private List<ExpressionAtom> parseInputPolynomial(String inputExpression) {
inputExpression = identifyUnaryMinuses(inputExpression);
inputExpression = insertMultiplicationSigns(inputExpression);
List<ExpressionAtom> inputExpressionTokens = new ArrayList<ExpressionAtom>();
char[] inputChars = inputExpression.toCharArray();
for (int i = 0; i < inputChars.length; ++i) {
if (isOperator(inputChars[i]) || inputChars[i] == '%') {
inputExpressionTokens.add(
new ExpressionAtom(String.valueOf(inputChars[i]), AtomType.OPERATOR, 1));
} else {
int lastIndex = inputExpressionTokens.size() - 1;
if (lastIndex >= 0
&& inputExpressionTokens.get(lastIndex).getAtomType() == AtomType.OPERAND) {
ExpressionAtom lastElement = inputExpressionTokens.remove(lastIndex);
if (Character.isDigit(inputChars[i])) {
lastElement.setCoefficient(
lastElement.getCoefficient() * 10 + Character.getNumericValue(inputChars[i]));
} else {
lastElement.setVariablesOrOperator(
lastElement.getVariablesOrOperator() + String.valueOf(inputChars[i]));
}
inputExpressionTokens.add(lastElement);
} else if (Character.isDigit(inputChars[i])) {
inputExpressionTokens.add(
new ExpressionAtom("", AtomType.OPERAND, Character.getNumericValue(inputChars[i])));
} else {
inputExpressionTokens.add(
new ExpressionAtom(String.valueOf(inputChars[i]), AtomType.OPERAND, 1));
}
}
}
return inputExpressionTokens;
}
@Override
public List<ExpressionAtom> evaluate(
List<ExpressionAtom> loperands, List<ExpressionAtom> roperands) {
if (roperands == null) {
List<ExpressionAtom> product = new ArrayList<ExpressionAtom>();
for (int x = 0; x < loperands.size(); x++) {
if (product.size() == 0) {
product.add(loperands.get(x));
} else {
ExpressionAtom atom = product.get(0);
atom.setCoefficient(atom.getCoefficient() * loperands.get(x).getCoefficient());
String var =
incrementDegree(
loperands.get(x).getVariablesOrOperator(), atom.getVariablesOrOperator());
atom.setVariablesOrOperator(var);
}
}
return product;
} else {
return multiple(loperands, roperands);
}
}
