private void ParsePenCommand(ParseTreeNode node)
{
var commandNode = node.ChildNodes[0];
switch (commandNode.Term.Name)
{
case "PEN_UP":
this.OnPenUp(EventArgs.Empty);
break;
case "PEN_DOWN":
this.OnPenDown(EventArgs.Empty);
break;
case "SET_PEN_COLOR":
switch (commandNode.ChildNodes[1].Term.Name)
{
case "TUPLE":
var rgb = new List <float>();
ParseTupleValues(commandNode.ChildNodes[1], rgb);
if (rgb.Count != 3)
{
throw new ParsingException("Incorrect command invocation.", new[]
{
ParsingError.FromParseTreeNode(node, $"The number of arguments must be 3, instead of {rgb.Count}.")
});
}
if (rgb.Any(v => v < 0 || v > 255))
{
throw new ParsingException("Command parameters are out of range.", new[]
{
ParsingError.FromParseTreeNode(node, "The parameter value should be greater than or equal to 0 and less than or equal to 255.")
});
}
this.OnSetPenColor(new PenColorEventArgs(Convert.ToInt32(rgb[0]), Convert.ToInt32(rgb[1]), Convert.ToInt32(rgb[2])));
break;
case "EXPRESSION":
var evaluation = this.EvaluateArithmeticExpression(commandNode.ChildNodes[1]);
var colorIndex = Convert.ToInt32(evaluation.Value) % 16;
var colorValue = colorTable[colorIndex];
this.OnSetPenColor(new PenColorEventArgs(colorValue.Item1, colorValue.Item2, colorValue.Item3));
break;
}
break;
}
}
private Evaluation EvaluateArithmeticExpression(ParseTreeNode expression)
{
switch (expression.Term.Name)
{
case "EXPRESSION":
if (expression.ChildNodes.Count == 1)
{
return(EvaluateArithmeticExpression(expression.ChildNodes[0]));
}
else if (expression.ChildNodes.Count == 3 &&
expression.ChildNodes[0].Token.Text == "(" &&
expression.ChildNodes[2].Token.Text == ")")
{
return(EvaluateArithmeticExpression(expression.ChildNodes[1]));
}
else
{
throw new RuntimeException($"Invalid expression at: {expression.Span.Location}");
}
case "VARIABLE_REF":
var variableName = expression.ChildNodes[1].Token.Text;
if (!CurrentProcedureScope.Exists(variableName))
{
throw new ParsingException("Variable has not been defined.", new[] { ParsingError.FromParseTreeNode(expression, $"The requested parameter '{variableName}' is not defined.") });
}
return(new ConstantEvaluation(Convert.ToSingle(CurrentProcedureScope[variableName])));
case "BINARY_EXPRESSION":
var leftNode = expression.ChildNodes[0];
var operatorNode = expression.ChildNodes[1];
var rightNode = expression.ChildNodes[2];
var leftEvaluation = EvaluateArithmeticExpression(leftNode);
var rightEvaluation = EvaluateArithmeticExpression(rightNode);
var binaryOperation = BinaryOperation.Add;
switch (operatorNode.Term.Name)
{
case "+":
binaryOperation = BinaryOperation.Add;
break;
case "-":
binaryOperation = BinaryOperation.Sub;
break;
case "*":
binaryOperation = BinaryOperation.Mul;
break;
case "/":
binaryOperation = BinaryOperation.Div;
break;
}
return(new BinaryEvaluation(leftEvaluation, rightEvaluation, binaryOperation));
case "REP_COUNT":
if (CurrentRepeatScope != null)
{
return(new ConstantEvaluation(CurrentRepeatScope.RepCount));
}
throw new ParsingException("Variable repCount doesn't have a valid value.", new[] { ParsingError.FromParseTreeNode(expression, "Reference to repCount variable is not in a valid REPEAT scope.") });
case "FUNCTION_CALL":
var val = ExecuteProcedureCall(expression);
return(new ConstantEvaluation(Convert.ToSingle(val)));
default:
return(new ConstantEvaluation(Convert.ToSingle(expression.Token.Text)));
}
}