expr.c

一个小型的嵌入式数据库

    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 || sqlite3_malloc_failed );
    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];
    pNewItem->zDatabase = sqliteStrDup(pOldItem->zDatabase);
    pNewItem->zName = sqliteStrDup(pOldItem->zName);
    pNewItem->zAlias = sqliteStrDup(pOldItem->zAlias);
    pNewItem->jointype = pOldItem->jointype;
    pNewItem->iCursor = pOldItem->iCursor;
    pNewItem->pTab = pOldItem->pTab;
    if( pNewItem->pTab ){
      pNewItem->pTab->isTransient = 0;
    }
    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 ) 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->ppOpenTemp = 0;
  pNew->pFetch = 0;
  pNew->isResolved = p->isResolved;
  pNew->isAgg = p->isAgg;
  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 ){
      /* sqlite3ExprDelete(pExpr); // Leak memory if malloc fails */
      return 0;
    }
    assert( pList->nAlloc==0 );
  }
  if( pList->nAlloc<=pList->nExpr ){
    pList->nAlloc = pList->nAlloc*2 + 4;
    pList->a = sqliteRealloc(pList->a, pList->nAlloc*sizeof(pList->a[0]));
    if( pList->a==0 ){
      /* sqlite3ExprDelete(pExpr); // Leak memory if malloc fails */
      pList->nExpr = pList->nAlloc = 0;
      return pList;
    }
  }
  assert( pList->a!=0 );
  if( pExpr || pName ){
    struct ExprList_item *pItem = &pList->a[pList->nExpr++];
    memset(pItem, 0, sizeof(*pItem));
    pItem->pExpr = pExpr;
    pItem->zName = sqlite3NameFromToken(pName);
  }
  return pList;
}

/*
** 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.
*/
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);
  return 0;
}


/*
** This routine is designed as an xFunc for walkExprTree().
**
** pArg is really a pointer to an integer.  If we can tell by looking
** at pExpr that the expression that contains pExpr is not a constant
** expression, then set *pArg to 0 and return 2 to abandon the tree walk.
** If pExpr does does not disqualify the expression from being a constant
** then do nothing.
**
** After walking the whole tree, if no nodes are found that disqualify
** the expression as constant, then we assume the whole expression
** is constant.  See sqlite3ExprIsConstant() for additional information.
*/
static int exprNodeIsConstant(void *pArg, Expr *pExpr){
  switch( pExpr->op ){
    case TK_ID:
    case TK_COLUMN:
    case TK_DOT:
    case TK_AGG_FUNCTION:
    case TK_FUNCTION:
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_SELECT:
    case TK_EXISTS:
#endif
      *((int*)pArg) = 0;
      return 2;
    default:
      return 0;
  }
}

/*
** Walk an expression tree.  Return 1 if the expression is constant
** and 0 if it involves variables.
**
** For the purposes of this function, a double-quoted string (ex: "abc")
** is considered a variable but a single-quoted string (ex: 'abc') is
** a constant.
*/
int sqlite3ExprIsConstant(Expr *p){
  int isConst = 1;
  walkExprTree(p, exprNodeIsConstant, &isConst);
  return isConst;
}

/*
** If the expression p codes a constant integer that is small enough
** to fit in a 32-bit integer, return 1 and put the value of the integer
** in *pValue.  If the expression is not an integer or if it is too big
** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.
*/
int sqlite3ExprIsInteger(Expr *p, int *pValue){
  switch( p->op ){
    case TK_INTEGER: {
      if( sqlite3GetInt32(p->token.z, pValue) ){
        return 1;
      }
      break;
    }
    case TK_UPLUS: {
      return sqlite3ExprIsInteger(p->pLeft, pValue);
    }
    case TK_UMINUS: {
      int v;
      if( sqlite3ExprIsInteger(p->pLeft, &v) ){
        *pValue = -v;
        return 1;
      }
      break;
    }
    default: break;
  }
  return 0;
}

