Package org.apache.iceberg.expressions

Class ExpressionVisitors

java.lang.Object

org.apache.iceberg.expressions.ExpressionVisitors

public class ExpressionVisitors
extends java.lang.Object

Utils for traversing expressions.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ExpressionVisitors.BoundExpressionVisitor<R>
static class	ExpressionVisitors.BoundVisitor<R>
static class	ExpressionVisitors.CustomOrderExpressionVisitor<R>
static class	ExpressionVisitors.ExpressionVisitor<R>

Method Summary

Modifier and Type	Method	Description
static <R> R	visit(Expression expr, ExpressionVisitors.CustomOrderExpressionVisitor<R> visitor)	Traverses the given expression with a visitor.
static <R> R	visit(Expression expr, ExpressionVisitors.ExpressionVisitor<R> visitor)	Traverses the given expression with a visitor.
static java.lang.Boolean	visitEvaluator(Expression expr, ExpressionVisitors.ExpressionVisitor<java.lang.Boolean> visitor)	Traverses the given expression with a visitor.

Methods inherited from class java.lang.Object

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

Method Detail

visit

public static <R> R visit(Expression expr,
                          ExpressionVisitors.ExpressionVisitor<R> visitor)

Traverses the given expression with a visitor.

The visitor will be called to handle each node in the expression tree in postfix order. Result values produced by child nodes are passed when parent nodes are handled.

Type Parameters:

R - the return type produced by the expression visitor

Parameters:

expr - an expression to traverse

visitor - a visitor that will be called to handle each node in the expression tree

Returns:

the value returned by the visitor for the root expression node

visitEvaluator

public static java.lang.Boolean visitEvaluator(Expression expr,
                                               ExpressionVisitors.ExpressionVisitor<java.lang.Boolean> visitor)

Traverses the given expression with a visitor.

The visitor will be called to handle only nodes required for determining result in the expression tree in postfix order. Result values produced by child nodes are passed when parent nodes are handled.

Parameters:

expr - an expression to traverse

visitor - a visitor that will be called to handle each node in the expression tree

Returns:

the value returned by the visitor for the root expression node

visit

public static <R> R visit(Expression expr,
                          ExpressionVisitors.CustomOrderExpressionVisitor<R> visitor)

Traverses the given expression with a visitor.

This passes a Supplier to each non-leaf visitor method. The supplier returns the result of traversing child expressions. Getting the result of the supplier allows traversing the expression in the desired order.

Type Parameters:

R - the return type produced by the expression visitor

Parameters:

expr - an expression to traverse

visitor - a visitor that will be called to handle each node in the expression tree

Returns:

the value returned by the visitor for the root expression node