Initial revision

src/win95/list_tem.hpp

@@ -0,0 +1,871 @@
+// Doubly linked list class.
+//
+// Inserts new entries at the *end* of the list -- so add_entry()
+// followed by delete_last_entry() will do nothing.
+//
+//
+// Usage:
+//
+// List<Thing> l;               creates an empty list.
+// Thing a; List<Thing> l(a);   creates a list containing a.
+//      
+// void l.add_entry(Thing a);        adds an entry.
+// void l.delete_entry(Thing a);     removes `a' from the list if it's there, 
+//                                   aborts if it's not.
+// void l.delete_{first,last}_entry  deletes the first/last entry.
+// Thing l.{first,last}_entry        returns the first/last entry.
+// bool l.contains(Thing a)          is a in the list?
+#ifndef list_template_hpp
+#define list_template_hpp
+
+#pragma once
+
+#include <stdio.h>
+
+#ifdef _CPPRTTI // run time type information available
+	#include <typeinfo.h>
+	#define LIST_TEM_TYPEID_THIS typeid(*this).name()
+#else
+	#define LIST_TEM_TYPEID_THIS "?"
+#endif
+
+#if defined(engine) 
+// Not all preprocessors do lazy evaluation. DW
+#if engine
+	#include "mem3dc.h"
+#endif
+#endif
+
+#ifdef NDEBUG
+	#define fail if (0)
+	#define list_fail_get_data_from_sentinel NULL
+	#define list_fail_add_entry_after NULL
+	#define list_fail_add_entry_before NULL
+	#define list_fail_delete_entry NULL
+	#define list_fail_delete_entry_by_pointer NULL
+	#define list_fail_alter_entry NULL
+	#define list_fail_next_entry_nonexist NULL
+	#define list_fail_next_entry_sentinel NULL
+	#define list_fail_prev_entry_nonexist NULL
+	#define list_fail_prev_entry_sentinel NULL
+	#define list_fail_last_entry NULL
+	#define list_fail_first_entry NULL
+	#define list_fail_similar_entry NULL
+	#define list_fail_delete_last_entry NULL
+	#define list_fail_delete_first_entry NULL
+	#define list_fail_operator NULL
+	#define lit_fail_next NULL
+	#define lit_fail_operator NULL
+	#define lit_fail_delete_current NULL
+	#define lit_fail_change_current NULL
+#else
+	#include "fail.h"
+	extern char const * list_fail_get_data_from_sentinel;
+	extern char const * list_fail_add_entry_after;
+	extern char const * list_fail_add_entry_before;
+	extern char const * list_fail_delete_entry;
+	extern char const * list_fail_delete_entry_by_pointer;
+	extern char const * list_fail_alter_entry;
+	extern char const * list_fail_next_entry_nonexist;
+	extern char const * list_fail_next_entry_sentinel;
+	extern char const * list_fail_prev_entry_nonexist;
+	extern char const * list_fail_prev_entry_sentinel;
+	extern char const * list_fail_last_entry;
+	extern char const * list_fail_first_entry;
+	extern char const * list_fail_similar_entry;
+	extern char const * list_fail_delete_last_entry;
+	extern char const * list_fail_delete_first_entry;
+	extern char const * list_fail_operator;
+	extern char const * lit_fail_next;
+	extern char const * lit_fail_operator;
+	extern char const * lit_fail_delete_current;
+	extern char const * lit_fail_change_current;
+#endif
+
+// The first declaration of these class templates was previously as friends
+// of List. However, Visual C++ 5 can't parse them unless we give a 
+// forward declaration first - I think this is a compiler bug - Garry.
+template<class T>
+class List_Iterator_Forward;
+template<class T>
+class ConstList_Iterator_Forward;
+template<class T>
+class List_Iterator_Backward;
+template<class T>
+class ConstList_Iterator_Backward;
+template<class T>
+class List_Iterator_Loop;
+
+template<class T>
+struct List_Member;
+
+template<class T>
+struct List_Member_Base
+{
+	union
+	{
+		List_Member_Base<T> *prev;
+		#ifndef __WATCOMC__
+	   	List_Member<T> *prev_debug; // encourage the debugger to display the list members data
+		#endif                      // hopefully casting from base to derived class would not
+		                            // cause the actual value of the ptr to change, so the debugger
+		                            // will display the information correctly, and this union
+		                            // won't cause any kind of performance hit
+
+									//watcom doesn't appear to like this, unfortunately.
