<Swing Dev> Extension method for AbstractDocument.Content?

Pavel Porvatov pavel.porvatov at oracle.com
Fri Jun 29 12:40:11 UTC 2012

Hi Paulo,
> Hi Pavel.
> On Thu, Jun 21, 2012 at 2:13 PM, Pavel Porvatov 
> <pavel.porvatov at oracle.com <mailto:pavel.porvatov at oracle.com>> wrote:
>     Hi Paulo,
>         Hi. I've noticed that DefaultStyledDocument has a slowness
>         issue when inserting text. Even if you subclass it and expose
>         the faster method:
>         protected void insert(int offset, ElementSpec[] data)
>         the body of the method still uses a stringbuilder to append
>         all char[] inside of the data before actually inserting into
>         the content.
>         This is because the only method for insertion in the default
>         content interface is:
>         public UndoableEdit insertString(int where, String str)
>         Now if there are going to be extension methods in java 8, it
>         would be nice to have a
>         public UndoableEdit insert(int where, int index, int length,
>         char[] str) default {
>           return insert(where, new String(index, length, str);
>         }
>     In which class do you suggest to add the new method?
> It would need to be part of AbstractDocument.Content with the new 
> extension method feature in order to be able to be part of the public 
> interface of Content and be useable generally without casts.
Unfortunately we can't do that because of backward compatibility.
> I suppose you can also just modify the current method
> DefaultStyledDocument.insert(int offset, ElementSpec[] data)
> by using 'getContent() instanceof GapContent', casting and using the 
> GapVector (superclass of GapContent) replace method directly, instead 
> of going through the public Content API, which needs to a string (thus 
> the stringbuilder, creating a string that is only used as a char [] 
> holder.
>         with a adequate specialization in GapContent (that obviously
>         doesn't call the string version), and that that new method is
>         used in the
>         protected void insert(int offset, ElementSpec[] data)
>         method (and where it makes sense)
>     I'm not sure I understand correctly the last sentence. Could you
>     please clarify that, please?
> It's how i understood the new extension methods work; you provide a 
> simple no-state implementation in the interface (which is possible in 
> this case with AbstractDocument.Content.insertString(int where, String 
> str) ) and then implementations specialize the method for speed.
> I was also speculating that this is maybe not the only place where 
> such a method makes sense.
> Anyway, the speed penalty of the buffered insert (which you have to 
> extend DefaultStyledDocument or use reflection to access anyway) of 
> first creating a new large string with all the text that is only going 
> to be String.toCharArray() in the next method is very significant if 
> your text is actually something you'd like to buffer (like war and 
> peace for instance).
> Either way that the bulk insert method is improved, either by 
> instanceof cast or new public api in Content taking advantage of 
> extension methods, i think it should be fixed.
If you have ideas how to fix some problems or improve some functionality 
in jdk you can become a contributor, see details here

Regards, Pavel
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