XML as a collection

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Introduction

If you ever dreamed about a simple MFC-Based collection to handle an ANSI XML file then here is the solution.

CXXMLFile : (Class) eXtended XML File

This class reads simple XML files. It assumes the HTML/XML conventions in symbols and tags. But, the tag <? .... ?> is ignored for now. This means that no codepage support is available (to make code simpler).

When CXXMLFile reads a file it creates a tag tree with tree types of nodes:

Legend:

1. CElementPart. Abstract base class for all node types. It includes the common member variable 'm_Text'.
2. CText. Derived from CElementPart. It represents a piece of text, it can be surrounded by any kind of nodes. Symbol replacement will be applied here, for example &nbsp; in HTML code.
3. CComment. A comment in form <!--something-->. It is not affected by symbol replacement.
4. CElement. A tag. It has three properties: m_Text (the tag name), AttributeMap(A string map atname -> at value), and by inheritance a CList of Nodes.

Then, only a CElement node type should have children.

CXXMLFile Class Reference

Public Methods

Public Attributes

Private Methods

Private Attributes

Header

// XXMLFile.h: interface for the CXXMLFile class.

//

//////////////////////////////////////////////////////////////////////


#if !defined(AFX_XXMLFILE_H__F5E3CD25_0B84_4191_A1A7_B3669180DFFA__INCLUDED_)
#define AFX_XXMLFILE_H__F5E3CD25_0B84_4191_A1A7_B3669180DFFA__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000


#include <afxtempl.h>



//************************************************************************//

/*!  \class CXXMLFile
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief A class to work with XML files as tree collections.
 */
class CXXMLFile  {
public:
    CXXMLFile();
    virtual ~CXXMLFile();
public:
    // Abstract node

    class CElementPart;
    class CElementPart{
    public:
        CElementPart* m_Parent;
        CString m_Text;
        enum TType { TElement, TText, TComment } m_Type;
    public:
        CElementPart(){};
        virtual ~CElementPart(){};
    };

    // Element node

    class CElement : public CElementPart, public CList<CElementPart*,CElementPart*>{
    public:
        CElement(){ m_Type=TElement; };
        virtual ~CElement();
    public:
        CMapStringToString AttributeToValue;
    };

    // Text node

    class CText : public CElementPart{
    public:
        CText(){ m_Type=TText; };
    };

    // Comment node

    class CComment : public CElementPart{
    public:
        CComment(){ m_Type=TComment; };
    };
public:
    // The error list, after executing Write() or Read() (if any)

    CStringList m_ErrorList;

    // Symbol table functions

    void RemoveAll();
    void AddSymbol(CString coded, CString decoded);
    void DefaultSymbols();
    void ClearSymbols();
    void AddOpenTag(CString tag);

    // File manipulation routines

    bool Write();
    CString GetFile();
    void SetFile(CString filename);
    bool Read();

    // Tree manipulation routines

    CElementPart* Root();
    CElementPart* AddElement(CElementPart* Parent);
    CElementPart* AddComment(CElementPart* Parent, CString text);
    CElementPart* AddText(CElementPart* Parent, CString text);
    void SetText(CElementPart* node, CString text);
    void GetText(CElementPart* node, CString &text);
    bool IsElement(CElementPart* node);
    bool IsComment(CElementPart* node);
    bool IsText(CElementPart* node);
    CMapStringToString* GetElementAttrMap(CElementPart* node);
    bool BuildChildList(CElementPart* node, CList<CElementPart*,CElementPart*> &l);
private:
    // The XML tree

    CElementPart* m_Root;

    // Symbol codification functions

    void Decodify(CString &html);
    void Codify(CString &html);
    CMapStringToString m_Symbols; // encoded to decoded


    // Part management

    void WritePart(CStdioFile *f, CElementPart * p, int Depth, bool bNoIdent=false);

    // Filename

    CString m_Filename;

    // Open tags map (acts like a set, so second value is ignored)

    CMapStringToString m_OpenTags;
};

#endif // !defined(AFX_XXMLFILE_H__F5E3CD25_0B84_4191_A1A7_B3669180DFFA__INCLUDED_)

Source

// XXMLFile.cpp: implementation of the CXXMLFile class.

