Eric H. Jung wrote:
Thanks for the help, Alex and Neil. I can't claim to understand the subleties
of what's going on
here. Based on your back-and-forth, I have the following. I did some testing,
but not rigorously.
Do you see any problems?
_boundedStack : {
_max : 500,
push: function(aElem) {
this._current++;
if (this._current == this._max) {
this._current = 0;
this._overfly = true;
}
this._buffer[this._current] = aElem;
},
get length() {
return this._overfly ? this._max : this._current;
},
item : function(aIndex) {
if (aIndex == 0)
aIndex = 1;
This is wrong, just try to get item(0).
Neil is right, if you want to reverse the order, you have to fiddle with
the getter here.
else if (this._overfly) {
aIndex += this._current + 1; //XXX check this logic
}
if you increment _current at the end of push, you don't need the + 1
here, but then you need to adjust legth().
I'd leave it as is and not be too picky about what current "usually is".
aIndex = aIndex % this._max;
return this._buffer[aIndex];
}
}
Thank you,
Eric
--- Axel Hecht <[EMAIL PROTECTED]> wrote:
Neil wrote:
Axel Hecht wrote:
BoundedStack.prototype = {
push: function(aElem) {
this._current++;
if (this._current == this._max)
this._current = 0;
this._overflew = true;
}
this._buffer[this._current] = aElem;
},
get length() {
return this._overflew ? this._max : this._current;
},
get: function(aIndex) {
if (this._overflew) {
aIndex += this._current + 1; //XXX check this logic
}
aIndex = aIndex % this._max;
return this._buffer[aIndex];
}
}
This is from the top of my head, without testing, all numbers in the
getter could be off by one. Consider this to be devmo-style MIT
License ;-)
* You don't need the +1.
* You only need the % in the overflow case.
* Your get function is 1-indexed, fix this by incrementing current
at the end of push, not at the beginning, or by starting with
current equal to max and decrementing at the
I don't think so.
0 % 500 == 0 and 500 % 500 == 0. Sounds 0 based to me.
Doing the mod afterwards is some half hearted out-of-bounds check, I
should have checked aIndex > 0, too. Of course I should out-of-bounds
check !this._overflown, too (<= this._current).
this._current is the last written element, for aIndex == 0, it should
return the next one as first element.
I guess I had to actually test this code to be sure.
beginning (in which
case, always add current to index, % max).
* Your get function should be named item. (Isn't get a keyword?)
probably, yes.
* Overflew is actually the past participle of overfly.
oops ;-), I'm fly!
Axel
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