Incremental changes. These files are not yet part of the build.

string/public/nsAReadableString.h

@@ -71,6 +71,10 @@ template <class CharT> class basic_nsAWritableString;
 template <class CharT> class basic_nsLiteralString;
   // ...because we sometimes use them as in params to force the conversion of |CharT*|s
 
+template <class CharT> class nsPromiseConcatenation;
+template <class CharT> class nsPromiseSubstring;
+template <class CharT> PRBool SameImplementation( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+
 
 enum nsFragmentRequest { kPrevFragment, kFirstFragment, kLastFragment, kNextFragment, kFragmentAt };
 
@@ -221,21 +225,6 @@ class nsReadingIterator
 
           return *this;
         }
-
-
-        // Damn again!  Problems with templates made me implement comparisons as members.
-
-      PRBool
-      operator==( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition == rhs.mPosition;
-        }
-
-      PRBool
-      operator!=( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition != rhs.mPosition;
-        }
   };
 
 
@@ -249,20 +238,21 @@ class basic_nsAReadableString
       ...
     */
   {
-    // friend class nsReadingIterator<CharT>;
+    protected:
+
+      friend PRBool SameImplementation<CharT>( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+      virtual const void* Implementation() const;
+
+      friend class nsReadingIterator<CharT>;
+      friend class nsPromiseConcatenation<CharT>;
+      friend class nsPromiseSubstring<CharT>;
+      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
+
 
     public:
 
       typedef nsReadingIterator<CharT> ConstIterator;
 
-    public:
-
-      virtual const void* Implementation() const;
-
-        // Damn!  Had to make |GetReadableFragment| public because the compilers suck.  Should be protected.
-      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
-
-
       nsReadingIterator<CharT>
       BeginReading( PRUint32 aOffset = 0 ) const
         {
@@ -400,6 +390,24 @@ nsReadingIterator<CharT>::normalize_backward()
         mPosition = mFragment.mEnd;
   }
 
+
+template <class CharT>
+inline
+PRBool
+operator==( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() == rhs.operator->();
+  }
+
+template <class CharT>
+inline
+PRBool
+operator!=( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() != rhs.operator->();
+  }
+
+
 #define NS_DEF_1_STRING_COMPARISON_OPERATOR(comp, T1, T2) \
   inline                                        \
   PRBool                                        \
@@ -890,6 +898,57 @@ nsPromiseSubstring<CharT>::GetReadableFragment( nsReadableFragment<CharT>& aFrag
   // Global functions
   //
 
+template <class InputIterator, class OutputIterator>
+OutputIterator
+string_copy( InputIterator first, InputIterator last, OutputIterator result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<InputIterator::value_type>::copy(result.operator->(), first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class InputIterator, class CharT>
+CharT*
+string_copy( InputIterator first, InputIterator last, CharT* result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32(first.size_forward());
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<CharT>::copy(result, first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class CharT>
+inline
+PRBool
+SameImplementation( const basic_nsAReadableString<CharT>& lhs, const basic_nsAReadableString<CharT>& rhs )
+  {
+    const void* imp_tag = lhs.Implementation();
+    return imp_tag && (imp_tag==rhs.Implementation());
+  }
+
 template <class CharT>
 nsPromiseSubstring<CharT>
 Substring( const basic_nsAReadableString<CharT>& aString, PRUint32 aStartPos, PRUint32 aSubstringLength )

string/public/nsAWritableString.h

@@ -323,7 +323,7 @@ inline
 PRBool
 operator==( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition == rhs.mPosition;
+    return lhs.operator->() == rhs.operator->();
   }
 
 template <class CharT>
@@ -331,29 +331,9 @@ inline
 PRBool
 operator!=( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition != rhs.mPosition;
+    return lhs.operator->() != rhs.operator->();
   }
 
