joinstr.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 88 行

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*
*                            Open Watcom Project
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*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
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*    This file contains Original Code and/or Modifications of Original
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// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
// %     Copyright (C) 1992, by WATCOM International Inc.  All rights    %
// %     reserved.  No part of this software may be reproduced or        %
// %     used in any form or by any means - graphic, electronic or       %
// %     mechanical, including photocopying, recording, taping or        %
// %     information storage and retrieval systems - except with the     %
// %     written permission of WATCOM International Inc.                 %
// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//
//  Modified    By              Reason
//  ========    ==              ======
//  92/01/09    Steve McDowell  Initial simple implementation using C library
//                              string functions wherever possible.
//  92/01/20    ...             Added checking for invalid Strings, including
//                              adding the ! operator, the == and !=
//                              operators with integer arguments, and the
//                              "valid" member and friend functions.
//  92/03/11    ...             Re-implemented using StringReps (reference
//                              counts, offset and length).
//  92/10/08    Greg Bentz      Cleanup.
//  93/08/31    Greg Bentz      - make extractor skip whitespace if
//                                ios::skipws is set
//                              - correct offset computation in substring
//  93/10/07    Greg Bentz      - alloc_mult_size() not setting new value right
//  93/10/19    Raymond Tang    split into separate files
//  94/04/06    Greg Bentz      combine header files

#include "strng.h"

void String::__JoinStrings( const   char *l, size_t  llen,
                            const   char *r, size_t  rlen ) {
/***********************************************************/
// Join two strings, specified by l/llen and r/rlen.
// Store the result in *this, which may have a value already.
    String::StringRep *new_srep;

    if( l == NULL ) llen = 0;
    if( r == NULL ) rlen = 0;
    new_srep = __AllocStringRep( NULL, llen + rlen );
    if( new_srep == NULL ) {
        __FreeStringRep();
        return;
    }
    if( llen > 0 ) {
        ::memcpy( new_srep->__value, l, llen );
    }
    if( rlen > 0 ) {
        ::memcpy( new_srep->__value + llen, r, rlen );
    }
    __FreeStringRep();
    __srep    = new_srep;
    __slength = llen + rlen;
    __offset  = 0;
}