Subject: [htdig3-dev] feedback on ParseTree
From: Quim Sanmarti (qss@gtd.es)
Date: Wed Aug 23 2000 - 03:54:55 PDT
I've being playing a bit with the ParseTree framework (the version I found
in the 082000 snapshot).
1. I was particularly interested in how the boolean queries are parsed. The
first thing I tried was:
a or b and c and d
This parsed without errors, yielding as LogicalWords for boolean parsing:
: (a or b and c and d)
Nice, but this gives no clue of about what would be the structure of the
resulting tree. Consequently, I modified slightly AndParseTree and
OrParseTree to insert parens around the string returned in GetLogicalWords.
Retrying parsetest, I find the surprising result below:
: ((((a or b) and c) and d))
Hmm. Does this imply that the parser generates *binary* children when
trying boolean? Trying only with 'and' operators, does much the same...
2. Next, I tried
a and b or c
and
a or b and c
Yielding respectively
: (((a and b) or c))
: (((a or b) and c))
Hmm. No precedence is defined between 'or' and 'and'.
3. Next, I tried to force precedence by inserting parens in the query. So
a or (b and c)
yields
: (((a or b) and c)
It seems to be ignoring the parens.
4. I tried to include a phrase:
a or "b c"
with the result
Parsing as a boolean query FAILED
[silence, infinite loop]
a single phrase "a b c" does the same.
// Joaquim Sanmarti
// GTD Ingenieria de sistemas y software industrial, S.A.
// c/Rosa Sensat 9-11
// 08005 Barcelona SPAIN
// Tel. +34 93 225 77 00
// Fax. +34 93 225 77 08
// mailto:qss@gtd.es
// http://www.gtd.es
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