[new-parser] Anonymous classes not supported

[yurloc]

Parent issue

• Experiment: New DRL parser #5678

Failing tests

• org.drools.mvel.integrationtests.Misc2Test#testJittingFunctionReturningAnInnerClass

Notes

At the end of line 3, a semi is expected instead of class body. This is because DRL6Expressions.g4 overrides the classCreatorRest rule and does not allow classBody?.

Rule code snippet

import java.util.function.Function
function Function<String, Integer> f() {
    return new Function<String, Integer>() {
        public Integer apply(String s) {
            return s.length();
        }
    };
}

Error output

### parse : ANTLR4_PARSER_ENABLED = true
line 3:43 missing ';' at '{'
line 4:23 missing '.' at 'apply'
line 4:28 mismatched input '(' expecting '.'
line 4:36 extraneous input 's' expecting ')'
line 4:39 extraneous input '{' expecting {'abstract', 'class', 'final', 'interface', 'private', 'protected', 'public', 'static', 'strictfp', 'module', 'open', 'requires', 'exports', 'opens', 'to', 'uses', 'provides', 'with', 'transitive', 'var', 'yield', 'record', 'sealed', 'permits', 'non-sealed', '@', IDENTIFIER}
11:06:45.941 [main] ERROR o.d.c.k.b.impl.AbstractKieProject.buildKnowledgePackages:280 - Unable to build KieBaseModel:KieBaseModelName
[3,43]: missing ';' at '{'
[4,23]: missing '.' at 'apply'
[4,28]: mismatched input '(' expecting '.'
[4,36]: extraneous input 's' expecting ')'
[4,39]: extraneous input '{' expecting {'abstract', 'class', 'final', 'interface', 'private', 'protected', 'public', 'static', 'strictfp', 'module', 'open', 'requires', 'exports', 'opens', 'to', 'uses', 'provides', 'with', 'transitive', 'var', 'yield', 'record', 'sealed', 'permits', 'non-sealed', '@', IDENTIFIER}
[0,0]: Parser returned a null Package

11:06:45.949 [main] ERROR o.d.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem:165 - KieBuilder errors: [Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=3, column=0
   text=missing ';' at '{'], Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=missing '.' at 'apply'], Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=mismatched input '(' expecting '.'], Message [id=4, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input 's' expecting ')'], Message [id=5, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input '{' expecting {'abstract', 'class', 'final', 'interface', 'private', 'protected', 'public', 'static', 'strictfp', 'module', 'open', 'requires', 'exports', 'opens', 'to', 'uses', 'provides', 'with', 'transitive', 'var', 'yield', 'record', 'sealed', 'permits', 'non-sealed', '@', IDENTIFIER}], Message [id=6, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=0, column=0
   text=Parser returned a null Package]]

java.lang.AssertionError: [[Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=3, column=0
   text=missing ';' at '{'], Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=missing '.' at 'apply'], Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=mismatched input '(' expecting '.'], Message [id=4, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input 's' expecting ')'], Message [id=5, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input '{' expecting {'abstract', 'class', 'final', 'interface', 'private', 'protected', 'public', 'static', 'strictfp', 'module', 'open', 'requires', 'exports', 'opens', 'to', 'uses', 'provides', 'with', 'transitive', 'var', 'yield', 'record', 'sealed', 'permits', 'non-sealed', '@', IDENTIFIER}], Message [id=6, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=0, column=0
   text=Parser returned a null Package]]] 
Expecting empty but was: [Message [id=1, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=3, column=0
   text=missing ';' at '{'],
    Message [id=2, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=missing '.' at 'apply'],
    Message [id=3, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=mismatched input '(' expecting '.'],
    Message [id=4, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input 's' expecting ')'],
    Message [id=5, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=4, column=0
   text=extraneous input '{' expecting {'abstract', 'class', 'final', 'interface', 'private', 'protected', 'public', 'static', 'strictfp', 'module', 'open', 'requires', 'exports', 'opens', 'to', 'uses', 'provides', 'with', 'transitive', 'var', 'yield', 'record', 'sealed', 'permits', 'non-sealed', '@', IDENTIFIER}],
    Message [id=6, kieBase=KieBaseModelName, level=ERROR, path=rules1.drl, line=0, column=0
   text=Parser returned a null Package]]

	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:169)
	at org.drools.testcoverage.common.util.KieUtil.getKieBuilderFromKieFileSystem(KieUtil.java:134)
	at org.drools.testcoverage.common.util.KieUtil.buildAndInstallKieModuleIntoRepo(KieUtil.java:78)
	at org.drools.testcoverage.common.util.KieUtil.buildAndInstallKieModuleIntoRepo(KieUtil.java:72)
	at org.drools.testcoverage.common.util.KieUtil.getKieModuleFromResources(KieUtil.java:249)
	at org.drools.testcoverage.common.util.KieUtil.getKieModuleFromResources(KieUtil.java:238)
	at org.drools.testcoverage.common.util.KieBaseUtil.getKieBaseFromKieModuleFromResources(KieBaseUtil.java:102)
	at org.drools.testcoverage.common.util.KieBaseUtil.getKieBaseFromKieModuleFromDrl(KieBaseUtil.java:115)
	at org.drools.mvel.integrationtests.Misc2Test.testJittingFunctionReturningAnInnerClass(Misc2Test.java:8019)

[yurloc]

good-first-issue

[tkobayas]

functiondef : DRL_FUNCTION typeTypeOrVoid? drlIdentifier formalParameters drlBlock ;

Probably drlBlock can be replaced with LBRACE chunk? RBRACE just like old parser.

[yurloc]

functiondef : DRL_FUNCTION typeTypeOrVoid? drlIdentifier formalParameters drlBlock ;

Probably drlBlock can be replaced with LBRACE chunk? RBRACE just like old parser.

That's the easy solution. I'm not against it as our goal for the ANTL4 rewrite is not to improve the parser's capability.

But another solution exists.

If you traverse the parser rules according to the parse tree above, you'll find out that classCreatorRest is declared in DRL6Expressions.g4 and it effectively overrides a rule with the same name in JavaParser.g4. The difference between the two rules is that the one in DRL6Expressions.g4 does not allow class body:

incubator-kie-drools/drools-drl/drools-drl-parser/src/main/antlr4/org/drools/drl/parser/antlr4/DRL6Expressions.g4

Lines 843 to 845 in 8997956

	classCreatorRest
	: arguments //classBody? //sotty: restored classBody to allow for inline, anonymous classes
	;

The obvious fix would be to uncomment classBody? but that would be an unnecessary change in the DRL6Expressions.g4 grammar. I would prefer simply renaming the classCreatorRest rule in DRL6Expressions.g4 leaving its behavior unchanged and letting the drlCreator rule in DRLParser.g4 use the classCreatorRest from JavaParser.g4.

[tkobayas]

Fixed by #5979