private bool TryReadFrac(
out FloatLiteral frac,
int fracBase,
Func <BigInteger, char, BigInteger?> tryAccumulateFracDigit)
{
(BigInteger, int)pair;
bool parsed = TryReadNum(out pair, (BigInteger.Zero, 0), (acc, c) =>
{
var(i, n) = acc;
var maybeAcc = tryAccumulateFracDigit(i, c);
if (maybeAcc.HasValue)
{
return(maybeAcc.Value, n + 1);
}
else
{
return(null);
}
});
if (parsed)
{
var(i, n) = pair;
frac = FloatLiteral.Number(i, fracBase, -n);
return(true);
}
else
{
frac = FloatLiteral.Zero(fracBase);
return(false);
}
}
private bool TryReadUnsignedNumber(
bool negate,
out object result,
IntegerReader tryReadNum,
FloatReader tryReadFrac,
char exponentChar,
int exponent)
{
BigInteger num;
if (tryReadNum(out num))
{
if (Expect('.'))
{
FloatLiteral frac;
if (!tryReadFrac(out frac))
{
frac = FloatLiteral.Zero(exponent);
}
var floatNum = num + frac;
if (Expect(exponentChar) || Expect(char.ToUpperInvariant(exponentChar)))
{
floatNum = floatNum.ChangeBase(exponent);
if (!TryAppendExponent(floatNum, out floatNum))
{
result = null;
return(false);
}
}
result = MaybeNegate(floatNum, negate);
}
else if (Expect(exponentChar) || Expect(char.ToUpperInvariant(exponentChar)))
{
FloatLiteral floatNum;
if (!TryAppendExponent(FloatLiteral.Number(num, exponent), out floatNum))
{
result = null;
return(false);
}
result = MaybeNegate(floatNum, negate);
}
else
{
result = MaybeNegate(num, negate);
}
return(true);
}
else
{
result = null;
return(false);
}
}