Here is a side-by-side comparison with the styled version on the right 
and the same text unstyled on the left. Note the difference in runStopIndex


On 7/4/18 2:49 PM, David T. Lewis wrote:
> I tried reverting #scanCharactersFrom:to:in:rightX:stopConditions:kern:
> to the earlier version (cmm 6/12/2010 11:52), but I still get failures
> with cursor and mouse in the class comment text when browsing the FooClient
> class. There must be something else going on here, and it is certainly
> not obvious to me why it is happening only with the FooClient test
> example.
>
> Dave
>
> On Wed, Jul 04, 2018 at 02:10:00PM -0400, Bob Arning wrote:
>> perhaps this will help:
>>
>> This version does not seem to exhibit the error and it limits stopIndex
>> to the size of the string
>>
>> !CharacterScanner methodsFor: 'scanning' stamp: 'cmm 6/12/2010 11:52'!
>> scanCharactersFrom: startIndex to: stopIndex in: sourceString rightX:
>> rightX stopConditions: stops kern: kernDelta
>>
>> ?????? | startEncoding selector |
>> ?????? (sourceString isByteString) ifTrue: [^ self
>> basicScanCharactersFrom: startIndex *to: (stopIndex min: sourceString
>> size)* in: sourceString rightX: rightX stopConditions: stops kern:
>> kernDelta.].
>>
>> ?????? (sourceString isWideString) ifTrue: [
>> ?????? ?????? startIndex > stopIndex ifTrue: [lastIndex := stopIndex. ^
>> stops endOfRun].
>> ?????? ?????? startEncoding :=?? (sourceString at: startIndex) leadingChar.
>> ?????? ?????? selector := EncodedCharSet scanSelectorAt: startEncoding.
>> ?????? ?????? ^ self perform: selector withArguments: (Array with:
>> startIndex with: stopIndex with: sourceString with: rightX with: stops
>> with: kernDelta).
>> ?????? ].
>>
>> ?????? ^ stops endOfRun
>> ! !
>>
>> This version fails and does not limit the stopIndex.
>>
>> !CharacterScanner methodsFor: 'scanning' stamp: 'nice 10/22/2013 20:49'!
>> scanCharactersFrom: startIndex to: stopIndex in: sourceString rightX:
>> rightX
>> ?????? ^sourceString scanCharactersFrom: startIndex *to: stopIndex* with:
>> self rightX: rightX font: font! !
>>
>>
>> On 7/4/18 11:53 AM, David T. Lewis wrote:
>>> On Wed, Jul 04, 2018 at 02:35:59PM +0200, karl ramberg wrote:
>>>> On Wed, Jul 4, 2018 at 11:10 AM K K Subbu <kksubbu.ml at gmail.com> wrote:
>>>>
>>>>> On Tuesday 03 July 2018 04:40 AM, Tim Johnson wrote:
>>>>>> 1. File-in the .cs as attached*.
>>>>>> 2. In a system browser, click on the class, then click on the [?] button
>>>>>> to view class comment.
>>>>>> 3. Notice the styled text in the comment.
>>>>>> 4. Click around the comment pane a bit.
>>>>>> 5. Eventually, see "Error: subscript is out of bounds: 71" appear over
>>>>>> and over until you interrupt.
>>>>> In step 4, it is sufficient to click once near the bottom of the pane
>>>>> when the cursor changes from I-bar to arrow and then wait. This will
>>>>> trigger the error, but the error window triggers itself recursively
>>>>> around 50 times before stopping and displaying the windows.
>>>>>
>>>>> I added an assert to catch it before recursion:
>>>>>
>>>>>      self assert: lastIndex < sourceString size.
>>>>>
>>>>> The assert window itself throws up another error, but that is a topic
>>>>> for another thread ;-).
>>>>>
>>>>> Regards .. Subbu
>>>> Hi,
>>>> See class comment i NewParagraph for a hint of what happens.
>>>> A empty lineSpan 71 to: 70 is added to the end of the paragraph, when you
>>>> double click below the text.
>>>> When the character scanner looks for characters outside of the string at
>>>> index 71 it cause a recursion.
>>>>
>>>> Best,
>>>> Karl
>>>>
>>> Good tiip to look at the NewParagraph class comment, there is apparently
>>> some left over messiness in here somewhere.
>>>
>>> Another way to trigger the bug using the test case with FooClient is
>>> to position the cursor in the comment pane and use keyboard right cursor
>>> to move to the end of the comment. This causes the same bounds error but
>>> takes a different path through the code leading to the error.
>>>
>>> Looking through the stack in a debugger after triggering the error with
>>> the mouse, here are a few notes (but no conclusions):
>>>
>>> On mouseUp: we enter Editor>>selectWord then call
>>> Editor>>selectWordLeftDelimiters:rightDelimiters:
>>> which has this:
>>>
>>> 	"Select the whole text when clicking before first or after last
>>> 	character"
>>> 	(here > string size or: [here < 2]) ifTrue: [^self selectFrom: 1 to:
>>> 	string size].
>>>
>>> where string is the 70 character String derived from the Text.
>>>
>>> At this point we are trying to select from 1 to 70 (the whole string for
>>> the entire text) in TextEditor>>selectFrom:to:
>>>
>>> This calls Editor>>selectInvisiblyFrom:to: and here the stop index is
>>> set past the size of the string:
>>>
>>>    selectInvisiblyFrom: start to: stop
>>>       "Select the designated characters, inclusive.  Make no visual
>>>       changes."
>>>
>>>       self markIndex: start pointIndex: stop + 1
>>>
>>>  From this point we are trying to go from index 1 to index 71 over a string
>>> of size 70, and eventually end up with the out of bounds exception.
>>>
>>> A clue that this might be accumulation of kludges: Looking at senders of
>>> selectInvisiblyFrom:to: (such as TextEditor>>addText:event:) shows a number
>>> of methods that subtract 1 from the stop index when before calling the
>>> method
>>> that adds 1 back to the stop index. This certainly does not have a good
>>> smell.
>>>
>>> It is not clear to me why selectInvisiblyFrom:to: would be adding one to
>>> the
>>> stop index, but I see that the method stamp is jmv 5/27/2011, which
>>> suggests
>>> to me that we should take a look at Cuis to figure out how this is intended
>>> to function. Cuis does not show any cases of senders of
>>> selectInvisiblyFrom:to:
>>> that subtract 1 from the stop index, and the Cuis implementation of
>>> selectInvisiblyFrom:to: is that same as Squeak.
>>>
>>> Dave
>>>
>>>
>

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