//

//////////////////////////////////////////////////////////////////////


#include "stdafx.h"

#include "XXMLFile.h"


#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

//////////////////////////////////////////////////////////////////////

// Construction/Destruction

//////////////////////////////////////////////////////////////////////



//************************************************************************//

/*!  \fn CXXMLFile::CXXMLFile()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Constructor
 */
CXXMLFile::CXXMLFile()
{
    // The root is null

    m_Root=NULL;

    // clean tables, and create a default root node

    RemoveAll();

    // set default symbols and open tags

    DefaultSymbols();
}


//************************************************************************//

/*!  \fn CXXMLFile::~CXXMLFile()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Destructor
 */
CXXMLFile::~CXXMLFile()
{
    // clean up root (and then, the full tree)

    if(m_Root!=NULL) delete m_Root;
}


//************************************************************************//

/*!  \fn CXXMLFile::CElement::~CElement()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Element destructor (clean up the list of elements)
 */
CXXMLFile::CElement::~CElement(){
    // You must clean up the possible list of elements

    while(!IsEmpty()) delete RemoveHead();
};


//************************************************************************//

/*!  \fn bool IsSeparator(char ch){
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Ask for an XML separator 
 */
static bool IsSeparator(char ch){
    switch (ch){
    case ' ': return true;
    case '\t': return true;
    case '\r': return true;
    case '\n': return true;
    default: return false;
    };
};

//************************************************************************//

/*!  \fn bool HopSeparators(CString &html, int &pos,int FileRow)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief For internal use (Read()). It jumps over separators in a string by 
 * incrementing an integer pointer.
 */
static bool HopSeparators(CString &html, int &pos,int FileRow){
    while( (pos<html.GetLength()) && (IsSeparator(html.GetAt(pos))) ){
        if(html.GetAt(pos)=='\n') 
            FileRow++;
        pos++;
    }
    if(pos>=html.GetLength()) return false; else return true;
};

//************************************************************************//

/*!  \fn int CountChars(CString s,char ch)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief A brute-force character counter.
 */
static int CountChars(CString s,char ch){
    return s.Replace(CString()+ch,"");
};

//************************************************************************//

/*!  \fn int FindChars(CString &html, int pos, LPCTSTR chars)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief For internal use (Read()). It secuentially look for any char in 
 * a given set from an starting pointer in a string.
 */
static int FindChars(CString &html, int pos, LPCTSTR chars){
    int tmp=pos;
    CString seps = chars;
    while(tmp<html.GetLength()) {
        if(seps.FindOneOf( CString(html.GetAt(tmp)) )!=-1){
            return tmp;
        }
        tmp++;
    }
    return -1;
};


//************************************************************************//

/*!  \fn bool CXXMLFile::Read()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief The read XML function.
 */
bool CXXMLFile::Read()
{
    CString filename = m_Filename;
    int FileRow=1;

    // Init Tree

    if(m_Root!=NULL) delete m_Root;
    CElementPart** crut = &m_Root;
    CElement* Element = new CElement();
    Element->m_Parent=(*crut);
    (*crut)=Element;
    ((CElement*)(*crut))->m_Text = "?root?";

    // Clean up errors

    m_ErrorList.RemoveAll();

    // A brute-force reading of a text file (the most faster)

    CString html;
    TRY{
        CFile * f = new CFile(filename,CFile::modeRead|CFile::shareDenyNone);
        if(f==NULL) ::AfxThrowFileException(CFileException::fileNotFound,-1,filename);
        html.Empty();
        char * buf = html.GetBufferSetLength(f->GetLength());
        f->SeekToBegin();
        f->Read(buf,f->GetLength());
        f->Close();
        delete f;
        html.ReleaseBuffer();
        html.FreeExtra();
        html.Replace("\r\n","\n");
    }CATCH_ALL(e){
        m_ErrorList.AddTail("Error: File not found.");
        return false;
    }END_CATCH_ALL

