expr.c

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

      pExpr->iTable = ++pParse->nVar;
      if( pParse->nVarExpr>=pParse->nVarExprAlloc-1 ){
        pParse->nVarExprAlloc += pParse->nVarExprAlloc + 10;
        pParse->apVarExpr = sqliteReallocOrFree(pParse->apVarExpr,
                       pParse->nVarExprAlloc*sizeof(pParse->apVarExpr[0]) );
      }
      if( !sqlite3MallocFailed() ){
        assert( pParse->apVarExpr!=0 );
        pParse->apVarExpr[pParse->nVarExpr++] = pExpr;
      }
    }
  } 
  if( !pParse->nErr && pParse->nVar>SQLITE_MAX_VARIABLE_NUMBER ){
    sqlite3ErrorMsg(pParse, "too many SQL variables");
  }
}

/*
** Recursively delete an expression tree.
*/
void sqlite3ExprDelete(Expr *p){
  if( p==0 ) return;
  if( p->span.dyn ) sqliteFree((char*)p->span.z);
  if( p->token.dyn ) sqliteFree((char*)p->token.z);
  sqlite3ExprDelete(p->pLeft);
  sqlite3ExprDelete(p->pRight);
  sqlite3ExprListDelete(p->pList);
  sqlite3SelectDelete(p->pSelect);
  sqliteFree(p);
}

/*
** The Expr.token field might be a string literal that is quoted.
** If so, remove the quotation marks.
*/
void sqlite3DequoteExpr(Expr *p){
  if( ExprHasAnyProperty(p, EP_Dequoted) ){
    return;
  }
  ExprSetProperty(p, EP_Dequoted);
  if( p->token.dyn==0 ){
    sqlite3TokenCopy(&p->token, &p->token);
  }
  sqlite3Dequote((char*)p->token.z);
}


/*
** The following group of routines make deep copies of expressions,
** expression lists, ID lists, and select statements.  The copies can
** be deleted (by being passed to their respective ...Delete() routines)
** without effecting the originals.
**
** The expression list, ID, and source lists return by sqlite3ExprListDup(),
** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded 
** by subsequent calls to sqlite*ListAppend() routines.
**
** Any tables that the SrcList might point to are not duplicated.
*/
Expr *sqlite3ExprDup(Expr *p){
  Expr *pNew;
  if( p==0 ) return 0;
  pNew = sqliteMallocRaw( sizeof(*p) );
  if( pNew==0 ) return 0;
  memcpy(pNew, p, sizeof(*pNew));
  if( p->token.z!=0 ){
    pNew->token.z = (u8*)sqliteStrNDup((char*)p->token.z, p->token.n);
    pNew->token.dyn = 1;
  }else{
    assert( pNew->token.z==0 );
  }
  pNew->span.z = 0;
  pNew->pLeft = sqlite3ExprDup(p->pLeft);
  pNew->pRight = sqlite3ExprDup(p->pRight);
  pNew->pList = sqlite3ExprListDup(p->pList);
  pNew->pSelect = sqlite3SelectDup(p->pSelect);
  return pNew;
}
void sqlite3TokenCopy(Token *pTo, Token *pFrom){
  if( pTo->dyn ) sqliteFree((char*)pTo->z);
  if( pFrom->z ){
    pTo->n = pFrom->n;
    pTo->z = (u8*)sqliteStrNDup((char*)pFrom->z, pFrom->n);
    pTo->dyn = 1;
  }else{
    pTo->z = 0;
  }
}
ExprList *sqlite3ExprListDup(ExprList *p){
  ExprList *pNew;
  struct ExprList_item *pItem, *pOldItem;
  int i;
  if( p==0 ) return 0;
  pNew = sqliteMalloc( sizeof(*pNew) );
  if( pNew==0 ) return 0;
  pNew->nExpr = pNew->nAlloc = p->nExpr;
  pNew->a = pItem = sqliteMalloc( p->nExpr*sizeof(p->a[0]) );
  if( pItem==0 ){
    sqliteFree(pNew);
    return 0;
  } 
  pOldItem = p->a;
  for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){
    Expr *pNewExpr, *pOldExpr;
    pItem->pExpr = pNewExpr = sqlite3ExprDup(pOldExpr = pOldItem->pExpr);
    if( pOldExpr->span.z!=0 && pNewExpr ){
      /* Always make a copy of the span for top-level expressions in the
      ** expression list.  The logic in SELECT processing that determines
      ** the names of columns in the result set needs this information */
      sqlite3TokenCopy(&pNewExpr->span, &pOldExpr->span);
    }
    assert( pNewExpr==0 || pNewExpr->span.z!=0 
            || pOldExpr->span.z==0
            || sqlite3MallocFailed() );
    pItem->zName = sqliteStrDup(pOldItem->zName);
    pItem->sortOrder = pOldItem->sortOrder;
    pItem->isAgg = pOldItem->isAgg;
    pItem->done = 0;
  }
  return pNew;
}

