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import RopeSequence from 'rope-sequence';
import { Mapping } from 'prosemirror-transform';
import { PluginKey, Plugin } from 'prosemirror-state';
// ProseMirror's history isn't simply a way to roll back to a previous
// state, because ProseMirror supports applying changes without adding
// them to the history (for example during collaboration).
//
// To this end, each 'Branch' (one for the undo history and one for
// the redo history) keeps an array of 'Items', which can optionally
// hold a step (an actual undoable change), and always hold a position
// map (which is needed to move changes below them to apply to the
// current document).
//
// An item that has both a step and a selection bookmark is the start
// of an 'event' — a group of changes that will be undone or redone at
// once. (It stores only the bookmark, since that way we don't have to
// provide a document until the selection is actually applied, which
// is useful when compressing.)
// Used to schedule history compression
const max_empty_items = 500;
class Branch {
constructor(items, eventCount) {
this.items = items;
this.eventCount = eventCount;
}
// Pop the latest event off the branch's history and apply it
// to a document transform.
popEvent(state, preserveItems) {
if (this.eventCount == 0)
return null;
let end = this.items.length;
for (;; end--) {
let next = this.items.get(end - 1);
if (next.selection) {
--end;
break;
}
}
let remap, mapFrom;
if (preserveItems) {
remap = this.remapping(end, this.items.length);
mapFrom = remap.maps.length;
}
let transform = state.tr;
let selection, remaining;
let addAfter = [], addBefore = [];
this.items.forEach((item, i) => {
if (!item.step) {
if (!remap) {
remap = this.remapping(end, i + 1);
mapFrom = remap.maps.length;
}
mapFrom--;
addBefore.push(item);
return;
}
if (remap) {
addBefore.push(new Item(item.map));
let step = item.step.map(remap.slice(mapFrom)), map;
if (step && transform.maybeStep(step).doc) {
map = transform.mapping.maps[transform.mapping.maps.length - 1];
addAfter.push(new Item(map, undefined, undefined, addAfter.length + addBefore.length));
}
mapFrom--;
if (map)
remap.appendMap(map, mapFrom);
}
else {
transform.maybeStep(item.step);
}
if (item.selection) {
selection = remap ? item.selection.map(remap.slice(mapFrom)) : item.selection;
remaining = new Branch(this.items.slice(0, end).append(addBefore.reverse().concat(addAfter)), this.eventCount - 1);
return false;
}
}, this.items.length, 0);
return { remaining: remaining, transform, selection: selection };
}
// Create a new branch with the given transform added.
addTransform(transform, selection, histOptions, preserveItems) {
let newItems = [], eventCount = this.eventCount;
let oldItems = this.items, lastItem = !preserveItems && oldItems.length ? oldItems.get(oldItems.length - 1) : null;
for (let i = 0; i < transform.steps.length; i++) {
let step = transform.steps[i].invert(transform.docs[i]);
let item = new Item(transform.mapping.maps[i], step, selection), merged;
if (merged = lastItem && lastItem.merge(item)) {
item = merged;
if (i)
newItems.pop();
else
oldItems = oldItems.slice(0, oldItems.length - 1);
}
newItems.push(item);
if (selection) {
eventCount++;
selection = undefined;
}
if (!preserveItems)
lastItem = item;
}
let overflow = eventCount - histOptions.depth;
if (overflow > DEPTH_OVERFLOW) {
oldItems = cutOffEvents(oldItems, overflow);
eventCount -= overflow;
}
return new Branch(oldItems.append(newItems), eventCount);
}
remapping(from, to) {
let maps = new Mapping;
this.items.forEach((item, i) => {
let mirrorPos = item.mirrorOffset != null && i - item.mirrorOffset >= from
? maps.maps.length - item.mirrorOffset : undefined;
maps.appendMap(item.map, mirrorPos);
}, from, to);
return maps;
}
addMaps(array) {
if (this.eventCount == 0)
return this;
return new Branch(this.items.append(array.map(map => new Item(map))), this.eventCount);
}
// When the collab module receives remote changes, the history has
// to know about those, so that it can adjust the steps that were
// rebased on top of the remote changes, and include the position
// maps for the remote changes in its array of items.
