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lint: skiplist

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John McLear 2020-12-21 23:23:16 +00:00 committed by Richard Hansen
parent f72ce463ef
commit 29179e512f
1 changed files with 65 additions and 112 deletions
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177
src/static/js/skiplist.js
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@ -1,3 +1,5 @@
'use strict';
/** /**
* This code is mostly from the old Etherpad. Please help us to comment this code. * This code is mostly from the old Etherpad. Please help us to comment this code.
* This helps other people to understand this code better and helps them to improve it. * This helps other people to understand this code better and helps them to improve it.
@ -28,15 +30,13 @@ const noop = Ace2Common.noop;
function SkipList() { function SkipList() {
let PROFILER = window.PROFILER; let PROFILER = window.PROFILER;
if (!PROFILER) { if (!PROFILER) {
PROFILER = function () { PROFILER = () => ({
return { start: noop,
start: noop, mark: noop,
mark: noop, literal: noop,
literal: noop, end: noop,
end: noop, cancel: noop,
cancel: noop, });
};
};
} }
// 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
@ -68,7 +68,7 @@ function SkipList() {
// this point. // this point.
function _getPoint(targetLoc) { const _getPoint = (targetLoc) => {
const numLevels = start.levels; const numLevels = start.levels;
let lvl = numLevels - 1; let lvl = numLevels - 1;
let i = -1; let i = -1;
@ -99,13 +99,11 @@ function SkipList() {
idxs, idxs,
loc: targetLoc, loc: targetLoc,
widthSkips, widthSkips,
toString() { toString: () => `getPoint(${targetLoc})`,
return `getPoint(${targetLoc})`;
},
}; };
} };
function _getNodeAtOffset(targetOffset) { const _getNodeAtOffset = (targetOffset) => {
let i = 0; let i = 0;
let n = start; let n = start;
let lvl = start.levels - 1; let lvl = start.levels - 1;
@ -117,16 +115,14 @@ function SkipList() {
lvl--; lvl--;
} }
if (n === start) return (start.downPtrs[0] || null); if (n === start) return (start.downPtrs[0] || null);
else if (n === end) return (targetOffset == totalWidth ? (end.upPtrs[0] || null) : null); else if (n === end) return (targetOffset === totalWidth ? (end.upPtrs[0] || null) : null);
return n; return n;
} };
function _entryWidth(e) { const _entryWidth = (e) => (e && e.width) || 0;
return (e && e.width) || 0;
}
function _insertKeyAtPoint(point, newKey, entry) { const _insertKeyAtPoint = (point, newKey, entry) => {
const p = PROFILER('insertKey', false); const p = PROFILER('insertKey', false); // eslint-disable-line new-cap
const newNode = { const newNode = {
key: newKey, key: newKey,
levels: 0, levels: 0,
@ -145,10 +141,10 @@ function SkipList() {
// The new node will have at least level 1 // The new node will have at least level 1
// With a proability of 0.01^(n-1) the nodes level will be >= n // With a proability of 0.01^(n-1) the nodes level will be >= n
while (newNode.levels == 0 || Math.random() < 0.01) { while (newNode.levels === 0 || Math.random() < 0.01) {
var lvl = newNode.levels; const lvl = newNode.levels;
newNode.levels++; newNode.levels++;
if (lvl == pNodes.length) { if (lvl === pNodes.length) {
// assume we have just passed the end of point.nodes, and reached one level greater // assume we have just passed the end of point.nodes, and reached one level greater
// than the skiplist currently supports // than the skiplist currently supports
pNodes[lvl] = start; pNodes[lvl] = start;
@ -162,7 +158,7 @@ function SkipList() {
point.widthSkips[lvl] = 0; point.widthSkips[lvl] = 0;
} }
const me = newNode; const me = newNode;
var up = pNodes[lvl]; const up = pNodes[lvl];
const down = up.downPtrs[lvl]; const down = up.downPtrs[lvl];
const skip1 = pLoc - pIdxs[lvl]; const skip1 = pLoc - pIdxs[lvl];
