[ https://issues.apache.org/jira/browse/LUCENE-7921?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Dawid Weiss updated LUCENE-7921: -------------------------------- Attachment: capture-7.png capture-8.png A smaller example that shows what's going on. {{REGEXP_CONCATENATION}} expands elements of a concatenated regexp; the repeated-min-max on its own is much larger than a sequence of optionals. > More efficient way to transform a RegExp to an Automaton > -------------------------------------------------------- > > Key: LUCENE-7921 > URL: https://issues.apache.org/jira/browse/LUCENE-7921 > Project: Lucene - Core > Issue Type: Improvement > Affects Versions: 6.5.1 > Reporter: Thomas Poppe > Priority: Minor > Attachments: capture-7.png, capture-8.png > > > Consider the following example: > {code:title=ToAutomatonExample.java|borderStyle=solid} > public static void main(String[] args) { > org.apache.lucene.util.automaton.RegExp regExp = > new > org.apache.lucene.util.automaton.RegExp("[a-z]{1,13}x[a-z][a-z]?[a-z]?[a-z]?[a-z]?[a-z]{0,8}"); > org.apache.lucene.util.automaton.Automaton automaton = > regExp.toAutomaton(); > System.out.println("states: " + automaton.getNumStates()); > System.out.println("transitions: " + automaton.getNumTransitions()); > System.out.println("-------------------------------"); > try { > regExp = new > org.apache.lucene.util.automaton.RegExp("[a-z]{1,13}x[a-z]{1,13}"); > automaton = regExp.toAutomaton(); > System.out.println("Will not happen..."); > } catch > (org.apache.lucene.util.automaton.TooComplexToDeterminizeException e) { > automaton = regExp.toAutomaton(1_000_000); > System.out.println("states: " + automaton.getNumStates()); > System.out.println("transitions: " + > automaton.getNumTransitions()); > System.out.println("-------------------------------"); > } > } > {code} > Both regular expressions are equivalent, but it's much more efficient to > "unroll" the repetition. It might be possible to optimize the > Regex#toAutomaton() method to handle this repetition without going over the > default number of determinized states, and using less memory and CPU? -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org