/*
** If cursors, triggers, views and subqueries are all omitted from
** the build, then none of the following routines, except for 
** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes
** called with a NULL argument.
*/
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \
 || !defined(SQLITE_OMIT_SUBQUERY)
SrcList *sqlite3SrcListDup(SrcList *p){
  SrcList *pNew;
  int i;
  int nByte;
  if( p==0 ) return 0;
  nByte = sizeof(*p) + (p->nSrc>0 ? sizeof(p->a[0]) * (p->nSrc-1) : 0);
  pNew = sqliteMallocRaw( nByte );
  if( pNew==0 ) return 0;
  pNew->nSrc = pNew->nAlloc = p->nSrc;
  for(i=0; i<p->nSrc; i++){
    struct SrcList_item *pNewItem = &pNew->a[i];
    struct SrcList_item *pOldItem = &p->a[i];
    Table *pTab;
    pNewItem->zDatabase = sqliteStrDup(pOldItem->zDatabase);
    pNewItem->zName = sqliteStrDup(pOldItem->zName);
    pNewItem->zAlias = sqliteStrDup(pOldItem->zAlias);
    pNewItem->jointype = pOldItem->jointype;
    pNewItem->iCursor = pOldItem->iCursor;
    pNewItem->isPopulated = pOldItem->isPopulated;
    pTab = pNewItem->pTab = pOldItem->pTab;
    if( pTab ){
      pTab->nRef++;
    }
    pNewItem->pSelect = sqlite3SelectDup(pOldItem->pSelect);
    pNewItem->pOn = sqlite3ExprDup(pOldItem->pOn);
    pNewItem->pUsing = sqlite3IdListDup(pOldItem->pUsing);
    pNewItem->colUsed = pOldItem->colUsed;
  }
  return pNew;
}
IdList *sqlite3IdListDup(IdList *p){
  IdList *pNew;
  int i;
  if( p==0 ) return 0;
  pNew = sqliteMallocRaw( sizeof(*pNew) );
  if( pNew==0 ) return 0;
  pNew->nId = pNew->nAlloc = p->nId;
  pNew->a = sqliteMallocRaw( p->nId*sizeof(p->a[0]) );
  if( pNew->a==0 ){
    sqliteFree(pNew);
    return 0;
  }
  for(i=0; i<p->nId; i++){
    struct IdList_item *pNewItem = &pNew->a[i];
    struct IdList_item *pOldItem = &p->a[i];
    pNewItem->zName = sqliteStrDup(pOldItem->zName);
    pNewItem->idx = pOldItem->idx;
  }
  return pNew;
}
Select *sqlite3SelectDup(Select *p){
  Select *pNew;
  if( p==0 ) return 0;
  pNew = sqliteMallocRaw( sizeof(*p) );
  if( pNew==0 ) return 0;
  pNew->isDistinct = p->isDistinct;
  pNew->pEList = sqlite3ExprListDup(p->pEList);
  pNew->pSrc = sqlite3SrcListDup(p->pSrc);
  pNew->pWhere = sqlite3ExprDup(p->pWhere);
  pNew->pGroupBy = sqlite3ExprListDup(p->pGroupBy);
  pNew->pHaving = sqlite3ExprDup(p->pHaving);
  pNew->pOrderBy = sqlite3ExprListDup(p->pOrderBy);
  pNew->op = p->op;
  pNew->pPrior = sqlite3SelectDup(p->pPrior);
  pNew->pLimit = sqlite3ExprDup(p->pLimit);
  pNew->pOffset = sqlite3ExprDup(p->pOffset);
  pNew->iLimit = -1;
  pNew->iOffset = -1;
  pNew->isResolved = p->isResolved;
  pNew->isAgg = p->isAgg;
  pNew->usesEphm = 0;
  pNew->disallowOrderBy = 0;
  pNew->pRightmost = 0;
  pNew->addrOpenEphm[0] = -1;
  pNew->addrOpenEphm[1] = -1;
  pNew->addrOpenEphm[2] = -1;
  return pNew;
}
#else
Select *sqlite3SelectDup(Select *p){
  assert( p==0 );
  return 0;
}
#endif


