On 11/3/06, Ivanov, Alexey A wrote:
>-----Original Message-----
>From: Stepan Mishura
>Sent: Friday, November 03, 2006 9:43 AM
>To: harmony-dev@incubator.apache.org
>Subject: Re: [classlib][swing] compatibility:
j.s.text.GapContent.replace()
>behaviour
>
>On 11/2/06, Ivanov, Alexey A wrote:
>>
>> Hi all,
>>
>> I've started fixing HARMONY-1809. To remove throws clause from the
>> declaration of replace method, as it was proposed by Oleg in
>> HARMONY-1975, I placed removeItems() and insertItems() calls into
>> try-catch block. This would work OK for any valid arguments.
>>
<SNIP>
>>
>>
>> Any objections, comments, opinions?
>
>
>
>Hi Alexey,
Hi Stepan,
>I'm not quite convinced by your evaluation (I'm not an expert in Swing
API
>so I may be wrong). My experiments with GapContent showed that Harmony
Let me give a quick introduction what GapContent is then. This class
serves as the default storage for all Document implementations within
javax.swing.text. It stores text in char[] array... but with a gap in
it.
Using the default constructor the array will have length 10. And one
character will be placed into the buffer; the other 9 characters in the
array will be the gap, and they are not considered to be portion of the
content. This prevents frequent re-allocations of the underlying storage
array where text is inserted or removed. Moving the gap is cheaper than
re-allocating the array.
When an insert or remove occurs, the gap is moved so that it starts at
the position of insert or remove.
Thanks for the explanation.
initially created different object then RI, for example, if you create
an
>object with GapContent() constructor, Harmony will return start==0 and
>end==9 while RI will return start==1 and end==10. The next point that
It doesn't really matter where the gap is. This difference shows only
that the gap in the text buffer is located at different location. Using
content.shiftGap(0) on RI, you'll get start = 0, end = 9. Accordingly
using content.shiftGap(1) on Harmony, you'll get start = 1, end = 10.
IMO it might be compatibly issue. I can extend GapContent class and it may
depend on what getGapStart() and getGapEnd() return.
What matters is that content.length() = 1 in both cases, and
content.getString(0, content.length()) returns "\n".
Actually, setting the gap to be at 0 is more efficient because the next
(or first) insert is likely to happen at position 0 rather than 1.
Therefore to insert text at position 0, the gap will be moved to 0 on RI
(which involves array copying and some other operations). This won't be
the case with Harmony because the gap is already at 0.
If you do:
GapContent gc = new GapContent();
gc.insertString(0, "text");
then gc.getGapStart() returns 4 on RI not 0 as you wrote.
confuses me that the spec. says about position as "logical position in
the
>storage"...and... "This is not the location in the underlying storage
>array". So negative value for position may be considered as valid.
It's all about how the text is stored in GapContent. Because there's a
gap modeled "the location in the underlying storage array" differs from
"the logical position in storage". If you look at the spec of any
methods which throw BadLocationException, you'll see that position (it's
called 'where') is to be >= 0. Since this method is used to perform
operations of insertString() and remove() in RI, negative positions are
invalid. I believe they put no checks here because validation of
parameters is performed in those methods which call replace().
As I understood the spec. it is true for methods that change content but
there is no such restriction for methods that work with gap (see
shiftGapEndUp, shiftGapStartDown, shiftEnd, shiftGap)
Another point is that replace() in never used in Harmony implementation
- it's called from tests only.
But it can be used by some app. so it should be compatible.
Thanks,
Stepan.
Thanks,
Alexey.
P.S. The related JIRA issues:
https://issues.apache.org/jira/browse/HARMONY-1809
https://issues.apache.org/jira/browse/HARMONY-1975
GapContent Javadoc:
http://java.sun.com/j2se/1.5.0/docs/api/javax/swing/text/GapContent.html
Description of GapContent.replace:
http://java.sun.com/j2se/1.5.0/docs/api/javax/swing/text/GapContent.html
#replace(int,%20int,%20java.lang.Object,%20int)
--
Alexey A. Ivanov
Intel Middleware Product Division
--
Stepan Mishura
Intel Middleware Products Division
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--
Alexey A. Ivanov
Intel Middleware Product Division
--
Stepan Mishura
Intel Middleware Products Division
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