public static bool PeekAndParse(CharStream cs, out FTL.AST.MemberList memberList)
{
// if next char is not a newline, we can just as well skip already
char next = cs.PeekNext();
if (CharStream.IsEOF(next) || !CharStream.IsNL(next))
{
memberList = null;
return(false);
}
// let's keep peeking further, requiring our buffer
int bufferPos = cs.Position;
NewLine.Parse(cs);
WhiteSpace.Parse(cs);
// we'll always want to rewind no matter what
bool isMemberList = Member.Peek(cs);
cs.Rewind(bufferPos);
if (isMemberList)
{
memberList = Parse(cs);
return(true);
}
memberList = null;
return(false);
}
public static FTL.AST.INode Parse(CharStream cs)
{
FTL.AST.INode expression = Expresson.Parse(cs);
int bufferPos = cs.Position;
WhiteSpace.Parse(cs);
if (cs.PeekNext() != SEPERATOR[0])
{
// it's not a select expression, so let's return early
cs.Rewind(bufferPos);
return(expression);
}
// it must be a select expression
cs.SkipString(SEPERATOR);
WhiteSpace.Parse(cs);
// we expect now a memberList (REQUIRED)
FTL.AST.MemberList memberList = MemberList.Parse(cs);
// skip extra new-line in case one is available
if (CharStream.IsNL(cs.PeekNext()))
{
NewLine.Parse(cs);
}
// return it all
return(new FTL.AST.SelectExpression(expression, memberList));
}
public static FTL.AST.MemberList Parse(CharStream cs)
{
// starts with a newline and optional newline
NewLine.Parse(cs);
WhiteSpace.Parse(cs);
FTL.AST.MemberList memberList = new FTL.AST.MemberList();
// parse first required member, as we always need at least 1
memberList.AddMember(Member.Parse(cs));
char next;
int bufferPos;
do
{
next = cs.PeekNext();
if (CharStream.IsEOF(next) || !CharStream.IsNL(next))
{
break;
}
bufferPos = cs.Position;
NewLine.Parse(cs);
WhiteSpace.Parse(cs);
if (!Member.Peek(cs))
{
cs.Rewind(bufferPos);
break;
}
memberList.AddMember(Member.Parse(cs));
} while(true);
return(memberList);
}
