45 lines
1.6 KiB
JavaScript
Executable File
45 lines
1.6 KiB
JavaScript
Executable File
"use strict";
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var utils = require('./utils');
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var LinkedList = module.exports = {
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// basic validity tests on a circular linked list a
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valid: function(a) {
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utils.assert(a, "list falsy");
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utils.assert(a._previousSibling, "previous falsy");
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utils.assert(a._nextSibling, "next falsy");
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// xxx check that list is actually circular
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return true;
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},
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// insert a before b
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insertBefore: function(a, b) {
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utils.assert(LinkedList.valid(a) && LinkedList.valid(b));
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var a_first = a, a_last = a._previousSibling;
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var b_first = b, b_last = b._previousSibling;
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a_first._previousSibling = b_last;
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a_last._nextSibling = b_first;
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b_last._nextSibling = a_first;
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b_first._previousSibling = a_last;
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utils.assert(LinkedList.valid(a) && LinkedList.valid(b));
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},
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// replace a single node a with a list b (which could be null)
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replace: function(a, b) {
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utils.assert(LinkedList.valid(a) && (b===null || LinkedList.valid(b)));
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if (b!==null) {
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LinkedList.insertBefore(b, a);
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}
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LinkedList.remove(a);
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utils.assert(LinkedList.valid(a) && (b===null || LinkedList.valid(b)));
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},
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// remove single node a from its list
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remove: function(a) {
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utils.assert(LinkedList.valid(a));
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var prev = a._previousSibling;
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if (prev === a) { return; }
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var next = a._nextSibling;
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prev._nextSibling = next;
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next._previousSibling = prev;
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a._previousSibling = a._nextSibling = a;
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utils.assert(LinkedList.valid(a));
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}
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};
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