python - Earley Parser Recursion -


does earley parser have expected problems simple cycles?

i've made own implementation, it's pretty similar one, readable , 150 lines total (and i, of course, didn't write it):

http://www.nightmare.com/rushing/python/earley.py

that 1 looks me, , works in provided test case, simple grammar

e : [[e,e],[ident]]

doesn't seem work. should generate arbitrary number of "ident" tokens, assuming e starting non-terminal , ident terminal. grammar, , similar style grammar, missed parser.

is problem in earley algoritm (i don't think is), or problem in implementation; if it's implementation based, there (relatively) easy solution or algorithm need rebuilt?

yes, has expected problem groups of rules of kind:

x1 ::= x2

x2 ::= x3

...

xn ::= x1

in case algorithm may enter in infinite recursion loop, if not checking states you've added earley chart.

in case you've presented above must not enter in infinite loop, because expansions of rule e ::= e e limited input. check implementation here:

https://en.wikipedia.org/wiki/earley_parser#the_algorithm

i have used implementation, , works fine.


Comments

Post a Comment

Popular posts from this blog

php - SPIP: From Tag directly to an article -

i work spip , plugin called tagsphere works fine tags in spip. have tag groupe put 1 article tag. when click on tag in tagsphere send me before menu can see articles linked tag. want send me directly article without see tag menu before. here code model of thagsphere: <div id="tagsphere-#env{id_article}"> <ul> <boucle_mot(mots){id_groupe ?}> <li>[<a href="#url_mot">(#titre)</a>]</li> </boucle_mot> </ul> </div> anybody idea? if want skip tag page, have link directly article. <b_article> block prevents display tag if no article linked. <div id="tagsphere-#env{id_article}"> <ul> <boucle_mot(mots){id_groupe ?}> <b_article> <li> <a<boucle_article(articles){...
Read more

jquery - isAjaxRequest always return false -

i got error message 404,'model has not been saved' following code my action controller public function actionextend($id) { $model=$this->loadmodel($id); if(yii::app()->request->isajaxrequest) { $model->todate = date('y-m-d h:i:s a',(strtotime('next month',strtotime(date('y-01-d'))))); if($model->save()) { yii::app()->end(); } else { throw new chttpexception(404,'model has not been saved'); } } } the jquery call $("#buttonextend<?php echo $this->post_row;?>").click(function(e){ $.ajax({ type: "post", url: "<?php echo yii::app()->createurl('post/extend', array('id' => $data['id'])); ?>", }); }); why not ajax call ? thank help i found response, missed } , function ...
Read more

ruby on rails - In a controller spec, how to find a specific tag in the generated view? -

i know integration tests preferred need ran in controller test, i'm testing gem injecting html code in view, xhr can't run in feature spec (if can, please explain me how :) ) so rspec controller tests can assert selector present (with capybara) : response.body.should have_selector('#foobar') has_selector? call all method capybara find selector. what want last child of body , assert id in particular. afaik it's not possible have_selector. what : all('body:first-child').first.id.should == '#foobar' however, capybara dsl, defined (more or less): def all(*args) page.all(*args) end and page empty unless use visit it's integrations specs. how can use capybara all method inside rspec controller test ? i can't test right after googling seems trick def page capybara::node::simple.new(response.body) end source
Read more