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71 lines
1.9 KiB
JavaScript
71 lines
1.9 KiB
JavaScript
/*
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* Copyright 2012, Mozilla Foundation and contributors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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/**
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* A History object remembers commands that have been entered in the past and
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* provides an API for accessing them again.
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* See Bug 681340: Search through history (like C-r in bash)?
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*/
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function History() {
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// This is the actual buffer where previous commands are kept.
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// 'this._buffer[0]' should always be equal the empty string. This is so
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// that when you try to go in to the "future", you will just get an empty
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// command.
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this._buffer = [''];
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// This is an index in to the history buffer which points to where we
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// currently are in the history.
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this._current = 0;
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}
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/**
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* Avoid memory leaks
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*/
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History.prototype.destroy = function() {
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this._buffer = undefined;
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};
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/**
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* Record and save a new command in the history.
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*/
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History.prototype.add = function(command) {
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this._buffer.splice(1, 0, command);
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this._current = 0;
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};
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/**
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* Get the next (newer) command from history.
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*/
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History.prototype.forward = function() {
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if (this._current > 0 ) {
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this._current--;
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}
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return this._buffer[this._current];
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};
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/**
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* Get the previous (older) item from history.
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*/
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History.prototype.backward = function() {
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if (this._current < this._buffer.length - 1) {
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this._current++;
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}
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return this._buffer[this._current];
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};
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exports.History = History;
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