org.eclipse.persistence.jpa.internal.jpql.parser

Class NullExpression

java.lang.Object

org.eclipse.persistence.jpa.internal.jpql.parser.StringExpression

org.eclipse.persistence.jpa.internal.jpql.parser.AbstractExpression

org.eclipse.persistence.jpa.internal.jpql.parser.NullExpression

All Implemented Interfaces:

Expression

public final class NullExpression
extends AbstractExpression

A null Expression is used instead of a true null, allowing operations to be performed without doing a null check.

Since:

2.3

Version:

2.3

Author:

Pascal Filion

Field Summary

Fields inherited from class org.eclipse.persistence.jpa.internal.jpql.parser.AbstractExpression

COMMA, DOT, DOUBLE_QUOTE, LEFT_CURLY_BRACKET, LEFT_PARENTHESIS, NOT_DEFINED, RIGHT_CURLY_BRACKET, RIGHT_PARENTHESIS, SINGLE_QUOTE, SPACE, UNDERSCORE

Fields inherited from interface org.eclipse.persistence.jpa.internal.jpql.parser.Expression

ABS, ALL, AND, ANY, AS, ASC, AVG, BETWEEN, BIT_LENGTH, BOTH, CASE, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, CONCAT, COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DELETE, DELETE_FROM, DESC, DIFFERENT, DISTINCT, DIVISION, ELSE, EMPTY, END, ENTRY, EQUAL, ESCAPE, EXISTS, FALSE, FETCH, FROM, FUNC, GREATER_THAN, GREATER_THAN_OR_EQUAL, GROUP_BY, HAVING, IN, INDEX, INNER, INNER_JOIN, INNER_JOIN_FETCH, IS, IS_EMPTY, IS_NOT_EMPTY, IS_NOT_NULL, IS_NULL, JOIN, JOIN_FETCH, KEY, LEADING, LEFT, LEFT_JOIN, LEFT_JOIN_FETCH, LEFT_OUTER_JOIN, LEFT_OUTER_JOIN_FETCH, LENGTH, LIKE, LOCATE, LOWER, LOWER_THAN, LOWER_THAN_OR_EQUAL, MAX, MEMBER, MEMBER_OF, MIN, MINUS, MOD, MULTIPLICATION, NAMED_PARAMETER, NEW, NOT, NOT_BETWEEN, NOT_EXISTS, NOT_IN, NOT_LIKE, NOT_MEMBER, NOT_MEMBER_OF, NULL, NULLIF, OBJECT, OF, OR, ORDER_BY, OUTER, PLUS, POSITION, POSITIONAL_PARAMETER, QUOTE, SELECT, SET, SIZE, SOME, SQRT, SUBSTRING, SUM, THEN, TRAILING, TREAT, TRIM, TRUE, TYPE, UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE

Method Summary

Methods

Modifier and Type	Method and Description
void	accept(ExpressionVisitor visitor) Visits this Expression by the given visitor.
void	acceptChildren(ExpressionVisitor visitor) Visits the children of this Expression.
JPQLQueryBNF	findQueryBNF(AbstractExpression expression) Retrieves the JPQLQueryBNF that was used to parse the given Expression.
JPQLQueryBNF	getQueryBNF() Returns the BNF of this Expression.
boolean	isNull() Determines whether this expression is a null Expression or any other subclass.

Methods inherited from class org.eclipse.persistence.jpa.internal.jpql.parser.AbstractExpression

children, getChildren, getParent, getRoot, identifierRole, identifiers, identifierVersion, isAncestor, isIdentifier, isVirtual, orderedChildren, queryBNF, toActualText, toParsedText, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

accept

public void accept(ExpressionVisitor visitor)

Visits this Expression by the given visitor.

Parameters:

visitor - The visitor to visit this object

acceptChildren

public void acceptChildren(ExpressionVisitor visitor)

Visits the children of this Expression. This method can be used to optimize traversing the children since a new list is not created every time Expression.children() or Expression.getChildren() is called.

This does not traverse the Expression sub-hierarchy, use an subclass of AbstractTraverseChildrenVisitor in order to traverse the entire sub-hierarchy.

Parameters:

visitor - The visitor to visit the children of this object.

findQueryBNF

public JPQLQueryBNF findQueryBNF(AbstractExpression expression)

Retrieves the JPQLQueryBNF that was used to parse the given Expression.

Overrides:

findQueryBNF in class AbstractExpression

Parameters:

expression - The expression for which its BNF is needed

Returns:

The JPQLQueryBNF that was used to parse the given expression

getQueryBNF

public JPQLQueryBNF getQueryBNF()

Returns the BNF of this Expression.

Specified by:

getQueryBNF in class AbstractExpression

Returns:

The JPQLQueryBNF, which represents the grammar of this Expression

isNull

public boolean isNull()

Determines whether this expression is a null Expression or any other subclass.

Returns:

false by default