// Parse a single Crst type definition.
void ParseCrst()
{
// The next token had better be an identifier (the Crst type name).
Token token = NextToken();
if (token.Id != KeywordId.Id)
{
throw new UnexpectedTokenError(token, KeywordId.Id);
}
// The Crst instance might already exist in the dictionary (forward references to a Crst type cause
// these entries to auto-vivify). But in that case the entry better not be marked as 'Defined' which
// would indicate a double declaration.
CrstType crst;
if (m_crsts.ContainsKey(token.Text))
{
crst = m_crsts[token.Text];
if (crst.Defined)
{
throw new ParseError(String.Format("Duplicate definition for CrstType '{0}'", token.Text), token);
}
}
else
{
// Otherwise this Crst type hasn't been seen thus far so we allocate a new instance and add it to
// the dictionary.
crst = new CrstType(token.Text);
m_crsts.Add(crst.Name, crst);
}
// We're defining, not just referencing this type.
crst.Defined = true;
// Parse any attributes inside this definition (until we see an 'End' token).
bool parsingCrst = true;
while (parsingCrst)
{
// Get the next token. Either some attribute keyword or 'End'.
token = NextToken();
List <CrstType> list;
switch (token.Id)
{
case KeywordId.AcquiredBefore:
// Simply parse the following list of Crst types into the current type's AcquiredBefore list.
ParseList(crst.AcquiredBeforeList);
break;
case KeywordId.AcquiredAfter:
// AcquiredAfter is trickier. To make the ranking algorithm's life easier we actually
// normalize all rules to the AcquiredBefore form (see LevelCrsts() for the reasoning). So we
// capture the list of Crst types that follow the AcquiredAfter keyword and then append the
// current type to the AcquiredBefore list of each type found.
list = new List <CrstType>();
ParseList(list);
foreach (CrstType priorCrst in list)
{
priorCrst.AcquiredBeforeList.Add(crst);
}
break;
case KeywordId.SameLevelAs:
// Parse the following list of Crst types them let the CrstTypeGroup class handle the
// resulting updates to the type groups we're currently maintaining. See the comments for the
// CrstTypeGroup class for more details.
list = new List <CrstType>();
ParseList(list);
foreach (CrstType sameLevelCrst in list)
{
CrstTypeGroup.Join(crst, sameLevelCrst);
}
break;
case KeywordId.Unordered:
crst.Level = CrstType.CrstUnordered;
break;
case KeywordId.End:
parsingCrst = false;
break;
default:
throw new UnexpectedTokenError(token,
KeywordId.AcquiredBefore,
KeywordId.AcquiredAfter,
KeywordId.SameLevelAs,
KeywordId.Unordered);
}
}
}
