Tree Class

Class for presenting tree structures in C++.

1. Data objects:
- The purpose of the Data class is to keep the actual data. It keeps the data until all actual references to it are dead. This is done with reference counting (COM like). I know somebody may find this worthless and useless, but it makes the data more capsulated and secure. The implementation is divided in two classes Data and Ref (reference). All the data is stored in the Data class.All the job is done by Ref class, which manipulates the data class.

template <class Type> class Data {
private:
...// all methods  vars are private
   friend class Ref<Type>; // Ref class will manipulate us
};
template <class Type> class Ref {
    Ref(Type *p);
    Ref();
    Ref(const Ref<Type> rhs);
    //destructor
    virtual ~Ref();

//operators =
    Ref operator=(const Ref<Type> rhs);
    Ref operator=(const Type t);
    Ref operator=(Type *p); 
// operator ==
    bool operator==(const Ref<Type> rhs) 
// misc

Ref Clone();
    void Release();
    bool IsNull();

// accessors to the actual data 
// (check if it's null first)
    Type *operator->();
    Type get_Data();
    operator Type();
}

2. Tree object:
- Tree class represents a node in the tree, so it has parent and it has children. in this way i use a single class for representing a node and a tree, so the the tree is a node without praent. It also has reference (Ref) to the data. It's implementation is divided between two classes NodeData and Tree. NodeData objects holds the actual data for the parent and the children, but Tree object manipualtes this data and gives access to them. Actually you'll always use only Tree class directly.

- definitions
- node - a simple node or leaf in the tree
- leaf - a node without children
- root (tree) - a node without parent (i.e. prent is Null)
- Null - null node

template <class Type> class NodeData {
private:
    .... // all methods  vars are private
    friend class Tree<Type>;
}

template <class Type> class Tree {
public:
    // we'll call the tree node
    typedef Tree<Type> Node;
    
    // parent
    Node Parent();
    
    // children - Nodes
    __declspec( property( get=get_Nodes) ) Node Nodes[];
    __declspec( property( get=get_Count) ) int Count;

    Node get_Nodes(int nIndex);
    int get_Count();
    
    // data acess
    __declspec( property( get=get_Data) ) Ref<Type> Data;

    operator Type();
    Type *operator->();
    Ref<Type> get_Data();

    // node functions (isLeaf and so on
    bool IsLeaf();
    bool IsNode();
    bool IsRoot();

    // comparision
    bool operator == (const Node rhs)
          { return *(NodeBase*)this==(NodeBase )rhs;};

    // node operations
    Node AddNode(const Type t); 
    void Delete();
    void DeleteNode(int nIndex);
    void DeleteNode(Node node);

    // constructors
    Tree(const Type Data);
    Tree(Type *Data);
    
    Tree();
    Tree(const Tree<Type> rhs);
    Tree(const NodeBase rhs);
    
    // destructor
    virtual ~Tree();
}

3. Simple usage:

// function for printing nodes
void PrintNode(StringNode node,int nLevel) {
    // print new line
    fputs("\n",stdout);
    // print spaces for indent (2 for every level)
    string s;
    s.resize(nLevel*2,' ');
    fputs(s.c_str(),stdout);

    // print the value
    fputs(node.get_Data()->c_str(),stdout);

    // iterate through children
    nLevel++;
    for(int n=0;n<node.Count;n++) {
        PrintNode(node.Nodes[n],nLevel);
    }
}

int main(int argc, char* argv[])
{
    // define the tree
    StringTree tree; 
    ((string)tree)="Root";

    //add few nodes
    StringNode node=tree;

    node.AddNode("1").AddNode("11");
    StringNode node2=node.AddNode("2");

    node2.AddNode("21").AddNode("211");
    node2.AddNode("22");
    node2.AddNode("23");
    
    node.AddNode("3");

    // print the tree
    PrintNode(tree,0);

    // wait for enter
    char buf[3];
    fputs("\nPress ENTER :",stdout);
    fgets(buf,3,stdin);
    return 0;
}

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