printf.c

这是一个开源的数据库系统,值得学习啊, 里面用了SQL语句,与微软的SQL SERVIER,差不了多少

        if( bufpt==0 ){
          bufpt = "";
        }else if( xtype==etDYNSTRING ){
          zExtra = bufpt;
        }
        length = strlen(bufpt);
        if( precision>=0 && precision<length ) length = precision;
        break;
      case etSQLESCAPE:
      case etSQLESCAPE2:
      case etSQLESCAPE3: {
        int i, j, n, ch, isnull;
        int needQuote;
        char q = ((xtype==etSQLESCAPE3)?'"':'\'');   /* Quote character */
        char *escarg = va_arg(ap,char*);
        isnull = escarg==0;
        if( isnull ) escarg = (xtype==etSQLESCAPE2 ? "NULL" : "(NULL)");
        for(i=n=0; (ch=escarg[i])!=0; i++){
          if( ch==q )  n++;
        }
        needQuote = !isnull && xtype==etSQLESCAPE2;
        n += i + 1 + needQuote*2;
        if( n>etBUFSIZE ){
          bufpt = zExtra = sqlite3_malloc( n );
          if( bufpt==0 ) return -1;
        }else{
          bufpt = buf;
        }
        j = 0;
        if( needQuote ) bufpt[j++] = q;
        for(i=0; (ch=escarg[i])!=0; i++){
          bufpt[j++] = ch;
          if( ch==q ) bufpt[j++] = ch;
        }
        if( needQuote ) bufpt[j++] = q;
        bufpt[j] = 0;
        length = j;
        /* The precision is ignored on %q and %Q */
        /* if( precision>=0 && precision<length ) length = precision; */
        break;
      }
      case etTOKEN: {
        Token *pToken = va_arg(ap, Token*);
        if( pToken && pToken->z ){
          (*func)(arg, (char*)pToken->z, pToken->n);
        }
        length = width = 0;
        break;
      }
      case etSRCLIST: {
        SrcList *pSrc = va_arg(ap, SrcList*);
        int k = va_arg(ap, int);
        struct SrcList_item *pItem = &pSrc->a[k];
        assert( k>=0 && k<pSrc->nSrc );
        if( pItem->zDatabase && pItem->zDatabase[0] ){
          (*func)(arg, pItem->zDatabase, strlen(pItem->zDatabase));
          (*func)(arg, ".", 1);
        }
        (*func)(arg, pItem->zName, strlen(pItem->zName));
        length = width = 0;
        break;
      }
    }/* End switch over the format type */
    /*
    ** The text of the conversion is pointed to by "bufpt" and is
    ** "length" characters long.  The field width is "width".  Do
    ** the output.
    */
    if( !flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        count += nspace;
        while( nspace>=etSPACESIZE ){
          (*func)(arg,spaces,etSPACESIZE);
          nspace -= etSPACESIZE;
        }
        if( nspace>0 ) (*func)(arg,spaces,nspace);
      }
    }
    if( length>0 ){
      (*func)(arg,bufpt,length);
      count += length;
    }
    if( flag_leftjustify ){
      register int nspace;
      nspace = width-length;
      if( nspace>0 ){
        count += nspace;
        while( nspace>=etSPACESIZE ){
          (*func)(arg,spaces,etSPACESIZE);
          nspace -= etSPACESIZE;
        }
        if( nspace>0 ) (*func)(arg,spaces,nspace);
      }
    }
    if( zExtra ){
      sqlite3_free(zExtra);
    }
  }/* End for loop over the format string */
  return errorflag ? -1 : count;
} /* End of function */


/* This structure is used to store state information about the
** write to memory that is currently in progress.
*/
struct sgMprintf {
  char *zBase;     /* A base allocation */
  char *zText;     /* The string collected so far */
  int  nChar;      /* Length of the string so far */
  int  nTotal;     /* Output size if unconstrained */
  int  nAlloc;     /* Amount of space allocated in zText */
  void *(*xRealloc)(void*,int);  /* Function used to realloc memory */
  int  iMallocFailed;            /* True if xRealloc() has failed */
};

/* 
** This function implements the callback from vxprintf. 
**
** This routine add nNewChar characters of text in zNewText to
** the sgMprintf structure pointed to by "arg".
*/
static void mout(void *arg, const char *zNewText, int nNewChar){
  struct sgMprintf *pM = (struct sgMprintf*)arg;
  if( pM->iMallocFailed ) return;
  pM->nTotal += nNewChar;
  if( pM->zText ){
    if( pM->nChar + nNewChar + 1 > pM->nAlloc ){
      if( pM->xRealloc==0 ){
        nNewChar =  pM->nAlloc - pM->nChar - 1;
      }else{
        int nAlloc = pM->nChar + nNewChar*2 + 1;
        if( pM->zText==pM->zBase ){
          pM->zText = pM->xRealloc(0, nAlloc);
          if( pM->zText==0 ){
            pM->nAlloc = 0;
            pM->iMallocFailed = 1;
            return;
          }else if( pM->nChar ){
            memcpy(pM->zText, pM->zBase, pM->nChar);
          }
        }else{
          char *zNew;
          zNew = pM->xRealloc(pM->zText, nAlloc);
          if( zNew ){
            pM->zText = zNew;
          }else{
            pM->iMallocFailed = 1;
            pM->xRealloc(pM->zText, 0);
            pM->zText = 0;
            pM->nAlloc = 0;
            return;
          }
        }
        pM->nAlloc = nAlloc;
      }
    }
    if( nNewChar>0 ){
      memcpy(&pM->zText[pM->nChar], zNewText, nNewChar);
      pM->nChar += nNewChar;
    }
    pM->zText[pM->nChar] = 0;
  }
}

