[jira] [Comment Edited] (LUCENE-7921) More efficient way to transform a RegExp to an Automaton
[
https://issues.apache.org/jira/browse/LUCENE-7921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119540#comment-16119540
]
Thomas Poppe edited comment on LUCENE-7921 at 8/9/17 9:46 AM:
--
Thanks for your comment Dawid. One more thing I would like to note: the second
case also takes more memory and CPU to convert to an automaton, so there might
be an opportunity to optimize - but I guess you were already suggesting that.
was (Author: thomaspoppe):
Thanks for your comment Dawid. One more think I would like to note: the second
case also takes more memory and CPU to convert to an automaton, so there might
be an opportunity to optimize - but I guess you were already suggesting that.
> 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?
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[jira] [Comment Edited] (LUCENE-7921) More efficient way to transform a RegExp to an Automaton
[
https://issues.apache.org/jira/browse/LUCENE-7921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119580#comment-16119580
]
Dawid Weiss edited comment on LUCENE-7921 at 8/9/17 8:41 AM:
-
I think we should optimize {{Operations.repeat}} so that it produces saner
input for minimization (single start state and epsilon arcs if x>=1 in
\{x,y\}). It still wouldn't be the same behavior (concatenation would see
different input clauses of a larger regexp), but it should be less costly
(fewer states).
was (Author: dweiss):
I think we should optimize {{Operations.repeat}} so that it produces saner
input for minimization (single start state and epsilon arcs if x>=1 in {x,y}).
It still wouldn't be the same behavior (concatenation would see different input
clauses of a larger regexp), but it should be less costly (fewer states).
> 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?
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[jira] [Comment Edited] (LUCENE-7921) More efficient way to transform a RegExp to an Automaton
[
https://issues.apache.org/jira/browse/LUCENE-7921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119540#comment-16119540
]
Thomas Poppe edited comment on LUCENE-7921 at 8/9/17 7:56 AM:
--
Thanks for your comment Dawid. One more think I would like to note: the second
case also takes more memory and CPU to convert to an automaton, so there might
be an opportunity to optimize - but I guess you were already suggesting that.
was (Author: thomaspoppe):
Thanks for your comment Dawid. One more think I would like to note: the second
case also takes more memory and CPU to convert to an automaton, so there might
be an opportunity to optimize.
> 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
>
> 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?
--
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