diff -r 000000000000 -r 6474c204b198 xpcom/string/public/nsStringIterator.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/string/public/nsStringIterator.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,327 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsStringIterator_h___
+#define nsStringIterator_h___
+
+#include "nsCharTraits.h"
+#include "nsAlgorithm.h"
+#include "nsDebug.h"
+
+  /**
+   * @see nsTAString
+   */
+
+template <class CharT>
+class nsReadingIterator
+  {
+    public:
+      typedef nsReadingIterator<CharT>    self_type;
+      typedef ptrdiff_t                   difference_type;
+      typedef CharT                       value_type;
+      typedef const CharT*                pointer;
+      typedef const CharT&                reference;
+
+    private:
+      friend class nsAString;
+      friend class nsACString;
+
+        // unfortunately, the API for nsReadingIterator requires that the
+        // iterator know its start and end positions.  this was needed when
+        // we supported multi-fragment strings, but now it is really just
+        // extra baggage.  we should remove mStart and mEnd at some point.
+
+      const CharT* mStart;
+      const CharT* mEnd;
+      const CharT* mPosition;
+
+    public:
+      nsReadingIterator() { }
+      // nsReadingIterator( const nsReadingIterator<CharT>& );                    // auto-generated copy-constructor OK
+      // nsReadingIterator<CharT>& operator=( const nsReadingIterator<CharT>& );  // auto-generated copy-assignment operator OK
+
+      inline void normalize_forward() {}
+      inline void normalize_backward() {}
+
+      pointer
+      start() const
+        {
+          return mStart;
+        }
+
+      pointer
+      end() const
+        {
+          return mEnd;
+        }
+
+      pointer
+      get() const
+        {
+          return mPosition;
+        }
+      
+      CharT
+      operator*() const
+        {
+          return *get();
+        }
+
+#if 0
+        // An iterator really deserves this, but some compilers (notably IBM VisualAge for OS/2)
+        //  don't like this when |CharT| is a type without members.
+      pointer
+      operator->() const
+        {
+          return get();
+        }
+#endif
+
+      self_type&
+      operator++()
+        {
+          ++mPosition;
+          return *this;
+        }
+
+      self_type
+      operator++( int )
+        {
+          self_type result(*this);
+          ++mPosition;
+          return result;
+        }
+
+      self_type&
+      operator--()
+        {
+          --mPosition;
+          return *this;
+        }
+
+      self_type
+      operator--( int )
+        {
+          self_type result(*this);
+          --mPosition;
+          return result;
+        }
+
+      difference_type
+      size_forward() const
+        {
+          return mEnd - mPosition;
+        }
+
+      difference_type
+      size_backward() const
+        {
+          return mPosition - mStart;
+        }
+
+      self_type&
+      advance( difference_type n )
+        {
+          if (n > 0)
+            {
+              difference_type step = XPCOM_MIN(n, size_forward());
+
+              NS_ASSERTION(step>0, "can't advance a reading iterator beyond the end of a string");
+
+              mPosition += step;
+            }
+          else if (n < 0)
+            {
+              difference_type step = XPCOM_MAX(n, -size_backward());
+
+              NS_ASSERTION(step<0, "can't advance (backward) a reading iterator beyond the end of a string");
+
+              mPosition += step;
+            }
+          return *this;
+        }
+  };
+
+  /**
+   * @see nsTAString
+   */
+
+template <class CharT>
+class nsWritingIterator
+  {
+    public:
+      typedef nsWritingIterator<CharT>   self_type;
+      typedef ptrdiff_t                  difference_type;
+      typedef CharT                      value_type;
+      typedef CharT*                     pointer;
+      typedef CharT&                     reference;
+
+    private:
+      friend class nsAString;
+      friend class nsACString;
+
+        // unfortunately, the API for nsWritingIterator requires that the
+        // iterator know its start and end positions.  this was needed when
+        // we supported multi-fragment strings, but now it is really just
+        // extra baggage.  we should remove mStart and mEnd at some point.
+
+      CharT* mStart;
+      CharT* mEnd;
+      CharT* mPosition;
+
+    public:
+      nsWritingIterator() { }
+      // nsWritingIterator( const nsWritingIterator<CharT>& );                    // auto-generated copy-constructor OK
+      // nsWritingIterator<CharT>& operator=( const nsWritingIterator<CharT>& );  // auto-generated copy-assignment operator OK
+
+      inline void normalize_forward() {}
+      inline void normalize_backward() {}
+
+      pointer
+      start() const
+        {
+          return mStart;
+        }
+
+      pointer
+      end() const
+        {
+          return mEnd;
+        }
+
+      pointer
+      get() const
+        {
+          return mPosition;
+        }
+      
+      reference
+      operator*() const
+        {
+          return *get();
+        }
+
+#if 0
+        // An iterator really deserves this, but some compilers (notably IBM VisualAge for OS/2)
+        //  don't like this when |CharT| is a type without members.
+      pointer
+      operator->() const
+        {
+          return get();
+        }
+#endif
+
+      self_type&
+      operator++()
+        {
+          ++mPosition;
+          return *this;
+        }
+
+      self_type
+      operator++( int )
+        {
+          self_type result(*this);
+          ++mPosition;
+          return result;
+        }
+
+      self_type&
+      operator--()
+        {
+          --mPosition;
+          return *this;
+        }
+
+      self_type
+      operator--( int )
+        {
+          self_type result(*this);
+          --mPosition;
+          return result;
+        }
+
+      difference_type
+      size_forward() const
+        {
+          return mEnd - mPosition;
+        }
+
+      difference_type
+      size_backward() const
+        {
+          return mPosition - mStart;
+        }
+
+      self_type&
+      advance( difference_type n )
+        {
+          if (n > 0)
+            {
+              difference_type step = XPCOM_MIN(n, size_forward());
+
+              NS_ASSERTION(step>0, "can't advance a writing iterator beyond the end of a string");
+
+              mPosition += step;
+            }
+          else if (n < 0)
+            {
+              difference_type step = XPCOM_MAX(n, -size_backward());
+
+              NS_ASSERTION(step<0, "can't advance (backward) a writing iterator beyond the end of a string");
+
+              mPosition += step;
+            }
+          return *this;
+        }
+
+      void
+      write( const value_type* s, uint32_t n )
+        {
+          NS_ASSERTION(size_forward() > 0, "You can't |write| into an |nsWritingIterator| with no space!");
+
+          nsCharTraits<value_type>::move(mPosition, s, n);
+          advance( difference_type(n) );
+        }
+  };
+
+template <class CharT>
+inline
+bool
+operator==( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.get() == rhs.get();
+  }
+
+template <class CharT>
+inline
+bool
+operator!=( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.get() != rhs.get();
+  }
+
+
+  //
+  // |nsWritingIterator|s
+  //
+
+template <class CharT>
+inline
+bool
+operator==( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
+  {
+    return lhs.get() == rhs.get();
+  }
+
+template <class CharT>
+inline
+bool
+operator!=( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
+  {
+    return lhs.get() != rhs.get();
+  }
+
+#endif /* !defined(nsStringIterator_h___) */