const skip2 = up.downSkips[lvl] + 1 - skip1; const skip2 = up.downSkips[lvl] + 1 - skip1;
@ -179,8 +175,8 @@ function SkipList() {
} }
p.mark('loop2'); p.mark('loop2');
p.literal(pNodes.length, 'PNL'); p.literal(pNodes.length, 'PNL');
for (var lvl = newNode.levels; lvl < pNodes.length; lvl++) { for (let lvl = newNode.levels; lvl < pNodes.length; lvl++) {
var up = pNodes[lvl]; const up = pNodes[lvl];
up.downSkips[lvl]++; up.downSkips[lvl]++;
up.downSkipWidths[lvl] += newWidth; up.downSkipWidths[lvl] += newWidth;
} }
@ -189,30 +185,17 @@ function SkipList() {
numNodes++; numNodes++;
totalWidth += newWidth; totalWidth += newWidth;
p.end(); p.end();
} };
function _getNodeAtPoint(point) { const _getNodeAtPoint = (point) => point.nodes[0].downPtrs[0];
return point.nodes[0].downPtrs[0];
}
function _incrementPoint(point) { const _deleteKeyAtPoint = (point) => {
point.loc++;
for (let i = 0; i < point.nodes.length; i++) {
if (point.idxs[i] + point.nodes[i].downSkips[i] < point.loc) {
point.idxs[i] += point.nodes[i].downSkips[i];
point.widthSkips[i] += point.nodes[i].downSkipWidths[i];
point.nodes[i] = point.nodes[i].downPtrs[i];
}
}
}
function _deleteKeyAtPoint(point) {
const elem = point.nodes[0].downPtrs[0]; const elem = point.nodes[0].downPtrs[0];
const elemWidth = _entryWidth(elem.entry); const elemWidth = _entryWidth(elem.entry);
for (let i = 0; i < point.nodes.length; i++) { for (let i = 0; i < point.nodes.length; i++) {
if (i < elem.levels) { if (i < elem.levels) {
var up = elem.upPtrs[i]; const up = elem.upPtrs[i];
var down = elem.downPtrs[i]; const down = elem.downPtrs[i];
const totalSkip = up.downSkips[i] + elem.downSkips[i] - 1; const totalSkip = up.downSkips[i] + elem.downSkips[i] - 1;
up.downPtrs[i] = down; up.downPtrs[i] = down;
down.upPtrs[i] = up; down.upPtrs[i] = up;
@ -220,8 +203,7 @@ function SkipList() {
const totalWidthSkip = up.downSkipWidths[i] + elem.downSkipWidths[i] - elemWidth; const totalWidthSkip = up.downSkipWidths[i] + elem.downSkipWidths[i] - elemWidth;
up.downSkipWidths[i] = totalWidthSkip; up.downSkipWidths[i] = totalWidthSkip;
} else { } else {
var up = point.nodes[i]; const up = point.nodes[i];
var down = up.downPtrs[i];
up.downSkips[i]--; up.downSkips[i]--;
up.downSkipWidths[i] -= elemWidth; up.downSkipWidths[i] -= elemWidth;
} }
@ -229,9 +211,9 @@ function SkipList() {
delete keyToNodeMap[`$KEY$${elem.key}`]; delete keyToNodeMap[`$KEY$${elem.key}`];
numNodes--; numNodes--;
totalWidth -= elemWidth; totalWidth -= elemWidth;
} };
function _propagateWidthChange(node) { const _propagateWidthChange = (node) => {
const oldWidth = node.downSkipWidths[0]; const oldWidth = node.downSkipWidths[0];
const newWidth = _entryWidth(node.entry); const newWidth = _entryWidth(node.entry);
const widthChange = newWidth - oldWidth; const widthChange = newWidth - oldWidth;
@ -245,9 +227,9 @@ function SkipList() {
} }
} }
totalWidth += widthChange; totalWidth += widthChange;
} };
function _getNodeIndex(node, byWidth) { const _getNodeIndex = (node, byWidth) => {
let dist = (byWidth ? 0 : -1); let dist = (byWidth ? 0 : -1);
let n = node; let n = node;
while (n !== start) { while (n !== start) {
@ -257,27 +239,26 @@ function SkipList() {
else dist += n.downSkips[lvl]; else dist += n.downSkips[lvl];
} }
return dist; return dist;
} };
function _getNodeByKey(key) { const _getNodeByKey = (key) => keyToNodeMap[`$KEY$${key}`];
return keyToNodeMap[`$KEY$${key}`];
}
// Returns index of first entry such that entryFunc(entry) is truthy, // Returns index of first entry such that entryFunc(entry) is truthy,
// or length() if no such entry. Assumes all falsy entries come before // or length() if no such entry. Assumes all falsy entries come before
// all truthy entries. // all truthy entries.
