org.apache.chemistry.opencmis.jcr.query

Class ParseTreeWalker<T>

java.lang.Object

org.apache.chemistry.opencmis.jcr.query.ParseTreeWalker<T>

Type Parameters:

T - type of the result determined by the Evaluator used.

All Implemented Interfaces:

PredicateWalkerBase

public class ParseTreeWalker<T>
extends Object
implements PredicateWalkerBase

This implementation of PredicateWalkerBase traverses the parse tree of a CMIS query. It uses an Evaluator to accumulate the result of the traversal. Evaluator has a corresponding method for each node type in the parse tree. ParseTreeWalker calls these methods while traversing the parse tree passing an Evaluator for each of the corresponding operation's arguments.
The walkPredicate(Tree) serves as entry point for traversing a parse tree. After successful traversal, the result is obtained from the getResult() method.

Constructor Summary

Constructors

Constructor and Description
ParseTreeWalker(Evaluator<T> evaluator) Create a new instance for traversing CMIS query parse trees.

Method Summary

Methods

Modifier and Type	Method and Description
T	getResult() Retrieve the result of a successful traversal.
protected T	walkOtherExpr(Evaluator<?> evaluator, org.antlr.runtime.tree.Tree node) For extensibility.
protected T	walkOtherPredicate(Evaluator<?> evaluator, org.antlr.runtime.tree.Tree node) For extensibility.
Boolean	walkPredicate(org.antlr.runtime.tree.Tree node)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ParseTreeWalker

public ParseTreeWalker(Evaluator<T> evaluator)

Create a new instance for traversing CMIS query parse trees.

Parameters:

evaluator - Evaluator for evaluating the nodes of the parse tree

Method Detail

getResult

public T getResult()

Retrieve the result of a successful traversal.

Returns:

result of traversal or null if either not yet traversed, an error occurred on traversal or the query has an empty where clause.

walkPredicate

public Boolean walkPredicate(org.antlr.runtime.tree.Tree node)

Specified by:

walkPredicate in interface PredicateWalkerBase

walkOtherExpr

protected T walkOtherExpr(Evaluator<?> evaluator,
              org.antlr.runtime.tree.Tree node)

For extensibility.

walkOtherPredicate

protected T walkOtherPredicate(Evaluator<?> evaluator,
                   org.antlr.runtime.tree.Tree node)

For extensibility.