+
+									
+		
+	};
+	union
+	{
+		List_Member_Base<T> *next;
+		#ifndef __WATCOMC__
+		List_Member<T> *next_debug;
+		#endif
+	};
+	virtual ~List_Member_Base() {}
+};
+
+template<class T>
+struct List_Member : public List_Member_Base<T>
+{
+  T data;
+  List_Member<T>(const T& n) : data(n) {}
+};
+
+template<class T>
+class List {
+private:
+  List_Member_Base<T> *sentinel;
+  int n_entries;
+  mutable T **entry_pointers;
+  mutable bool calculated_indices;
+
+  T& data(List_Member_Base<T>* e) const
+  {
+    if (e == sentinel)
+      fail(list_fail_get_data_from_sentinel,LIST_TEM_TYPEID_THIS);
+    return ((List_Member<T>*)e)->data;
+  }
+
+public:
+  List() {
+    sentinel = new List_Member_Base<T>;
+
+    sentinel->next = sentinel;
+    sentinel->prev = sentinel;
+        
+    n_entries = 0;
+    entry_pointers = 0;
+    calculated_indices = false;
+  }
+
+  List(const T& n) {
+    sentinel = new List_Member_Base<T>;
+    sentinel->next = sentinel;
+    sentinel->prev = sentinel;
+    n_entries = 0;       
+    entry_pointers = 0;
+    calculated_indices = false;
+
+    add_entry(n);
+  }
+
+  List(const List<T>& l) {
+    sentinel = new List_Member_Base<T>;
+
+    sentinel->next = sentinel;
+    sentinel->prev = sentinel;
+    n_entries = 0;
+
+    entry_pointers = 0;
+    calculated_indices = false;
+
+    List_Member_Base<T>* m = l.sentinel->next;
+    while (m != l.sentinel) {
+      add_entry(data(m));
+      m = m->next;
+    }
+
+  }  
+
+  List<T>& operator= (const List<T>& l) {
+    while(n_entries != 0) delete_last_entry();
+    if (entry_pointers != 0)
+      delete[] entry_pointers;
+
+    List_Member_Base<T>* m = l.sentinel->next;
+    while (m != l.sentinel) {
+      add_entry(data(m));
+      m = m->next;
+    }
+    calculated_indices = false;
+    entry_pointers = 0;
+    return *this;
+  }
+    
+  ~List() {
+    while (n_entries != 0) delete_last_entry();
+    delete sentinel;
+    delete[] entry_pointers; 
+  }
+
+  void add_entry(const T& n) {
+    add_entry_end(n);
+  }
+
+  void add_entry_end(const T& n) {
+    List_Member<T> *e = new List_Member<T>(n);
+    e->next = sentinel;
+    e->prev = sentinel->prev;
+    sentinel->prev->next = e;
+    sentinel->prev = e;
+    n_entries++;
+    cleanup();
+  }
+
+  void add_entry_start(const T& n) {
+    List_Member<T> *e = new List_Member<T>(n);
+    e->prev = sentinel;
+    e->next = sentinel->next;
+    sentinel->next->prev = e;
+    sentinel->next = e;
+    n_entries++;
+    cleanup();
+  }
+
+  void add_entry_after(const T& n, const T& d) {
+    List_Member_Base<T> *f = sentinel->next;
+    while (f != sentinel && data(f) != d) {
+      f = f->next;
+    }
+    if (f == sentinel) {
+      fail(list_fail_add_entry_after,LIST_TEM_TYPEID_THIS);
+    } else {
+      List_Member<T> *e = new List_Member<T>(n);
+      e->next = f->next;
+      e->prev = f;
+      e->next->prev = e;
+      f->next = e;
+      n_entries++;
+    }
+    cleanup();
+  }
+
+  void add_entry_before(const T& n, const T& d) {
+    List_Member_Base<T> *f = sentinel->next;
+    while (f != sentinel && data(f) != d) {
+      f = f->next;
+    }
+    if (f == sentinel) {
+      fail(list_fail_add_entry_before,LIST_TEM_TYPEID_THIS);
+    } else {
+      List_Member<T> *e = new List_Member<T>(n);
+      e->prev = f->prev;
+      e->next = f;
+      e->prev->next = e;
+      f->prev = e;
+      n_entries++;
+    }
+    cleanup();
+  }
+
+  void delete_entry(const T& d) {
