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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 helps other people to understand this code better and helps them to improve it.
@ -23,8 +25,8 @@
const Changeset = require('./Changeset');
const _ = require('./underscore');
var undoModule = (function () {
const stack = (function () {
const undoModule = (() => {
const stack = (() => {
const stackElements = [];
// two types of stackElements:
// 1) { elementType: UNDOABLE_EVENT, eventType: "anything", [backset: <changeset>,]
@ -36,7 +38,7 @@ var undoModule = (function () {
const UNDOABLE_EVENT = 'undoableEvent';
const EXTERNAL_CHANGE = 'externalChange';
function clearStack() {
const clearStack = () => {
stackElements.length = 0;
stackElements.push(
{
@ -44,22 +46,23 @@ var undoModule = (function () {
eventType: 'bottom',
});
numUndoableEvents = 1;
}
};
clearStack();
function pushEvent(event) {
const pushEvent = (event) => {
const e = _.extend(
{}, event);
e.elementType = UNDOABLE_EVENT;
stackElements.push(e);
numUndoableEvents++;
// dmesg("pushEvent backset: "+event.backset);
}
};
function pushExternalChange(cs) {
const pushExternalChange = (cs) => {
const idx = stackElements.length - 1;
if (stackElements[idx].elementType == EXTERNAL_CHANGE) {
stackElements[idx].changeset = Changeset.compose(stackElements[idx].changeset, cs, getAPool());
if (stackElements[idx].elementType === EXTERNAL_CHANGE) {
stackElements[idx].changeset =
Changeset.compose(stackElements[idx].changeset, cs, getAPool());
} else {
stackElements.push(
{
@ -67,14 +70,14 @@ var undoModule = (function () {
changeset: cs,
});
}
}
};
function _exposeEvent(nthFromTop) {
const _exposeEvent = (nthFromTop) => {
// precond: 0 <= nthFromTop < numUndoableEvents
const targetIndex = stackElements.length - 1 - nthFromTop;
let idx = stackElements.length - 1;
while (idx > targetIndex || stackElements[idx].elementType == EXTERNAL_CHANGE) {
if (stackElements[idx].elementType == EXTERNAL_CHANGE) {
while (idx > targetIndex || stackElements[idx].elementType === EXTERNAL_CHANGE) {
if (stackElements[idx].elementType === EXTERNAL_CHANGE) {
const ex = stackElements[idx];
const un = stackElements[idx - 1];
if (un.backset) {
@ -86,15 +89,16 @@ var undoModule = (function () {
const newSel = Changeset.characterRangeFollow(excs, un.selStart, un.selEnd);
un.selStart = newSel[0];
un.selEnd = newSel[1];
if (un.selStart == un.selEnd) {
if (un.selStart === un.selEnd) {
un.selFocusAtStart = false;
}
}
}
stackElements[idx - 1] = ex;
stackElements[idx] = un;
if (idx >= 2 && stackElements[idx - 2].elementType == EXTERNAL_CHANGE) {
ex.changeset = Changeset.compose(stackElements[idx - 2].changeset, ex.changeset, getAPool());
if (idx >= 2 && stackElements[idx - 2].elementType === EXTERNAL_CHANGE) {
ex.changeset =
Changeset.compose(stackElements[idx - 2].changeset, ex.changeset, getAPool());
stackElements.splice(idx - 2, 1);
idx--;
}
@ -102,24 +106,22 @@ var undoModule = (function () {
idx--;
}
}
}
};
function getNthFromTop(n) {
const getNthFromTop = (n) => {
// precond: 0 <= n < numEvents()
_exposeEvent(n);
return stackElements[stackElements.length - 1 - n];
}
};
function numEvents() {
return numUndoableEvents;
}
const numEvents = () => numUndoableEvents;
function popEvent() {
const popEvent = () => {
// precond: numEvents() > 0
_exposeEvent(0);
numUndoableEvents--;
return stackElements.pop();
}
};
return {
numEvents,
@ -134,12 +136,12 @@ var undoModule = (function () {
// invariant: stack always has at least one undoable event
let undoPtr = 0; // zero-index from top of stack, 0 == top
function clearHistory() {
const clearHistory = () => {
stack.clearStack();
undoPtr = 0;
}
};
function _charOccurrences(str, c) {
const _charOccurrences = (str, c) => {
let i = 0;
let count = 0;
while (i >= 0 && i < str.length) {
