private IExpressionNode booleanExpression() throws ParserException {
IExpressionNode expr = expression();
String comparator = lookahead.sequence;
nextToken();
IExpressionNode expr2 = expression();
try {
if (comparator.equals(LT))
return new BooleanExpressionNode(expr.getValue() < expr2.getValue());
if (comparator.equals(GT))
return new BooleanExpressionNode(expr.getValue() > expr2.getValue());
if (comparator.equals(LTEQ))
return new BooleanExpressionNode(expr.getValue() <= expr2.getValue());
if (comparator.equals(GTEQ))
return new BooleanExpressionNode(expr.getValue() >= expr2.getValue());
if (comparator.equals(NTEQ))
return new BooleanExpressionNode(expr.getValue() != expr2.getValue());
} catch (EvaluationException ex) {
throw new ParserException(
"EvaluationException caught when calculating boolean expression"
+ ": "
+ expr.toString()
+ comparator
+ expr2.toString());
}
throw new ParserException("No Comparator found, instead found: " + comparator);
}
private IExpressionNode argument() throws ParserException {
if (lookahead.token == Token.FUNCTION) {
// argument -> FUNCTION argument
int function = FunctionExpressionNode.stringToFunction(lookahead.sequence);
nextToken();
IExpressionNode expr = argument();
return new FunctionExpressionNode(function, expr);
} else if (lookahead.token == Token.PRINT) {
// argumement -> PRINT expression
nextToken();
IExpressionNode expr = expression();
try {
System.out.println(expr.getValue());
} catch (EvaluationException ex) {
Logger.getLogger(LOGGER_NAME)
.severe("EvaulationException thrown while printing the value of: " + expr.toString());
}
return expr;
} else if (lookahead.token == Token.LPAREN) {
// argument -> LPAREN sum RPAREN
nextToken();
IExpressionNode expr = expression();
if (lookahead.token != Token.RPAREN)
throw new ParserException(String.format(ERR_RPAREN, lookahead.sequence));
nextToken();
return expr;
}
// argument -> value
return value();
}
private IExpressionNode assignmentOp(IExpressionNode variable) throws ParserException {
if (lookahead.token == Token.EQUALS) {
nextToken();
IExpressionNode newVariable = expression();
if (!(variable.getType() == IExpressionNode.VARIABLE_NODE))
throw new ParserException(String.format(ERR_VARIABLE, variable.toString()));
try {
variable.accept(
new SetVariable(((VariableExpressionNode) variable).getName(), newVariable.getValue()));
} catch (EvaluationException ex) {
throw new ParserException(
String.format("The variable [%s] did not return a valid value", newVariable));
}
}
return variable;
}