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lint: undomodule

pull/4601/head
John McLear 2020-12-21 23:11:17 +00:00 committed by Richard Hansen
parent 89bcfa2b4a
commit f72ce463ef
1 changed files with 57 additions and 59 deletions
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116
src/static/js/undomodule.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.
@ -23,8 +25,8 @@
const Changeset = require('./Changeset'); const Changeset = require('./Changeset');
const _ = require('./underscore'); const _ = require('./underscore');
var undoModule = (function () { const undoModule = (() => {
const stack = (function () { const stack = (() => {
const stackElements = []; const stackElements = [];
// two types of stackElements: // two types of stackElements:
// 1) { elementType: UNDOABLE_EVENT, eventType: "anything", [backset: <changeset>,] // 1) { elementType: UNDOABLE_EVENT, eventType: "anything", [backset: <changeset>,]
@ -36,7 +38,7 @@ var undoModule = (function () {
const UNDOABLE_EVENT = 'undoableEvent'; const UNDOABLE_EVENT = 'undoableEvent';
const EXTERNAL_CHANGE = 'externalChange'; const EXTERNAL_CHANGE = 'externalChange';
function clearStack() { const clearStack = () => {
stackElements.length = 0; stackElements.length = 0;
stackElements.push( stackElements.push(
{ {
@ -44,22 +46,23 @@ var undoModule = (function () {
eventType: 'bottom', eventType: 'bottom',
}); });
numUndoableEvents = 1; numUndoableEvents = 1;
} };
clearStack(); clearStack();
function pushEvent(event) { const pushEvent = (event) => {
const e = _.extend( const e = _.extend(
{}, event); {}, event);
e.elementType = UNDOABLE_EVENT; e.elementType = UNDOABLE_EVENT;
stackElements.push(e); stackElements.push(e);
numUndoableEvents++; numUndoableEvents++;
// dmesg("pushEvent backset: "+event.backset); // dmesg("pushEvent backset: "+event.backset);
} };
function pushExternalChange(cs) { const pushExternalChange = (cs) => {
const idx = stackElements.length - 1; const idx = stackElements.length - 1;
if (stackElements[idx].elementType == EXTERNAL_CHANGE) { if (stackElements[idx].elementType === EXTERNAL_CHANGE) {
stackElements[idx].changeset = Changeset.compose(stackElements[idx].changeset, cs, getAPool()); stackElements[idx].changeset =
Changeset.compose(stackElements[idx].changeset, cs, getAPool());
} else { } else {
stackElements.push( stackElements.push(
{ {
@ -67,14 +70,14 @@ var undoModule = (function () {
changeset: cs, changeset: cs,
}); });
} }
} };
function _exposeEvent(nthFromTop) { const _exposeEvent = (nthFromTop) => {
// precond: 0 <= nthFromTop < numUndoableEvents // precond: 0 <= nthFromTop < numUndoableEvents
const targetIndex = stackElements.length - 1 - nthFromTop; const targetIndex = stackElements.length - 1 - nthFromTop;
let idx = stackElements.length - 1; let idx = stackElements.length - 1;
while (idx > targetIndex || stackElements[idx].elementType == EXTERNAL_CHANGE) { while (idx > targetIndex || stackElements[idx].elementType === EXTERNAL_CHANGE) {
if (stackElements[idx].elementType == EXTERNAL_CHANGE) { if (stackElements[idx].elementType === EXTERNAL_CHANGE) {
const ex = stackElements[idx]; const ex = stackElements[idx];
const un = stackElements[idx - 1]; const un = stackElements[idx - 1];
if (un.backset) { if (un.backset) {
@ -86,15 +89,16 @@ var undoModule = (function () {
const newSel = Changeset.characterRangeFollow(excs, un.selStart, un.selEnd); const newSel = Changeset.characterRangeFollow(excs, un.selStart, un.selEnd);
un.selStart = newSel[0]; un.selStart = newSel[0];
un.selEnd = newSel[1]; un.selEnd = newSel[1];
if (un.selStart == un.selEnd) { if (un.selStart === un.selEnd) {
un.selFocusAtStart = false; un.selFocusAtStart = false;
