private void value() {
if (token == Lexer.VARIABLE || token == Lexer.NUMBER) {
root = NodeFactory.createTerminal(token, lexer.getValue());
if (token == Lexer.VARIABLE && allowedIdentifiers != null) {
if (!allowedIdentifiers.contains(root.getSymbol()))
throw new MalformedExpressionException(
String.format("Unknown identifier '%s'", root.getSymbol()));
}
token = lexer.nextToken();
} else {
throw new MalformedExpressionException(
String.format("Value instead of <%s> expected.", token));
}
}
