Added gp, example file in t-eoSymreg.cpp

eo/gp/eoParseTree.h

@@ -0,0 +1,238 @@
+#ifndef EO_PARSE_TREE_H
+#define EO_PARSE_TREE_H
+
+#include <list>
+
+#include "EO.h"
+#include "eoOp.h"
+#include "eoInserter.h"
+#include "eoIndiSelector.h"
+#include "parse_tree.h"
+#include "eoRnd.h"
+
+using namespace gp_parse_tree;
+using namespace std;
+
+template <class FType, class Node>
+class eoParseTree : public EO<FType>, public parse_tree<Node>
+{
+public :
+    
+    typedef typename parse_tree<Node>::subtree Type;
+
+    eoParseTree(void) : EO<FType>(), parse_tree<Node>() {}
+    eoParseTree(unsigned _size, eoRnd<Type>& _rnd) 
+        : EO<FType>(), parse_tree<Node>(_rnd()) 
+    {
+        pruneTree(_size);
+    }
+
+    void pruneTree(unsigned _size)
+    {
+        if (_size < 1)
+            return;
+
+        if (size() > _size)
+        {
+            Type* sub = &operator[](size() - 2); // prune tree
+
+            while (sub->size() > _size)
+            {
+                sub = &sub->operator[](0);
+            }
+
+            back() = *sub;
+        }
+    }
+
+    eoParseTree(std::istream& is) : EO<FType>(), parse_tree<Node>() 
+    {
+        readFrom(is);
+    }
+
+    string className(void) const { return "eoParseTree"; }
+
+    void printOn(std::ostream& os) const
+    {
+        os << fitness() << ' ';
+
+        std::copy(ebegin(), eend(), ostream_iterator<Node>(os));
+    }
+
+    void readFrom(std::istream& is) 
+    {
+        FType fit;
+
+        is >> fit;
+
+        fitness(fit);
+
+        std::copy(istream_iterator<Node>(is), istream_iterator<Node>(), back_inserter(*this));
+    }
+};
+
+template <class FType, class Node>
+std::ostream& operator<<(std::ostream& os, const eoParseTree<FType, Node>& eot)
+{
+    eot.printOn(os);
+    return os;
+}
+
+template <class FType, class Node>
+std::istream& operator>>(std::istream& is, eoParseTree<FType, Node>& eot)
+{
+    eot.readFrom(is);
+    return is;
+}
+
+
+
+template <class FType, class Node>
+class eoGpDepthInitializer : public eoRnd< eoParseTree<FType, Node>::Type >
+{
+    public :
+
+    typedef eoParseTree<FType, Node> EoType;
+
+	eoGpDepthInitializer(
+        unsigned _max_depth,
+		const vector<Node>& _initializor,
+        bool _grow = true) 
+            :
+            eoRnd<EoType::Type>(),
+			max_depth(_max_depth),
+			initializor(_initializor),
+			grow(_grow) 
+    {}
+
+	virtual string className() const { return "eoDepthInitializer"; };
+
+    EoType::Type operator()(void)
+	{
+        list<Node> sequence;
+        
+        generate(sequence, max_depth);
+        
+        parse_tree<Node> tree(sequence.begin(), sequence.end());
+
+        return tree.root();
+	}
+
+    void generate(list<Node>& sequence, int the_max, int last_terminal = -1)
+    {
+	    if (last_terminal == -1)
+	    { // check where the last terminal in the sequence resides
+            vector<Node>::iterator it;
+		    for (it = initializor.begin(); it != initializor.end(); ++it)
+		    {
+			    if (it->arity() > 1)
+				    break;
+		    }
+		
+		    last_terminal = it - initializor.begin();
+	    }
+
+	    if (the_max == 1)
+	    { // generate terminals only
+		    vector<Node>::iterator it = initializor.begin() + rng.random(last_terminal);
+		    sequence.push_front(*it);
+		    return;
+	    }
+	
+	    vector<Node>::iterator what_it;
+
+	    if (grow)
+	    {
+		    what_it = initializor.begin() + rng.random(initializor.size());
+	    }
+	    else // full
+	    {
+		    what_it = initializor.begin() + last_terminal + rng.random(initializor.size() - last_terminal);
+	    }
+
+	    sequence.push_front(*what_it);
+
+	    for (int i = 0; i < what_it->arity(); ++i)
+		    generate(sequence, the_max - 1, last_terminal);
+    }
+
+
+private :
+
+	unsigned max_depth; 
+    std::vector<Node> initializor;
+	bool grow; 
+};
+
+template<class FType, class Node>
+class eoSubtreeXOver: public eoGeneralOp< eoParseTree<FType, Node> > {
+public:
+
+  typedef eoParseTree<FType, Node> EoType;
+
+  eoSubtreeXOver( unsigned _max_length)
+    : eoGeneralOp<EoType>(), max_length(_max_length) {};
+
+  virtual string className() const { return "eoSubtreeXOver"; };