+    List_Member_Base<T> *e = sentinel->next;
+    while (e != sentinel && data(e) != d && e != sentinel) {
+      e = e->next;
+    }
+    if (e == sentinel) {
+      fail(list_fail_delete_entry,LIST_TEM_TYPEID_THIS);
+    } else {
+      e->prev->next = e->next;
+      e->next->prev = e->prev;
+      delete e;
+    }
+    n_entries--;
+    cleanup();
+  }
+
+  void delete_entry_backward(const T& d) {
+    List_Member_Base<T> *e = sentinel->prev;
+    while (e != sentinel && data(e) != d && e != sentinel) {
+      e = e->prev;
+    }
+    if (e == sentinel) {
+      fail(list_fail_delete_entry,LIST_TEM_TYPEID_THIS);
+    } else {
+      e->prev->next = e->next;
+      e->next->prev = e->prev;
+      delete e;
+    }
+    n_entries--;
+    cleanup();
+  }
+
+  void delete_entry_by_pointer(List_Member_Base<T>* l) {
+    if (l == sentinel)
+      fail(list_fail_delete_entry_by_pointer,LIST_TEM_TYPEID_THIS);
+    l->next->prev = l->prev;
+    l->prev->next = l->next;
+    delete l;
+    l = 0; // so we get a seg if we try and reuse it
+    n_entries--;
+    cleanup();
+  }
+
+  void alter_entry(const T& od, const T& nd) {
+    List_Member_Base<T> *e = sentinel->next;
+    while (e != sentinel && data(e) != od) {
+      e = e->next;
+    }
+    if (e == sentinel) {
+      fail(list_fail_alter_entry,LIST_TEM_TYPEID_THIS);
+    } else {
+      // Remove this entry, and put a new one in it's place. We can't
+      // just do e->data = nd, because that's assignment, and we don't
+      // want to require an assignment operator to be defined for
+      // every thing that we put on a list.
+      List_Member<T> * n = new List_Member<T>(nd);
+      e->prev->next = n;
+      e->next->prev = n;
+      n->next = e->next;
+      n->prev = e->prev;
+      delete e;
+    }
+    cleanup();
+  }
+
+  T next_entry(const T& d) const {
+    List_Member_Base<T> *e = sentinel->next;
+    while (e != sentinel && data(e) != d && e != sentinel) {
+      e = e->next;
+    }
+    if (e == sentinel) {
+      fail(list_fail_next_entry_nonexist,LIST_TEM_TYPEID_THIS);
+    } else { 
+      if (e->next == sentinel)
+        fail(list_fail_next_entry_sentinel,LIST_TEM_TYPEID_THIS);
+      return data(e->next);
+    }
+	  return data(e->next);
+  }
+
+  T prev_entry(const T& d) const {
+    List_Member_Base<T> *e = sentinel->next;
+    while (e!= sentinel && data(e) != d) {
+      e = e->next;
+    }
+    if (e == sentinel) {
+      fail(list_fail_prev_entry_nonexist,LIST_TEM_TYPEID_THIS);
+    } else { 
+      if (e->prev == sentinel)
+        fail(list_fail_prev_entry_sentinel,LIST_TEM_TYPEID_THIS);
+      return data(e->prev);
+    }
+      return data(e->prev);
+  }
+
+  T const & similar_entry(T const& d) const
+  {
+      List_Member_Base<T> *e = sentinel->next;
+      while (e != sentinel)
+      {
+          if (data(e) == d)
+          	break;
+          e = e->next;
+		  
+      }
+      if (e == sentinel) 
+      {
+          fail(list_fail_similar_entry,LIST_TEM_TYPEID_THIS);
+      } 
+      return data(e);
+  }
+  
+  bool contains(const T& d) {
+    List_Member_Base<T> *e = sentinel->next;
+    while (e != sentinel && data(e) != d) {
+      e = e->next;
+    }
+    if (e == sentinel) return false;
+    else               return true;
+  }
+
+  void delete_last_entry() {
+    if (sentinel->prev == sentinel) {
+      fail(list_fail_delete_last_entry,LIST_TEM_TYPEID_THIS);
+    } else {
+      // aiee. These lines work, but are a bit hairy.
