Пример #1
0
    }                                           // or null
    public override string GetExpected()
    {
        var s = "";

        if (Min > 0)
        {
            s += $"{ItemProd.GetExpected()} ";
        }
        s += $"[ {SeparatorProd?.GetExpected() ?? ""} {ItemProd.GetExpected()} ]*";
        return(s);
    }
Пример #2
0
 public override MatchResult?MatchStep(MatchStack stack, MatchFrame frame, TokenQueue q)
 {
     if (frame.ListState == ListTermState.Start)
     {
         frame.ListState = ListTermState.MatchItem;
         stack.Push(ItemProd);
         return(null); // -> MatchItem
     }
     else if (frame.ListState == ListTermState.MatchSeparator)
     {
         var result = frame.SubResult;
         if (result.IsMatch)
         {
             // we have a separator.  now try to match the item following it.
             frame.ListState = ListTermState.MatchItem;
             stack.Push(ItemProd);
             return(null); // -> MatchItem
         }
         else if (result.ErrorMessage == null)
         {
             // we didn't find a separator.  this list is done.  back up to the beginning of where
             // the not-separator started and we're done.
             q.Jump(frame.ListSeparatorStartLoc);
             if (frame.ListCount < Min)
             {
                 return(MatchResult.Error(
                            $"At least {Min} list item{(Min == 1 ? " is" : "s are")} required, but only " +
                            $"{frame.ListCount} {(frame.ListCount == 1 ? "was" : "were")} provided. " +
                            $"Expected list item: {ItemProd.GetExpected()}"));
             }
             else
             {
                 return(MatchResult.Matched);
             }
         }
         else
         {
             return(result); // error
         }
     }
     else if (frame.ListState == ListTermState.MatchItem)
     {
         var result = frame.SubResult;
         if (result.IsMatch)
         {
             // we have an item.  is there another?
             frame.ListCount++;
             if (SeparatorProd == null)
             {
                 // there is no separator, so match the next item
                 frame.ListState             = ListTermState.MatchItem;
                 frame.ListSeparatorStartLoc = q.GetLocation();
                 stack.Push(ItemProd);
                 return(null); // -> MatchItem
             }
             else
             {
                 // match separator + item
                 frame.ListState             = ListTermState.MatchSeparator;
                 frame.ListSeparatorStartLoc = q.GetLocation();
                 stack.Push(SeparatorProd);
                 return(null); // -> MatchSeparator
             }
         }
         else if (result.ErrorMessage == null)
         {
             if (frame.ListCount == 0)
             {
                 // the first item might be missing because the list can potentially be optional.
                 return(Min == 0 ? MatchResult.Matched : MatchResult.NoMatch);
             }
             else if (SeparatorProd == null)
             {
                 // there's no separator, so eventually we'll end up here when the list ends.
                 q.Jump(frame.ListSeparatorStartLoc);
                 if (frame.ListCount < Min)
                 {
                     return(MatchResult.Error(
                                $"At least {Min} list item{(Min == 1 ? " is" : "s are")} required, but only " +
                                $"{frame.ListCount} {(frame.ListCount == 1 ? "was" : "were")} provided. " +
                                $"Expected list item: {ItemProd.GetExpected()}"));
                 }
                 else
                 {
                     return(MatchResult.Matched);
                 }
             }
             else
             {
                 // subsequent items must be present because, in the MatchItem state, we've already consumed a
                 // separator so there must be an item following it.
                 return(MatchResult.Error($"Expected list item: {ItemProd.GetExpected()}"));
             }
         }
         else
         {
             return(result); // error
         }
     }
     else
     {
         throw new Exception($"Unrecognized state: {frame.ListState}");
     }
 }