+
+  /// Dtor
+  virtual ~eoSubtreeXOver () {};
+
+  void operator()(eoIndiSelector<EoType>& _source, eoInserter<EoType>& _sink ) const
+  {
+      EoType eo1 = _source.select();
+      const EoType& eo2 = _source.select();
+
+	  int i = rng.random(eo1.size());
+	  int j = rng.random(eo2.size());
+
+	  eo1[i] = eo2[j]; // insert subtree
+	  	  
+	  eo1.pruneTree(max_length);
+	  
+	  eo1.invalidate();
+      _sink.insert(eo1);
+  }
+
+  unsigned max_length;
+};
+
+template<class FType, class Node>
+class eoBranchMutation: public eoGeneralOp< eoParseTree<FType, Node> > 
+{
+public:
+
+  typedef eoParseTree<FType, Node> EoType;
+
+  eoBranchMutation(eoRnd<EoType::Type>& _init, unsigned _max_length)
+    : eoGeneralOp<EoType>(), max_length(_max_length), initializer(_init) 
+  {};
+
+  virtual string className() const { return "eoBranchMutation"; };
+
+  /// Dtor
+  virtual ~eoBranchMutation() {};
+
+  void operator()(eoIndiSelector<EoType>& _source, eoInserter<EoType>& _sink ) const
+  {
+      EoType eo1 = _source.select();
+	  int i = rng.random(eo1.size());
+      
+      EoType eo2(eo1[i].size(), initializer); // create random other to cross with
+
+	  eo1[i] = eo2.back(); // insert subtree
+	  	  
+	  eo1.pruneTree(max_length);
+
+	  eo1.invalidate();
+      _sink.insert(eo1);
+  }
+
+private :
+
+  unsigned max_length;
+  eoRnd<EoType::Type>& initializer; 
+};
+
+
+#endif

eo/gp/node_pool.h

@@ -0,0 +1,228 @@
+
+#ifndef node_pool_h
+#define node_pool_h
+
+class MemPool
+{
+public :
+    
+    MemPool(unsigned int sz) : esize(sz<sizeof(Link)? sizeof(Link) : sz) {}
+    ~MemPool()
+    {
+        Chunk* n = chunks;
+        while(n)
+        {
+            Chunk* p = n;
+            n = n->next;
+            delete p;
+        }
+    }
+    
+    void* allocate()
+    {
+        if (head == 0) grow();
+        Link* p = head;
+        head = p->next;
+        return static_cast<void*>(p);
+    }
+
+    void deallocate(void* b)
+    {
+        Link* p = static_cast<Link*>(b);
+        p->next = head;
+        head = p;
+    }
+
+private :
+
+    void grow()
+    {
+        Chunk* n = new Chunk;
+        n->next = chunks;
+        chunks = n;
+
+        const int nelem = Chunk::size/esize;
+        char* start = n->mem;
+        char* last  = &start[(nelem-1)*esize];
+        for (char* p = start; p < last; p += esize)
+        {
+            reinterpret_cast<Link*>(p)->next = 
+                reinterpret_cast<Link*>(p + esize);
+        }
+        
+        reinterpret_cast<Link*>(last)->next = 0;
+        head = reinterpret_cast<Link*>(start);
+    }
+
+    struct Link
+    {
+        Link* next;
+    };
+
+    struct Chunk
+    {
+        enum {size = 8 * 1024 - 16};
+        Chunk* next;
+        char mem[size];
+    };
+
+    Chunk* chunks;
+    const unsigned int esize;
+    Link* head;
+};
+
+template<class T>
+class Node_alloc
+{
+public :
+    Node_alloc() {};
+
+    T* allocate(void) 
+    {
+        T* t = static_cast<T*>(mem.allocate());
+        t = new  (t) T;
+        //t->T(); // call constructor;
+        return t;
+    }
+
+    void deallocate(T* t)
+    {
+        t->~T(); // call destructor
+        mem.deallocate(static_cast<void*>(t));
+    }
+
+private :
+    static MemPool mem;
+};
+
+template <class T> 
+class Standard_alloc
+{
+public :
+    Standard_alloc() {}
+
+    T* allocate(size_t arity = 1)
+    {
+        if (arity == 0)
+            return 0;
+
+        return new T [arity];
+    }
+
+    void deallocate(T* t, size_t arity = 1)
+    {
+        if (arity == 0)
+            return ;
+
+        delete [] t;
+    }
+
+};
+
+template <class T> 
+class Standard_Node_alloc
+{
+public :
+    Standard_Node_alloc() {}
+
+    T* allocate(void)
+    {
+        return new T;// [arity];
+    }
+
+    void deallocate(T* t)
+    {
+        delete t;
+    }
+
+};
+
+template <class T>
+class Tree_alloc
+{
+public :
+    Tree_alloc() {}
+
+    T* allocate(size_t arity)
+    {
+        T* t;
+
+        switch(arity)
+        {
+
+        case 0 : return 0;
+        case 1 :
+            {
+                t = static_cast<T*>(mem1.allocate());
+                new (t) T;
