使用 CString 预解析 XML

引言

在解析类似 XML 的文档时，由于存在重复的属性-值对，或者作者意外地省略了一些空格，可能无法直接使用 XML DOM 打开它，需要先进行预解析。

背景

我有很多由客户端生成和卸载的 XML 文档，但其中总是存在一些错误。

使用代码

读取 XML 字符串 buf，例如，strxml。然后调用 PreFormatXML(strxml)；之后，您可以创建一个 xmldom 的实例，并调用 LoadXML。

以下是涉及到的函数

void PreFormatXML(CString& strxml)
{
    // it is possible that the tooltip include a \r\n
    strxml.Remove(_T('\r'));
    strxml.Replace(_T('\n'),_T(' '));
    strxml.Replace(_T('\t'),_T(' '));
    //Dump(strxml,_T("e:\\bbb.xml"));

    //////////////////////// in the following, you should reassign \r\n
    ////////// now just one line
    int iStart = 0;
    int iEnd1,iEnd2;
    while(iStart>-1)
    {
        iEnd1 = strxml.Find(_T("<!--"),iStart);
        if(iEnd1<0) 
            break;
        iEnd2 = strxml.Find(_T("-->"),iEnd1);
        if(iEnd2<0) 
            break;

        if(iEnd2>iEnd1) {
            strtemp = strxml.Mid(iEnd1,iEnd2-iEnd1+3);
            int n = strxml.Replace(strtemp,_T(" "));
            iStart = 0;
            continue;
        }
        iStart = iEnd2+1;
    }

    iStart  = 0;
    iEnd1    = 0;
    iEnd2    = 0;
    CString strcmp = strxml;
    while(iEnd2>-1)
    {
        iEnd1 = strxml.Find(_T('\"'),iStart);
        iEnd2 = strxml.Find(_T('\"'),iEnd1+1);
        if(iEnd1>-1&&iEnd2>-1) {
            for(int i=iEnd1;i<iEnd2+1;i++)
                strcmp.SetAt(i,_T('*'));
        }
        else
            break;
        iStart = iEnd2+1;
    }

    strcmp.MakeLower();

    // minimize all tag and split concat attr
    int i1 = 0;
    int i2 = 0;
    int nlen = strcmp.GetLength();
    while(i1<nlen)
    {
        TCHAR ch1 = strcmp.GetAt(i1);
        if(ch1!=_T('*')) 
            strxml.SetAt(i2,ch1);

        if(ch1==_T('>'))
        {
            strxml.Insert(i2+1,_T('\n'));
            strxml.Insert(i2+1,_T('\r'));
            i2 += 2;
        }

        if(ch1==_T('*')) 
        {
            if(i1<nlen-1)
            {
                TCHAR ch2 = strcmp.GetAt(i1+1);
                if(ch2!=_T('*'))
                {
                    /// the 
                    if(ch2>_T('a'-1)&&ch2<_T('z'+1))
                    {
                        strxml.Insert(i2+1,_T(' '));
                        i2++;
                    }
                }
            }
        }
        i1++;
        i2++;
    }

    ////// the following remove duplicate tag, and makelower
    //     of everything except attribute value.
    ////int nlen;
    nlen = strxml.GetLength();
    strxml.Insert(nlen,_T("\r\n"));
    ////Dump(strxml,_T("e:\\aaaa.txt"));
    
    CString strtemp,strfake,strleft,strright;

    ///////////////////////////////////////////////////////////////////
    int size = m_ArrPreDefTag.GetSize();
    preTag pa;
    CString strnodename,strattr;

    iStart    = iEnd1    = iEnd2    = 0;
    while(iEnd1>-1)
    {
        nlen  = strxml.GetLength();
        iEnd1 = strxml.Find(_T('<'),iStart);
        if(iEnd1<0)
            break;
        iEnd2 = strxml.Find(_T(">\r\n"),iEnd1);
        if(iEnd2<0)
            break;
            
        //// keep left and right
        strleft.Empty();
        strright.Empty();
        strleft = strxml.Left(iEnd1+1);
        strright= strxml.Right(nlen-iEnd2);
        // pick out <> and process it
        strtemp = strxml.Mid(iEnd1+1,iEnd2-iEnd1-1);
        strfake = strtemp;
        strfake.TrimLeft();
        strfake.TrimRight();

        int lensub = strfake.GetLength();
        if(lensub>0) 
        {
            bool bselfClosed    = _T('/')==strfake.GetAt(lensub-1);
            if(bselfClosed)
                strfake = strfake.Left(lensub-1);

            strfake.TrimLeft();
            strfake.TrimRight();
            bool breversetag    =_T('/')==strfake.GetAt(0);
            if(breversetag) 
            {
                strfake = strfake.Right(lensub-1);
                int n1 = strfake.Find(_T(' '));

