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Bug 336235

Summary: [formatter/matcher] Matcher loses track if ParserRule contains only optional tokens
Product: [Modeling] TMF Reporter: Carl Wannheden <carl.wannheden>
Component: XtextAssignee: Project Inbox <tmf.xtext-inbox>
Status: CLOSED FIXED QA Contact:
Severity: normal    
Priority: P3 CC: moritz.eysholdt
Version: 0.8.0   
Target Milestone: ---   
Hardware: All   
OS: All   
Whiteboard:
Attachments:
Description Flags
MyDsl.xtext grammar
none
MyDsl format configuration
none
Example file
none
Graphviz diagram of format configuration none

Description Carl Wannheden CLA 2011-02-03 09:47:24 EST 
Build Identifier: 20100917-0705

For the attached grammar, format configuration and example the indentation keeps growing without the optional element. With the optional element the formatting works as expected.

Reproducible: Always

Steps to Reproduce:
1.Created MyDsl project with attached grammar and format configuration
2.Format attached example in the MyDsl editor - indent keeps growing
3.Uncomment "init" and format - expected result
Comment 1 Carl Wannheden CLA 2011-02-03 09:49:13 EST 
Created attachment 188232 [details]
MyDsl.xtext grammar
Comment 2 Carl Wannheden CLA 2011-02-03 09:49:44 EST 
Created attachment 188233 [details]
MyDsl format configuration
Comment 3 Carl Wannheden CLA 2011-02-03 09:50:19 EST 
Created attachment 188235 [details]
Example file
Comment 4 Carl Wannheden CLA 2011-02-03 09:51:58 EST 
Created attachment 188236 [details]
Graphviz diagram of format configuration
Comment 5 Moritz Eysholdt CLA 2011-02-09 11:46:23 EST 
fixed in "master" and "Helios_maintenance".

It turns out that the Matcher "lost track" when there is a parser rule with only optional syntactical elements.

In case you have been accessing internals of Xtext's Matcher directly, there is one method that now has an additional parameter for loop protection:

protected Pair<List<MatcherTransition>, List<MatcherState>> findTransitionPath(MatcherState from, AbstractElement to, boolean returning, boolean canReturn, Set<Pair<Boolean, MatcherState>> visited);
Comment 6 Moritz Eysholdt CLA 2011-02-09 11:48:44 EST 
The class I was referring to is org.eclipse.xtext.formatting.impl.ElementMatcherProvider
Comment 7 Karsten Thoms CLA 2017-09-19 17:13:08 EDT 
Closing all bugs that were set to RESOLVED before Neon.0
Comment 8 Karsten Thoms CLA 2017-09-19 17:24:36 EDT 
Closing all bugs that were set to RESOLVED before Neon.0