+                break;
+            }
+        case 2 :
+            {
+                t = static_cast<T*>(mem2.allocate());
+                new (t) T;
+                new (&t[1]) T;
+                break;
+            }
+        case 3 :
+            {
+                t = static_cast<T*>(mem3.allocate());
+                new (t) T;
+                new (&t[1]) T;
+                new (&t[2]) T;
+                break;
+            }
+        default :
+            {
+                return new T[arity];
+            }
+        }
+
+        return t;
+     }
+
+    void deallocate(T* t, size_t arity)
+    {
+        switch(arity)
+        {
+        case 0: return;
+        case 3 : 
+            {
+                t[2].~T(); t[1].~T(); t[0].~T();
+                mem3.deallocate(static_cast<void*>(t));
+                return;
+            }
+        case 2 : 
+            {
+                t[1].~T(); t[0].~T();
+                mem2.deallocate(static_cast<void*>(t));
+                return;
+            }
+        case 1 : 
+            {
+                t[0].~T();
+                mem1.deallocate(static_cast<void*>(t));
+                return;
+            }
+        default :
+            {
+                delete [] t;
+                return;
+            }
+        }
+    }
+    
+
+private :
+    static MemPool mem1;
+    static MemPool mem2;
+    static MemPool mem3;
+};
+
+// static (non thread_safe) memory pools
+template <class T> MemPool Node_alloc<T>::mem  = sizeof(T);
+template <class T> MemPool Tree_alloc<T>::mem1 = sizeof(T);
+template <class T> MemPool Tree_alloc<T>::mem2 = sizeof(T) * 2;
+template <class T> MemPool Tree_alloc<T>::mem3 = sizeof(T) * 3;
+
+#endif

eo/gp/parse_tree.h

@@ -0,0 +1,915 @@
+#ifndef PARSE_TREE_HH
+#define PARSE_TREE_HH
+
+/**
+
+ *	Parse_tree and subtree classes 
+ *		(c) Maarten Keijzer 1999 
+
+ * These classes may be used for educational and 
+ * other non-commercial purposes only. Even if I
+ * wanted to, I am not at liberty to place this file 
+ * under the GNU Lesser Public Library License, as this
+ * would limit my and my institution's freedom to use
+ * this file in closed-source software. 
+ 
+ * This material is provided "as is", with absolutely no warranty expressed
+ * or implied. Any use is at your own risk.
+ *
+ * Permission to use or copy this software for non-commercial purpose is hereby granted 
+ * without fee, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+
+
+  Usage information.
+
+  class Node (your node in the tree) must have the following implemented:
+
+  ******      Arity      ******
+  
+	int arity(void) const
+
+	Note:	the default constructor of a Node should provide a 
+			Node with arity 0!
+
+  ******    Evaluation   ******
+
+  A parse_tree is evaluated through one of it's apply() members:
+  
+	1) parse_tree::apply(void)			
+	
+	   is the simplest evaluation, it will call 
+	
+	   RetVal Node::operator()(subtree<Node, RetVal>::const_iterator)
+	
+	2) parse_tree::apply(It values)		
+
+       will call:
+
+       RetVal Node::operator()(subtree<... , It values)
+
+       where It is whatever type you desire (most of the time
+	   this will be a vector containing the values of your
+	   variables);
+
+	3) parse_tree::apply(It values, It2 moreValues)
+
+       will call:
+
+       RetVal Node::operator()(subtree<... , It values, It2 moreValues)
+		
+	   although I do not see the immediate use of this, however...
+
+	4) parse_tree::apply(It values, It2 args, It3 adfs)
+
+		that calls:
+
+       RetVal Node::operator()(subtree<... , It values, It2 args, It3 adfs)
+
+		can be useful for implementing adfs. 
+
+  
+	In general it is a good idea to leave the specifics of the 
+	arguments open so that different ways of evaluation remain
+	possible. Implement the simplest eval as:
+
+	template <class It>
+		RetVal operator()(It begin) const
+
+  ******	Internal Structure    ******
+
+  A parse_tree has two template arguments: the Node and the ReturnValue
+  produced by evaluating the node. The structure of the tree is defined
+  through a subtree class that has the same two template arguments.
