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Java > Open Source Codes > expr > eval > Calculator


1 package expr.eval;
2
3 import java.io.IOException JavaDoc;
4 import java.io.StringReader JavaDoc;
5 import beaver.Symbol;
6 import beaver.Parser;
7
8 public class Calculator
9 {
10     public static void main(String JavaDoc[] args)
11     {
12         ExpressionScanner input = new ExpressionScanner(new StringReader JavaDoc(args[0]));
13         try
14         {
15             Expr result = (Expr) new ExpressionParser().parse(input);
16             System.out.println("= " + result.val);
17         }
18         catch (IOException JavaDoc e)
19         {
20             System.err.println("Failed to read expression: " + e.getMessage());
21         }
22         catch (Parser.Exception e)
23         {
24             System.err.println("Invalid expression: " + e.getMessage());
25         }
26     }
27 }
28
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