function _search(entryFunc) { const _search = (entryFunc) => {
let low = start; let low = start;
let lvl = start.levels - 1; let lvl = start.levels - 1;
let lowIndex = -1; let lowIndex = -1;
function f(node) { const f = (node) => {
if (node === start) return false; if (node === start) return false;
else if (node === end) return true; else if (node === end) return true;
else return entryFunc(node.entry); else return entryFunc(node.entry);
} };
while (lvl >= 0) { while (lvl >= 0) {
let nextLow = low.downPtrs[lvl]; let nextLow = low.downPtrs[lvl];
while (!f(nextLow)) { while (!f(nextLow)) {
@ -288,7 +269,7 @@ function SkipList() {
lvl--; lvl--;
} }
return lowIndex + 1; return lowIndex + 1;
} };
/* /*
The skip-list contains "entries", JavaScript objects that each must have a unique "key" property The skip-list contains "entries", JavaScript objects that each must have a unique "key" property
@ -296,16 +277,14 @@ that is a string.
*/ */
const self = this; const self = this;
_.extend(this, { _.extend(this, {
length() { length: () => numNodes,
return numNodes; atIndex: (i) => {
},
atIndex(i) {
if (i < 0) console.warn(`atIndex(${i})`); if (i < 0) console.warn(`atIndex(${i})`);
if (i >= numNodes) console.warn(`atIndex(${i}>=${numNodes})`); if (i >= numNodes) console.warn(`atIndex(${i}>=${numNodes})`);
return _getNodeAtPoint(_getPoint(i)).entry; return _getNodeAtPoint(_getPoint(i)).entry;
}, },
// differs from Array.splice() in that new elements are in an array, not varargs // differs from Array.splice() in that new elements are in an array, not varargs
splice(start, deleteCount, newEntryArray) { splice: (start, deleteCount, newEntryArray) => {
if (start < 0) console.warn(`splice(${start}, ...)`); if (start < 0) console.warn(`splice(${start}, ...)`);
if (start + deleteCount > numNodes) { if (start + deleteCount > numNodes) {
console.warn(`splice(${start}, ${deleteCount}, ...), N=${numNodes}`); console.warn(`splice(${start}, ${deleteCount}, ...), N=${numNodes}`);
@ -315,26 +294,22 @@ that is a string.