+  
+  The nodes are stored in a tree like :
+
+			node4
+			/  \
+		 node3 node2
+		        / \
+            node1 node0 
+
+  where nodes 2 and 4 have arity 2 and nodes 0,1 and 3 arity 0 (terminals)
+
+  The nodes are subtrees, containing the structure of the tree, together
+  with its size and depth. They contain a Node, the user defined template
+  argument. To access these nodes from a subtree, use operator-> or operator*.
+  
+  The numbers behind the nodes define a reverse-polish or postfix 
+  traversel through the tree. The parse_tree defines iterators
+  on the tree such that 
+
+  tree.begin() points at the subtree at node0 and
+  tree.back()  returns the subtree at node4, the complete tree
+
+  Likewise operator[] is defined on the tree, such that:
+
+  tree[0] will return the subtree at node0, while
+  tree[2] will return the subtree at node2
+
+  Assigments of subtrees is protected so that the code:
+
+  tree[2] = tree[0];
+
+  will not crash and result in a tree structured as:
+
+		node4
+		/  \
+	 node3 node0
+
+  Note that the rank numbers no longer specify their place in the tree:
+
+  tree[0] still points at node0, but
+  tree[1] now points to node3 and
+  tree[2] points at the root node4
+
+  Embedded iterators are implemented to iterate over nodes rather
+  than subtrees. So an easy way to copy your tree to a vector is:
+
+  vector<Node> vec(tree.size());
+  copy(tree.ebegin(), tree.eend(), vec.begin());
+
+  You can also copy it to an ostream_iterator with this 
+  technique, given that your Node implements an appropriate
+  operator<<. Reinitializing a tree with the vector is also 
+  simple:
+
+  tree.clear();
+  copy(vec.begin(), vec.end(), back_inserter(tree));
+
+  Note that the back_inserter must be used as there is no
+  resize member in the parse_tree. back_inserter will use
+  the push_back member from the parse_tree
+
+*/
+
+#include <vector>
+#include <utility> // for swap
+
+#ifdef _MSC_VER
+#pragma warning(disable : 4786) // disable this nagging warning about the limitations of the mirkosoft debugger
+#endif
+	
+namespace gp_parse_tree
+{
+
+#include "node_pool.h"
+
+
+template <class T>
+inline void do_the_swap(T& a, T& b) 
+{
+  T tmp = a;
+  a = b;
+  b = tmp;
+}
+
+template <class T> class parse_tree
+{
+  public :
+
+class subtree
+{
+
+// a bit nasty way to use a pool allocator (which would otherwise use slooow new and delete)
+#if (defined(__GNUC__) || defined(_MSC_VER)) && !defined(_MT)    
+    Node_alloc<T>         node_allocator;
+    Tree_alloc<subtree>   tree_allocator;
+#else
+    Standard_Node_alloc<T>    node_allocator;
+    Standard_alloc<subtree>   tree_allocator;
+#endif
+
+public :
+
+    typedef subtree* iterator;
+    typedef const subtree* const_iterator;
+	//typedef std::vector<subtree >::const_reverse_iterator const_reverse_iterator;
+	
+	/* Constructors, assignments */
+
+    subtree(void) : content(node_allocator.allocate()), args(0), parent(0), _cumulative_size(0), _depth(0), _size(1) 
+			{}
+    subtree(const subtree& s) : content(node_allocator.allocate()), args(0), parent(0), _cumulative_size(0), _depth(0), _size(1) 
+			{ copy(s); } 
+    subtree(const T& t) : content(node_allocator.allocate()), args(0), parent(0), _cumulative_size(0), _depth(0), _size(1)
+			{ copy(t); } 
+
+    template <class It>
+        subtree(It b, It e) : content(node_allocator.allocate()), args(0), parent(0), _cumulative_size(0), _depth(0), _size(1) 
+    { // initialize in prefix way for efficiency reasons
+        init(b, --e);
+    }
+
+    virtual ~subtree(void)    { tree_allocator.deallocate(args, arity()); node_allocator.deallocate(content); }
+    
+    subtree& operator=(const subtree& s) 
+	{ 
+	    if (s.get_root() == get_root())
+        { // from the same tree, maybe a child. Don't take any chances
+            subtree anotherS = s;
+            return copy(anotherS);
+        }
+
+		return copy(s); 
+	}
+
+    subtree& operator=(const T& t)       { return copy(t); }
+
+	/* Access to the nodes */
+
+    T&       operator*(void)             { return *content; } 
+    const T& operator*(void) const       { return *content; }
+    T*       operator->(void)            { return content; } 
