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package net.sven_eisenhauer.swa_prakt1;
public class ExpressionIterator implements ArithmeticIterator {
private ArithmeticExpression baseNode;
public ExpressionIterator(ArithmeticExpression baseNode) {
this.baseNode = baseNode;
}
public void print() {
if(baseNode instanceof ArithmeticVariable) {
System.out.print(((ArithmeticVariable) baseNode).getName());
} else {
ArithmeticOperation actOperation = (ArithmeticOperation) baseNode;
ArithmeticIterator leftIter = new ExpressionIterator(actOperation.getLeftOperand());
ArithmeticIterator rightIter = new ExpressionIterator(actOperation.getRightOperand());
System.out.print("(");
leftIter.print();
System.out.print(actOperation.getOperationSign());
rightIter.print();
System.out.print(")");
}
}
public Number evaluate() {
if(baseNode instanceof ArithmeticVariable) {
return ((ArithmeticVariable) baseNode).getValue();
} else {
ArithmeticOperation actOperation = (ArithmeticOperation) baseNode;
ArithmeticIterator leftIter = new ExpressionIterator(actOperation.getLeftOperand());
ArithmeticIterator rightIter = new ExpressionIterator(actOperation.getRightOperand());
Number leftVal = leftIter.evaluate();
Number rightVal = rightIter.evaluate();
if(actOperation instanceof ArithmeticAddition) {
return leftVal.doubleValue() + rightVal.doubleValue();
} else if(actOperation instanceof ArithmeticSubstraction) {
return leftVal.doubleValue() - rightVal.doubleValue();
} else if(actOperation instanceof ArithmeticDivision) {
return leftVal.doubleValue() / rightVal.doubleValue();
} else if(actOperation instanceof ArithmeticMultiplication) {
return leftVal.doubleValue() * rightVal.doubleValue();
} else {
return null;
}
}
}
}
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