if (!newEntryArray) newEntryArray = []; if (!newEntryArray) newEntryArray = [];
const pt = _getPoint(start); const pt = _getPoint(start);
for (var i = 0; i < deleteCount; i++) { for (let i = 0; i < deleteCount; i++) {
_deleteKeyAtPoint(pt); _deleteKeyAtPoint(pt);
} }
for (var i = (newEntryArray.length - 1); i >= 0; i--) { for (let i = (newEntryArray.length - 1); i >= 0; i--) {
const entry = newEntryArray[i]; const entry = newEntryArray[i];
_insertKeyAtPoint(pt, entry.key, entry); _insertKeyAtPoint(pt, entry.key, entry);
const node = _getNodeByKey(entry.key); const node = _getNodeByKey(entry.key);
node.entry = entry; node.entry = entry;
} }
}, },
next(entry) { next: (entry) => _getNodeByKey(entry.key).downPtrs[0].entry || null,
return _getNodeByKey(entry.key).downPtrs[0].entry || null; prev: (entry) => _getNodeByKey(entry.key).upPtrs[0].entry || null,
}, push: (entry) => {
prev(entry) {
return _getNodeByKey(entry.key).upPtrs[0].entry || null;
},
push(entry) {
self.splice(numNodes, 0, [entry]); self.splice(numNodes, 0, [entry]);
}, },
slice(start, end) { slice: (start, end) => {
// act like Array.slice() // act like Array.slice()
if (start === undefined) start = 0; if (start === undefined) start = 0;
else if (start < 0) start += numNodes; else if (start < 0) start += numNodes;
@ -346,7 +321,7 @@ that is a string.
if (end < 0) end = 0; if (end < 0) end = 0;
if (end > numNodes) end = numNodes; if (end > numNodes) end = numNodes;
dmesg(String([start, end, numNodes])); window.dmesg(String([start, end, numNodes]));
if (end <= start) return []; if (end <= start) return [];
let n = self.atIndex(start); let n = self.atIndex(start);
const array = [n]; const array = [n];
@ -356,56 +331,34 @@ that is a string.
} }
return array; return array;
}, },
atKey(key) { atKey: (key) => _getNodeByKey(key).entry,
return _getNodeByKey(key).entry; indexOfKey: (key) => _getNodeIndex(_getNodeByKey(key)),
}, indexOfEntry: (entry) => self.indexOfKey(entry.key),
indexOfKey(key) { containsKey: (key) => !!(_getNodeByKey(key)),
return _getNodeIndex(_getNodeByKey(key));
},
indexOfEntry(entry) {
return self.indexOfKey(entry.key);
},
containsKey(key) {
return !!(_getNodeByKey(key));
},
// gets the last entry starting at or before the offset // gets the last entry starting at or before the offset
atOffset(offset) { atOffset: (offset) => _getNodeAtOffset(offset).entry,
return _getNodeAtOffset(offset).entry; keyAtOffset: (offset) => self.atOffset(offset).key,
}, offsetOfKey: (key) => _getNodeIndex(_getNodeByKey(key), true),
keyAtOffset(offset) { offsetOfEntry: (entry) => self.offsetOfKey(entry.key),
return self.atOffset(offset).key; setEntryWidth: (entry, width) => {
},
offsetOfKey(key) {
return _getNodeIndex(_getNodeByKey(key), true);
},
offsetOfEntry(entry) {
return self.offsetOfKey(entry.key);
},
setEntryWidth(entry, width) {
entry.width = width; entry.width = width;
_propagateWidthChange(_getNodeByKey(entry.key)); _propagateWidthChange(_getNodeByKey(entry.key));
}, },
totalWidth() { totalWidth: () => totalWidth,
return totalWidth; offsetOfIndex: (i) => {
},
offsetOfIndex(i) {
if (i < 0) return 0; if (i < 0) return 0;
if (i >= numNodes) return totalWidth; if (i >= numNodes) return totalWidth;
return self.offsetOfEntry(self.atIndex(i)); return self.offsetOfEntry(self.atIndex(i));
}, },
indexOfOffset(offset) { indexOfOffset: (offset) => {
if (offset <= 0) return 0; if (offset <= 0) return 0;
if (offset >= totalWidth) return numNodes; if (offset >= totalWidth) return numNodes;
return self.indexOfEntry(self.atOffset(offset)); return self.indexOfEntry(self.atOffset(offset));
}, },
search(entryFunc) { search: (entryFunc) => _search(entryFunc),
return _search(entryFunc);
},
// debugToString: _debugToString, // debugToString: _debugToString,
debugGetPoint: _getPoint, debugGetPoint: _getPoint,
debugDepth() { debugDepth: () => start.levels,
return start.levels;
},
}); });
} }