com.bigdata.rdf.sparql.ast.optimizers

Class ASTSetValueExpressionsOptimizer

java.lang.Object

com.bigdata.rdf.sparql.ast.optimizers.ASTSetValueExpressionsOptimizer

All Implemented Interfaces:

IASTOptimizer

public class ASTSetValueExpressionsOptimizer
extends Object
implements IASTOptimizer

Visit all the value expression nodes and convert them into value expressions using AST2BOpUtility#toVE(String, IValueExpressionNode). If a value expression can be evaluated to a constant, then it is replaced by that constant.

Note: toVE() is a NOP for VarNodes and ConstantNodes. In fact, in only acts on the value expression of an AssignmentNode and FunctionNodes.

Note: This has to be done carefully to avoid a side-effect during traversal.

Version:

$Id: ASTSetValueExpressionsOptimizer.java 5193 2011-09-15 14:18:56Z thompsonbry $

Author:

Bryan Thompson

Constructor Summary

Constructors

Constructor and Description
ASTSetValueExpressionsOptimizer()

Method Summary

Methods

Modifier and Type	Method and Description
QueryNodeWithBindingSet	optimize(AST2BOpContext context, QueryNodeWithBindingSet input) Optimize the AST.

Methods inherited from class java.lang.Object

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

Constructor Detail

ASTSetValueExpressionsOptimizer

public ASTSetValueExpressionsOptimizer()

Method Detail

optimize

public QueryNodeWithBindingSet optimize(AST2BOpContext context,
                               QueryNodeWithBindingSet input)

Description copied from interface: IASTOptimizer

Optimize the AST.

Specified by:

optimize in interface IASTOptimizer

Parameters:

context - The evaluation context.

input - The input to the optimizer, consisting of a queryNode and input binding set.

Returns:

An instance of type QueryNodeWithBindingSet.