rebased(rebasedTransform, rebasedCount) {
if (!this.eventCount)
return this;
let rebasedItems = [], start = Math.max(0, this.items.length - rebasedCount);
let mapping = rebasedTransform.mapping;
let newUntil = rebasedTransform.steps.length;
let eventCount = this.eventCount;
this.items.forEach(item => { if (item.selection)
eventCount--; }, start);
let iRebased = rebasedCount;
this.items.forEach(item => {
let pos = mapping.getMirror(--iRebased);
if (pos == null)
return;
newUntil = Math.min(newUntil, pos);
let map = mapping.maps[pos];
if (item.step) {
let step = rebasedTransform.steps[pos].invert(rebasedTransform.docs[pos]);
let selection = item.selection && item.selection.map(mapping.slice(iRebased + 1, pos));
if (selection)
eventCount++;
rebasedItems.push(new Item(map, step, selection));
}
else {
rebasedItems.push(new Item(map));
}
}, start);
let newMaps = [];
for (let i = rebasedCount; i < newUntil; i++)
newMaps.push(new Item(mapping.maps[i]));
let items = this.items.slice(0, start).append(newMaps).append(rebasedItems);
let branch = new Branch(items, eventCount);
if (branch.emptyItemCount() > max_empty_items)
branch = branch.compress(this.items.length - rebasedItems.length);
return branch;
}
emptyItemCount() {
let count = 0;
this.items.forEach(item => { if (!item.step)
count++; });
return count;
}
// Compressing a branch means rewriting it to push the air (map-only
// items) out. During collaboration, these naturally accumulate
// because each remote change adds one. The `upto` argument is used
// to ensure that only the items below a given level are compressed,
// because `rebased` relies on a clean, untouched set of items in
// order to associate old items with rebased steps.
compress(upto = this.items.length) {
let remap = this.remapping(0, upto), mapFrom = remap.maps.length;
let items = [], events = 0;
this.items.forEach((item, i) => {
if (i >= upto) {
items.push(item);
if (item.selection)
events++;
}
else if (item.step) {
let step = item.step.map(remap.slice(mapFrom)), map = step && step.getMap();
mapFrom--;
if (map)
remap.appendMap(map, mapFrom);
if (step) {
let selection = item.selection && item.selection.map(remap.slice(mapFrom));
if (selection)
events++;
let newItem = new Item(map.invert(), step, selection), merged, last = items.length - 1;
if (merged = items.length && items[last].merge(newItem))
items[last] = merged;
else
items.push(newItem);
}
}
else if (item.map) {
mapFrom--;
}
}, this.items.length, 0);
return new Branch(RopeSequence.from(items.reverse()), events);
}
}
Branch.empty = new Branch(RopeSequence.empty, 0);
function cutOffEvents(items, n) {
let cutPoint;
items.forEach((item, i) => {
if (item.selection && (n-- == 0)) {
cutPoint = i;
return false;
}
});
return items.slice(cutPoint);
}
class Item {
constructor(
// The (forward) step map for this item.
map,
// The inverted step
step,
// If this is non-null, this item is the start of a group, and
// this selection is the starting selection for the group (the one
// that was active before the first step was applied)
selection,
// If this item is the inverse of a previous mapping on the stack,
// this points at the inverse's offset
mirrorOffset) {
this.map = map;
this.step = step;
this.selection = selection;
this.mirrorOffset = mirrorOffset;
}
merge(other) {
if (this.step && other.step && !other.selection) {
let step = other.step.merge(this.step);
if (step)
return new Item(step.getMap().invert(), step, this.selection);
}
}
}
// The value of the state field that tracks undo/redo history for that
// state. Will be stored in the plugin state when the history plugin
// is active.
class HistoryState {
constructor(done, undone, prevRanges, prevTime) {
this.done = done;
this.undone = undone;
this.prevRanges = prevRanges;
this.prevTime = prevTime;
}
}
const DEPTH_OVERFLOW = 20;
// Record a transformation in undo history.
function applyTransaction(history, state, tr, options) {
let historyTr = tr.getMeta(historyKey), rebased;
if (historyTr)
return historyTr.historyState;
if (tr.getMeta(closeHistoryKey))
history = new HistoryState(history.done, history.undone, null, 0);
let appended = tr.getMeta("appendedTransaction");
if (tr.steps.length == 0) {
return history;
}
else if (appended && appended.getMeta(historyKey)) {
if (appended.getMeta(historyKey).redo)
return new HistoryState(history.done.addTransform(tr, undefined, options, mustPreserveItems(state)), history.undone, rangesFor(tr.mapping.maps[tr.steps.length - 1]), history.prevTime);
else
return new HistoryState(history.done, history.undone.addTransform(tr, undefined, options, mustPreserveItems(state)), null, history.prevTime);
}
else if (tr.getMeta("addToHistory") !== false && !(appended && appended.getMeta("addToHistory") === false)) {
// Group transforms that occur in quick succession into one event.
let newGroup = history.prevTime == 0 || !appended && (history.prevTime < (tr.time || 0) - options.newGroupDelay ||
!isAdjacentTo(tr, history.prevRanges));
let prevRanges = appended ? mapRanges(history.prevRanges, tr.mapping) : rangesFor(tr.mapping.maps[tr.steps.length - 1]);
return new HistoryState(history.done.addTransform(tr, newGroup ? state.selection.getBookmark() : undefined, options, mustPreserveItems(state)), Branch.empty, prevRanges, tr.time);
}
else if (rebased = tr.getMeta("rebased")) {
// Used by the collab module to tell the history that some of its
// content has been rebased.