    int p1,p2,p3,p4;
    p1=p2=p3=p4=0;
    while(true){
        if(p1>=html.GetLength()) return true;
        p2 = html.Find('<',p1);
        if(p2==-1){
            m_ErrorList.AddTail("Warning at line "+CString(FileRow)+
                ": There's some text before EOF, ignoring.");
            return true;
        } 
        CString text = html.Mid(p1,p2-p1);
        Decodify(text);
        if(!text.IsEmpty()){
            if( (*crut)==NULL ){
                m_ErrorList.AddTail("Warning at line "+CString(FileRow)
                +": No tag active but text found, must be at the start, ignoring.");
            } else {
                CText * t = new CText();
                t->m_Text = text;
                ((CElement*)(*crut))->AddTail( t );
                FileRow+=CountChars(text,'\n');
            }
        }

        // tag part

        p1=p2+1;
        if(p1>=html.GetLength()){ 
            m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                ": Tag started buf EOF found.");
            return false;
        } else
        if(html.Mid(p1,3)=="!--"){ // comment

            p1=p1+3;
            p2 = html.Find("-->",p1);
            CString text = html.Mid(p1,p2-p1);
            if(p2==-1){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Comment tag unclosed.");
                return false;
            }
            if( (*crut)==NULL ){
                m_ErrorList.AddTail("Warning at line "+CString(FileRow)+
                    ": No tag active but text found, ignoring.");
            } else {
                CComment * t = new CComment();
                t->m_Text = text;
                ((CElement*)(*crut))->AddTail( t );
                FileRow+=CountChars(text,'\n');
            }
            p1=p2+=3;
        } else 
        if(html.GetAt(p1)=='?'){ // ?xml or something to avoid

            p2 = html.Find("?>",p1+1);
            if(p2==-1){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Tag <? unclosed.");
                return false;
            } else {
                p1=p2+2;
                continue;
            }
        } else 
        if(html.GetAt(p1)=='/'){ // an end tag

            p2 = html.Find('>',p1);
            if(p2==-1){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Tag unclosed.");
                return false;
            }
            p1++;
            CString tagname = html.Mid(p1,p2-p1);
            tagname.TrimLeft();
            tagname.TrimRight();
            if( (*crut)==NULL ){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Closing tag when no tag???.");
                return false;
            }
            if( (*crut)->m_Text!=tagname ){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Closing tag differs from open tag.");
                return false;
            }
            (*crut)=(*crut)->m_Parent;
            p1=p2+1;
        } else { // a start tag

            // < _ tag ...

            if(!HopSeparators(html,p1,FileRow)){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Unspected EOF.");
                return false;
            }
            // < tag _ ...

            p2=FindChars(html,p1," \t\r\n>");
            if(p2==-1){
                m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                    ": Unspected EOF.");
                return false;
            }
            CString tag = html.Mid(p1,p2-p1);             
            CElement* Element = new CElement();
            Element->m_Parent=(*crut);
            ((CElement*)(*crut))->AddTail( ((CElementPart*)Element) );
            (*crut)=Element;
            ((CElement*)(*crut))->m_Text = tag;
            p1=p2;
            while(true){
                // _ >... 

                // _ value="...

                if(!HopSeparators(html,p1,FileRow)){
                    m_ErrorList.AddTail("Error at line "+
                        CString(FileRow)+": Unspected EOF.");
                    return false;
                }
                if(html.GetAt(p1)=='>'){
                    // _ >... 

                    p1+=1;
                    tag.MakeLower(); // tag string will be no longer used

                    CString value;
                    if(m_OpenTags.Lookup(tag,value)){
                        // It's an open tag, that means that it will never be closed

                        // Eg: <br> in HTML

                        (*crut)=(*crut)->m_Parent; // closing node

                    }
                    break;
                };
                if(html.Mid(p1,2)=="/>"){
                    // _ />... 