/*
** Return TRUE if the given string is a row-id column name.
*/
int sqlite3IsRowid(const char *z){
  if( sqlite3StrICmp(z, "_ROWID_")==0 ) return 1;
  if( sqlite3StrICmp(z, "ROWID")==0 ) return 1;
  if( sqlite3StrICmp(z, "OID")==0 ) return 1;
  return 0;
}

/*
** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
** that name in the set of source tables in pSrcList and make the pExpr 
** expression node refer back to that source column.  The following changes
** are made to pExpr:
**
**    pExpr->iDb           Set the index in db->aDb[] of the database holding
**                         the table.
**    pExpr->iTable        Set to the cursor number for the table obtained
**                         from pSrcList.
**    pExpr->iColumn       Set to the column number within the table.
**    pExpr->op            Set to TK_COLUMN.
**    pExpr->pLeft         Any expression this points to is deleted
**    pExpr->pRight        Any expression this points to is deleted.
**
** The pDbToken is the name of the database (the "X").  This value may be
** NULL meaning that name is of the form Y.Z or Z.  Any available database
** can be used.  The pTableToken is the name of the table (the "Y").  This
** value can be NULL if pDbToken is also NULL.  If pTableToken is NULL it
** means that the form of the name is Z and that columns from any table
** can be used.
**
** If the name cannot be resolved unambiguously, leave an error message
** in pParse and return non-zero.  Return zero on success.
*/
static int lookupName(
  Parse *pParse,      /* The parsing context */
  Token *pDbToken,     /* Name of the database containing table, or NULL */
  Token *pTableToken,  /* Name of table containing column, or NULL */
  Token *pColumnToken, /* Name of the column. */
  NameContext *pNC,    /* The name context used to resolve the name */
  Expr *pExpr          /* Make this EXPR node point to the selected column */
){
  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 */
  sqlite3 *db = pParse->db;  /* The database */
  struct SrcList_item *pItem;       /* Use for looping over pSrcList items */
  struct SrcList_item *pMatch = 0;  /* The matching pSrcList item */
  NameContext *pTopNC = pNC;        /* First namecontext in the list */

  assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */
  zDb = sqlite3NameFromToken(pDbToken);
  zTab = sqlite3NameFromToken(pTableToken);
  zCol = sqlite3NameFromToken(pColumnToken);
  if( sqlite3_malloc_failed ){
    return 1;  /* Leak memory (zDb and zTab) if malloc fails */
  }

  pExpr->iTable = -1;
  while( pNC && cnt==0 ){
    SrcList *pSrcList = pNC->pSrcList;
    ExprList *pEList = pNC->pEList;

    pNC->nRef++;
    /* assert( zTab==0 || pEList==0 ); */
    if( pSrcList ){
      for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
        Table *pTab = pItem->pTab;
        Column *pCol;
  
        if( pTab==0 ) continue;
        assert( pTab->nCol>0 );
        if( zTab ){
          if( pItem->zAlias ){
            char *zTabName = pItem->zAlias;
            if( sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
          }else{
            char *zTabName = pTab->zName;
            if( zTabName==0 || sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
            if( zDb!=0 && sqlite3StrICmp(db->aDb[pTab->iDb].zName, zDb)!=0 ){
              continue;
            }
          }
        }
        if( 0==(cntTab++) ){
          pExpr->iTable = pItem->iCursor;
          pExpr->iDb = pTab->iDb;
          pMatch = pItem;
        }
        for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
          if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
            cnt++;
            pExpr->iTable = pItem->iCursor;
            pMatch = pItem;
            pExpr->iDb = pTab->iDb;
            /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
            pExpr->iColumn = j==pTab->iPKey ? -1 : j;
            pExpr->affinity = pTab->aCol[j].affinity;
            pExpr->pColl = pTab->aCol[j].pColl;
            break;
          }
        }
      }
    }

#ifndef SQLITE_OMIT_TRIGGER
    /* 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 && sqlite3StrICmp("new", zTab) == 0 ){