git.gag.com Git - debian/openrocket/blob - core/src/net/sf/openrocket/util/ExpressionParser.java

   1 package net.sf.openrocket.util;
   2
   3 import de.congrace.exp4j.Calculable;
   4 import de.congrace.exp4j.ExpressionBuilder;
   5 import de.congrace.exp4j.UnknownFunctionException;
   6 import de.congrace.exp4j.UnparsableExpressionException;
   7
   8 public class ExpressionParser {
   9
  10
  11         public double parse(String expression) throws InvalidExpressionException {
  12                 try {
  13                         ExpressionBuilder builder = new ExpressionBuilder(modify(expression));
  14                         Calculable calc = builder.build();
  15                         return calc.calculate();
  16                 } catch (java.lang.NumberFormatException e) {
  17                         throw new InvalidExpressionException("Invalid expression: " + expression, e);
  18                 } catch (UnknownFunctionException e) {
  19                         throw new InvalidExpressionException("Invalid expression: " + expression, e);
  20                 } catch (UnparsableExpressionException e) {
  21                         throw new InvalidExpressionException("Invalid expression: " + expression, e);
  22                 } catch (java.util.EmptyStackException e) {
  23                         throw new InvalidExpressionException("Invalid expression: " + expression, e);
  24                 }
  25         }
  26
  27         private String modify(String exp) throws InvalidExpressionException {
  28                 char[] chars = exp.toCharArray();
  29                 for( int i = 0; i< chars.length; i++ ) {
  30                         int value = Character.getNumericValue(chars[i]);
  31                         if ( value >= 0 && value < 10 ) {
  32                                 chars[i] = Character.toChars(48 + value)[0];
  33                         }
  34                         if ( chars[i] == '\u2044') {
  35                                 chars[i] = '/';
  36                         }
  37                 }
  38                 exp = String.copyValueOf(chars);
  39                 exp = exp.replaceAll("(\\d+)\\s+(\\d+)\\s*/\\s*(\\d+)", "($1+$2/$3)");
  40                 exp = exp.replace(',', '.');
  41                 // Disallow spaces between numbers - default is to remove spaces!
  42                 if (exp.matches(".*[0-9.]\\s+[0-9.].*")) {
  43                         throw new InvalidExpressionException("Invalid expression: " + exp);
  44                 }
  45                 return exp;
  46         }
  47
  48 }