+    const T* operator->(void) const      { return content; }
+
+	/* Equality, inequality check, Node needs to implement operator== */
+
+	bool operator==(const subtree& other) const
+	{
+		if (! (*content == *other.content))
+			return false;
+
+		for (int i = 0; i < arity(); i++)
+		{
+			if (!(args[i] == other.args[i]))
+				return false;
+		}
+
+		return true;
+	}
+
+	bool operator !=(const subtree& other) const
+	{
+		return !operator==(other);
+	}
+
+	/* Arity */
+    int arity(void) const                { return content->arity(); }
+
+	/* Evaluation with an increasing amount of user defined arguments */
+	template <class RetVal>
+	RetVal   apply(RetVal v) const				 { return (*content)(v, begin()); }
+	
+	template <class RetVal, class It>
+		RetVal   apply(RetVal v, It values) const		 { return (*content)(v, begin(), values); }
+
+	template <class RetVal, class It, class It2>
+		RetVal   apply(RetVal v, It values, It2 moreValues) const		 
+		{ return (*content)(v, begin(), values, moreValues); }
+
+	template <class RetVal, class It, class It2, class It3>
+		RetVal   apply(RetVal v, It values, It2 moreValues, It3 evenMoreValues) const		 
+		{ return (*content)(v, begin(), values, moreValues, evenMoreValues); }
+
+
+	/* Iterators */
+
+    iterator begin(void)              { return args; }
+    const_iterator begin(void) const  { return args; }
+
+    iterator end(void)                { return args + arity(); }
+    const_iterator end(void) const    { return args + arity(); }
+
+	subtree& operator[](int i)		  { return *(begin() + i); }
+	const subtree& operator[](int i) const { return *(begin() + i); }
+
+	/* Some statistics */
+
+    size_t size(void) const { return _size; }
+        
+    size_t cumulative_size(void) const { return _cumulative_size; }
+    size_t depth(void) const           { return _depth; }
+    
+    const subtree& select_cumulative(size_t which) const
+    { return imp_select_cumulative(which); }
+
+    subtree& select_cumulative(size_t which) 
+    { return const_cast<subtree&>(imp_select_cumulative(which)); }
+
+    subtree& get_node(size_t which)
+    { return const_cast<subtree&>(imp_get_node(which));}
+    const subtree& get_node(size_t which) const
+    { return imp_get_node(which); }
+    
+    subtree*       get_parent(void)        { return parent; }
+    const subtree* get_parent(void) const  { return parent; }
+
+	void clear(void)
+	{ tree_allocator.deallocate(args, arity()); args = 0; *content = T(); parent = 0; _cumulative_size = 0; _depth = 0; _size = 0; }
+
+	void swap(subtree& y)
+	{
+		do_the_swap(content, y.content);
+		do_the_swap(args, y.args);
+		do_the_swap(parent, y.parent);
+
+		do_the_swap(_cumulative_size, y._cumulative_size);
+		do_the_swap(_depth, y._depth);
+		do_the_swap(_size, y._size);
+		updateAfterInsert();
+	}
+
+	friend void swap(subtree& x, subtree& y)
+	{
+		x.swap(y);
+	}
+
+protected :
+
+	virtual void updateAfterInsert(void)
+    {
+        _depth = 0;
+        _size = 1;    
+        _cumulative_size = 0;
+
+        for (iterator it = begin(); it != end(); ++it)
+        {
+            _size += it->size();
+            _cumulative_size += it->_cumulative_size;
+            _depth = it->_depth > _depth? it->_depth: _depth;
+        }
+        _cumulative_size += _size;
+        _depth++;
+
+        if (parent)
+            parent->updateAfterInsert();
+    }
+
+private :
+
+    const subtree& imp_select_cumulative(size_t which) const
+    {
+        if (which >= (_cumulative_size - size()))
+            return *this;
+        // else
+
+        for (int i = arity() - 1; i >= 0; --i)
+		{
+            if (which < args[i]._cumulative_size)
+                return args[i].imp_select_cumulative(which);
+            which -= args[i]._cumulative_size;
+        }
+    
+        return *this; // error!
+    }
+
+    const subtree& imp_get_node(size_t which) const
+    {
+        if (which == size() - 1)
+            return *this;
+    
+        for (int i = arity() - 1; i >= 0; --i)
+		{
+            unsigned c_size = args[i].size();
+            if (which < c_size)
+                return args[i].imp_get_node(which);
+            which -= c_size;
+        }
+
+        return *this; // error!
