State SawUntil(Token t)
{
if (t.type == TokenType.Expression) {
var exp = mExpParser.Parse(t.data);
if (exp == null) { return null; }
exp = new UnaryOperationExpression(UnaryOperation.Complement, exp);
mBlock.Push(new WhileBlock(exp, mScratchpad));
return Idle;
}
return null;
}
bool ParseTokenSlice(List<Token> tokens, int start, int len, out Expression result)
{
result = null;
if (len == 0) {
return false;
}
if (len == 1) {
switch(tokens[start].type) {
case TokenType.SubExpression: return ParseSubExpression(tokens[start].expr, out result);
case TokenType.Element: return ParseElement(tokens[start].expr, out result);
default: return false;
}
}
int opIndex;
if (FindHighestPriorityOperator(tokens, start, len, out opIndex)) {
if (opIndex == start) {
Expression right;
if (!ParseTokenSlice(tokens, start+1, len-1, out right)) { return false; }
result = new UnaryOperationExpression(mUnaryOpTable[mOps[tokens[opIndex].opId]], right);
return true;
} else {
Expression left, right;
if (!ParseTokenSlice(tokens, start, opIndex-start, out left)) { return false; }
if (!ParseTokenSlice(tokens, opIndex+1, start + len - opIndex - 1, out right)) { return false; }
result = new BinaryOperationExpression(mBinaryOpTable[mOps[tokens[opIndex].opId]], left, right);
return true;
}
} else {
return false;
}
}
State ExpectingBackwardMove(Token t)
{
if (t.type == TokenType.Expression) {
var exp = mExpParser.Parse(t.data);
if (exp == null) { return null; }
exp = new UnaryOperationExpression(UnaryOperation.Negate, exp);
mScratchpad.Add(new ActionInstruction(moveAction, exp));
return Idle;
}
return null;
}