} }
} }
} }
stackElements[idx - 1] = ex; stackElements[idx - 1] = ex;
stackElements[idx] = un; stackElements[idx] = un;
if (idx >= 2 && stackElements[idx - 2].elementType == EXTERNAL_CHANGE) { if (idx >= 2 && stackElements[idx - 2].elementType === EXTERNAL_CHANGE) {
ex.changeset = Changeset.compose(stackElements[idx - 2].changeset, ex.changeset, getAPool()); ex.changeset =
Changeset.compose(stackElements[idx - 2].changeset, ex.changeset, getAPool());
stackElements.splice(idx - 2, 1); stackElements.splice(idx - 2, 1);
idx--; idx--;
} }
@ -102,24 +106,22 @@ var undoModule = (function () {
idx--; idx--;
} }
} }
} };
function getNthFromTop(n) { const getNthFromTop = (n) => {
// precond: 0 <= n < numEvents() // precond: 0 <= n < numEvents()
_exposeEvent(n); _exposeEvent(n);
return stackElements[stackElements.length - 1 - n]; return stackElements[stackElements.length - 1 - n];
} };
function numEvents() { const numEvents = () => numUndoableEvents;
return numUndoableEvents;
}
function popEvent() { const popEvent = () => {
// precond: numEvents() > 0 // precond: numEvents() > 0
_exposeEvent(0); _exposeEvent(0);
numUndoableEvents--; numUndoableEvents--;
return stackElements.pop(); return stackElements.pop();
} };
return { return {
numEvents, numEvents,
@ -134,12 +136,12 @@ var undoModule = (function () {
// invariant: stack always has at least one undoable event // invariant: stack always has at least one undoable event
let undoPtr = 0; // zero-index from top of stack, 0 == top let undoPtr = 0; // zero-index from top of stack, 0 == top
function clearHistory() { const clearHistory = () => {
stack.clearStack(); stack.clearStack();
undoPtr = 0; undoPtr = 0;
} };
function _charOccurrences(str, c) { const _charOccurrences = (str, c) => {
let i = 0; let i = 0;
let count = 0; let count = 0;
while (i >= 0 && i < str.length) { while (i >= 0 && i < str.length) {
@ -150,13 +152,11 @@ var undoModule = (function () {
} }
} }
return count; return count;
} };
function _opcodeOccurrences(cs, opcode) { const _opcodeOccurrences = (cs, opcode) => _charOccurrences(Changeset.unpack(cs).ops, opcode);
return _charOccurrences(Changeset.unpack(cs).ops, opcode);
}
function _mergeChangesets(cs1, cs2) { const _mergeChangesets = (cs1, cs2) => {
if (!cs1) return cs2; if (!cs1) return cs2;
if (!cs2) return cs1; if (!cs2) return cs1;
@ -170,40 +170,40 @@ var undoModule = (function () {
const plusCount2 = _opcodeOccurrences(cs2, '+'); const plusCount2 = _opcodeOccurrences(cs2, '+');
const minusCount1 = _opcodeOccurrences(cs1, '-'); const minusCount1 = _opcodeOccurrences(cs1, '-');
const minusCount2 = _opcodeOccurrences(cs2, '-'); const minusCount2 = _opcodeOccurrences(cs2, '-');
if (plusCount1 == 1 && plusCount2 == 1 && minusCount1 == 0 && minusCount2 == 0) { if (plusCount1 === 1 && plusCount2 === 1 && minusCount1 === 0 && minusCount2 === 0) {
var merge = Changeset.compose(cs1, cs2, getAPool()); const merge = Changeset.compose(cs1, cs2, getAPool());
var plusCount3 = _opcodeOccurrences(merge, '+'); const plusCount3 = _opcodeOccurrences(merge, '+');
var minusCount3 = _opcodeOccurrences(merge, '-'); const minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 == 1 && minusCount3 == 0) { if (plusCount3 === 1 && minusCount3 === 0) {
return merge; return merge;
} }
} else if (plusCount1 == 0 && plusCount2 == 0 && minusCount1 == 1 && minusCount2 == 1) { } else if (plusCount1 === 0 && plusCount2 === 0 && minusCount1 === 1 && minusCount2 === 1) {
var merge = Changeset.compose(cs1, cs2, getAPool()); const merge = Changeset.compose(cs1, cs2, getAPool());
var plusCount3 = _opcodeOccurrences(merge, '+'); const plusCount3 = _opcodeOccurrences(merge, '+');
