How do I get declared variables in version 3?

[VincentJoshuaET]

How do I get declared variables in version 3?

[uklimaschewski]

There is this method:

  /**
   * Returns all variables or constants that are used i the expression, excluding the standard
   * constants like e.g. <code>PI</code> or <code>TRUE</code> and <code>FALSE</code>.
   *
   * @return All used variables and constants less the standard constants.
   * @throws ParseException If there were problems while parsing the expression.
   */
  public Set<String> getUsedVariables() throws ParseException;

[VincentJoshuaET]

There is this method:

  /**
   * Returns all variables or constants that are used i the expression, excluding the standard
   * constants like e.g. <code>PI</code> or <code>TRUE</code> and <code>FALSE</code>.
   *
   * @return All used variables and constants less the standard constants.
   * @throws ParseException If there were problems while parsing the expression.
   */
  public Set<String> getUsedVariables() throws ParseException;

In version 2.x, getUsedVariables and getDeclaredVariables are different. Used variables are variables inside the expression string. Declared variables are variables that we input with with or and. They may or may not be equal.

[VincentJoshuaET]

https://github.com/ezylang/EvalEx/blob/2.x/src/main/java/com/udojava/evalex/Expression.java

/**
   * Exposing declared variables in the expression.
   *
   * @return All declared variables.
*/
public Set<String> getDeclaredVariables() {
    return Collections.unmodifiableSet(variables.keySet());
}

/**
   * Returns a list of the variables in the expression.
   *
   * @return A list of the variable names in this expression.
   */
  public List<String> getUsedVariables() {
    List<String> result = new ArrayList<String>();
    Tokenizer tokenizer = new Tokenizer(expressionString);
    while (tokenizer.hasNext()) {
      Token nextToken = tokenizer.next();
      String token = nextToken.toString();
      if (nextToken.type != TokenType.VARIABLE || DEFAULT_CONSTANTS.containsKey(token)) {
        continue;
      }
      result.add(token);
    }
    return result;
}

[uklimaschewski]

There are two possibilities.
One is to write an own data accessor that allows you to also control the declared variables.
Or you could code it like this, checking the data accessor for each used variable:

  void checkVariables() throws ParseException {

    Expression expression = new Expression("a+B*b-A/PI*(1/2)*pi+e-E+a").with("a", 12);

    DataAccessorIfc dataAccessor = expression.getConfiguration().getDataAccessorSupplier().get();

    for (String variable : expression.getUsedVariables()) {
      if (dataAccessor.getData(variable) == null) {
        System.out.println("Variable not declared: " + variable);
      }
    }
  }

[VincentJoshuaET]

Will it not be possible for a straightforward method anymore like in 2.x?

[uklimaschewski]

Sure is this possible, but why not a method that directly returns the undeclared variables? e.g. public Set<String> getUndeclaredVariables() ?

[VincentJoshuaET]

Yeah that would work too! Or maybe a method that checks if the expression can be evaluated or not (because some variables needed were not declared)