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/*
* Copyright 2013 Canonical Ltd.
*
* This file is part of ubuntu-calculator-app.
*
* ubuntu-calculator-app 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; version 3.
*
* ubuntu-calculator-app 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/>.
*/
Qt.include("engine.js");
var context = new Context;
function Formula() {
var previous = new Token(0, T_NUMBER);
var formula = '';
var results = [];
var lookupTbl = {
'-': '−',
'/': '÷',
'*': '×'
};
var _calculate = function(func){
try{
var result = parse(func, context);
if (result === Number.POSITIVE_INFINITY)
result = '∞';
else if (result === Number.NEGATIVE_INFINITY)
result = '-∞';
}catch(exception){
if(exception instanceof DivisionByZeroError){
result = "division by zero error";
} else{
throw new SyntaxError("malformed calculation");
}
}
return result;
}
this.push = function(digit){
if(results.length > 0) throw new SyntaxError("cannot push");
var last = (new Scanner(previous.value.toString()+digit, context)).tokens.pop();
switch(last.type){
case T_PLUS:
case T_MINUS:
case T_DIV:
case T_TIMES:
if(previous.type & T_OPERATOR) return;
break;
case T_UNARY_PLUS:
case T_UNARY_MINUS:
if(previous.type === T_UNARY_MINUS || previous.type === T_UNARY_PLUS ) return;
break;
}
formula += digit;
previous = last;
var ret = {value: '', type: last.type};
if(lookupTbl[digit] !== undefined){
ret.value = lookupTbl[digit];
} else {
ret.value = digit;
}
return ret;
};
this.pop = function(){
if(results.length > 0){
results.pop();
return;
}
var scannedFormula = new Scanner(formula, context);
var last = {type:T_NUMBER};
var removeSize = 0;
while(scannedFormula.tokens.length > 0 && (last.type === T_NUMBER || last.type === T_UNARY_PLUS || last.type === T_UNARY_MINUS)){
last = scannedFormula.tokens.pop();
removeSize += last.value.toString().length
}
formula = formula.substring(0, formula.length - removeSize);
previous = scannedFormula.tokens.pop();
};
this.calculate = function(){
var result;
var previousSize = previous.value.toString().length;
if(formula.length <= previousSize) return;
var scannedFormula = new Scanner(formula, context);
var last = scannedFormula.tokens.pop();
if(results.length > 0){
var newFormula = last.value.toString();
while(last.type !== T_PLUS &&
last.type !== T_MINUS &&
last.type !== T_DIV &&
last.type !== T_TIMES ){
last = scannedFormula.tokens.pop();
newFormula = last.value.toString() + newFormula;
}
result = _calculate(results[results.length-1]+newFormula);
} else{
// check previous input
if(last.type === T_PLUS ||
last.type === T_MINUS ||
last.type === T_DIV ||
last.type === T_TIMES){
// getting the first value
var firstVal = scannedFormula.tokens.pop();
// adding the first value to formula
formula = formula + firstVal.value.toString()
}
result = _calculate(formula);
}
results.push(result.toString());
return result;
}
this.changeSign = function(){
if(results.length > 0) throw new SyntaxError("cannot edit formula");
switch(previous.type){
case T_PLUS:
case T_MINUS:
case T_DIV:
case T_TIMES:
formulaPush("-");
break;
default:
var scannedFormula = new Scanner(formula, context);
var last = {type: undefined};
var toAdd = [];
var addMinus = true;
while(scannedFormula.tokens.length > 0 && last.type !== T_PLUS &&
last.type !== T_MINUS &&
last.type !== T_DIV &&
last.type !== T_TIMES ){
last = scannedFormula.tokens.pop();
if(last.type !== T_UNARY_MINUS && last.type !== T_UNARY_PLUS){
toAdd.push(last);
} else {
if(last.type === T_UNARY_MINUS)
addMinus = false;
}
}
formulaPop();
while(toAdd.length > 0){
var el = toAdd.pop()
formulaPush(el.value.toString());
if((el.type & T_OPERATOR) && addMinus){
formulaPush('-');
}
}
}
}
this.hasResults = function(){
if(results.length > 0){
return true;
}
return false;
}
}
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