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skiplist: Define a new Node class

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This commit is contained in:
Richard Hansen 2021-04-11 23:50:42 -04:00
parent 9fc88f3601
commit fc103e7f2a
1 changed files with 15 additions and 25 deletions
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40
src/static/js/skiplist.js
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@ -24,6 +24,18 @@
const _entryWidth = (e) => (e && e.width) || 0; const _entryWidth = (e) => (e && e.width) || 0;
class Node {
constructor(entry, levels = 0, downSkips = 1, downSkipWidths = 0) {
this.key = entry != null ? entry.key : null;
this.entry = entry;
this.levels = levels;
this.upPtrs = Array(levels).fill(null);
this.downPtrs = Array(levels).fill(null);
this.downSkips = Array(levels).fill(downSkips);
this.downSkipWidths = Array(levels).fill(downSkipWidths);
}
}
// A "point" object at index x allows modifications immediately after the first x elements of the // A "point" object at index x allows modifications immediately after the first x elements of the
// skiplist, such as multiple inserts or deletes. After an insert or delete using point P, the point // skiplist, such as multiple inserts or deletes. After an insert or delete using point P, the point
// is still valid and points to the same index in the skiplist. Other operations with other points // is still valid and points to the same index in the skiplist. Other operations with other points
@ -67,15 +79,7 @@ class Point {
} }
insert(entry) { insert(entry) {
const newNode = { const newNode = new Node(entry);
key: entry.key,
entry,
levels: 0,
upPtrs: [],
downPtrs: [],
downSkips: [],
downSkipWidths: [],
};
const pNodes = this.nodes; const pNodes = this.nodes;
const pIdxs = this.idxs; const pIdxs = this.idxs;
const pLoc = this.loc; const pLoc = this.loc;
@ -162,22 +166,8 @@ class Point {
class SkipList { class SkipList {
constructor() { constructor() {
// if there are N elements in the skiplist, "start" is element -1 and "end" is element N // if there are N elements in the skiplist, "start" is element -1 and "end" is element N
this._start = { this._start = new Node(null, 1);
key: null, this._end = new Node(null, 1, null, null);
levels: 1,
upPtrs: [null],
downPtrs: [null],
downSkips: [1],
downSkipWidths: [0],
};
this._end = {
key: null,
levels: 1,
upPtrs: [null],
downPtrs: [null],
downSkips: [null],
downSkipWidths: [null],
};
this._numNodes = 0; this._numNodes = 0;
this._totalWidth = 0; this._totalWidth = 0;
this._keyToNodeMap = {}; this._keyToNodeMap = {};