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|
LinkedListNode {
var <>prev, <>next, <>obj;
// this class supports the LinkedList class
*new { arg item;
^super.new.obj_(item)
}
remove {
if (prev.notNil, { prev.next_(next); });
if (next.notNil, { next.prev_(prev); });
next = prev = nil;
}
}
LinkedList : SequenceableCollection {
var head, tail, <size = 0;
copy {
var copy = LinkedList.new;
this.do {|item| copy.add(item) }
^copy
}
species { ^this.class }
do { arg function;
var i = 0;
var node = head;
while ({ node.notNil },{
function.value(node.obj, i);
node = node.next;
i = i + 1;
});
}
reverseDo { arg function;
var i = size - 1;
var node = tail;
while ({ node.notNil },{
function.value(node.obj, i);
node = node.prev;
i = i - 1;
});
}
addFirst { arg obj;
var node = LinkedListNode.new(obj);
if (head.notNil, {
node.next_(head);
head.prev_(node);
});
head = node;
if (tail.isNil, {
tail = node;
});
size = size + 1;
}
add { arg obj;
var node = LinkedListNode.new(obj);
if (tail.notNil, {
node.prev_(tail);
tail.next_(node);
});
tail = node;
if (head.isNil, {
head = node;
});
size = size + 1;
}
remove { arg obj;
var node = this.findNodeOfObj(obj);
if ( node.notNil, {
if (head == node, { head = node.next; });
if (tail == node, { tail = node.prev; });
node.remove;
size = size - 1;
});
}
pop {
var node;
if ( tail.notNil, {
node = tail;
tail = node.prev;
if (head == node, { head = nil; });
node.remove;
size = size - 1;
^node.obj
},{
^nil
});
}
popFirst {
var node;
if ( head.notNil, {
node = head;
head = node.next;
if (tail == node, { tail = nil; });
node.remove;
size = size - 1;
^node.obj
},{
^nil
});
}
first { if (head.notNil, { ^head.obj },{ ^nil }) }
last { if (tail.notNil, { ^tail.obj },{ ^nil }) }
at { arg index;
var node = this.nodeAt(index);
if (node.notNil, {
^node.obj
},{
^nil
})
}
put { arg index, item;
var node = this.nodeAt(index);
if (node.notNil, {
node.obj_(item);
});
}
removeAt { arg index;
var node = this.nodeAt(index);
if (node.notNil, {
if (head == node, { head = node.next; });
if (tail == node, { tail = node.prev; });
node.remove;
size = size - 1;
^node.obj
},{
^nil
});
}
// private
nodeAt { arg index;
var i = 0, node;
if ( index >= 0 and: { index < size }, {
if (index < (size - index), {
node = head;
while ({ i != index },{
node = node.next;
i = i + 1;
});
^node
},{
i = size - 1;
node = tail;
while ({ i != index },{
node = node.prev;
i = i - 1;
});
^node
});
},{
this.indexOutOfRange;
^nil
})
}
findNodeOfObj { arg obj;
var node = head;
while ({ node.notNil },{
if (node.obj == obj, { ^node });
node = node.next;
});
^nil
}
}
|
