bool TryGetExistingExponent(string s, out ExponentMeasureUnit u)
{
u = null;
if (_allUnits.TryGetValue(s, out var unit))
{
Debug.Assert(unit is ExponentMeasureUnit);
u = (ExponentMeasureUnit)unit;
return(true);
}
return(false);
}
bool TryParseExponent(Match match, out ExponentMeasureUnit u, bool skipFirstLookup = false)
{
if (!skipFirstLookup && TryGetExistingExponent(match.ToString(), out u))
{
return(true);
}
u = null;
// Handling dimensionless unit.
var factor = match.Groups[4].Value;
if (factor.Length > 0)
{
var f = ParseFactor(factor, ExpFactor.Neutral);
u = RegisterPrefixed(f, MeasureStandardPrefix.None, MeasureUnit.None);
return(true);
}
string sExp = match.Groups[3].Value;
int exp = sExp.Length > 0 ? Int32.Parse(sExp) : 1;
if (exp == 0)
{
u = MeasureUnit.None;
return(true);
}
string withoutExp = match.Groups[1].Value + match.Groups[2].Value;
if (_allUnits.TryGetValue(withoutExp, out var unit))
{
if (exp == 1 && unit is ExponentMeasureUnit direct)
{
u = direct;
return(true);
}
if (!(unit is AtomicMeasureUnit atomic))
{
return(false);
}
u = RegisterExponent(exp, atomic);
return(true);
}
ExpFactor adjustment = ExpFactor.Neutral;
foreach (Capture f in match.Groups[1].Captures)
{
adjustment = ParseFactor(f.Value, adjustment);
}
string withoutAdjustment = match.Groups[2].Value;
if (_allUnits.TryGetValue(withoutAdjustment, out unit))
{
if (!(unit is AtomicMeasureUnit basic))
{
return(false);
}
if (basic is PrefixedMeasureUnit prefix)
{
adjustment = adjustment.Multiply(prefix.AdjustmentFactor).Multiply(prefix.Prefix.Factor);
basic = prefix.AtomicMeasureUnit;
}
u = CreateExponentPrefixed(exp, adjustment, basic);
return(true);
}
var p = MeasureStandardPrefix.FindPrefix(withoutAdjustment);
if (p == MeasureStandardPrefix.None)
{
return(false);
}
withoutAdjustment = withoutAdjustment.Substring(p.Abbreviation.Length);
if (withoutAdjustment.Length == 0)
{
return(false);
}
if (_allUnits.TryGetValue(withoutAdjustment, out unit))
{
if (!(unit is AtomicMeasureUnit basic))
{
return(false);
}
if (basic is PrefixedMeasureUnit prefix)
{
return(false);
}
adjustment = adjustment.Multiply(p.Factor);
u = CreateExponentPrefixed(exp, adjustment, basic);
return(true);
}
return(false);
}
internal ExponentMeasureUnit RegisterExponent(int exp, AtomicMeasureUnit u)
{
var names = ExponentMeasureUnit.ComputeNames(exp, u);
return(Register(names.A, names.N, () => new ExponentMeasureUnit(this, names, exp, u), null));
}