FWD » Core Development » Conversion Tools

The problem¶

For the following 4gl code conversion throws NullPointerException:

FORM sometable WITH FRAME f.
ENABLE ALL WITH FRAME f.

where sometable is a database (not temporary) table with at least one field.

Environment¶

bzr revno
11327

How to reproduce¶

• go to testcases:

pushd ~/testcases/uast

• make a symbolic link to the directory with a build p2j project under test:

ln -s <p2j-branch-to-test> p2j

• create a file named 4154.p with the following contents:

FORM Book WITH FRAME f.
ENABLE ALL WITH FRAME f.

here Book is the name of a table in the @p2j_test* database.

• edit the file-cvt-list.txt, put the 4154.p into it;
• run

P2J_HOME=p2j ant convert-all jar -D4gl.file.list=file-cvt-list.txt

or just

java -classpath p2j/build/lib/p2j.jar com.goldencode.p2j.convert.ConversionDriver f0 4154.p

You should see these warning and error messages in the program output:

------------------------------------------------------------------------------
Scanning Progress Source (lexer, parser, persist ASTs)
------------------------------------------------------------------------------

abl/bad.p
WARNING: Null annotation (name) for p2j_test.book.publisher [FIELD_CHAR] @0:0
WARNING: Null annotation (name) for p2j_test.book.book-title [FIELD_CHAR] @0:0
WARNING: Null annotation (name) for p2j_test.book.book-id [FIELD_INT] @0:0
WARNING: Null annotation (name) for p2j_test.book.isbn [FIELD_CHAR] @0:0
WARNING: Null annotation (name) for p2j_test.book.sold-qty [FIELD_INT] @0:0
WARNING: Null annotation (name) for p2j_test.book.pub-date [FIELD_DATE] @0:0
WARNING: Null annotation (name) for p2j_test.book.author-id [FIELD_INT] @0:0
WARNING: Null annotation (name) for p2j_test.book.on-hand-qty [FIELD_INT] @0:0
WARNING: Null annotation (name) for p2j_test.book.price [FIELD_DEC] @0:0
WARNING: Null annotation (name) for p2j_test.book.cost [FIELD_DEC] @0:0
Failure in file '4154.p':
com.goldencode.ast.AstException: Error processing ./abl/bad.p
    at com.goldencode.p2j.uast.AstGenerator.processFile(AstGenerator.java:972)
    at com.goldencode.p2j.uast.ScanDriver.lambda$scan$0(ScanDriver.java:375)
    at com.goldencode.p2j.uast.ScanDriver.scan(ScanDriver.java:410)
    at com.goldencode.p2j.uast.ScanDriver.scan(ScanDriver.java:248)
    at com.goldencode.p2j.convert.TransformDriver.runScanDriver(TransformDriver.java:352)
    at com.goldencode.p2j.convert.TransformDriver.front(TransformDriver.java:223)
    at com.goldencode.p2j.convert.TransformDriver.executeJob(TransformDriver.java:862)
    at com.goldencode.p2j.convert.ConversionDriver.main(ConversionDriver.java:983)
Caused by: java.lang.NullPointerException: null value for annotation 'name':p2j_test.book.sold-qty [FIELD_INT]:12884901913 @0:0 HIDDEN

    at com.goldencode.ast.XmlFilePlugin.writeSingleAnnotation(XmlFilePlugin.java:1115)
    at com.goldencode.ast.XmlFilePlugin.writeAnnotations(XmlFilePlugin.java:1076)
    at com.goldencode.ast.XmlFilePlugin.writeAst(XmlFilePlugin.java:1035)
    at com.goldencode.ast.XmlFilePlugin.writeAst(XmlFilePlugin.java:1041)
    at com.goldencode.ast.XmlFilePlugin.writeAst(XmlFilePlugin.java:1041)
    at com.goldencode.ast.XmlFilePlugin.writeAst(XmlFilePlugin.java:1041)
    at com.goldencode.ast.XmlFilePlugin.writeAst(XmlFilePlugin.java:1041)
    at com.goldencode.ast.XmlFilePlugin.saveTree(XmlFilePlugin.java:487)
    at com.goldencode.ast.AstManager.saveTree(AstManager.java:322)
    at com.goldencode.p2j.uast.AstGenerator.persistAst(AstGenerator.java:1790)
    at com.goldencode.p2j.uast.AstGenerator.parse(AstGenerator.java:1543)
    at com.goldencode.p2j.uast.AstGenerator.processFile(AstGenerator.java:967)
    ... 7 more

Analysis¶

The NPE arises while the resulting XML is generated. It is caused by a badly formed "note" annotation in the AST node: the annotation exists in the Map, but the value of the MapEntry is null.

I do not know why this situation is ever allowed in any program. Do such annotation exist by design?

The annotation is created by the following code (src/com/goldencode/p2j/uast/progress.g, line 18453) in the enable_stmt():

wid.putAnnotation("name", (String) fld.getAnnotation("name"));

the fld AST node has no annotation names "name", so the null value is written to the annotation map.

The fld value, in turn, is created in the form_stmt(), which in turn, calls the record_spec() to fill the field list, which creates an AST node with the "schemaname" and "bufname" annotations only:

Aast fldRef = new ProgressAst();
fldRef.setType(fld.getType());
fldRef.setText(bufname + "." + fname);
fldRef.putAnnotation("schemaname", sname + "." + fname);
fldRef.putAnnotation("bufname", bufname);

As we may see, the field, which is used in the enable_stmt() in the fld variable, has no "name" annotation.

