgg, int *pIsAgg){
  int nErr = 0;
  if( pExpr==0 ) return 0;
  switch( pExpr->op ){
    case TK_GLOB:
    case TK_LIKE:
    case TK_FUNCTION: {
      int n = pExpr->pList ? pExpr->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 */