                    // This kind of tag means that no close tag is expected.

                    p1+=2;
                    (*crut)=(*crut)->m_Parent; // collapse node

                    break;
                };
                // _ value="...

                p2=html.Find("=\"",p1);
                if(p2==-1){
                    m_ErrorList.AddTail("Error at line "+CString(FileRow)+
                        ": Unspected value form.");
                    return false;
                }
                CString valname = html.Mid(p1,p2-p1);
                valname.TrimLeft();
                valname.TrimRight();
                p1=p2+2;
                CString value;
                while(true){
                    if(p1>=html.GetLength()){
                        m_ErrorList.AddTail("Error at line "+
                            CString(FileRow)+": Unspected EOF.");
                        return false;
                    } else
                    if(html.GetAt(p1)=='\"'){
                        p1++;
                        break;
                    } else
                    if(html.Mid(p1,2)=="\\\""){
                        value+="\"";
                        p1+=2;
                    } else {
                        value+=html.GetAt(p1);
                        p1++;
                    }
                }
                Element->AttributeToValue[valname]=value;
            }
        }
    }
}


//************************************************************************//

/*!  \fn void CXXMLFile::SetFile(CString filename)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Set XML filename.
 */
void CXXMLFile::SetFile(CString filename)
{
    m_Filename=filename;
}


//************************************************************************//

/*!  \fn CString CXXMLFile::GetFile()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Get XML filename.
 */
CString CXXMLFile::GetFile()
{
    return m_Filename;
}


//************************************************************************//

/*!  \fn void CXXMLFile::WritePart(CStdioFile *f, CXXMLFile::CElementPart * p, 
 *                                 int Depth, bool bNoIdent){
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Writes an XML node to a file (used by Write only).
 *
 *   \param f The target file.
 *   \param p The tree node.
 *   \param Depth The node depth (for identation).
 *   \param bNoIdent Boolean value used to cancel identation if the node is alone,
 * that is, without children and siblings.
 */
void CXXMLFile::WritePart(CStdioFile *f, CElementPart * p, int Depth, bool bNoIdent){
    int j;
    if(p->m_Type==CElementPart::TElement){
        {// Write identation

            // Avoid line-feed at the begining of the file

            if(f->GetPosition()!=0) 
                f->WriteString("\n"); 
            // the Identation with spaces

            for(j=0;j<Depth;j++) 
                f->WriteString(" ");
        }
        // Write tag header

        f->WriteString("<"+p->m_Text);

        // Write values

        POSITION pos = ((CElement*)p)->AttributeToValue.GetStartPosition();
        while(pos!=NULL){
            CString AtName,AtValue;
            ((CElement*)p)->AttributeToValue.GetNextAssoc(pos,AtName,AtValue);
            f->WriteString(" "+AtName+"=\""+AtValue+"\"");
        };

        // If the Element does not have subelements, sub-texts, or sub-comments

        // write it closed

        if(((CElement*)p)->IsEmpty()) {
            // Is an open tag (like HTML <br>)?

            CString tag;
            tag = p->m_Text;
            tag.MakeLower();
            CString value;
            if(m_OpenTags.Lookup(tag,value)){
                // It's an open tag, that means that it will 

                // never be closed Eg: <br> in HTML

                f->WriteString(">");
            } else {
                // Not an open tag

                f->WriteString("/>");
            }
        } else {
            f->WriteString(">");

            // Optimization to block ident on single subtext in element.

            bool NoIdent = false;
            if(((CElement*)p)->GetCount()==1)
                NoIdent=true;

            // For each element...

            pos = ((CElement*)p)->GetHeadPosition();
            while(pos!=NULL){
                CElementPart*e = ((CElement*)p)->GetAt(pos);
                WritePart(f,e,Depth+1,NoIdent);
                ((CElement*)p)->GetNext(pos);
            }

            // Optimization to block ident on single subtext in element.

            if(!NoIdent){
                {// Write identation

                    // Avoid line-feed at the begining of the file

                    if(f->GetPosition()!=0) 
                        f->WriteString("\n"); 
                    // the Identation with spaces

                    for(j=0;j<Depth;j++) 
                        f->WriteString(" ");
                }            
            }

            // Close tag

            f->WriteString("</"+p->m_Text+">");
        }
    } else 
    if(p->m_Type==CElementPart::TComment){
        // Write comment AS-IS

