public static bool TryParsePostOfficeBox(string input, out PostOfficeBoxSyntaxNode result)
{
var tokens = Tokenizer.Tokenize(input).Reverse().ToImmutableArray();
var state = new ParserState(tokens);
var success = TryParsePostOfficeBox(ref state, out var syntax) && state.Current.IsNone;
result = success ? syntax : null;
return(success);
}
private static bool TryParsePostOfficeBox(ref ParserState state, out PostOfficeBoxSyntaxNode result)
{
result = null;
var snapshot = state;
if (TryParseRange(ref state, out var boxNumber))
{
state.ConsumeWhiteSpace();
if (state.TryConsume(t => t.IsOctothorpe))
{
state.ConsumeWhiteSpace();
}
if (state.TryConsume("caller"))
{
state.ConsumeWhiteSpace();
state.TryConsume("firm");
}
else if (state.TryConsume(t => t.Matches("box") || t.Matches("drawer") || t.Matches("bin") || t.Matches("drawer") || t.Matches("lockbox")))
{
// no-op
}
else
{
goto Failure;
}
var boxKeywordTokens = state.TakeBuffer();
if (TryParsePostOfficeBoxKeywords(ref state, out var additionalTokens))
{
boxKeywordTokens = additionalTokens.AddRange(boxKeywordTokens);
}
result = new PostOfficeBoxSyntaxNode(boxKeywordTokens, boxNumber);
return(true);
}
Failure:
state = snapshot;
return(false);
}