Geoff Hutchison writes:
>
> One final concern: this model makes it very difficult to add the
> AltaVista url: syntax for adding in URL restricts. I'm not sure how a
> ParseTree should pass up information like this about how the search
> should be performed. For now I'm content to shelve the problem until
> we can get a clean, working replacement for the current code. ;-)
>
> What do people think?
I recently implemented a search algorithm (in the current mifluz package
from CVS file mifluz/test/search.cc) and found that it was convinient that
the base class of the syntax tree inherit from the iterator of the WordList
class. Each node of the syntax tree has a semantic that mimics the WordList
iterator and implementing various retrieval models is made easier. If it is
not desirable to implement a syntax tree that depends on WordList, another
class hierarchy can be built and the 'pure' syntax tree can be mutated into
a WordList inherited syntax tree for query resolution purpose.
Instead of building a binary syntax tree (each node has a left/right child)
I also find it a lot more convinient to build a N-ary tree. For instance
a Or node has N children and the query:
(or foo bar frob) is
or -> foo
-> bar
-> frob
This also makes it quite easy to implement the AltaVista like simple syntax
search. In fact the NOT operator is implemented as a minus in simple AltaVista
query syntax in all cases.
( or foo bar ( not ( and frob nitz ) ) ) is handle in the same way than
( or foo bar -frob )
The current test implementation of mifluz does not allow to implement
ranking of results the way Ht://Dig currently do because it does not return
the list of all possible matches, just the matches from N to M occurences.
It's still a test case as far as Ht://Dig is concerned.
Cheers,
--
Loic Dachary
24 av Secretan
75019 Paris
Tel: 33 1 42 45 09 16
e-mail: [EMAIL PROTECTED]
URL: http://www.senga.org/
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