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SVG.Queue = SVG.invent({
create: function () {
this._first = null
this._last = null
this.length = 0
this.id = 0
},
extend: {
push: function (value) {
// An item stores an id and the provided value
var item = { id: this.id++, value: value }
// Deal with the queue being empty or populated
if (this._last) {
this._last = this._last.next = item
} else {
this._last = this._first = item
}
this.length++
},
shift: function () {
if (this.length == 0) {
return
}
var remove = this._first
this._first = remove.next
this._last = --this.length ? this._last : null
return remove.value
},
// Shows us the first item in the list
first: function () {
return this._first && this._first.value
},
// Shows us the last item in the list
last: function () {
return this._last && this._last.value
},
// Removes the first item from the front where matcher returns true
remove: function (matcher) {
// Find the first match
var previous = null
var current = this._first
while (current) {
// If we have a match, we are done
if (matcher(current)) break
// Otherwise, advance both of the pointers
previous = current
current = current.next
}
// If we got the first item, adjust the first pointer
if (current && current === this._first)
this._first = this._first.next
// If we got the last item, adjust the last pointer
if (current && current === this._last)
this._last = previous
// If we got an item, fix the list and return the item
if (current) {
--this.length
if (previous) {
previous.next = current.next
}
return current.item
}
}
}
})
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