/// <summary>
/// Implementation for codex "Vyhodnocovani vyrazu"
/// Has parametrized input and output streams for testing purposes of evaluating in int precision.
/// </summary>
/// <param name="input">Input stream. (e.g. Console.In)</param>
/// <param name="output">Output stream. (e.g. Console.Out)</param>
public static void RunInt(TextReader input, TextWriter output)
{
string expression = input.ReadLine();
try {
ExpressionParser parser = new ExpressionParser();
IntVisitor visitor = new IntVisitor();
Node root = parser.ParsePrefixExpression(expression);
if (root == null)
{
throw new FormatException();
}
output.WriteLine(root.Accept(visitor));
}
catch (OverflowException) {
output.WriteLine("Overflow Error");
}
catch (DivideByZeroException) {
output.WriteLine("Divide Error");
}
catch (FormatException) {
output.WriteLine("Format Error");
}
}
/// <summary>
/// Implementation for codex "Vyhodnocovani vyrazu II"
/// Has parametrized input and output streams for testing purposes.
/// Evaluates line by line for lines like:
/// "= 'valid expression'" which will parse expression for further evaluation
/// "i" which evaluates parsed expression in int precission
/// "d" which evaluates parsed expression in double precission
/// </summary>
/// <param name="input">Input stream. (e.g. Console.In)</param>
/// <param name="output">Output stream. (e.g. Console.Out)</param>
public static void Run(TextReader input, TextWriter output)
{
var parser = new ExpressionParser();
var doubleVisitor = new DoubleVisitor();
var intVisitor = new IntVisitor();
Node lastExpressionTree = null;
bool intEvaluated = false;
bool doubleEvaluated = false;
string expression = input.ReadLine();
while (expression != null && expression != "end")
{
if (expression.Length == 0)
{
expression = input.ReadLine();
continue;
}
try {
switch (expression[0])
{
case '=':
lastExpressionTree = null;
intEvaluated = false;
doubleEvaluated = false;
if (expression.Length <= 2 || expression[1] != ' ')
{
throw new FormatException();
}
lastExpressionTree = parser.ParsePrefixExpression(expression.Substring(1));
if (lastExpressionTree == null)
{
throw new FormatException();
}
break;
case 'i':
if (expression.Length > 1)
{
throw new FormatException();
}
if (lastExpressionTree == null)
{
throw new NullReferenceException();
}
if (intEvaluated)
{
output.WriteLine(intVisitor.lastEvaluation);
}
else
{
output.WriteLine(lastExpressionTree.Accept(intVisitor));
}
intEvaluated = true;
break;
case 'd':
if (expression.Length > 1)
{
throw new FormatException();
}
if (lastExpressionTree == null)
{
throw new NullReferenceException();
}
if (doubleEvaluated)
{
output.WriteLine("{0:F5}", doubleVisitor.lastEvaluation);
}
else
{
output.WriteLine("{0:F5}", lastExpressionTree.Accept(doubleVisitor));
}
doubleEvaluated = true;
break;
default:
throw new FormatException();
}
}
catch (NullReferenceException) {
output.WriteLine("Expression Missing");
}
catch (OverflowException) {
output.WriteLine("Overflow Error");
}
catch (DivideByZeroException) {
output.WriteLine("Divide Error");
}
catch (FormatException) {
output.WriteLine("Format Error");
}
expression = input.ReadLine();
}
}