return new HistoryState(history.done.rebased(tr, rebased), history.undone.rebased(tr, rebased), mapRanges(history.prevRanges, tr.mapping), history.prevTime);
}
else {
return new HistoryState(history.done.addMaps(tr.mapping.maps), history.undone.addMaps(tr.mapping.maps), mapRanges(history.prevRanges, tr.mapping), history.prevTime);
}
}
function isAdjacentTo(transform, prevRanges) {
if (!prevRanges)
return false;
if (!transform.docChanged)
return true;
let adjacent = false;
transform.mapping.maps[0].forEach((start, end) => {
for (let i = 0; i < prevRanges.length; i += 2)
if (start <= prevRanges[i + 1] && end >= prevRanges[i])
adjacent = true;
});
return adjacent;
}
function rangesFor(map) {
let result = [];
map.forEach((_from, _to, from, to) => result.push(from, to));
return result;
}
function mapRanges(ranges, mapping) {
if (!ranges)
return null;
let result = [];
for (let i = 0; i < ranges.length; i += 2) {
let from = mapping.map(ranges[i], 1), to = mapping.map(ranges[i + 1], -1);
if (from <= to)
result.push(from, to);
}
return result;
}
// Apply the latest event from one branch to the document and shift the event
// onto the other branch.
function histTransaction(history, state, dispatch, redo) {
let preserveItems = mustPreserveItems(state);
let histOptions = historyKey.get(state).spec.config;
let pop = (redo ? history.undone : history.done).popEvent(state, preserveItems);
if (!pop)
return;
let selection = pop.selection.resolve(pop.transform.doc);
let added = (redo ? history.done : history.undone).addTransform(pop.transform, state.selection.getBookmark(), histOptions, preserveItems);
let newHist = new HistoryState(redo ? added : pop.remaining, redo ? pop.remaining : added, null, 0);
dispatch(pop.transform.setSelection(selection).setMeta(historyKey, { redo, historyState: newHist }).scrollIntoView());
}
let cachedPreserveItems = false, cachedPreserveItemsPlugins = null;
// Check whether any plugin in the given state has a
// `historyPreserveItems` property in its spec, in which case we must
// preserve steps exactly as they came in, so that they can be
// rebased.
function mustPreserveItems(state) {
let plugins = state.plugins;
if (cachedPreserveItemsPlugins != plugins) {
cachedPreserveItems = false;
cachedPreserveItemsPlugins = plugins;
for (let i = 0; i < plugins.length; i++)
if (plugins[i].spec.historyPreserveItems) {
cachedPreserveItems = true;
break;
}
}
return cachedPreserveItems;
}
/**
Set a flag on the given transaction that will prevent further steps
from being appended to an existing history event (so that they
require a separate undo command to undo).
*/
function closeHistory(tr) {
return tr.setMeta(closeHistoryKey, true);
}
const historyKey = new PluginKey("history");
const closeHistoryKey = new PluginKey("closeHistory");
/**
Returns a plugin that enables the undo history for an editor. The
plugin will track undo and redo stacks, which can be used with the
[`undo`](https://prosemirror.net/docs/ref/#history.undo) and [`redo`](https://prosemirror.net/docs/ref/#history.redo) commands.
You can set an `"addToHistory"` [metadata
property](https://prosemirror.net/docs/ref/#state.Transaction.setMeta) of `false` on a transaction
to prevent it from being rolled back by undo.
*/
function history(config = {}) {
config = { depth: config.depth || 100,
newGroupDelay: config.newGroupDelay || 500 };
return new Plugin({
key: historyKey,
state: {
init() {
return new HistoryState(Branch.empty, Branch.empty, null, 0);
},
apply(tr, hist, state) {
return applyTransaction(hist, state, tr, config);
}
},
config,
props: {
handleDOMEvents: {
beforeinput(view, e) {
let inputType = e.inputType;
let command = inputType == "historyUndo" ? undo : inputType == "historyRedo" ? redo : null;
if (!command)
return false;
e.preventDefault();
return command(view.state, view.dispatch);
}
}
}
});
}
/**
A command function that undoes the last change, if any.
*/
const undo = (state, dispatch) => {
let hist = historyKey.getState(state);
if (!hist || hist.done.eventCount == 0)
return false;
if (dispatch)
histTransaction(hist, state, dispatch, false);
return true;
};
/**
A command function that redoes the last undone change, if any.
*/
const redo = (state, dispatch) => {
let hist = historyKey.getState(state);
if (!hist || hist.undone.eventCount == 0)
return false;
if (dispatch)
histTransaction(hist, state, dispatch, true);
return true;
};
/**
The amount of undoable events available in a given state.
*/
function undoDepth(state) {
let hist = historyKey.getState(state);
return hist ? hist.done.eventCount : 0;
}
/**
The amount of redoable events available in a given editor state.
*/
function redoDepth(state) {
let hist = historyKey.getState(state);
return hist ? hist.undone.eventCount : 0;
}
export { closeHistory, history, redo, redoDepth, undo, undoDepth };