public static Expression CreateOld(MatchIterator iterator)
{
Token opToken;
if (iterator.NextIsToken(TokenType.Operator, out opToken))
{
// assume a left operator for now
Expression righExpr = Create(iterator);
return(new OperatorCall(opToken, null, righExpr));
}
Expression nextExpr;
if (iterator.NextIsKeySymbol(Symbols.OpenBracket))
{
iterator.AssertExpression(out nextExpr);
iterator.AssertKeySymbol(Symbols.CloseBracket, out _);
}
else
{
iterator.AssertExpression(out nextExpr);
}
if (iterator.AtEnd())
{
return(nextExpr);
}
if (iterator.Next(out List <CollectedIndex> indices))
{
foreach (CollectedIndex index in indices)
{
nextExpr = new Indexer(nextExpr, index.Open, index.Index, index.Close);
}
iterator.MoveNext();
}
if (iterator.AtEnd())
{
return(nextExpr);
}
iterator.AssertTokenType(TokenType.Operator, out opToken);
if (iterator.AtEnd())
{
// Assume a right operator for now
return(new OperatorCall(opToken, nextExpr, null));
}
// Assume a binary operator for now
Expression remainder = Create(iterator);
return(new OperatorCall(opToken, nextExpr, remainder));
}
public static LoopHeader Loop(MatchIterator iterator)
{
Expression array;
iterator.AssertKeyword(Keywords.Loop);
Token loop = (Token)iterator.Current;
if (iterator.AtEnd())
{
LoopHeader result = new LoopHeader(loop);
return(result);
}
iterator.AssertExpression(out Expression firstExpression);
if (iterator.AtEnd())
{
// Actually checking that this expression is an array is for
// a later step, when the messenger is available.
array = firstExpression;
LoopHeader result = new LoopHeader(loop, array);
return(result);
}
if (iterator.NextIsKeyword(Keywords.In, out Token inToken))
{
// Again, actually checking that this is indeed just a name
// has to wait for a later stage.
Expression name = firstExpression;
iterator.AssertExpression(out array);
iterator.AssertEnd();
LoopHeader result = new LoopHeader(loop, name, inToken, array);
return(result);
}
if (iterator.NextIsKeyword(Keywords.From, out Token from))
{
Expression name = firstExpression;
iterator.AssertExpression(out Expression start);
iterator.AssertKeyword(Keywords.To, out Token to);
iterator.AssertExpression(out Expression end);
iterator.AssertEnd();
LoopHeader result = new LoopHeader(
loop, name, from, start, to, end);
return(result);
}
throw iterator.UnexpectedEnd();
}
private static Expression GetValue(MatchIterator iterator)
{
if (iterator.NextIsToken(TokenType.Operator, out Token opToken))
{
// Early out: if we are starting with an operator, than it is
// a right unary operator, and unary ops have the highest
// precedence at the moment.
return(new OperatorCall(opToken, null, GetValue(iterator)));
}
Expression expression;
// We don't have to recursively descend through the brackets -
// that is handled at the pattern matching level. As far as we are
// concerned, there are either expressions or expressions wrapped
// in brackets.
if (iterator.NextIsKeySymbol(Symbols.OpenBracket, out Token open))
{
iterator.AssertExpression(out Expression value);
iterator.AssertKeySymbol(Symbols.CloseBracket, out Token close);
expression = new Group(open, value, close);
}
else
{
iterator.AssertExpression(out expression);
}
// Finally, consider any indexing that follow the expression.
// Sprak only allows one level of this, but that will be enforced
// later where a more friendly error can be displayed.
if (iterator.Next(out List <CollectedIndex> indices))
{
foreach (CollectedIndex index in indices)
{
expression = new Indexer(expression, index.Open, index.Index, index.Close);
}
iterator.MoveNext();
}
return(expression);
}