var minusCount3 = _opcodeOccurrences(merge, '-'); const minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 == 0 && minusCount3 == 1) { if (plusCount3 === 0 && minusCount3 === 1) {
return merge; return merge;
} }
} }
return null; return null;
} };
function reportEvent(event) { const reportEvent = (event) => {
const topEvent = stack.getNthFromTop(0); const topEvent = stack.getNthFromTop(0);
function applySelectionToTop() { const applySelectionToTop = () => {
if ((typeof event.selStart) === 'number') { if ((typeof event.selStart) === 'number') {
topEvent.selStart = event.selStart; topEvent.selStart = event.selStart;
topEvent.selEnd = event.selEnd; topEvent.selEnd = event.selEnd;
topEvent.selFocusAtStart = event.selFocusAtStart; topEvent.selFocusAtStart = event.selFocusAtStart;
} }
} };
if ((!event.backset) || Changeset.isIdentity(event.backset)) { if ((!event.backset) || Changeset.isIdentity(event.backset)) {
applySelectionToTop(); applySelectionToTop();
} else { } else {
let merged = false; let merged = false;
if (topEvent.eventType == event.eventType) { if (topEvent.eventType === event.eventType) {
const merge = _mergeChangesets(event.backset, topEvent.backset); const merge = _mergeChangesets(event.backset, topEvent.backset);
if (merge) { if (merge) {
topEvent.backset = merge; topEvent.backset = merge;
@ -225,15 +225,15 @@ var undoModule = (function () {
} }
undoPtr = 0; undoPtr = 0;
} }
} };
function reportExternalChange(changeset) { const reportExternalChange = (changeset) => {
if (changeset && !Changeset.isIdentity(changeset)) { if (changeset && !Changeset.isIdentity(changeset)) {
stack.pushExternalChange(changeset); stack.pushExternalChange(changeset);
} }
} };
function _getSelectionInfo(event) { const _getSelectionInfo = (event) => {
if ((typeof event.selStart) !== 'number') { if ((typeof event.selStart) !== 'number') {
return null; return null;
} else { } else {
@ -243,7 +243,7 @@ var undoModule = (function () {
selFocusAtStart: event.selFocusAtStart, selFocusAtStart: event.selFocusAtStart,
}; };
} }
} };
// For "undo" and "redo", the change event must be returned // For "undo" and "redo", the change event must be returned
// by eventFunc and NOT reported through the normal mechanism. // by eventFunc and NOT reported through the normal mechanism.
@ -251,7 +251,7 @@ var undoModule = (function () {
// or can be called with no arguments to mean that no undo is possible. // or can be called with no arguments to mean that no undo is possible.
// "eventFunc" will be called exactly once. // "eventFunc" will be called exactly once.
function performUndo(eventFunc) { const performUndo = (eventFunc) => {
if (undoPtr < stack.numEvents() - 1) { if (undoPtr < stack.numEvents() - 1) {
const backsetEvent = stack.getNthFromTop(undoPtr); const backsetEvent = stack.getNthFromTop(undoPtr);
const selectionEvent = stack.getNthFromTop(undoPtr + 1); const selectionEvent = stack.getNthFromTop(undoPtr + 1);
@ -259,9 +259,9 @@ var undoModule = (function () {
stack.pushEvent(undoEvent); stack.pushEvent(undoEvent);
undoPtr += 2; undoPtr += 2;
} else { eventFunc(); } } else { eventFunc(); }
} };
function performRedo(eventFunc) { const performRedo = (eventFunc) => {
if (undoPtr >= 2) { if (undoPtr >= 2) {
const backsetEvent = stack.getNthFromTop(0); const backsetEvent = stack.getNthFromTop(0);
const selectionEvent = stack.getNthFromTop(1); const selectionEvent = stack.getNthFromTop(1);
@ -269,11 +269,9 @@ var undoModule = (function () {
stack.popEvent(); stack.popEvent();
undoPtr -= 2; undoPtr -= 2;
} else { eventFunc(); } } else { eventFunc(); }
} };
function getAPool() { const getAPool = () => undoModule.apool;
return undoModule.apool;
}
return { return {
clearHistory, clearHistory,