+
+      sentinel->prev = sentinel->prev->prev;
+      delete sentinel->prev->next;
+      sentinel->prev->next = sentinel;
+      n_entries--;
+    }
+    cleanup();
+  }
+
+  void delete_first_entry() {
+    if (sentinel->next == sentinel) {
+      fail(list_fail_delete_last_entry,LIST_TEM_TYPEID_THIS);
+    } else {
+      sentinel->next = sentinel->next->next;
+      delete sentinel->next->prev;
+      sentinel->next->prev = sentinel;
+      n_entries--;
+    }
+    cleanup();
+  }
+
+  T const & operator[](int i) const {
+    if (i < 0 || i >= n_entries)
+      fail(list_fail_operator,LIST_TEM_TYPEID_THIS, i+1, n_entries);
+
+    if (!calculated_indices) {
+      if (entry_pointers != 0)
+        delete[] entry_pointers;
+      entry_pointers = new T*[n_entries+1];
+      List_Member_Base<T>*e = sentinel->next;
+      int j = 0;
+      while (e != sentinel) {
+        entry_pointers[j] = &data(e);
+        e = e->next;
+        j++;
+      }
+      calculated_indices = true;
+    }
+    return *entry_pointers[i];
+  }
+    
+  T & last_entry() 
+  {
+    if (n_entries == 0)
+      fail(list_fail_last_entry,LIST_TEM_TYPEID_THIS);
+    return data(sentinel->prev);
+  }
+
+  T const & last_entry() const
+  {
+    if (n_entries == 0)
+      fail(list_fail_last_entry,LIST_TEM_TYPEID_THIS);
+    return data(sentinel->prev);
+  }
+
+  T & first_entry() 
+  {
+    if (n_entries == 0)
+      fail(list_fail_first_entry,LIST_TEM_TYPEID_THIS);
+    return data(sentinel->next);
+  }
+
+  T const & first_entry() const 
+  {
+    if (n_entries == 0)
+      fail(list_fail_first_entry,LIST_TEM_TYPEID_THIS);
+    return data(sentinel->next);
+  }
+    
+  int size() const { return n_entries; }
+
+  void cleanup() { calculated_indices = false; if (entry_pointers != 0) delete[] entry_pointers; entry_pointers = 0;}
+
+  bool operator==(const List <T> &l1) const
+  {
+    if (n_entries != l1.n_entries) return false;
+    for (List_Member_Base<T> * e = sentinel->next, *e1 = l1.sentinel->next; e != sentinel; e = e->next, e1 = e1->next)
+    {
+      if (((List_Member<T> *)e)->data != ((List_Member<T> *)e1)->data) return false;
+    }
+    return true;
+  }
+
+  bool operator!=(const List <T> &l1) const
+  {
+    if (n_entries != l1.n_entries) return true;
+    for (List_Member_Base<T> * e = sentinel->next, *e1 = l1.sentinel->next; e != sentinel; e = e->next, e1 = e1->next)
+    {
+      if (((List_Member<T> *)e)->data != ((List_Member<T> *)e1)->data) return true;
+    }
+    return false;
+  }
+
+    friend class List_Iterator_Forward<T>;
+    friend class ConstList_Iterator_Forward<T>;
+    friend class List_Iterator_Backward<T>;
+    friend class ConstList_Iterator_Backward<T>;
+    friend class List_Iterator_Loop<T>;
+};
+
+// Use List_Iterator_{Forward,Backward} as follows:
+//
+//     for(List_Iterator_Forward<T*> oi(&(List_of_T*)); // a _pointer_ 
+//                                                      // to the list.
+//           !oi.done();
+//           oi.next()    )    {
+//          do_something( oi() ) ;
+//     }
+//
+// First entry is the one past the sentinel, and next() and
+// operator() fail if you try and iterate too far; check if it's
+// done() before doing anything else, basically.
+//
+// As it's a doubly-linked list, we can go backwards and
+// forwards. next() takes us to the entry that the type of iterator
+// suggests; un_next() takes us in the other direction. un_next() is
+// an ugly name, but next() and prev() are too suggestive of a
+// particular direction.
+
+template<class T>
+class List_Iterator_Forward
+{
+private:
+  union
+  {
+    List_Member_Base<T> *m;
+    List_Member<T> *m_debug; // encourage the debugger to display the list members data
+                             // hopefully casting from base to derived class would not
+                             // cause the actual value of the ptr to change, so the debugger
+                             // will display the information correctly, and this union
+                             // won't cause any kind of performance hit
+  };
+  List<T> *l;
+
+public:
+  List_Iterator_Forward() {}
+  List_Iterator_Forward(List<T> *list) { l = list; m = l->sentinel->next; }
+   
+  void next() {
+    if (m != l->sentinel) {
+      m = m->next;
+    } else
+      fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+  }
+    
+  void un_next() {
+    if (m != l->sentinel) {
+      m = m->prev;
+    } else 
+      fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+  }
+  
+  T & operator() () const {
+      if (m == l->sentinel)
+          fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+      return l->data(m);
+  }
+
+  void delete_current() {
+    if (m != l->sentinel) {
+      m = m->next;
+      l->delete_entry_by_pointer(m->prev);
+    } else
+      fail(lit_fail_delete_current,LIST_TEM_TYPEID_THIS);
+  }
+
+  void change_current(T const &new_val) const {
+    if (m != l->sentinel) {
+      // Delete the current member out of the list, put a new one in.
