/**
* symbol2unicode: convert a string of ascii symbols to unicode
*
* copyright (C) 2016, 2017 Huub de Beer <Huub@heerdebeer.org>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* The ConverterHistory keeps track of the strings that already have been
* replaced.
*/
class ConverterHistory {
/**
* Create a new ConverterHistory.
*/
constructor () {
this.history = [];
this.currentIndex = -1;
}
/**
* Add a string that has been converted to the history.
*
* @param {String} str
*/
add (str) {
if (0 < this.history.length) {
const top = this.history[this.history.length - 1];
if (top !== str) {
this.history.push(str);
}
} else {
this.history.push(str);
}
this.currentIndex = this.history.length - 1;
}
/**
* Move to the previous converted string and return it.
*
* @returns {String} the string that has been converted before the current
* one or, if there is no such string, the empty string.
*/
previous () {
let str = "";
if (0 <= this.currentIndex) {
str = this.history[this.currentIndex];
this.currentIndex--;
}
return str;
}
/**
* Move to the next converted string and return it.
*
* @returns {String} the string that has been converted after the current
* one or, if there is no such string, the empty string.
*/
next () {
let str = "";
if (this.history.length - 1 > this.currentIndex) {
this.currentIndex++;
str = this.history[this.currentIndex];
}
return str;
}
}
export default ConverterHistory;