lemme take a crack at it..
_boundedStack: {
_max: 500,
_stack: [],
_current: 0, // next position to be written
_overfly: false,
push: function(obj) {
var current = this._current; // minor optimization
this._stack[current] = obj;
if (current >= this._max) {
this._current = 0;
this._overfly = true;
}
},
length: function() { return this._stack.length; }, // note_1
item: function(idx) { // note_2
if (this._overfly) {
idx += this._current;
if (idx >= this._max) { idx -= this._max; }
}
return this._stack[idx];
}
}
note_1: it'll probably be a little faster to call myStack._stack.length
directly
note_2: caller needs to bound-check. this can be done implicitly: get
the length first, then only ask for elements within that length.
logic check: _current points to next field to write into. when getting
an element by index, _current points to oldest element iff there was an
overflow.
By the way, never skimp on the curly braces {}: for some reason Fx 1.0
favors the code with lots of {}s, by a slight margin (or so my testing
showed).
also, does it have to be an array? what if you just use a linked list of
objects? it may work faster if you keep retrieving the whole list each
time, not just a certain item
_boundedStack: {
first: null,
last: null,
len: 0,
max: 500,
push: function(obj) {
if (null == this.last) { this.last = obj; }
else {
this.last.next = obj;
this.last = obj;
}
this.len++;
if (null == first) { first = obj; }
else if (this.len >= this.max) {
this.first = this.first.next;
this.len--;
}
}
}
obj should be fairly easy to implement, i think..
to get the length of your stack, just grab the len variable
to get the list, get the first element then .next until .next == null
disclaimer: i didn't test either implementation, may i messed it up =)
~Fry-kun
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