+
+      List_Member<T> * n = new List_Member<T>(new_val);
+      m->prev->next = n;
+      m->next->prev = n;
+      n->next = m->next;
+      n->prev = m->prev;
+      delete m;
+      *(List_Member_Base<T> **)&m =n; // or we're pointing at the thing we just deleted.
+      l->cleanup(); // because it's changed, but the List doesn't know that.
+    } else
+      fail(lit_fail_change_current,LIST_TEM_TYPEID_THIS);
+  }
+
+  bool done() { if (m == l->sentinel) return true; else return false; }
+  void restart() { m = l->sentinel->next; }       
+  // Go to the end of the list.
+  void end() { m = l->sentinel->prev; }
+};
+
+#define LIF List_Iterator_Forward
+
+template<class T>
+class ConstList_Iterator_Forward
+{
+  private:
+  union
+  {
+    List_Member_Base<T> *m;
+    List_Member<T> *m_debug; // encourage the debugger to display the list members data
+  };
+    List<T> const *l;
+
+  public:
+    ConstList_Iterator_Forward(List<T> const *list) { l = list; m = l->sentinel->next; }
+    ConstList_Iterator_Forward(){}
+   
+    void next() {
+        if (m == l->sentinel) {
+            fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+        }
+        m = m->next;
+    }
+    
+    void un_next() {
+        if (m == l->sentinel) {
+            fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+        }
+        m = m->prev;
+    }
+
+    T const & operator() () const {
+        if (m == l->sentinel)
+            fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+        return l->data(m);
+    }
+
+    #if 0 // shouldn't really be available on a const list
+    void change_current(T const & new_val) const {
+        if (m != l->sentinel) {
+            m->data = new_val;
+        } else
+            fail(lit_fail_change_current,LIST_TEM_TYPEID_THIS);
+    }
+    #endif
+
+    bool done() const { if (m == l->sentinel) return true; else return false; }
+    void restart() { m = l->sentinel->next; }       
+	// Go to the end of the list.
+	void end() { m = l->sentinel->prev; }
+};
+
+#define CLIF ConstList_Iterator_Forward
+
+template<class T>
+class List_Iterator_Backward
+{
+private:
+  union
+  {
+    List_Member_Base<T> *m;
+    List_Member<T> *m_debug; // encourage the debugger to display the list members data
+  };
+  List<T> *l;
+
+public:
+  List_Iterator_Backward() {}
+  List_Iterator_Backward(List<T> *list) { l = list; m = l->sentinel->prev; }
+   
+  void next() {
+    if (m != l->sentinel) {
+      m = m->prev;
+    } else
+      fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+  }
+
+  void un_next() {
+    if (m != l->sentinel) {
+      m = m->next;
+    } else
+      fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+  }
+
+  T & operator() () const {
+      if (m == l->sentinel)
+          fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+      return l->data(m);
+  }
+
+  void delete_current() {
+    if (m != l->sentinel) {
+      m = m->prev;
+      l->delete_entry_by_pointer(m->next);
+    } else
+      fail(lit_fail_delete_current,LIST_TEM_TYPEID_THIS);
+  }
+
+  void change_current(T const & new_val)  {
+    if (m != l->sentinel) {
+      // Delete the current member out of the list, put a new one in.
+
+      List_Member<T> * n = new List_Member<T>(new_val);
+      m->prev->next = n;
+      m->next->prev = n;
+      n->next = m->next;
+      n->prev = m->prev;
+      delete m;
+      m = n; // or we're pointing at the thing we just deleted.
+      l->cleanup(); // because it's changed, but the List doesn't know that.
+    } else
+      fail(lit_fail_change_current,LIST_TEM_TYPEID_THIS);
+  }
+
+  bool done() { if (m == l->sentinel) return true; else return false; }
+  void restart() { m = l->sentinel->prev; }
+  // Go to the end of the list.