                // just truncate it. reverse tag has no attr-value pair
                if(n1>1)
                    strfake = strfake.Left(n1-1);        

                for(int isize=0;isize<size;isize++)
                {
                    pa = m_ArrPreDefTag[isize];
                    if(strfake.CompareNoCase(pa.tag)==0)
                    {
                        strfake = pa.oritag;
                        break;
                    }
                }
                strfake.MakeLower();
            }
            else
            {
                /// replace tag with predefined tag
                int n0 = strfake.GetLength();
                int n1 = strfake.Find(_T(' '));
                if(n1>0) /// yeah, it include serveral fields
                {
                    strnodename = strfake.Left(n1);
                    strnodename.MakeLower();
                    for(int isize=0;isize<size;isize++)
                    {
                        pa = m_ArrPreDefTag[isize];
                        if(strnodename.CompareNoCase(pa.tag)==0)
                        {
                            strnodename = pa.oritag + _T(" ") + pa.preattrs;
                            break;
                        }
                    }
                    // reconcat 
                    // find out nodename, attr-pair;
                    ATLASSERT(n0>n1);
                    strfake = strnodename+strfake.Right(n0-n1);
                    // breplaced is possible to change in this tag.
                    RemoveDuplicate(strfake);
                }
                ///only one tag, and no attr-value pair

            }
            strtemp = ((breversetag&&!bselfClosed)?_T("/"):_T("")) + 
                strfake +     ((bselfClosed&&!breversetag)?_T("/"):_T("")) ;
            strxml = strleft + strtemp    +     strright;
            iEnd2    = strtemp.GetLength()+iEnd1;
        }
        else
            ATLASSERT(0);        // there must be no < > things 
        iStart = iEnd2+3;
    }
    return;
}

void RemoveDuplicate(CString& str)
{
    str.TrimLeft();
    str.TrimRight();

    // replace simplified tag and spawn attribute array.
    // fill out attr-pair map;

    CString strnodename;
    int n0 = str.GetLength();
    int n1 = str.Find(_T(' '));
    if(n1>0) 
    {
        strnodename = str.Left(n1);
        strnodename.MakeLower();

        CString strfake;
        CSimpleMap<CString,CString> attributes;
        CString strattr,strvalue;

        strfake = str.Right(n0-n1);
        strfake.TrimLeft();
        strfake.TrimRight();
        /// find attr-value in strfake

        int m0 = 0;
        int m1 = 0;
        int m2 = 0;
        int mlen;
        ////////////////////
        while(m0>-1)
        {
            mlen = strfake.GetLength();
            m1 = strfake.Find(_T('\"'),m0);
            if(m1<0)
                break;

            m2 = strfake.Find(_T('\"'),m1+1);
            if(m1<0)
                break;

            strattr  = strfake.Mid(m0,m1-m0-1);
            strattr.Remove(_T('='));
            strattr.MakeLower();
            strattr.TrimLeft();
            strattr.TrimRight();

            strvalue = strfake.Mid(m1+1,m2-m1-1);
            strvalue.TrimLeft();
            strvalue.TrimRight();
            int nd = attributes.FindKey(strattr);
            if(nd<0)
                attributes.Add(strattr,strvalue);
            m0 = m2+1;
        }
        /// process default id

        str = strnodename;
        int size = attributes.GetSize();
        for(int i=0;i<size;i++)
        {
            strattr     = attributes.GetKeyAt(i);
            strvalue    = attributes.GetValueAt(i);
            str += _T(" ");
            str += strattr;
            str += _T("=\"");
            str += strvalue;
            str += _T("\"");
        }
        attributes.RemoveAll();
    }
    return;
}

如上所述，我使用 CSimpleMap 重新组合了所有的属性-值对。当遇到重复的对时，它将被覆盖。 另外，在诸如 <a b="blah"c="interesting value"> 这样的字符串中，"blah" 和 c 之间添加了空格，否则无法成功加载。

此代码已在 XP、VS.NET 2002、WTL 71、ATL70 下测试过。 欢迎提出任何意见。