-template <class CharT>
-nsWritingIterator<CharT>
-copy_chunky( nsReadingIterator<CharT> first, nsReadingIterator<CharT> last, nsWritingIterator<CharT> result )
-  {
-    while ( first != last )
-      {
-        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
-        if ( first.fragment().mStart == last.fragment().mStart )
-          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
-
-        // assert(lengthToCopy > 0);
-
-        nsCharTraits<CharT>::copy(result.operator->(), first.operator->(), lengthToCopy);
-
-        first += PRInt32(lengthToCopy);
-        result += PRInt32(lengthToCopy);
-      }
-
-    return result;
-  }
 
 template <class CharT>
 nsWritingIterator<CharT>
@@ -382,7 +362,7 @@ void
 basic_nsAWritableString<CharT>::Assign( const basic_nsAReadableString<CharT>& rhs )
   {
     SetLength(rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
   }
 
 template <class CharT>
@@ -391,7 +371,7 @@ basic_nsAWritableString<CharT>::Append( const basic_nsAReadableString<CharT>& rh
   {
     PRUint32 oldLength = Length();
     SetLength(oldLength + rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
   }
 
 template <class CharT>
@@ -412,14 +392,14 @@ basic_nsAWritableString<CharT>::Insert( const basic_nsAReadableString<CharT>& aR
       copy_backward_chunky<CharT>(BeginReading(aPosition), BeginReading(oldLength), EndWriting());
     else
       aPosition = oldLength;
-    copy_chunky<CharT>(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
+    string_copy(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
   }
 
 template <class CharT>
 void
 basic_nsAWritableString<CharT>::Cut( PRUint32 cutStart, PRUint32 cutLength )
   {
-    copy_chunky<CharT>(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
+    string_copy(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
     SetLength(Length()-cutLength);
   }
 
@@ -439,12 +419,12 @@ basic_nsAWritableString<CharT>::Replace( PRUint32 cutStart, PRUint32 cutLength,
     PRUint32 newLength = oldLength - cutLength + replacementLength;
 
     if ( cutLength > replacementLength )
-      copy_chunky<CharT>(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
+      string_copy(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
     SetLength(newLength);
     if ( cutLength < replacementLength )
       copy_backward_chunky<CharT>(BeginReading(cutEnd), BeginReading(oldLength), BeginWriting(replacementEnd));
 
-    copy_chunky<CharT>(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
+    string_copy(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
   }
 
 // operator>>

string/public/nsSharedString.h

@@ -52,10 +52,10 @@ class basic_nsSharedString
           return mLength;
         }
 
-      basic_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
+      basic_nsSharedString( const CharT* data, size_t length )
+          : mRefCount(0), mData(data), mLength(length)
         {
-          mLength = aReadable.Length();
-          copy(aReadable.BeginReading(), aReadable.EndReading(), mData+0);
+          // nothing else to do here
         }
 
       nsrefcnt
@@ -75,8 +75,8 @@ class basic_nsSharedString
 
     private:
       mutable nsrefcnt  mRefCount;
+      const CharT*      mData;
       size_t            mLength;
-      CharT             mData[1];
   };
 
 NS_DEF_STRING_COMPARISONS(basic_nsSharedString<CharT>)
@@ -117,8 +117,20 @@ template <class CharT>
 basic_nsSharedString<CharT>*
 new_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
   {
-    void* in_buffer = operator new( sizeof(basic_nsSharedString<CharT>) + aReadable.Length()*sizeof(CharT) );
-    return new (in_buffer) basic_nsSharedString<CharT>(aReadable);
+    size_t object_size    = ((sizeof(basic_nsSharedString<CharT>) + sizeof(CharT) - 1) / sizeof(CharT)) * sizeof(CharT);
+    size_t string_length  = aReadable.Length();
+    size_t string_size    = string_length * sizeof(CharT);
+
+    void* object_ptr = operator new(object_size + string_size);
+    if ( object_ptr )
+      {
+        typedef CharT* CharT_ptr;
+        CharT* string_ptr = CharT_ptr(NS_STATIC_CAST(unsigned char*, object_ptr) + object_size);
+        string_copy(aReadable.BeginReading(), aReadable.EndReading(), string_ptr);
+        return new (object_ptr) basic_nsSharedString<CharT>(string_ptr, string_length);
+      }
+
+    return 0;
   }
 
 

xpcom/ds/nsAReadableString.h

@@ -71,6 +71,10 @@ template <class CharT> class basic_nsAWritableString;
 template <class CharT> class basic_nsLiteralString;
   // ...because we sometimes use them as in params to force the conversion of |CharT*|s
 
+template <class CharT> class nsPromiseConcatenation;
+template <class CharT> class nsPromiseSubstring;
+template <class CharT> PRBool SameImplementation( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+
 
 enum nsFragmentRequest { kPrevFragment, kFirstFragment, kLastFragment, kNextFragment, kFragmentAt };
 