+  void end() { m = l->sentinel->prev; }
+};
+
+#define LIB List_Iterator_Backward
+
+template<class T>
+class ConstList_Iterator_Backward
+{
+  private:
+  union
+  {
+    List_Member_Base<T> *m;
+    List_Member<T> *m_debug; // encourage the debugger to display the list members data
+  };
+    List<T> const *l;
+
+  public:
+    ConstList_Iterator_Backward(List<T> const *list) { l = list; m = l->sentinel->prev; }
+    ConstList_Iterator_Backward(){}
+   
+    void next() {
+        if (m == l->sentinel) {
+            fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+        }
+        m = m->prev;
+    }
+
+    void un_next() {
+        if (m == l->sentinel) {
+            fail(lit_fail_next,LIST_TEM_TYPEID_THIS);
+        }
+        m = m->next;
+    }
+
+    T const & operator() () const {
+        if (m == l->sentinel)
+            fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+        return l->data(m);
+    }
+
+    #if 0 // shouldn't really be available on a const list
+    void change_current(T const & new_val) const {
+        if (m != l->sentinel) {
+            m->data = new_val;
+        } else
+            fail(lit_fail_change_current,LIST_TEM_TYPEID_THIS);
+    }
+    #endif
+
+    bool done() const { if (m == l->sentinel) return true; else return false; }
+    void restart() { m = l->sentinel->prev; }
+	// Go to the end of the list.
+	void end() { m = l->sentinel->prev; }
+};
+
+#define CLIB ConstList_Iterator_Backward
+
+/*
+	A looping list iterator class :
+		next from the last member will go to the first
+		previous from the first member will go to the last
+*/
+
+template<class T>
+class List_Iterator_Loop
+{
+  private:
+  union
+  {
+    List_Member_Base<T> *m;
+    List_Member<T> *m_debug; // encourage the debugger to display the list members data
+  };
+    List<T> *l;
+
+  public:
+    List_Iterator_Loop(List<T> *list) { l = list; m = l->sentinel->next; }
+   
+    void next() {
+        m=m->next;
+        if (m == l->sentinel) {
+            m = m->next;
+        } 
+    }
+    
+    void previous() {
+        m=m->prev;
+        if (m == l->sentinel) {
+            m = m->prev;
+        }  
+    }
+
+    T const & operator() ()  {
+        if (m == l->sentinel)
+		{
+			m=m->next;//needed in case iterator was created before anything was added to the list
+	        if (m == l->sentinel)
+			{
+				fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+			}
+		}
+        return l->data(m);
+    }
+
+    void delete_current() {
+        if (m == l->sentinel)
+        {
+			m=m->next;//needed in case iterator was created before anything was added to the list
+			if (m == l->sentinel)
+			{
+			    fail(lit_fail_delete_current,LIST_TEM_TYPEID_THIS);
+			}
+        }
+        m = m->next;
+        l->delete_entry_by_pointer(m->prev);
+    }
+
+
+    void change_current(T const & new_val) 
+    {
+    	if (m == l->sentinel)
+       		m=m->next;//needed in case iterator was created before anything was added to the list
+      
+      	if (m != l->sentinel) 
+      	{
+        	// Delete the current member out of the list, put a new one in.
+			List_Member<T> * n = new List_Member<T>(new_val);
+        	m->prev->next = n;
+        	m->next->prev = n;
+        	n->next = m->next;
+        	n->prev = m->prev;
+        	delete m;
+        	m = n; // or we're pointing at the thing we just deleted.
+        	l->cleanup(); // because it's changed, but the List doesn't know that.
+      	}
+      	else
+        	fail(lit_fail_change_current,LIST_TEM_TYPEID_THIS);
+    }
+
+	// Go to the start of the list.
+    void restart() { m = l->sentinel->next; }       
+	
+	// Go to the end of the list.
+	void end() { m = l->sentinel->prev; }
+
+	// Is it on the last entry.
+    bool at_last() const { if (m == l->sentinel->prev) return true; else return false; }
+
+	// Get the next entry but done move the pointer.
+    T const & get_next()  {
+        if (m->next == l->sentinel)
+		{
+			if (m->next->next == l->sentinel)
+			{
+				fail(lit_fail_operator,LIST_TEM_TYPEID_THIS);
+			}
+	        return l->data(m->next->next);
+		}
+        return l->data(m->next);
+    }
+};
+
+#define LIL List_Iterator_Loop
+
+#ifdef NDEBUG
+	#undef fail // allow other code to have local variables called or differently scoped 'fail'
+#endif
+
+#endif