/*
** Add a new element to the end of an expression list.  If pList is
** initially NULL, then create a new expression list.
*/
ExprList *sqlite3ExprListAppend(ExprList *pList, Expr *pExpr, Token *pName){
  if( pList==0 ){
    pList = sqliteMalloc( sizeof(ExprList) );
    if( pList==0 ){
      goto no_mem;
    }
    assert( pList->nAlloc==0 );
  }
  if( pList->nAlloc<=pList->nExpr ){
    struct ExprList_item *a;
    int n = pList->nAlloc*2 + 4;
    a = sqliteRealloc(pList->a, n*sizeof(pList->a[0]));
    if( a==0 ){
      goto no_mem;
    }
    pList->a = a;
    pList->nAlloc = n;
  }
  assert( pList->a!=0 );
  if( pExpr || pName ){
    struct ExprList_item *pItem = &pList->a[pList->nExpr++];
    memset(pItem, 0, sizeof(*pItem));
    pItem->zName = sqlite3NameFromToken(pName);
    pItem->pExpr = pExpr;
  }
  return pList;

no_mem:     
  /* Avoid leaking memory if malloc has failed. */
  sqlite3ExprDelete(pExpr);
  sqlite3ExprListDelete(pList);
  return 0;
}

/*
** If the expression list pEList contains more than iLimit elements,
** leave an error message in pParse.
*/
void sqlite3ExprListCheckLength(
  Parse *pParse,
  ExprList *pEList,
  int iLimit,
  const char *zObject
){
  if( pEList && pEList->nExpr>iLimit ){
    sqlite3ErrorMsg(pParse, "too many columns in %s", zObject);
  }
}


#if SQLITE_MAX_EXPR_DEPTH>0
/* The following three functions, heightOfExpr(), heightOfExprList()
** and heightOfSelect(), are used to determine the maximum height
** of any expression tree referenced by the structure passed as the
** first argument.
**
** If this maximum height is greater than the current value pointed
** to by pnHeight, the second parameter, then set *pnHeight to that
** value.
*/
static void heightOfExpr(Expr *p, int *pnHeight){
  if( p ){
    if( p->nHeight>*pnHeight ){
      *pnHeight = p->nHeight;
    }
  }
}
static void heightOfExprList(ExprList *p, int *pnHeight){
  if( p ){
    int i;
    for(i=0; i<p->nExpr; i++){
      heightOfExpr(p->a[i].pExpr, pnHeight);
    }
  }
}
static void heightOfSelect(Select *p, int *pnHeight){
  if( p ){
    heightOfExpr(p->pWhere, pnHeight);
    heightOfExpr(p->pHaving, pnHeight);
    heightOfExpr(p->pLimit, pnHeight);
    heightOfExpr(p->pOffset, pnHeight);
    heightOfExprList(p->pEList, pnHeight);
    heightOfExprList(p->pGroupBy, pnHeight);
    heightOfExprList(p->pOrderBy, pnHeight);
    heightOfSelect(p->pPrior, pnHeight);
  }
}