+    }
+
+    const subtree* get_root(void) const
+    {
+        if (parent == 0)
+            return this;
+        // else
+
+        return parent->get_root();
+    }
+
+    subtree& copy(const subtree& s)
+    {
+		int oldArity = arity();
+
+		disown();
+        
+		int ar = s.arity();
+		
+		if (ar != oldArity)
+		{
+			tree_allocator.deallocate(args, oldArity);
+
+            args = tree_allocator.allocate(ar);
+
+			//if (ar > 0)
+			//	args = new subtree [ar];
+			//else 
+			//	args = 0;
+		}
+
+		switch(ar)
+		{
+		case 3 : args[2].copy(s.args[2]); // no break!
+		case 2 : args[1].copy(s.args[1]);
+		case 1 : args[0].copy(s.args[0]); break;
+		case 0 : break;
+		default :
+			{
+				for (int i = 0; i < ar; ++i)
+				{
+					args[i].copy(s.args[i]);
+				}
+			}
+		}
+		
+		*content = *s.content; 
+        
+        adopt();
+        updateAfterInsert();
+        return *this;
+    }
+
+    subtree& copy(const T& t)
+    {
+        int oldArity = arity();
+        
+		if (content != &t)
+            *content = t;
+		else
+			oldArity = -1; 
+        
+		int ar = arity();
+		
+		if (ar != oldArity)
+		{
+            if (oldArity != -1)
+			    tree_allocator.deallocate(args, oldArity);
+
+            args = tree_allocator.allocate(ar);
+			
+            //if (ar > 0)
+			//	args = new subtree [ar];
+			//else 
+			//	args = 0;
+		}
+
+        adopt();
+        updateAfterInsert();
+		return *this;
+    }
+
+	void disown(void)
+	{
+		switch(arity())
+		{
+		case 3 : args[2].parent = 0; // no break!
+		case 2 : args[1].parent = 0;
+		case 1 : args[0].parent = 0; break;
+		case 0 : break;
+		default :
+			{
+				for (iterator it = begin(); it != end(); ++it)
+				{
+					it->parent = 0;
+				}
+			}
+		}
+		
+	}
+
+    void adopt(void)
+    {
+		switch(arity())
+		{
+		case 3 : args[2].parent = this; // no break!
+		case 2 : args[1].parent = this;
+		case 1 : args[0].parent = this; break;
+		case 0 : break;
+		default :
+			{
+				for (iterator it = begin(); it != end(); ++it)
+				{
+					it->parent = this;
+				}
+			}
+		}		
+    }
+
+    template <class It>
+    void init(It b, It& last)
+    {
+        *this = *last;
+
+#ifndef NDEBUG
+        if (last == b && arity() > 0)
+        {
+            throw "subtree::init()";
+        }
+#endif
+
+        for (int i = 0; i < arity(); ++i)
+        {
+            args[i].parent = 0;
+            args[i].init(b, --last);
+            args[i].parent = this;
+        }
+
+        updateAfterInsert();
+    }
+
+    T* content;
+    subtree*			args;
+    subtree*			parent;
+
+	size_t _cumulative_size;
+    size_t _depth;
+    size_t _size;
+};
+
+// Continuing with parse_tree
+
+    typedef T value_type;
+
+	/* Constructors and Assignments */
+
+    parse_tree(void) : _root(), pushed() {}
+    parse_tree(const parse_tree& org) : _root(org._root), pushed(org.pushed) { }
+    parse_tree(const subtree& sub) : _root(sub), pushed() { }
+	
+    template <class It>
+        parse_tree(It b, It e) : _root(b, e), pushed() {}
+    
+    virtual ~parse_tree(void) {}
+
+    parse_tree& operator=(const parse_tree& org) { return copy(org); }
+	parse_tree& operator=(const subtree& sub) 
+		{ return copy(sub); }
+    
+
+	/* Equality and inequality */
+
+	bool operator==(const parse_tree& other) const
+	{ return _root == other._root; }
+	
+	bool operator !=(const parse_tree& other) const
+	{ return !operator==(other); }
+
+	/* Simple tree statistics */
+
+    size_t size(void) const  { return _root.size(); }
+	size_t depth(void) const { return _root.depth(); }
+    void clear(void)        { _root.clear(); pushed.resize(0); }
+
+	/* Evaluation (application), with an increasing number of user defined arguments */
+
+	template <class RetVal>
+	RetVal apply(RetVal v) const 
+		{ return _root.apply(v); }
+
+	template <class RetVal, class It>
+		RetVal apply(RetVal v, It varValues) const 
+		{ return _root.apply(v, varValues); }
+    
+	template <class RetVal, class It, class It2>
+		RetVal apply(RetVal v, It varValues, It2 moreValues) const 
+		{ return _root.apply(v, varValues, moreValues); }
+    
+	template <class RetVal, class It, class It2, class It3>
+		RetVal apply(RetVal v, It varValues, It2 moreValues, It3 evenMoreValues) const 
+		{ return _root.apply(v, varValues, moreValues, evenMoreValues); }
+    
+	/* Customized Swap */
+	void swap(parse_tree<T>& other)
+	{
+		do_the_swap(pushed, other.pushed);
+		_root.swap(other._root);
+	}
+
+	/* Definitions of the iterators */