@ -150,13 +152,11 @@ var undoModule = (function () {
}
}
return count;
}
};
function _opcodeOccurrences(cs, opcode) {
return _charOccurrences(Changeset.unpack(cs).ops, opcode);
}
const _opcodeOccurrences = (cs, opcode) => _charOccurrences(Changeset.unpack(cs).ops, opcode);
function _mergeChangesets(cs1, cs2) {
const _mergeChangesets = (cs1, cs2) => {
if (!cs1) return cs2;
if (!cs2) return cs1;
@ -170,40 +170,40 @@ var undoModule = (function () {
const plusCount2 = _opcodeOccurrences(cs2, '+');
const minusCount1 = _opcodeOccurrences(cs1, '-');
const minusCount2 = _opcodeOccurrences(cs2, '-');
if (plusCount1 == 1 && plusCount2 == 1 && minusCount1 == 0 && minusCount2 == 0) {
var merge = Changeset.compose(cs1, cs2, getAPool());
var plusCount3 = _opcodeOccurrences(merge, '+');
var minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 == 1 && minusCount3 == 0) {
if (plusCount1 === 1 && plusCount2 === 1 && minusCount1 === 0 && minusCount2 === 0) {
const merge = Changeset.compose(cs1, cs2, getAPool());
const plusCount3 = _opcodeOccurrences(merge, '+');
const minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 === 1 && minusCount3 === 0) {
return merge;
}
} else if (plusCount1 == 0 && plusCount2 == 0 && minusCount1 == 1 && minusCount2 == 1) {
var merge = Changeset.compose(cs1, cs2, getAPool());
var plusCount3 = _opcodeOccurrences(merge, '+');
var minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 == 0 && minusCount3 == 1) {
} else if (plusCount1 === 0 && plusCount2 === 0 && minusCount1 === 1 && minusCount2 === 1) {
const merge = Changeset.compose(cs1, cs2, getAPool());
const plusCount3 = _opcodeOccurrences(merge, '+');
const minusCount3 = _opcodeOccurrences(merge, '-');
if (plusCount3 === 0 && minusCount3 === 1) {
return merge;
}
}
return null;
}
};
function reportEvent(event) {
const reportEvent = (event) => {
const topEvent = stack.getNthFromTop(0);
function applySelectionToTop() {
const applySelectionToTop = () => {
if ((typeof event.selStart) === 'number') {
topEvent.selStart = event.selStart;
topEvent.selEnd = event.selEnd;
topEvent.selFocusAtStart = event.selFocusAtStart;
}
}
};
if ((!event.backset) || Changeset.isIdentity(event.backset)) {
applySelectionToTop();
} else {
let merged = false;
if (topEvent.eventType == event.eventType) {
if (topEvent.eventType === event.eventType) {
const merge = _mergeChangesets(event.backset, topEvent.backset);
if (merge) {
topEvent.backset = merge;
@ -225,15 +225,15 @@ var undoModule = (function () {
}
undoPtr = 0;
}
}
};
function reportExternalChange(changeset) {
const reportExternalChange = (changeset) => {
if (changeset && !Changeset.isIdentity(changeset)) {
stack.pushExternalChange(changeset);
}
}
};
function _getSelectionInfo(event) {
const _getSelectionInfo = (event) => {
if ((typeof event.selStart) !== 'number') {
return null;
} else {
@ -243,7 +243,7 @@ var undoModule = (function () {
selFocusAtStart: event.selFocusAtStart,
};
}
}
};
// For "undo" and "redo", the change event must be returned
// 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.
// "eventFunc" will be called exactly once.
function performUndo(eventFunc) {
const performUndo = (eventFunc) => {
if (undoPtr < stack.numEvents() - 1) {
const backsetEvent = stack.getNthFromTop(undoPtr);
const selectionEvent = stack.getNthFromTop(undoPtr + 1);
@ -259,9 +259,9 @@ var undoModule = (function () {
stack.pushEvent(undoEvent);
undoPtr += 2;
} else { eventFunc(); }
}
};
function performRedo(eventFunc) {
const performRedo = (eventFunc) => {
if (undoPtr >= 2) {
const backsetEvent = stack.getNthFromTop(0);
const selectionEvent = stack.getNthFromTop(1);
@ -269,11 +269,9 @@ var undoModule = (function () {
stack.popEvent();
undoPtr -= 2;
} else { eventFunc(); }
}
};
function getAPool() {
return undoModule.apool;
}
const getAPool = () => undoModule.apool;
return {
clearHistory,