@@ -221,21 +225,6 @@ class nsReadingIterator
 
           return *this;
         }
-
-
-        // Damn again!  Problems with templates made me implement comparisons as members.
-
-      PRBool
-      operator==( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition == rhs.mPosition;
-        }
-
-      PRBool
-      operator!=( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition != rhs.mPosition;
-        }
   };
 
 
@@ -249,20 +238,21 @@ class basic_nsAReadableString
       ...
     */
   {
-    // friend class nsReadingIterator<CharT>;
+    protected:
+
+      friend PRBool SameImplementation<CharT>( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+      virtual const void* Implementation() const;
+
+      friend class nsReadingIterator<CharT>;
+      friend class nsPromiseConcatenation<CharT>;
+      friend class nsPromiseSubstring<CharT>;
+      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
+
 
     public:
 
       typedef nsReadingIterator<CharT> ConstIterator;
 
-    public:
-
-      virtual const void* Implementation() const;
-
-        // Damn!  Had to make |GetReadableFragment| public because the compilers suck.  Should be protected.
-      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
-
-
       nsReadingIterator<CharT>
       BeginReading( PRUint32 aOffset = 0 ) const
         {
@@ -400,6 +390,24 @@ nsReadingIterator<CharT>::normalize_backward()
         mPosition = mFragment.mEnd;
   }
 
+
+template <class CharT>
+inline
+PRBool
+operator==( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() == rhs.operator->();
+  }
+
+template <class CharT>
+inline
+PRBool
+operator!=( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() != rhs.operator->();
+  }
+
+
 #define NS_DEF_1_STRING_COMPARISON_OPERATOR(comp, T1, T2) \
   inline                                        \
   PRBool                                        \
@@ -890,6 +898,57 @@ nsPromiseSubstring<CharT>::GetReadableFragment( nsReadableFragment<CharT>& aFrag
   // Global functions
   //
 
+template <class InputIterator, class OutputIterator>
+OutputIterator
+string_copy( InputIterator first, InputIterator last, OutputIterator result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<InputIterator::value_type>::copy(result.operator->(), first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class InputIterator, class CharT>
+CharT*
+string_copy( InputIterator first, InputIterator last, CharT* result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32(first.size_forward());
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<CharT>::copy(result, first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class CharT>
+inline
+PRBool
+SameImplementation( const basic_nsAReadableString<CharT>& lhs, const basic_nsAReadableString<CharT>& rhs )
+  {
+    const void* imp_tag = lhs.Implementation();
+    return imp_tag && (imp_tag==rhs.Implementation());
+  }
+
 template <class CharT>
 nsPromiseSubstring<CharT>
 Substring( const basic_nsAReadableString<CharT>& aString, PRUint32 aStartPos, PRUint32 aSubstringLength )

xpcom/ds/nsAWritableString.h

@@ -323,7 +323,7 @@ inline
 PRBool
 operator==( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition == rhs.mPosition;
+    return lhs.operator->() == rhs.operator->();
   }
 
 template <class CharT>
@@ -331,29 +331,9 @@ inline
 PRBool
 operator!=( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition != rhs.mPosition;
+    return lhs.operator->() != rhs.operator->();
   }
 
-template <class CharT>
-nsWritingIterator<CharT>
-copy_chunky( nsReadingIterator<CharT> first, nsReadingIterator<CharT> last, nsWritingIterator<CharT> result )
-  {
-    while ( first != last )
-      {
-        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
-        if ( first.fragment().mStart == last.fragment().mStart )
-          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
-
-        // assert(lengthToCopy > 0);
-
-        nsCharTraits<CharT>::copy(result.operator->(), first.operator->(), lengthToCopy);
-
-        first += PRInt32(lengthToCopy);
-        result += PRInt32(lengthToCopy);
-      }
-
-    return result;
-  }
 
 template <class CharT>
 nsWritingIterator<CharT>
@@ -382,7 +362,7 @@ void
 basic_nsAWritableString<CharT>::Assign( const basic_nsAReadableString<CharT>& rhs )
   {
     SetLength(rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
   }
 
 template <class CharT>
@@ -391,7 +371,7 @@ basic_nsAWritableString<CharT>::Append( const basic_nsAReadableString<CharT>& rh
   {
     PRUint32 oldLength = Length();
     SetLength(oldLength + rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
   }
 
 template <class CharT>
@@ -412,14 +392,14 @@ basic_nsAWritableString<CharT>::Insert( const basic_nsAReadableString<CharT>& aR
       copy_backward_chunky<CharT>(BeginReading(aPosition), BeginReading(oldLength), EndWriting());
     else
       aPosition = oldLength;
-    copy_chunky<CharT>(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
+    string_copy(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
   }
 
 template <class CharT>
 void
 basic_nsAWritableString<CharT>::Cut( PRUint32 cutStart, PRUint32 cutLength )
   {
-    copy_chunky<CharT>(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
+    string_copy(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
     SetLength(Length()-cutLength);
   }
 
