ssfstbuf.cpp

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C++ 代码 · 共 103 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
*    Public License version 1.0 (the 'License'). You may not use this file
*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
*    provided with the Original Code and Modifications, and is also
*    available at www.sybase.com/developer/opensource.
*
*    The Original Code and all software distributed under the License are
*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
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* Description:
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****************************************************************************/

#ifdef __SW_FH
#include "iost.h"
#else
#include "variety.h"
#include <string.h>
#include <strstrea>
#endif
#include "ioutil.h"

namespace std {

  // Initialize a strstreambuf. If "ptr" is NULL, then leave the
  // streambuf as a dynamic strstreambuf with no pre-allocated buffer.
  // Otherwise, create a static (non-dynamic) streambuf using the
  // specified area.
  //
  // If size > 0, it is the size of the streambuf area.
  // If size = 0, "ptr" points to a C-string whose length determines the size
  //              of the streambuf area.
  // If size < 0, "ptr" points to an "unlimited" streambuf area. (!)
  // If pstart = NULL, this is an input-only streambuf.
  //
  // Otherwise, it partitions the ptr/size area into a get area (from
  // ptr to pstart-1), and a put area (from pstart to ptr+size-1).

  void strstreambuf::__strstreambuf( char *ptr, int size, char *pstart ) {
    char *get;
    char *eget;
    char *put;
    char *eput;

    __lock_it( __b_lock );
    __dynamic         = 0;
    __unlimited       = 0;
    __frozen          = 0;
    __alloc_fn        = NULL;
    __free_fn         = NULL;
    __allocation_size = 32;
    __minbuf_size     = 0;
    if( ptr == NULL ) {                     // no buffer to set up?
        __dynamic = 1;
        return;
    }
    get = ptr;
    if( size > 0 ) {
        eget = get + size;
    } else if( size == 0 ) {
        eget = get + ::strlen( get );       // use up NULLCHAR, too!
    } else {
        __unlimited = 1;
        eget = get + DEFAULT_MAINBUF_SIZE;
    }
    setb( get, eget, FALSE );
    if( (pstart == NULL)
      ||(pstart < get)
      ||( (pstart >= eget) && (!__unlimited) ) ) {
        pstart = NULL;
        put  = NULL;
        eput = NULL;
    } else {
        put  = get;
        eput = eget;
    }
    setg( get, get, eget );
    setp( put, eput );
    if( pstart > put ) {
        pbump( pstart - put );
    }
  }

}