On 01/10/2015 11:00 AM, Michael McCandless wrote:
On Fri, Jan 9, 2015 at 6:42 AM, Olivier Binda <olivier.bi...@wanadoo.fr> wrote:
Hello.
1) What is the best way to check if an automaton (from a regex or a string
with a wildcard)
has at least 1 match against a FST (from a WFSTCompletionLookup) ?
You need to implement "intersect". We already have this method for
two automata (Operations.java); maybe you can start from that but
cutover to the FST APIs instead for the 2nd automaton?
I looked a bit into this. This is complicated stuff :/
I think I get what the nested loops in intersect() do : transitions
consist of a double dimension array, somehow those arays are intersected.
I don't understand yet why is there a .min and a .max for a transition
(why not just a codepoint ?)
Fst and automaton (and maybee the lucene codec stuff) are 3 different
implementations
of finite state machine/transducers, right ?
How does regexQuery (automaton) match against an index ?
Does it use intersect() internally ? (if it does, maybee I could reuse
that code too)
2) Also, is there a simple/efficient way to find the lowest and the highest
arcs of a FST that match against an automaton ?
Hmm arcs leaving which state? The initial state? You could simply
walk all arcs leaving the initial state from the FST and check if the
automaton accepts them leaving its initial state (assuming the
automaton has no dead states)?
Or, if you are already doing an intersection here, just save this
information as a side effect since you will have already computed it.
thanks for the tips, it helps.
Olivier
Mike McCandless
http://blog.mikemccandless.com
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