const_preorder_iterator and const_postorder_iterator and associated methods

[ginac.git] / ginac / ex.h

diff --git a/ginac/ex.h b/ginac/ex.h
index 14695fd9b1b10258a0d25cc1f8d864211f6db50b..ef121bc5d2402a1878f5f0a2d2869898f50a63bf 100644 (file)
--- a/ginac/ex.h
+++ b/ginac/ex.h
@@ -55,14 +55,15 @@ static library_init library_initializer;
 
 class scalar_products;
 class const_iterator;
+class const_preorder_iterator;
+class const_postorder_iterator;
 
 
 /** Lightweight wrapper for GiNaC's symbolic objects.  Basically all it does is
  *  to hold a pointer to the other objects, manage the reference counting and
  *  provide methods for manipulation of these objects.  (Some people call such
  *  a thing a proxy class.) */
-class ex
-{
+class ex {
        friend class archive_node;
        friend inline bool are_ex_trivially_equal(const ex &, const ex &);
        template<class T> friend inline const T &ex_to(const ex &);
@@ -106,6 +107,10 @@ public:
        // iterators
        const_iterator begin() const throw();
        const_iterator end() const throw();
+       const_preorder_iterator preorder_begin() const;
+       const_preorder_iterator preorder_end() const throw();
+       const_postorder_iterator postorder_begin() const;
+       const_postorder_iterator postorder_end() const throw();
 
        // evaluation
        ex eval(int level = 0) const { return bp->eval(level); }
@@ -404,8 +409,7 @@ bool ex::is_equal(const ex & other) const
 
 // Iterators
 
-class const_iterator : public std::iterator<std::random_access_iterator_tag, ex, ptrdiff_t, const ex *, const ex &>
-{
+class const_iterator : public std::iterator<std::random_access_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
        friend class ex;
        friend class const_preorder_iterator;
        friend class const_postorder_iterator;
@@ -551,27 +555,24 @@ struct _iter_rep {
 
 } // namespace internal
 
-class const_preorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &>
-{
+class const_preorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
 public:
        const_preorder_iterator() throw() {}
 
-       // Provide implicit conversion from const_iterator, so ex::begin() and
-       // ex::end() can be used to create const_preorder_iterators
-       const_preorder_iterator(const const_iterator & cit)
+       const_preorder_iterator(const ex &e, size_t n)
        {
-               s.push(internal::_iter_rep(cit.e, cit.i, cit.e.nops()));
+               s.push(internal::_iter_rep(e, 0, n));
        }
 
 public:
-       ex operator*() const
+       reference operator*() const
        {
                return s.top().e;
        }
 
-       std::auto_ptr<ex> operator->() const
+       pointer operator->() const
        {
-               return std::auto_ptr<ex>(new ex(operator*()));
+               return &(s.top().e);
        }
 
        const_preorder_iterator &operator++()
@@ -589,7 +590,7 @@ public:
 
        bool operator==(const const_preorder_iterator &other) const throw()
        {
-               return s.top() == other.s.top();
+               return s == other.s;
        }
 
        bool operator!=(const const_preorder_iterator &other) const throw()
@@ -602,8 +603,10 @@ private:
 
        void increment()
        {
-               while (s.top().i == s.top().i_end && s.size() > 1) {
+               while (!s.empty() && s.top().i == s.top().i_end) {
                        s.pop();
+                       if (s.empty())
+                               return;
                        ++s.top().i;
                }
 
@@ -616,31 +619,25 @@ private:
        }
 };
 
-class const_postorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &>
-{
+class const_postorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
 public:
        const_postorder_iterator() throw() {}
 
-       // Provide implicit conversion from const_iterator, so ex::begin() and
-       // ex::end() can be used to create const_postorder_iterators
-       const_postorder_iterator(const const_iterator & cit)
+       const_postorder_iterator(const ex &e, size_t n)
        {
-               size_t n = cit.e.nops();
-               if (cit.i != n) {
-                       s.push(internal::_iter_rep(cit.e, cit.i, n));
-                       descend();
-               }
+               s.push(internal::_iter_rep(e, 0, n));
+               descend();
        }
 
 public:
-       ex operator*() const
+       reference operator*() const
        {
                return s.top().e;
        }
 
-       std::auto_ptr<ex> operator->() const
+       pointer operator->() const
        {
-               return std::auto_ptr<ex>(new ex(operator*()));
+               return &(s.top().e);
        }
 
        const_postorder_iterator &operator++()
@@ -682,7 +679,7 @@ private:
        {
                if (s.top().i == s.top().i_end)
                        s.pop();
-               if (s.size() > 0) {
+               if (!s.empty()) {
                        ++s.top().i;
                        descend();
                }
@@ -699,6 +696,26 @@ inline const_iterator ex::end() const throw()
        return const_iterator(*this, nops());
 }
 
+inline const_preorder_iterator ex::preorder_begin() const
+{
+       return const_preorder_iterator(*this, nops());
+}
+
+inline const_preorder_iterator ex::preorder_end() const throw()
+{
+       return const_preorder_iterator();
+}
+
+inline const_postorder_iterator ex::postorder_begin() const
+{
+       return const_postorder_iterator(*this, nops());
+}
+
+inline const_postorder_iterator ex::postorder_end() const throw()
+{
+       return const_postorder_iterator();
+}
+
 
 // utility functions