About parsing to AST

[卓鑫雲]

Dear all,

I am a postgraduate student and my project is to implement the cypher to my own engine. I read the code for several days and still have some questions. Hope to get some help. Thanks very much. 

I run the function like this, and then get the result: 

Query(SingleQuery(List(Match(false,Pattern(List(EveryPath(RelationshipChain(NodePattern(Some(Variable(movie)),Some(Leaf(LabelName(Movie))),None,None),RelationshipPattern(None,Some(Leaf(RelTypeName(ACTED_IN))),None,None,None,INCOMING),NodePattern(Some(Variable(actor)),Some(Leaf(LabelName(Actor))),None,None))))),List(),None))))

Is this the final AST? I have this question because The type of To.statement is ast.statement, not a tree.

To know the meaning of the result, I find the definition of Match. But I don't know the meaning of optional, hints, position.  

[Arne Fischereit]

Hi again,

Thank you for your interest in the Cypher front end.

Regarding your questions:

• Yes, the result of `statement()` is a `Statement` which is the type of the root node in our AST. All nodes in the AST extend the trait `ASTNode`. Those are the nodes in the AST.
  
• The documentation on Cypher should give you ample information to start with on what an optional match or a hint is.

I hope that gave you some clarification for you immediate issues.

Cheers,

Arne

[卓鑫雲]

Thank you so much, I will see more about that.

[卓鑫雲]

Hi Arne,

Can I ask after I get the statement, how can I get the parameter within this statement? Do I need to split the statement by myself? OR I think after parsing, there will be a node "Match" and also other objects generated. Then if I can get that, I can get the value by for example, Match.option. I guess the function dup(children) is related but I don't know how to use it, since it needs a parameter children.

Kind regard,

zhuo