/*
** This routine is a wrapper around xprintf() that invokes mout() as
** the consumer.  
*/
static char *base_vprintf(
  void *(*xRealloc)(void*, int),  /* realloc() function. May be NULL */
  int useInternal,                /* Use internal %-conversions if true */
  char *zInitBuf,                 /* Initially write here, before mallocing */
  int nInitBuf,                   /* Size of zInitBuf[] */
  const char *zFormat,            /* format string */
  va_list ap                      /* arguments */
){
  struct sgMprintf sM;
  sM.zBase = sM.zText = zInitBuf;
  sM.nChar = sM.nTotal = 0;
  sM.nAlloc = nInitBuf;
  sM.xRealloc = xRealloc;
  sM.iMallocFailed = 0;
  vxprintf(mout, &sM, useInternal, zFormat, ap);
  assert(sM.iMallocFailed==0 || sM.zText==0);
  if( xRealloc && !sM.iMallocFailed ){
    if( sM.zText==sM.zBase ){
      sM.zText = xRealloc(0, sM.nChar+1);
      if( sM.zText ){
        memcpy(sM.zText, sM.zBase, sM.nChar+1);
      }
    }else if( sM.nAlloc>sM.nChar+10 ){
      char *zNew;
      sqlite3MallocBenignFailure(1);
      zNew = xRealloc(sM.zText, sM.nChar+1);
      if( zNew ){
        sM.zText = zNew;
      }
    }
  }
  return sM.zText;
}

/*
** Realloc that is a real function, not a macro.
*/
static void *printf_realloc(void *old, int size){
  return sqlite3_realloc(old, size);
}

/*
** Print into memory obtained from sqliteMalloc().  Use the internal
** %-conversion extensions.
*/
char *sqlite3VMPrintf(sqlite3 *db, const char *zFormat, va_list ap){
  char *z;
  char zBase[SQLITE_PRINT_BUF_SIZE];
  z = base_vprintf(printf_realloc, 1, zBase, sizeof(zBase), zFormat, ap);
  if( z==0 && db!=0 ){
    db->mallocFailed = 1;
  }
  return z;
}

/*
** Print into memory obtained from sqliteMalloc().  Use the internal
** %-conversion extensions.
*/
char *sqlite3MPrintf(sqlite3 *db, const char *zFormat, ...){
  va_list ap;
  char *z;
  char zBase[SQLITE_PRINT_BUF_SIZE];
  va_start(ap, zFormat);
  z = base_vprintf(printf_realloc, 1, zBase, sizeof(zBase), zFormat, ap);
  va_end(ap);
  if( z==0 && db!=0 ){
    db->mallocFailed = 1;
  }
  return z;
}

/*
** Print into memory obtained from sqlite3_malloc().  Omit the internal
** %-conversion extensions.
*/
char *sqlite3_vmprintf(const char *zFormat, va_list ap){
  char zBase[SQLITE_PRINT_BUF_SIZE];
  return base_vprintf(sqlite3_realloc, 0, zBase, sizeof(zBase), zFormat, ap);
}

/*
** Print into memory obtained from sqlite3_malloc()().  Omit the internal
** %-conversion extensions.
*/
char *sqlite3_mprintf(const char *zFormat, ...){
  va_list ap;
  char *z;
  va_start(ap, zFormat);
  z = sqlite3_vmprintf(zFormat, ap);
  va_end(ap);
  return z;
}

/*
** sqlite3_snprintf() works like snprintf() except that it ignores the
** current locale settings.  This is important for SQLite because we
** are not able to use a "," as the decimal point in place of "." as
** specified by some locales.
*/
char *sqlite3_snprintf(int n, char *zBuf, const char *zFormat, ...){
  char *z;
  va_list ap;

  if( n<=0 ){
    return zBuf;
  }
  zBuf[0] = 0;
  va_start(ap,zFormat);
  z = base_vprintf(0, 0, zBuf, n, zFormat, ap);
  va_end(ap);
  return z;
}

#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG) || defined(SQLITE_MEMDEBUG)
/*
** A version of printf() that understands %lld.  Used for debugging.
** The printf() built into some versions of windows does not understand %lld
** and segfaults if you give it a long long int.
*/
void sqlite3DebugPrintf(const char *zFormat, ...){
  extern int getpid(void);
  va_list ap;
  char zBuf[500];
  va_start(ap, zFormat);
  base_vprintf(0, 0, zBuf, sizeof(zBuf), zFormat, ap);
  va_end(ap);
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
}
#endif