META-INF.dirigible.dev-tools.sources.SimpleHistoryManager.js Maven / Gradle / Ivy
/*
* Copyright (C) 2014 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @interface
*/
export class HistoryEntry {
/**
* @return {boolean}
*/
valid() {
}
reveal() {}
}
/**
* @unrestricted
*/
export class SimpleHistoryManager {
/**
* @param {number} historyDepth
*/
constructor(historyDepth) {
this._entries = [];
this._activeEntryIndex = -1;
this._coalescingReadonly = 0;
this._historyDepth = historyDepth;
}
readOnlyLock() {
++this._coalescingReadonly;
}
releaseReadOnlyLock() {
--this._coalescingReadonly;
}
/**
* @return {boolean}
*/
readOnly() {
return !!this._coalescingReadonly;
}
/**
* @param {function(!HistoryEntry):boolean} filterOutCallback
*/
filterOut(filterOutCallback) {
if (this.readOnly()) {
return;
}
const filteredEntries = [];
let removedBeforeActiveEntry = 0;
for (let i = 0; i < this._entries.length; ++i) {
if (!filterOutCallback(this._entries[i])) {
filteredEntries.push(this._entries[i]);
} else if (i <= this._activeEntryIndex) {
++removedBeforeActiveEntry;
}
}
this._entries = filteredEntries;
this._activeEntryIndex = Math.max(0, this._activeEntryIndex - removedBeforeActiveEntry);
}
/**
* @return {boolean}
*/
empty() {
return !this._entries.length;
}
/**
* @return {?HistoryEntry}
*/
active() {
return this.empty() ? null : this._entries[this._activeEntryIndex];
}
/**
* @param {!HistoryEntry} entry
*/
push(entry) {
if (this.readOnly()) {
return;
}
if (!this.empty()) {
this._entries.splice(this._activeEntryIndex + 1);
}
this._entries.push(entry);
if (this._entries.length > this._historyDepth) {
this._entries.shift();
}
this._activeEntryIndex = this._entries.length - 1;
}
/**
* @return {boolean}
*/
rollback() {
if (this.empty()) {
return false;
}
let revealIndex = this._activeEntryIndex - 1;
while (revealIndex >= 0 && !this._entries[revealIndex].valid()) {
--revealIndex;
}
if (revealIndex < 0) {
return false;
}
this.readOnlyLock();
this._entries[revealIndex].reveal();
this.releaseReadOnlyLock();
this._activeEntryIndex = revealIndex;
return true;
}
/**
* @return {boolean}
*/
rollover() {
let revealIndex = this._activeEntryIndex + 1;
while (revealIndex < this._entries.length && !this._entries[revealIndex].valid()) {
++revealIndex;
}
if (revealIndex >= this._entries.length) {
return false;
}
this.readOnlyLock();
this._entries[revealIndex].reveal();
this.releaseReadOnlyLock();
this._activeEntryIndex = revealIndex;
return true;
}
}