+
+    class base_iterator
+    {
+    public :
+        
+		base_iterator() {}
+        base_iterator(subtree* n)  { node = n; }
+
+        base_iterator& operator=(const base_iterator& org)
+        { node = org.node; return *this; }
+
+        bool operator==(const base_iterator& org) const
+        { return node == org.node; }
+        bool operator!=(const base_iterator& org) const
+        { return !operator==(org); }
+
+		base_iterator operator+(size_t n) const
+		{
+			base_iterator tmp = *this;
+			
+			for(;n != 0; --n)
+			{
+				++tmp;
+			}
+
+			return tmp;
+		}
+        
+		base_iterator& operator++(void)
+        {
+            subtree* parent = node->get_parent();
+
+            if (parent == 0)
+            {
+                node = 0;
+                return *this;
+            }
+            // else
+			subtree::iterator it;
+            for (it = parent->begin(); it != parent->end(); ++it)
+            {
+                if (node == &(*it))
+                    break;
+            }
+
+            if (it == parent->begin())
+                node = parent;
+            else
+            {
+                node = &(--it)->get_node(0);
+            }
+            
+            return *this;
+        }
+
+        base_iterator operator++(int)
+        {
+            base_iterator tmp = *this;
+            operator++();
+            return tmp;
+        }
+
+    protected :
+        subtree* node;
+    };
+
+    class iterator : public base_iterator
+    {
+    public :
+		typedef std::forward_iterator_tag iterator_category;
+		typedef subtree value_type;
+		typedef size_t distance_type;
+		typedef size_t difference_type;
+		typedef subtree* pointer;
+		typedef subtree& reference;
+
+        iterator() : base_iterator() {}
+        iterator(subtree* n): base_iterator(n)  {}
+        iterator& operator=(const iterator& org)
+        { base_iterator::operator=(org); return *this; }
+
+        subtree& operator*(void)  { return *node; }
+        subtree* operator->(void) { return node; }
+    };
+
+    class embedded_iterator : public base_iterator
+    {
+    public :
+		typedef std::forward_iterator_tag iterator_category;
+		typedef T value_type;
+		typedef size_t distance_type;
+		typedef size_t difference_type;
+		typedef T* pointer;
+		typedef T& reference;
+
+        embedded_iterator() : base_iterator() {}
+        embedded_iterator(subtree* n): base_iterator(n)  {}
+        embedded_iterator& operator=(const embedded_iterator& org)
+        { base_iterator::operator=(org); return *this; }
+
+        T&  operator*(void)  { return **node; }
+        T* operator->(void) { return &**node; }
+    };
+
+    class base_const_iterator
+    {
+    public :
+        base_const_iterator() {}
+        base_const_iterator(const subtree* n)  { node = n; }
+
+        base_const_iterator& operator=(const base_const_iterator& org)
+        { node = org.node; return *this; }
+
+        bool operator==(const base_const_iterator& org) const
+        { return node == org.node; }
+        bool operator!=(const base_const_iterator& org) const
+        { return !operator==(org); }
+
+        base_const_iterator& operator++(void)
+        {
+            const subtree* parent = node->get_parent();
+
+            if (parent == 0)
+            {
+                node = 0;
+                return *this;
+            }
+            // else
+			subtree::const_iterator it;
+
+            for (it = parent->begin(); it != parent->end(); ++it)
+            {
+                if (node == &(*it))
+                    break;
+            }
+
+            if (it == parent->begin())
+                node = parent;
+            else
+                node = &(--it)->get_node(0);
+            return *this;
+        }
+
+        base_const_iterator operator++(int)
+        {
+            base_const_iterator tmp = *this;
+            operator++();
+            return tmp;
+        }
+
+    protected :
+       
+        const subtree* node;
+    };
+
+    class const_iterator : public base_const_iterator
+    {
+    public :
+		typedef std::forward_iterator_tag iterator_category;
+		typedef const subtree value_type;
+		typedef size_t distance_type;
+		typedef size_t difference_type;
+		typedef const subtree* pointer;
+		typedef const subtree& reference;
+
+        const_iterator() : base_const_iterator() {}
+        const_iterator(const subtree* n): base_const_iterator(n)  {}
+        const_iterator& operator=(const const_iterator& org)