@@ -439,12 +419,12 @@ basic_nsAWritableString<CharT>::Replace( PRUint32 cutStart, PRUint32 cutLength,
     PRUint32 newLength = oldLength - cutLength + replacementLength;
 
     if ( cutLength > replacementLength )
-      copy_chunky<CharT>(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
+      string_copy(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
     SetLength(newLength);
     if ( cutLength < replacementLength )
       copy_backward_chunky<CharT>(BeginReading(cutEnd), BeginReading(oldLength), BeginWriting(replacementEnd));
 
-    copy_chunky<CharT>(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
+    string_copy(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
   }
 
 // operator>>

xpcom/ds/nsSharedString.h

@@ -52,10 +52,10 @@ class basic_nsSharedString
           return mLength;
         }
 
-      basic_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
+      basic_nsSharedString( const CharT* data, size_t length )
+          : mRefCount(0), mData(data), mLength(length)
         {
-          mLength = aReadable.Length();
-          copy(aReadable.BeginReading(), aReadable.EndReading(), mData+0);
+          // nothing else to do here
         }
 
       nsrefcnt
@@ -75,8 +75,8 @@ class basic_nsSharedString
 
     private:
       mutable nsrefcnt  mRefCount;
+      const CharT*      mData;
       size_t            mLength;
-      CharT             mData[1];
   };
 
 NS_DEF_STRING_COMPARISONS(basic_nsSharedString<CharT>)
@@ -117,8 +117,20 @@ template <class CharT>
 basic_nsSharedString<CharT>*
 new_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
   {
-    void* in_buffer = operator new( sizeof(basic_nsSharedString<CharT>) + aReadable.Length()*sizeof(CharT) );
-    return new (in_buffer) basic_nsSharedString<CharT>(aReadable);
+    size_t object_size    = ((sizeof(basic_nsSharedString<CharT>) + sizeof(CharT) - 1) / sizeof(CharT)) * sizeof(CharT);
+    size_t string_length  = aReadable.Length();
+    size_t string_size    = string_length * sizeof(CharT);
+
+    void* object_ptr = operator new(object_size + string_size);
+    if ( object_ptr )
+      {
+        typedef CharT* CharT_ptr;
+        CharT* string_ptr = CharT_ptr(NS_STATIC_CAST(unsigned char*, object_ptr) + object_size);
+        string_copy(aReadable.BeginReading(), aReadable.EndReading(), string_ptr);
+        return new (object_ptr) basic_nsSharedString<CharT>(string_ptr, string_length);
+      }
+
+    return 0;
   }
 
 

xpcom/string/public/nsAReadableString.h

@@ -71,6 +71,10 @@ template <class CharT> class basic_nsAWritableString;
 template <class CharT> class basic_nsLiteralString;
   // ...because we sometimes use them as in params to force the conversion of |CharT*|s
 
+template <class CharT> class nsPromiseConcatenation;
+template <class CharT> class nsPromiseSubstring;
+template <class CharT> PRBool SameImplementation( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+
 
 enum nsFragmentRequest { kPrevFragment, kFirstFragment, kLastFragment, kNextFragment, kFragmentAt };
 
@@ -221,21 +225,6 @@ class nsReadingIterator
 
           return *this;
         }
-
-
-        // Damn again!  Problems with templates made me implement comparisons as members.
-
-      PRBool
-      operator==( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition == rhs.mPosition;
-        }
-
-      PRBool
-      operator!=( const nsReadingIterator<CharT>& rhs ) const
-        {
-          return mPosition != rhs.mPosition;
-        }
   };
 
