Ejemplo n.º 1
0
  private ExpressionType getExpressionType() {
    skipWhiteSpace();

    for (Pattern p : patternMap.keySet()) {
      Matcher expMatch = p.matcher(myInput.substring(myCurrentPosition));
      if (expMatch.lookingAt()) return patternMap.get(p);
    }

    throw new ParserException("Unexpected Character " + currentCharacter());
  }
Ejemplo n.º 2
0
 /**
  * Converts given string into expression tree.
  *
  * @param input expression given in the language to be parsed
  * @return expression tree representing the given formula
  */
 public Expression makeExpression(String input) {
   myInput = input;
   myCurrentPosition = 0;
   Expression result = parseExpression();
   skipWhiteSpace();
   if (notAtEndOfString()) {
     throw new ParserException(
         "Unexpected characters at end of the string: " + myInput.substring(myCurrentPosition),
         ParserException.Type.EXTRA_CHARACTERS);
   }
   return result;
 }
Ejemplo n.º 3
0
  private Expression parseParenExpression() {
    ArrayList<Expression> elements = new ArrayList<Expression>();

    Matcher expMatcher = EXPRESSION_BEGIN_REGEX.matcher(myInput);
    expMatcher.find(myCurrentPosition);
    String commandName = expMatcher.group(1);
    myCurrentPosition = expMatcher.end();

    while (notAtEndOfString()) {
      skipWhiteSpace();
      if (currentCharacter() == ')') {
        myCurrentPosition++;
        return expressionCreator(commandName, elements);
      }

      elements.add(parseExpression());
    }

    throw new ParserException(
        "Expected close paren, instead found " + myInput.substring(myCurrentPosition));
  }