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Inconvenience in Open Cypher ANTLRv4 grammar

The open cypher grammar says

oC_MultiPartQuery
              :  ( ( oC_ReadingClause SP? )* ( oC_UpdatingClause SP? )* oC_With SP? )+ oC_SinglePartQuery ;

However, when using a query like

MATCH (a) WITH a MATCH (b) SET a.prop = 'match 2' WITH a, b MATCH (c) WITH a, b, c MATCH (d) RETURN *

we cannot distinguish, whether the SET part belongs to the seconds MATCH or the first or third one.

My proposed solution to the problem is to change the grammar as following:

oC_MultiPartQuery
              :  ( oC_MultiPartQueryGroup )+ oC_SinglePartQuery ;

oC_MultiPartQueryGroup
              :  ( oC_ReadingClause SP? )* ( oC_UpdatingClause SP? )* oC_With SP? ;

Demo

This project contains a Spring application which takes the ANTLRv4 grammar of open cypher from https://s3.amazonaws.com/artifacts.opencypher.org/M18/Cypher.g4, generates a visitor from it on building of the project and then parses the example from above, displaying the content of the resulting oC_ReadingClause and oC_UpdatingClause contexts.

Running

To build and run the project, have Maven installed and run (for Linux):

mvn package
java -jar target/OpenCypherExperiments-0.0.1-SNAPSHOT.jar

The relevant output should be:

Enter visitOC_MultiPartQuery
Whole context: MATCH (a) WITH a MATCH (b) SET a.prop = 'match 2' WITH a, b MATCH (c) WITH a, b, c MATCH (d) RETURN *
OC_ReadingClause:
        MATCH (a)
        MATCH (b)
        MATCH (c)
OC_UpdatingClause:
        SET a.prop = 'match 2'
To which OC_ReadingClause does this OC_UpdatingClause belong?
Leave visitOC_MultiPartQuery

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  • Java 94.5%
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