<div dir="ltr"><div style="font-family:arial,helvetica,sans-serif" class="gmail_default"></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hello developers,</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">It's been a while but I'm returning to a discussion we were having about serializing EDS in the native format when there is no TOP and when there's no INDEX to backoff to. Stephan suggested that EDS is a line-based format (i.e., line breaks are required), while I would like to continue to support single-line EDS in PyDelphin. I think the last word on the subject from Stephan, at least on this list, was mid-September (<a href="http://lists.delph-in.net/archives/developers/2020/003140.html">http://lists.delph-in.net/archives/developers/2020/003140.html</a>), where he said he'd continue discussion on another thread, which presumably meant the thread from late August (<a href="http://lists.delph-in.net/archives/developers/2020/003127.html">http://lists.delph-in.net/archives/developers/2020/003127.html</a>). I don't think the discussion did continue, so I'm starting this thread in case anyone is interested.<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">As an example, here's an EDS (without properties) for "It rained."</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> {e2:<br> e2:_rain_v_1<3:9>[]<br> }<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">In PyDelphin, when an EDS has no TOP, I was outputting the first colon anyway, intentionally:</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> {:<br> e2:_rain_v_1<3:9>[]<br> }</div></div><div><br></div><div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">It's a bit ugly, but it allows me to detect, with 1 token of lookahead, if there's a top or not. If the colon is omitted then it's not clear if "e2:" is the top or the start of the first node. If line breaks are required, we just assume the first line is for the top, whether or not it's there. But for single-line EDS, we need 4 tokens of lookahead to determine if there's a top (assuming the parser treats variables and predicates as the same kinds of tokens):<br></div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> {e2: e2:_rain_v_1<3:9>[]}<br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> {e2:_rain_v_1<3:9>[]}</div></div></div></div><div><br></div><div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">Here is the parsing algorithm, once we've consumed the first '{':</div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default"><br></div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">1. If the 1st lookahead token is ':', '(fragmented)' (or another graph status), '}', or '|' (node status), then we know that TOP is missing (the ':' is for PyDelphin's current output)</div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">2. Otherwise the 1st and 2nd tokens must be a symbol and a colon, and if the 3rd token is a graph or node status, OR if the 4th token is ':', then the 1st token is the TOP</div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">3. Otherwise TOP must be missing<br></div></div><div><br></div><div><div style="font-family:arial,helvetica,sans-serif" class="gmail_default">I think this covers all the cases but let me know if I've missed anything.</div></div><div><br></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">-Michael Wayne Goodman</div></div>