+        { base_const_iterator::operator=(org); return *this; }
+
+        const subtree& operator*(void)  { return *node; }
+        const subtree* operator->(void) { return node; }
+    };
+
+    class embedded_const_iterator : public base_const_iterator
+    {
+    public :
+		typedef std::forward_iterator_tag iterator_category;
+		typedef const T value_type;
+		typedef size_t distance_type;
+		typedef size_t difference_type;
+		typedef const T* pointer;
+		typedef const T& reference;
+
+        embedded_const_iterator() : base_const_iterator() {}
+        embedded_const_iterator(const subtree* n): base_const_iterator(n)  {}
+        embedded_const_iterator& operator=(const embedded_const_iterator& org)
+        { base_const_iterator::operator=(org); return *this; }
+
+		embedded_const_iterator operator+(size_t n) const
+		{
+			embedded_const_iterator tmp = *this;
+			
+			for(;n != 0; --n)
+			{
+				++tmp;
+			}
+
+			return tmp;
+		}
+
+        const T&  operator*(void)  const { return **node; }
+        const T*  operator->(void) const { return node->operator->(); }
+    };
+
+	/* Iterator access */
+
+    iterator begin(void)            { return iterator(&operator[](0)); } 
+    const_iterator begin(void) const { return const_iterator(&operator[](0)); }
+    iterator end(void)               { return iterator(0); }
+    const_iterator end(void) const   { return const_iterator(0);}
+
+    embedded_iterator       ebegin(void)       { return embedded_iterator(&operator[](0)); } 
+    embedded_const_iterator ebegin(void) const { return embedded_const_iterator(&operator[](0)); }
+    embedded_iterator       eend(void)         { return embedded_iterator(0); }
+    embedded_const_iterator eend(void) const   { return embedded_const_iterator(0);}
+
+    bool empty(void) const { return size() == 0; }
+    bool valid(void) const { return pushed.empty(); }
+
+	/* push_back */
+
+	void push_back(const parse_tree<T>& tree)
+	{
+		if (!empty())
+			pushed.push_back(_root);
+
+		_root = tree.back();
+	}
+
+    void push_back(const T& t)
+    {
+        if (!empty())
+            pushed.push_back(_root);
+        
+		_root = t;
+
+        for (subtree::iterator it = _root.begin(); it != _root.end(); it++)
+        {
+			*it = pushed.back();   
+            pushed.pop_back();
+        }
+
+    }
+
+	/* Access to subtrees */
+
+    subtree& back(void)              { return _root; }
+    const subtree& back(void) const  { return _root; }
+    subtree& root(void)              { return _root; }
+    const subtree& root(void) const  { return _root; }
+    
+    subtree& front(void)              { return _root[0]; }
+    const subtree& front(void) const  { return _root[0]; }
+
+    subtree& operator[](size_t i)
+    { return const_cast<subtree&>(_root.get_node(i)); }
+    const subtree& operator[](size_t i) const
+    { return _root.get_node(i); }
+
+    subtree& get_cumulative(size_t i)
+    { return const_cast<subtree&>(_root.get_cumulative(i)); }
+    const subtree& get_cumulative(size_t i) const
+    { return get_cumulative(i); }
+
+    private :
+		
+    parse_tree& copy(const parse_tree& org)
+    { 
+        _root = org._root; 
+        pushed = org.pushed; 
+        
+        return *this; 
+    }
+
+	parse_tree& copy(const subtree& sub)
+    { _root = sub; pushed.resize(0); return *this; }
+
+    subtree _root;
+    std::vector<subtree > pushed;
+}; // end class parse_tree
+
+
+} // end namespace gp_parse_tree
+
+namespace std
+{ // for use with stlport on MSVC
+
+template <class T> inline 
+std::forward_iterator_tag iterator_category(gp_parse_tree::parse_tree<T>::embedded_iterator)
+{
+	return std::forward_iterator_tag();
+}
+
+template <class T> inline 
+ptrdiff_t*  distance_type(gp_parse_tree::parse_tree<T>::embedded_iterator)
+{
+	return 0;
+}
+
+template <class T> inline 
+std::forward_iterator_tag iterator_category(gp_parse_tree::parse_tree<T>::iterator)
+{
+	return std::forward_iterator_tag();
+}
+
+template <class T> inline 
+ptrdiff_t*  distance_type(gp_parse_tree::parse_tree<T>::iterator)
+{
+	return 0;
+}
+
+// Put customized swaps also in std...
+
+template<class T> inline
+void swap(gp_parse_tree::parse_tree<T>& a, gp_parse_tree::parse_tree<T>& b)
+{
+    a.swap(b);
+}
+
+template<class T> inline
+void iter_swap(vector<gp_parse_tree::parse_tree<T> >::iterator a, vector<gp_parse_tree::parse_tree<T> > b)
+{
+    a->swap(*b);
+}
+
+
+} // namespace std
+
+
+#endif