 
@@ -249,20 +238,21 @@ class basic_nsAReadableString
       ...
     */
   {
-    // friend class nsReadingIterator<CharT>;
+    protected:
+
+      friend PRBool SameImplementation<CharT>( const basic_nsAReadableString<CharT>&, const basic_nsAReadableString<CharT>& );
+      virtual const void* Implementation() const;
+
+      friend class nsReadingIterator<CharT>;
+      friend class nsPromiseConcatenation<CharT>;
+      friend class nsPromiseSubstring<CharT>;
+      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
+
 
     public:
 
       typedef nsReadingIterator<CharT> ConstIterator;
 
-    public:
-
-      virtual const void* Implementation() const;
-
-        // Damn!  Had to make |GetReadableFragment| public because the compilers suck.  Should be protected.
-      virtual const CharT* GetReadableFragment( nsReadableFragment<CharT>&, nsFragmentRequest, PRUint32 = 0 ) const = 0;
-
-
       nsReadingIterator<CharT>
       BeginReading( PRUint32 aOffset = 0 ) const
         {
@@ -400,6 +390,24 @@ nsReadingIterator<CharT>::normalize_backward()
         mPosition = mFragment.mEnd;
   }
 
+
+template <class CharT>
+inline
+PRBool
+operator==( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() == rhs.operator->();
+  }
+
+template <class CharT>
+inline
+PRBool
+operator!=( const nsReadingIterator<CharT>& lhs, const nsReadingIterator<CharT>& rhs )
+  {
+    return lhs.operator->() != rhs.operator->();
+  }
+
+
 #define NS_DEF_1_STRING_COMPARISON_OPERATOR(comp, T1, T2) \
   inline                                        \
   PRBool                                        \
@@ -890,6 +898,57 @@ nsPromiseSubstring<CharT>::GetReadableFragment( nsReadableFragment<CharT>& aFrag
   // Global functions
   //
 
+template <class InputIterator, class OutputIterator>
+OutputIterator
+string_copy( InputIterator first, InputIterator last, OutputIterator result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<InputIterator::value_type>::copy(result.operator->(), first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class InputIterator, class CharT>
+CharT*
+string_copy( InputIterator first, InputIterator last, CharT* result )
+  {
+    while ( first != last )
+      {
+        PRUint32 lengthToCopy = PRUint32(first.size_forward());
+        if ( first.fragment().mStart == last.fragment().mStart )
+          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
+
+        // assert(lengthToCopy > 0);
+
+        nsCharTraits<CharT>::copy(result, first.operator->(), lengthToCopy);
+
+        first += PRInt32(lengthToCopy);
+        result += PRInt32(lengthToCopy);
+      }
+
+    return result;
+  }
+
+template <class CharT>
+inline
+PRBool
+SameImplementation( const basic_nsAReadableString<CharT>& lhs, const basic_nsAReadableString<CharT>& rhs )
+  {
+    const void* imp_tag = lhs.Implementation();
+    return imp_tag && (imp_tag==rhs.Implementation());
+  }
+
 template <class CharT>
 nsPromiseSubstring<CharT>
 Substring( const basic_nsAReadableString<CharT>& aString, PRUint32 aStartPos, PRUint32 aSubstringLength )

xpcom/string/public/nsAWritableString.h

@@ -323,7 +323,7 @@ inline
 PRBool
 operator==( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition == rhs.mPosition;
+    return lhs.operator->() == rhs.operator->();
   }
 
 template <class CharT>
@@ -331,29 +331,9 @@ inline
 PRBool
 operator!=( const nsWritingIterator<CharT>& lhs, const nsWritingIterator<CharT>& rhs )
   {
-    return lhs.mPosition != rhs.mPosition;
+    return lhs.operator->() != rhs.operator->();
   }
 
-template <class CharT>
-nsWritingIterator<CharT>
-copy_chunky( nsReadingIterator<CharT> first, nsReadingIterator<CharT> last, nsWritingIterator<CharT> result )
-  {
-    while ( first != last )
-      {
-        PRUint32 lengthToCopy = PRUint32( NS_MIN(first.size_forward(), result.size_forward()) );
-        if ( first.fragment().mStart == last.fragment().mStart )
-          lengthToCopy = NS_MIN(lengthToCopy, PRUint32(last.operator->() - first.operator->()));
-
-        // assert(lengthToCopy > 0);
-
-        nsCharTraits<CharT>::copy(result.operator->(), first.operator->(), lengthToCopy);
-
-        first += PRInt32(lengthToCopy);
-        result += PRInt32(lengthToCopy);
-      }
-
-    return result;
-  }
 