Workaround¶

The wid node in the problematic code, in this very situation at least, NEED NOT to be annotated with "name", since it was already annotated on creation:

So the line probably can be deleted:

    wid.putAnnotation("name", (String) fld.getAnnotation("name"));

The question is why this line was ever added?

Update: now (3821c rev. 11487) the stack trace looks a bit different:

     [java] Optional rule set [customer_specific_annotations_prep] not found.
     [java] ./abl/bad.p
     [java] EXPRESSION EXECUTION ERROR:
     [java] ---------------------------
     [java] throwException(sprintf(spec, bufname, reftype), this)
     [java] ^  { Cannot find buffer named test3820.master_test3820.master for ref type 21! [FIELD_INT id <12884901914> 0:0] }
     [java] ---------------------------
     [java] Elapsed job time:  00:00:00.792
     [java] ERROR:
     [java] com.goldencode.p2j.pattern.TreeWalkException: ERROR!  Active Rule:
     [java] -----------------------
     [java]       RULE REPORT      
     [java] -----------------------
     [java] Rule Type :   WALK
     [java] Source AST:  [ master-id ] BLOCK/STATEMENT/KW_FORM/FORM_ITEM/FIELD_INT/ @0:0 {12884901914}
     [java] Copy AST  :  [ master-id ] BLOCK/STATEMENT/KW_FORM/FORM_ITEM/FIELD_INT/ @0:0 {12884901914}
     [java] Condition :  throwException(sprintf(spec, bufname, reftype), this)
     [java] Loop      :  false
     [java] --- END RULE REPORT ---
     [java] 
     [java] 
     [java] 
     [java]     at com.goldencode.p2j.pattern.PatternEngine.run(PatternEngine.java:1070)
     [java]     at com.goldencode.p2j.convert.TransformDriver.processTrees(TransformDriver.java:569)
     [java]     at com.goldencode.p2j.convert.ConversionDriver.back(ConversionDriver.java:573)
     [java]     at com.goldencode.p2j.convert.TransformDriver.executeJob(TransformDriver.java:956)
     [java]     at com.goldencode.p2j.convert.ConversionDriver.main(ConversionDriver.java:1025)
     [java] Caused by: com.goldencode.expr.ExpressionException: Expression execution error @1:1 [FIELD_INT id=12884901914]
     [java]     at com.goldencode.p2j.pattern.AstWalker.walk(AstWalker.java:275)
     [java]     at com.goldencode.p2j.pattern.AstWalker.walk(AstWalker.java:210)
     [java]     at com.goldencode.p2j.pattern.PatternEngine.apply(PatternEngine.java:1633)
     [java]     at com.goldencode.p2j.pattern.PatternEngine.processAst(PatternEngine.java:1531)
     [java]     at com.goldencode.p2j.pattern.PatternEngine.processAst(PatternEngine.java:1479)
     [java]     at com.goldencode.p2j.pattern.PatternEngine.run(PatternEngine.java:1034)
     [java]     ... 4 more
     [java] Caused by: com.goldencode.expr.ExpressionException: Expression execution error @1:1
     [java]     at com.goldencode.expr.Expression.execute(Expression.java:484)
     [java]     at com.goldencode.p2j.pattern.Rule.apply(Rule.java:497)
     [java]     at com.goldencode.p2j.pattern.Rule.executeActions(Rule.java:745)
     [java]     at com.goldencode.p2j.pattern.Rule.coreProcessing(Rule.java:712)
     [java]     at com.goldencode.p2j.pattern.Rule.apply(Rule.java:534)
     [java]     at com.goldencode.p2j.pattern.Rule.executeActions(Rule.java:745)
     [java]     at com.goldencode.p2j.pattern.Rule.coreProcessing(Rule.java:712)
     [java]     at com.goldencode.p2j.pattern.Rule.apply(Rule.java:534)
     [java]     at com.goldencode.p2j.pattern.Rule.executeActions(Rule.java:745)
     [java]     at com.goldencode.p2j.pattern.Rule.coreProcessing(Rule.java:712)
     [java]     at com.goldencode.p2j.pattern.Rule.apply(Rule.java:534)
     [java]     at com.goldencode.p2j.pattern.Rule.executeActions(Rule.java:745)
     [java]     at com.goldencode.p2j.pattern.Rule.coreProcessing(Rule.java:712)
     [java]     at com.goldencode.p2j.pattern.Rule.apply(Rule.java:534)
     [java]     at com.goldencode.p2j.pattern.RuleContainer.apply(RuleContainer.java:585)
     [java]     at com.goldencode.p2j.pattern.RuleSet.apply(RuleSet.java:98)
     [java]     at com.goldencode.p2j.pattern.AstWalker.walk(AstWalker.java:262)
     [java]     ... 9 more
     [java] Caused by: com.goldencode.p2j.pattern.CommonAstSupport$UserGeneratedException: Cannot find buffer named test3820.master_test3820.master for ref type 21! [FIELD_INT id <12884901914> 0:0]
     [java]     at com.goldencode.p2j.pattern.CommonAstSupport$Library.throwException(CommonAstSupport.java:2999)
     [java]     at com.goldencode.expr.CE7060.execute(Unknown Source)
     [java]     at com.goldencode.expr.Expression.execute(Expression.java:391)
     [java]     ... 25 more