com.mapr.ojai.store.impl

Class ExpressionPruner

java.lang.Object

com.mapr.ojai.store.impl.ExpressionVisitor

com.mapr.ojai.store.impl.ExpressionPruner

public class ExpressionPruner
extends ExpressionVisitor

An ExpressionVisitor that can be used to create a new expression tree which is pruned of unwanted references. The pruner works from the leaves up, omitting expressions that do not include the set of fields given to the constructor.

Constructor Summary

Constructors

Constructor and Description
ExpressionPruner(java.util.Set<org.ojai.FieldPath> fieldSet) Constructor.

Method Summary

Modifier and Type	Method and Description
Expression	getPrunedExpression() Get the result of the expression pruning.
void	visitField(FieldExpression fieldExpr) Visit a FieldExpression.
void	visitLiteral(LiteralExpression literalExpr) Visit a LiteralExpression.
void	visitNary(NaryOperator naryOp) Visit a NaryOperator.
void	visitRelational(RelationalOperator relOp) Visit a RelationalOperator.
void	visitUnary(UnaryOperator unaryOp) Visit a UnaryOperator.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionPruner

public ExpressionPruner(java.util.Set<org.ojai.FieldPath> fieldSet)

Constructor.

Parameters:

fieldSet - the set of fields whose references and containing expressions we want to keep.

Method Detail

getPrunedExpression

public Expression getPrunedExpression()

Get the result of the expression pruning.

Returns:

the pruned expression; may be null

visitField

public void visitField(FieldExpression fieldExpr)

Description copied from class: ExpressionVisitor

Visit a FieldExpression.

Overrides:

visitField in class ExpressionVisitor

Parameters:

fieldExpr - the field expression

visitLiteral

public void visitLiteral(LiteralExpression literalExpr)

Description copied from class: ExpressionVisitor

Visit a LiteralExpression.

Overrides:

visitLiteral in class ExpressionVisitor

Parameters:

literalExpr - the literal expression

visitNary

public void visitNary(NaryOperator naryOp)

Description copied from class: ExpressionVisitor

Visit a NaryOperator.

Overrides:

visitNary in class ExpressionVisitor

Parameters:

naryOp - the n-ary operator

visitRelational

public void visitRelational(RelationalOperator relOp)

Description copied from class: ExpressionVisitor

Visit a RelationalOperator. The default behavior is to call ExpressionVisitor.visitNary(NaryOperator). This only needs to be overriden if relational operators need different treatment.

Overrides:

visitRelational in class ExpressionVisitor

Parameters:

relOp - the relational operator

visitUnary

public void visitUnary(UnaryOperator unaryOp)

Description copied from class: ExpressionVisitor

Visit a UnaryOperator.

Overrides:

visitUnary in class ExpressionVisitor

Parameters:

unaryOp - the unary operator