QueryTreeWalker (Google App Engine API for Java)


Class QueryTreeWalker<T extends QueryTreeContext<T>>

  • java.lang.Object
    • com.google.appengine.api.search.query.QueryTreeWalker<T>
  • Type Parameters:
    T - the context used by the visitor

    public class QueryTreeWalker<T extends QueryTreeContext<T>>
    extends java.lang.Object
    The walking of the query tree. This class takes care of visiting a tree resulting from parsing a query. As it traverses the tree it calls appropriate methods of the visitor, set at the construction time. The class uses a depth-first search, visiting all children of a node, before visiting the node. The visit is done by calling an appropriate method of the visitor. Typical code should match the following pattern:
     class MyVisitor implements QueryTreeVisitor {
     class MyContext extends QueryTreeContext<MyContext> {
       protected MyContext newChildContext() {
         return new MyContext();
     MyContext context = new MyContext();
     QueryTreeWalker<MyContext> walker = new QueryTreeWalker<MyContext>(new MyVisitor());
     Tree root = parser.query(queryStr);
     walker.walk(root, context);
     // retrieve whatever information you need from context
    • Constructor Summary

      Constructor and Description
      QueryTreeWalker(QueryTreeVisitor<T> visitor)
      Creates a new query walker that calls the given visitor.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method and Description
      static Tree simplify(Tree tree) 
      void walk(Tree tree, T context) 
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • QueryTreeWalker

        public QueryTreeWalker(QueryTreeVisitor<T> visitor)
        Creates a new query walker that calls the given visitor.
        visitor - the visitor to be called by this walker
    • Method Detail

      • walk

        public void walk(Tree tree,
                         T context)
                  throws QueryTreeException
        tree - the tree to be walked
        context - the context in which the tree is walked
      • simplify

        public static Tree simplify(Tree tree)

Monitor your resources on the go

Get the Google Cloud Console app to help you manage your projects.

Send feedback about...

App Engine standard environment for Java