        {// Write identation

            // Avoid line-feed at the begining of the file

            if(f->GetPosition()!=0) 
                f->WriteString("\n"); 
            // the Identation with spaces

            for(j=0;j<Depth;j++) 
                f->WriteString(" ");
        }
        f->WriteString("<!--"+p->m_Text+"-->");
    } else 
    if(p->m_Type==CElementPart::TText){
        // Write text if it's not empty (an empty text can have sparators)

        CString empty_string = p->m_Text;
        empty_string.Replace('\n',' ');
        empty_string.Replace('\r',' ');
        empty_string.Replace('\t',' ');
        while(0!=empty_string.Replace("  "," "));
        if((!empty_string.IsEmpty())&&(empty_string!=" ")) {
            if(!bNoIdent){
                {// Write identation

                    // Avoid line-feed at the begining of the file

                    if(f->GetPosition()!=0) 
                        f->WriteString("\n"); 
                    // the Identation with spaces

                    for(j=0;j<Depth;j++) 
                        f->WriteString(" ");
                }
            }

            // The string must be written with symbol codification

            CString text = p->m_Text;
            Codify(text);
            f->WriteString(text);
        }
    } 
};


//************************************************************************//

/*!  \fn bool CXXMLFile::Write()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Writes XML file.
 */
bool CXXMLFile::Write()
{
    m_ErrorList.RemoveAll();

    // check tree

    if(m_Root==NULL) {
        m_ErrorList.AddTail("Error: NULL tree.");
        return false;
    }
    if(m_Root->m_Type!=CElementPart::TElement) {
        m_ErrorList.AddTail("Error: tree root is not an Element.");

        return false; // root must be TElement

    }
    if(((CElement*)m_Root)->m_Text!="?root?") {
        m_ErrorList.AddTail("Error: tree root is not named ?root?");
        return false; // bad-written root

    }

    // Ok write file;

    CStdioFile * f = new CStdioFile(m_Filename,CFile::modeCreate|
            CFile::modeWrite|CFile::shareDenyNone|CFile::typeText);
    if(f==NULL){
        m_ErrorList.AddTail("Error: cannot open '"+m_Filename+"' for writing.");
        return false; 
    } 

    CElement * root = ((CElement*)m_Root);
    POSITION pos = root->GetHeadPosition();
    while(pos!=NULL){
        CElementPart * p = root->GetAt(pos);
        WritePart(f,p,0);
        root->GetNext(pos);
    }

    f->Close();
    delete f;

    return true;
}


//************************************************************************//

/*!  \fn void CXXMLFile::DefaultSymbols()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Set default symbols.
 */
void CXXMLFile::DefaultSymbols()
{
    AddSymbol("&lt;","<");
    AddSymbol("&gt;",">");
    AddSymbol("&quot;","\"");
    AddSymbol(" "," ");
    AddSymbol("&apos;","'");
    AddSymbol("&amp;","&");
    m_OpenTags["br"];
}


//************************************************************************//

/*!  \fn void CXXMLFile::ClearSymbols()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Clear symbols.
 */
void CXXMLFile::ClearSymbols()
{
    // Clear symbol table

    m_Symbols.RemoveAll();

    // Remove open tags

    m_OpenTags.RemoveAll();
}


//************************************************************************//

/*!  \fn void CXXMLFile::AddSymbol(CString coded, CString decoded)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Adds a symbol.
 */
void CXXMLFile::AddSymbol(CString coded, CString decoded)
{
    m_Symbols[coded]=decoded;
}


//************************************************************************//

/*!  \fn void CXXMLFile::RemoveAll()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Delete all entries and make a default root node.
 */
void CXXMLFile::RemoveAll()
{
    // Clear symbol table

    ClearSymbols();

    // Remove open tags

    m_OpenTags.RemoveAll();

    // Clear tree and create the default main node

    if(m_Root!=NULL) delete m_Root;
    CElementPart** crut = &m_Root;
    CElement* Element = new CElement();
    Element->m_Parent=(*crut);
    (*crut)=Element;
    ((CElement*)(*crut))->m_Text = "?root?";
}


