bool ParseElement(string elem, out Expression result)
{
result = null;
elem = elem.Trim();
if (elem.Length == 0) { return false; }
if (elem[0] == '(') {
elem = elem.Substring(1, elem.Length-2).Trim();
}
int val;
if (int.TryParse(elem, out val)) {
result = new LiteralExpression(val);
} else {
// verify variable name
for(int i=0; i<elem.Length; ++i) {
if (!char.IsUpper(elem[i]) || elem[i] == '_' || char.IsNumber(elem[i])) {
return false;
}
}
result = new VariableExpression(elem);
}
return true;
}
State SawTurn(Token t)
{
Expression exp = null;
if (t.type == TokenType.Expression) {
exp = mExpParser.Parse(t.data);
} else {
switch(t.data) {
case "left": exp = new LiteralExpression(90); break;
case "right": exp = new LiteralExpression(-90); break;
}
}
if (exp != null) {
mScratchpad.Add(new ActionInstruction(turnAction, exp));
return Idle;
}
return null;
}