package MyEditor.xaspect.xpath;
import edu.neu.ccs.demeter.dj.*;
import java.util.*;

Main = <s> String.
public XPathExp =XPath.
public XPath: NormalXPath|SetCompoundXPath.
public NormalXPath = SimpleXPath [OrSimpleXPaths].
public OrSimpleXPaths ~ "|" SimpleXPath {"|" SimpleXPath}.

public SimpleXPath = NList(OneSegmentAxisPath).
public OneSegmentAxisPath =AxisOp Node.

public Node:SingleNode|Wildcard.
public SingleNode=Ident.
public Wildcard="*".

public AxisOp: Descendant|Child.
public Descendant = "/+/".
public Child ="/".

public SetCompoundXPath= SetOp "(" <t1>SetTerm "," <t2> SetTerm ")" .
public SetTerm: XPath | XPathRefName.
public CompoundXPath= SetCompoundXPath.

public SetOp: Intersect|Complement|Union.
public Intersect="intersect".
public Complement="except".
public Union="union".

public XPathRefName=Ident.

public List(S) ~ {S}.
public NList(S) ~ S{S}.
public CList(S) ~ "(" {"," S} ")".