//************************************************************************//

/*!  \fn void CXXMLFile::Codify(CString &html)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Codify using symbol table.
 */
void CXXMLFile::Codify(CString &html)
{
    int pos = 0;
    while(pos<html.GetLength()){
        POSITION p = m_Symbols.GetStartPosition();
        while(p!=NULL){
            CString coded, decoded;
            m_Symbols.GetNextAssoc(p,coded,decoded);
            if((pos+decoded.GetLength())<=html.GetLength()){
                if(html.Mid(pos,decoded.GetLength())==decoded){
                    html = html.Left(pos) + coded + 
                        html.Mid(pos+decoded.GetLength());
                    pos = pos + coded.GetLength()-1;
                    break;
                }
            }
        }
        pos++;
    }
}


//************************************************************************//

/*!  \fn void CXXMLFile::Decodify(CString &html)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Decodify using symbol table.
 */
void CXXMLFile::Decodify(CString &html)
{
    int pos = 0;
    while(pos<html.GetLength()){
        POSITION p = m_Symbols.GetStartPosition();
        while(p!=NULL){
            CString coded, decoded;
            m_Symbols.GetNextAssoc(p,coded,decoded);
            if((pos+coded.GetLength())<=html.GetLength()){
                if(html.Mid(pos,coded.GetLength())==coded){
                    html = html.Left(pos) + decoded + 
                        html.Mid(pos+coded.GetLength());
                    pos = pos + decoded.GetLength()-1;
                    break;
                }
            }
        }
        pos++;
    }
}

//************************************************************************//

/*!  \fn void CXXMLFile::AddOpenTag(CString tag)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Adds an open tag. (HTML <br>)
 */
void CXXMLFile::AddOpenTag(CString tag){
    tag.MakeLower();
    m_OpenTags[tag];
}

//************************************************************************//

/*!  \fn CXXMLFile::CElementPart* CXXMLFile::Root()
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Gets the root. (Create one if it's empty).
 */
CXXMLFile::CElementPart* CXXMLFile::Root(){
    if(m_Root!=NULL) 
        return (CXXMLFile::CElementPart*)m_Root;
    CElementPart** crut = &m_Root;
    CElement* Element = new CElement();
    Element->m_Parent=(*crut);
    (*crut)=Element;
    ((CElement*)(*crut))->m_Text = "?root?";
    return Element;
}

//************************************************************************//

/*!  \fn CXXMLFile::CElementPart* CXXMLFile::AddElement(CElementPart* Parent)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Adds a node type element
 */
CXXMLFile::CElementPart* CXXMLFile::AddElement(CElementPart* Parent){
    // Only TElement nodes support childs

    if(Parent->m_Type!=CXXMLFile::CElementPart::TElement)
        return NULL;
    CXXMLFile::CElement * elem = (CXXMLFile::CElement*)Parent;    
    CXXMLFile::CElement * new_elem = new CElement();
    elem->AddTail( ((CXXMLFile::CElementPart*)new_elem) );
    return new_elem;
}


//************************************************************************//

/*!  \fn void CXXMLFile::SetText(CElementPart* node, CString text)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Sets text property in a node.
 */
void CXXMLFile::SetText(CElementPart* node, CString text){
    node->m_Text = text;
};

//************************************************************************//

/*!  \fn void CXXMLFile::GetText(CElementPart* node, CString &text)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Gets text property in a node.
 */
void CXXMLFile::GetText(CElementPart* node, CString &text){
    text = node->m_Text;
};

//************************************************************************//

/*!  \fn CXXMLFile::CElementPart* CXXMLFile::AddComment(CElementPart* Parent, 
 *                                                      CString text)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Adds a comment node
 */
CXXMLFile::CElementPart* CXXMLFile::AddComment(CElementPart* Parent, CString text){
    // Only TElement nodes support childs

    if(Parent->m_Type!=CXXMLFile::CElementPart::TElement)
        return NULL;
    CXXMLFile::CElement * elem = (CXXMLFile::CElement*)Parent;    
    CXXMLFile::CComment * new_elem = new CComment();
    elem->AddTail( ((CXXMLFile::CElementPart*)new_elem) );
    return new_elem;
};