/*
** Set the Expr.nHeight variable in the structure passed as an 
** argument. An expression with no children, Expr.pList or 
** Expr.pSelect member has a height of 1. Any other expression
** has a height equal to the maximum height of any other 
** referenced Expr plus one.
*/
void sqlite3ExprSetHeight(Expr *p){
  int nHeight = 0;
  heightOfExpr(p->pLeft, &nHeight);
  heightOfExpr(p->pRight, &nHeight);
  heightOfExprList(p->pList, &nHeight);
  heightOfSelect(p->pSelect, &nHeight);
  p->nHeight = nHeight + 1;
}

/*
** Return the maximum height of any expression tree referenced
** by the select statement passed as an argument.
*/
int sqlite3SelectExprHeight(Select *p){
  int nHeight = 0;
  heightOfSelect(p, &nHeight);
  return nHeight;
}
#endif

/*
** Delete an entire expression list.
*/
void sqlite3ExprListDelete(ExprList *pList){
  int i;
  struct ExprList_item *pItem;
  if( pList==0 ) return;
  assert( pList->a!=0 || (pList->nExpr==0 && pList->nAlloc==0) );
  assert( pList->nExpr<=pList->nAlloc );
  for(pItem=pList->a, i=0; i<pList->nExpr; i++, pItem++){
    sqlite3ExprDelete(pItem->pExpr);
    sqliteFree(pItem->zName);
  }
  sqliteFree(pList->a);
  sqliteFree(pList);
}

/*
** Walk an expression tree.  Call xFunc for each node visited.
**
** The return value from xFunc determines whether the tree walk continues.
** 0 means continue walking the tree.  1 means do not walk children
** of the current node but continue with siblings.  2 means abandon
** the tree walk completely.
**
** The return value from this routine is 1 to abandon the tree walk
** and 0 to continue.
**
** NOTICE:  This routine does *not* descend into subqueries.
*/
static int walkExprList(ExprList *, int (*)(void *, Expr*), void *);
static int walkExprTree(Expr *pExpr, int (*xFunc)(void*,Expr*), void *pArg){
  int rc;
  if( pExpr==0 ) return 0;
  rc = (*xFunc)(pArg, pExpr);
  if( rc==0 ){
    if( walkExprTree(pExpr->pLeft, xFunc, pArg) ) return 1;
    if( walkExprTree(pExpr->pRight, xFunc, pArg) ) return 1;
    if( walkExprList(pExpr->pList, xFunc, pArg) ) return 1;
  }
  return rc>1;
}

/*
** Call walkExprTree() for every expression in list p.
*/
static int walkExprList(ExprList *p, int (*xFunc)(void *, Expr*), void *pArg){
  int i;
  struct ExprList_item *pItem;
  if( !p ) return 0;
  for(i=p->nExpr, pItem=p->a; i>0; i--, pItem++){
    if( walkExprTree(pItem->pExpr, xFunc, pArg) ) return 1;
  }
  return 0;
}

/*
** Call walkExprTree() for every expression in Select p, not including
** expressions that are part of sub-selects in any FROM clause or the LIMIT
** or OFFSET expressions..
*/
static int walkSelectExpr(Select *p, int (*xFunc)(void *, Expr*), void *pArg){
  walkExprList(p->pEList, xFunc, pArg);
  walkExprTree(p->pWhere, xFunc, pArg);
  walkExprList(p->pGroupBy, xFunc, pArg);
  walkExprTree(p->pHaving, xFunc, pArg);
  walkExprList(p->pOrderBy, xFunc, pArg);
  if( p->pPrior ){
    walkSelectExpr(p->pPrior, xFunc, pArg);
  }
  return 0;
}


/*
** This routine is designed as an xFunc for walkExprTree().
**