 template <class CharT>
 nsWritingIterator<CharT>
@@ -382,7 +362,7 @@ void
 basic_nsAWritableString<CharT>::Assign( const basic_nsAReadableString<CharT>& rhs )
   {
     SetLength(rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting());
   }
 
 template <class CharT>
@@ -391,7 +371,7 @@ basic_nsAWritableString<CharT>::Append( const basic_nsAReadableString<CharT>& rh
   {
     PRUint32 oldLength = Length();
     SetLength(oldLength + rhs.Length());
-    copy_chunky<CharT>(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
+    string_copy(rhs.BeginReading(), rhs.EndReading(), BeginWriting(oldLength));
   }
 
 template <class CharT>
@@ -412,14 +392,14 @@ basic_nsAWritableString<CharT>::Insert( const basic_nsAReadableString<CharT>& aR
       copy_backward_chunky<CharT>(BeginReading(aPosition), BeginReading(oldLength), EndWriting());
     else
       aPosition = oldLength;
-    copy_chunky<CharT>(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
+    string_copy(aReadable.BeginReading(), aReadable.EndReading(), BeginWriting(aPosition));
   }
 
 template <class CharT>
 void
 basic_nsAWritableString<CharT>::Cut( PRUint32 cutStart, PRUint32 cutLength )
   {
-    copy_chunky<CharT>(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
+    string_copy(BeginReading(cutStart+cutLength), EndReading(), BeginWriting(cutStart));
     SetLength(Length()-cutLength);
   }
 
@@ -439,12 +419,12 @@ basic_nsAWritableString<CharT>::Replace( PRUint32 cutStart, PRUint32 cutLength,
     PRUint32 newLength = oldLength - cutLength + replacementLength;
 
     if ( cutLength > replacementLength )
-      copy_chunky<CharT>(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
+      string_copy(BeginReading(cutEnd), EndReading(), BeginWriting(replacementEnd));
     SetLength(newLength);
     if ( cutLength < replacementLength )
       copy_backward_chunky<CharT>(BeginReading(cutEnd), BeginReading(oldLength), BeginWriting(replacementEnd));
 
-    copy_chunky<CharT>(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
+    string_copy(aReplacement.BeginReading(), aReplacement.EndReading(), BeginWriting(cutStart));
   }
 
 // operator>>

xpcom/string/public/nsSharedString.h

@@ -52,10 +52,10 @@ class basic_nsSharedString
           return mLength;
         }
 
-      basic_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
+      basic_nsSharedString( const CharT* data, size_t length )
+          : mRefCount(0), mData(data), mLength(length)
         {
-          mLength = aReadable.Length();
-          copy(aReadable.BeginReading(), aReadable.EndReading(), mData+0);
+          // nothing else to do here
         }
 
       nsrefcnt
@@ -75,8 +75,8 @@ class basic_nsSharedString
 
     private:
       mutable nsrefcnt  mRefCount;
+      const CharT*      mData;
       size_t            mLength;
-      CharT             mData[1];
   };
 
 NS_DEF_STRING_COMPARISONS(basic_nsSharedString<CharT>)
@@ -117,8 +117,20 @@ template <class CharT>
 basic_nsSharedString<CharT>*
 new_nsSharedString( const basic_nsAReadableString<CharT>& aReadable )
   {
-    void* in_buffer = operator new( sizeof(basic_nsSharedString<CharT>) + aReadable.Length()*sizeof(CharT) );
-    return new (in_buffer) basic_nsSharedString<CharT>(aReadable);
+    size_t object_size    = ((sizeof(basic_nsSharedString<CharT>) + sizeof(CharT) - 1) / sizeof(CharT)) * sizeof(CharT);
+    size_t string_length  = aReadable.Length();
+    size_t string_size    = string_length * sizeof(CharT);
+
+    void* object_ptr = operator new(object_size + string_size);
+    if ( object_ptr )
+      {
+        typedef CharT* CharT_ptr;
+        CharT* string_ptr = CharT_ptr(NS_STATIC_CAST(unsigned char*, object_ptr) + object_size);
+        string_copy(aReadable.BeginReading(), aReadable.EndReading(), string_ptr);
+        return new (object_ptr) basic_nsSharedString<CharT>(string_ptr, string_length);
+      }
+
+    return 0;
   }