//************************************************************************//

/*!  \fn CXXMLFile::CElementPart* CXXMLFile::AddText(CElementPart* Parent,
 *                                                   CString text)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Adds a text node
 */
CXXMLFile::CElementPart* CXXMLFile::AddText(CElementPart* Parent, CString text){
    // Only TElement nodes support childs

    if(Parent->m_Type!=CXXMLFile::CElementPart::TElement)
        return NULL;
    CXXMLFile::CElement * elem = (CXXMLFile::CElement*)Parent;    
    CXXMLFile::CText * new_elem = new CText();
    elem->AddTail( ((CXXMLFile::CElementPart*)new_elem) );
    return new_elem;
}

//************************************************************************//

/*!  \fn bool CXXMLFile::IsElement(CElementPart* node)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief  Determines wheter node is element. 
 */
bool CXXMLFile::IsElement(CElementPart* node)
{
    return (node->m_Type==CXXMLFile::CElementPart::TElement);
}

//************************************************************************//

/*!  \fn bool CXXMLFile::IsComment(CElementPart* node)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Determines wheter node is comment. 
 */
bool CXXMLFile::IsComment(CElementPart* node)
{
    return (node->m_Type==CXXMLFile::CElementPart::TComment);
}

//************************************************************************//

/*!  \fn bool CXXMLFile::IsText(CElementPart* node)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Determines wheter node is text. 
 */
bool CXXMLFile::IsText(CElementPart* node)
{
    return (node->m_Type==CXXMLFile::CElementPart::TText);
}

//************************************************************************//

/*!  \fn CMapStringToString* CXXMLFile::GetElementAttrMap(CElementPart* node)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Returns a pointer to the attribute map of the element.
 */
CMapStringToString* CXXMLFile::GetElementAttrMap(CElementPart* node)
{
    // Only TElement nodes support childs

    if(node->m_Type!=CXXMLFile::CElementPart::TElement)
        return NULL;
    CXXMLFile::CElement * elem = (CXXMLFile::CElement*)node;    
    return &elem->AttributeToValue;
}

//************************************************************************//

/*!  \fn bool CXXMLFile::BuildChildList(CElementPart* node, 
 *                                      CList<CElementPart*,CElementPart*> &l)
 *   \author Manuel Lucas Vi�as Livschitz (MLVL)
 *   \date 04/05/2002
 *   \brief Builds a list of child nodes.
 */
bool CXXMLFile::BuildChildList(CElementPart* node, 
                               CList<CElementPart*,CElementPart*> &l)
{
    // Only TElement nodes support childs

    if(node->m_Type!=CXXMLFile::CElementPart::TElement)
        return false;
    l.RemoveAll();
    l.AddTail( ((CElementPart*)node) );
    return true;
}

Example

The most simple example is in trying to load an XML file, converting in a CXMLFile collection and then writing back an XML file.

We will do the test with books.xml (from MSDN XML SDK)

Source code (extract)

// XMLTest.cpp : Defines the entry point for the console application.

//


#include "stdafx.h"

#include "XMLTest.h"


....

// read-write test

        CXXMLFile xml;
        xml.SetFile("books.xml");
        bool bok = xml.Read();

        if(!bok){
            POSITION pos = xml.m_ErrorList.GetHeadPosition();
            while(pos!=NULL){
                printf(xml.m_ErrorList.GetAt(pos)+"\n");
                xml.m_ErrorList.GetNext(pos);
            }
        } else {
            xml.SetFile("books_out.xml");
            xml.ClearSymbols(); // no html symbols (to avoid convering spaces into  

            bok = xml.Write();
            if(!bok){
                POSITION pos = xml.m_ErrorList.GetHeadPosition();
                while(pos!=NULL){
                    printf(xml.m_ErrorList.GetAt(pos)+"\n");
                    xml.m_ErrorList.GetNext(pos);
                }
            }
        }