private static AstNode parseAdditive(Parser parser)
{
AstNode left = parseMultiplicitive(parser);
while (parser.MatchToken(TokenType.Operation) || parser.MatchToken(TokenType.Identifier, "and") || parser.MatchToken(TokenType.Identifier, "or"))
{
switch ((string)parser.CurrentToken().Value)
{
case "+":
parser.AcceptToken(TokenType.Operation);
left = new BinaryOpNode(BinaryOperation.Addition, left, parseMultiplicitive(parser));
continue;
case "-":
parser.AcceptToken(TokenType.Operation);
left = new BinaryOpNode(BinaryOperation.Subtraction, left, parseMultiplicitive(parser));
continue;
case "and":
parser.AcceptToken(TokenType.Identifier);
left = new BinaryOpNode(BinaryOperation.And, left, parseMultiplicitive(parser));
continue;
case "or":
parser.AcceptToken(TokenType.Identifier);
left = new BinaryOpNode(BinaryOperation.Or, left, parseMultiplicitive(parser));
continue;
default:
break;
}
break;
}
return left;
}
private static AstNode parseComparison(Parser parser)
{
AstNode left = parseFunctionCall(parser);
while (parser.MatchToken(TokenType.Comparison))
{
switch ((string)parser.CurrentToken().Value)
{
case "=":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.Equal, left, parseFunctionCall(parser));
continue;
case "!=":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.NotEqual, left, parseFunctionCall(parser));
continue;
case ">":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.GreaterThan, left, parseFunctionCall(parser));
continue;
case "<":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.LessThan, left, parseFunctionCall(parser));
continue;
case ">=":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.GreaterThanOrEqual, left, parseFunctionCall(parser));
continue;
case "<=":
parser.AcceptToken(TokenType.Comparison);
left = new BinaryOpNode(BinaryOperation.LessThanOrEqual, left, parseFunctionCall(parser));
continue;
default:
break;
}
break;
}
return left;
}
private object interpretBinaryOperation(BinaryOpNode binaryNode)
{
switch (binaryNode.BinaryOperation)
{
case BinaryOperation.Addition:
return getLeft(binaryNode) + getRight(binaryNode);
case BinaryOperation.Subtraction:
return getLeft(binaryNode) - getRight(binaryNode);
case BinaryOperation.Multiplication:
return getLeft(binaryNode) * getRight(binaryNode);
case BinaryOperation.Division:
return getLeft(binaryNode) / getRight(binaryNode);
case BinaryOperation.Modulus:
return getLeft(binaryNode) % getRight(binaryNode);
case BinaryOperation.Equal:
return evaluateNode(binaryNode.Left).GetHashCode() == evaluateNode(binaryNode.Right).GetHashCode();
case BinaryOperation.NotEqual:
return evaluateNode(binaryNode.Left).GetHashCode() != evaluateNode(binaryNode.Right).GetHashCode();
case BinaryOperation.GreaterThan:
return getLeft(binaryNode) > getRight(binaryNode);
case BinaryOperation.LessThan:
return getLeft(binaryNode) < getRight(binaryNode);
case BinaryOperation.GreaterThanOrEqual:
return getLeft(binaryNode) >= getRight(binaryNode);
case BinaryOperation.LessThanOrEqual:
return getLeft(binaryNode) <= getRight(binaryNode);
case BinaryOperation.Assignment:
object value = evaluateNode(binaryNode.Left);
string variable = ((IdentifierNode)binaryNode.Right).Identifier;
if (variables.ContainsKey(variable))
variables.Remove(variable);
variables.Add(variable, value);
return value;
case BinaryOperation.And:
return (bool)evaluateNode(binaryNode.Left) && (bool)evaluateNode(binaryNode.Right);
case BinaryOperation.Or:
return (bool)evaluateNode(binaryNode.Left) || (bool)evaluateNode(binaryNode.Right);
default:
throw new Exception("Unexpected binary operation in interpreter: " + binaryNode.BinaryOperation);
}
}
private static AstNode parseMultiplicitive(Parser parser)
{
AstNode left = parseComparison(parser);
while (parser.MatchToken(TokenType.Operation))
{
switch ((string)parser.CurrentToken().Value)
{
case "*":
parser.AcceptToken(TokenType.Operation);
left = new BinaryOpNode(BinaryOperation.Multiplication, left, parseComparison(parser));
continue;
case "/":
parser.AcceptToken(TokenType.Operation);
left = new BinaryOpNode(BinaryOperation.Division, left, parseComparison(parser));
continue;
case "%":
parser.AcceptToken(TokenType.Operation);
left = new BinaryOpNode(BinaryOperation.Modulus, left, parseComparison(parser));
continue;
default:
break;
}
break;
}
return left;
}
private double getRight(BinaryOpNode binaryNode)
{
return Convert.ToDouble(evaluateNode(binaryNode.Right));
}