NullPointerException in ATNConfig.hashCode #45

JFinis · 2012-03-17T17:49:53Z

Hi,

I receive a NullPointerException when running the generated parser on an input. If you need a grammar and input to provoque the bug, let me know (but that will take some time).

Here is the stack trace:

Exception in thread "main" java.lang.NullPointerException
    at org.antlr.v4.runtime.atn.ATNConfig.hashCode(ATNConfig.java:149)
    at java.util.HashMap.put(Unknown Source)
    at java.util.HashSet.add(Unknown Source)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:924)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:946)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:912)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.computeReachSet(ParserATNSimulator.java:711)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.execATN(ParserATNSimulator.java:521)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.predictATN(ParserATNSimulator.java:331)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.adaptivePredict(ParserATNSimulator.java:296)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.strongExpr(ANTLRv4Parser.java:886)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.expr(ANTLRv4Parser.java:1146)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.grammarRule(ANTLRv4Parser.java:398)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.gramma(ANTLRv4Parser.java:150)
    at org.eeve.antlrgen.ANTLRGenTest.parseStatic(ANTLRGenTest.java:92)
    at org.eeve.antlrgen.ANTLRGenTest.main(ANTLRGenTest.java:38)

The text was updated successfully, but these errors were encountered:

sharwell · 2012-03-17T21:09:35Z

Do you happen to know which commit you're using? (Ideally the SHA hash for it)

JFinis · 2012-03-17T21:14:01Z

Yes, it is
28ee391
from parrt/antlr4

sharwell · 2012-03-17T22:23:54Z

Can you add the following assertions to track down the source of failure?

In the two ATNConfig constructors that set state and semanticContext, add:

assert state != null;
assert semanticContext != null;

JFinis · 2012-03-17T22:37:37Z

okay, here we go:

Exception in thread "main" java.lang.AssertionError: state is null
    at org.antlr.v4.runtime.atn.ATNConfig.<init>(ATNConfig.java:112)
    at org.antlr.v4.runtime.atn.ATNConfig.<init>(ATNConfig.java:98)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.actionTransition(ParserATNSimulator.java:1043)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.getEpsilonTarget(ParserATNSimulator.java:1032)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:990)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:946)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:1012)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.closure(ParserATNSimulator.java:912)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.computeReachSet(ParserATNSimulator.java:711)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.execATN(ParserATNSimulator.java:521)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.predictATN(ParserATNSimulator.java:331)
    at org.antlr.v4.runtime.atn.ParserATNSimulator.adaptivePredict(ParserATNSimulator.java:296)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.strongExpr(ANTLRv4Parser.java:886)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.expr(ANTLRv4Parser.java:1146)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.grammarRule(ANTLRv4Parser.java:398)
    at org.eeve.antlrgen.parser.ANTLRv4Parser.gramma(ANTLRv4Parser.java:150)
    at org.eeve.antlrgen.ANTLRGenTest.parseStatic(ANTLRGenTest.java:92)
    at org.eeve.antlrgen.ANTLRGenTest.main(ANTLRGenTest.java:38)

sharwell · 2012-03-17T22:47:34Z

It would definitely help if you are able to post an example grammar and input for me to duplicate this issue. You may not have to post input - it looks like you have a case where Transition is being constructed with target==null. You could add an assertion to the Transition constructor as a check.

Have you tried regenerating the code?

JFinis · 2012-03-18T09:24:31Z

Okay, here is the grammar

grammar ANTLRv4;

ruler returns [String r]
  :  t=ID  ':' alts+=expr ('|' alts+= expr)* ';'
      {  $r = "x"; }
   ;

strongExpr returns [String r]
  : ID                      { $r = "x"; }
  | '(' ep=parenExpr ')'            { $r = "x"; }
  | e1=strongExpr '?'             { $r = "x"; }
  ;  

expr returns [String r]
  : e=strongExpr (e2=expr)? { $r = "x"; }
  | e1=expr '->' ID {$r = "x"; }
  ;

parenExpr returns [String r]
  : e1=expr '|' e2=parenExpr { $r = "x"; }
  | expr              {$r = $expr.r; }
  ;

ID  :   ('A'..'Z'|'a'..'z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
    ;

And here is a test input:

x:x;

Code for parser execution:

ANTLRv4Lexer lex = new ANTLRv4Lexer(new ANTLRInputStream(new FileInputStream(new File("test.input"))));
CommonTokenStream tokens = new CommonTokenStream(lex);

new ANTLRv4Parser(tokens).ruler();

sharwell · 2012-03-18T17:28:33Z

Thanks, that's perfect. I was able to derive the following grammar as a unit test for the issue which I'm now working to fix.

grammar T;
start
  : ID ':' expr
  ;
expr
  : primary expr? {}
  | expr '->' ID
  ;
primary
  : ID
  ;

ID : [a-z]+;

Input: x:x

JFinis · 2012-03-27T11:45:46Z

well, after merging your commits, I get the anticipated exception during parser building

    [java] Exception in thread "main" java.lang.IllegalStateException: Cannot serialize a transition to a removed state.
    [java]  at org.antlr.v4.automata.ATNSerializer.serialize(ATNSerializer.java:138)
    [java]  at org.antlr.v4.automata.ATNSerializer.getSerialized(ATNSerializer.java:281)
    [java]  at org.antlr.v4.codegen.model.SerializedATN.<init>(SerializedATN.java:43)
    [java]  at org.antlr.v4.codegen.model.Parser.<init>(Parser.java:86)
    [java]  at org.antlr.v4.codegen.ParserFactory.parser(ParserFactory.java:54)
    [java]  at org.antlr.v4.codegen.OutputModelController.parser(OutputModelController.java:145)
    [java]  at org.antlr.v4.codegen.OutputModelController.buildParserOutputModel(OutputModelController.java:84)
    [java]  at org.antlr.v4.codegen.CodeGenerator.generateParser(CodeGenerator.java:132)
    [java]  at org.antlr.v4.codegen.CodeGenPipeline.process(CodeGenPipeline.java:51)
    [java]  at org.antlr.v4.Tool.processNonCombinedGrammar(Tool.java:353)
    [java]  at org.antlr.v4.Tool.process(Tool.java:319)
    [java]  at org.antlr.v4.Tool.processGrammarsOnCommandLine(Tool.java:283)
    [java]  at org.antlr.v4.Tool.main(Tool.java:173)

While this is better than a fail at runtime, it is still not satisfactory, as I don't know what I have done wrong.

sharwell · 2012-03-27T12:49:31Z

Once this issue is corrected, it will be tagged with "status:pull-request" until it gets closed. :) The test I've implemented so far is in place to help track down the issue, but like you saw it doesn't create a working grammar.

sharwell · 2012-10-25T22:32:20Z

I am no longer able to reproduce this bug.

Add the ability to explicitly specify the path to the Java executable

Added optional predicate parameter to ParserRuleContext.getChildren(), a...

small rule attribute fixes

Fixes antlr#43 Fixes antlr#45 Fixes antlr#46

JFinis mentioned this issue Mar 19, 2012

NullPointerException in LexerATNSimulator.execDFA #46

Closed

sharwell mentioned this issue Mar 19, 2012

ATN optimization consistency tests parrt/antlr4#50

Closed

sharwell closed this as completed Oct 25, 2012

parrt pushed a commit that referenced this issue Jun 30, 2015

Merge pull request #45 from sharwell/fix-32

6789bd6

Add the ability to explicitly specify the path to the Java executable

parrt pushed a commit that referenced this issue Jun 30, 2015

Merge pull request #45 from RedTailedHawk/master

415d709

Added optional predicate parameter to ParserRuleContext.getChildren(), a...

parrt pushed a commit that referenced this issue Nov 7, 2016

Merge pull request #45 from RYDB3RG/master

b9f81ab

small rule attribute fixes

ericvergnaud mentioned this issue Nov 8, 2016

Merge cpp #1346

Merged

sharwell added a commit to sharwell/antlr4 that referenced this issue Dec 28, 2020

Improve support for baseContext with other features

b93a379

Fixes antlr#43 Fixes antlr#45 Fixes antlr#46

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NullPointerException in ATNConfig.hashCode #45

NullPointerException in ATNConfig.hashCode #45

JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 18, 2012

sharwell commented Mar 18, 2012

JFinis commented Mar 27, 2012

sharwell commented Mar 27, 2012

sharwell commented Oct 25, 2012

NullPointerException in ATNConfig.hashCode #45

NullPointerException in ATNConfig.hashCode #45

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JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 17, 2012

sharwell commented Mar 17, 2012

JFinis commented Mar 18, 2012

sharwell commented Mar 18, 2012

JFinis commented Mar 27, 2012

sharwell commented Mar 27, 2012

sharwell commented Oct 25, 2012