EclipseLink 2.4.2, build 'v20130514-5956486' API Reference

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

java.lang.Object
  extended by org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
      extended by org.eclipse.persistence.jpa.jpql.parser.NullExpression
All Implemented Interfaces:
Expression

public final class NullExpression
extends AbstractExpression

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

Version:
2.4.2
Author:
Pascal Filion
Since:
2.3

Field Summary
 
Fields inherited from class org.eclipse.persistence.jpa.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.jpql.parser.Expression
ABS, ALL, AND, ANY, AS, ASC, AVG, BETWEEN, BIT_LENGTH, BOTH, CASE, CAST, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, COLUMN, CONCAT, COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DELETE, DELETE_FROM, DESC, DIFFERENT, DISTINCT, DIVISION, ELSE, EMPTY, END, ENTRY, EQUAL, ESCAPE, EXCEPT, EXISTS, EXTRACT, FALSE, FETCH, FROM, FUNC, FUNCTION, GREATER_THAN, GREATER_THAN_OR_EQUAL, GROUP_BY, HAVING, IN, INDEX, INNER, INNER_JOIN, INNER_JOIN_FETCH, INTERSECT, 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_EQUAL, NOT_EXISTS, NOT_IN, NOT_LIKE, NOT_MEMBER, NOT_MEMBER_OF, NULL, NULLIF, NULLS_FIRST, NULLS_LAST, OBJECT, OF, ON, OPERATOR, OR, ORDER_BY, OUTER, PLUS, POSITION, POSITIONAL_PARAMETER, QUOTE, REGEXP, SELECT, SET, SIZE, SOME, SQL, SQRT, SUBSTRING, SUM, TABLE, THEN, TRAILING, TREAT, TRIM, TRUE, TYPE, UNION, UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE
 
Constructor Summary
NullExpression(AbstractExpression parent)
          Creates a new NullExpression.
 
Method Summary
 void accept(ExpressionVisitor visitor)
          Visits this Expression by the given visitor.
 void acceptChildren(ExpressionVisitor visitor)
          Visits the children of this Expression.
 JPQLQueryBNF findQueryBNF(Expression expression)
          Retrieves the JPQLQueryBNF that represents the fragment of this Expression that was used when parsing 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.
protected  void parse(WordParser wordParser, boolean tolerant)
          Parses the query by starting at the current position, which is part of the given WordParser.
protected  void toParsedText(java.lang.StringBuilder writer, boolean actual)
          Generates a string representation of this Expression, including its children, if it has any.
 
Methods inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
acceptUnknownVisitor, acceptUnknownVisitor, addChildrenTo, addOrderedChildrenTo, buildExpressionFromFallingBack, buildNullExpression, buildStringExpression, buildStringExpression, buildUnknownExpression, calculatePosition, children, findFallBackExpressionFactory, getExpressionFactory, getExpressionRegistry, getGrammar, getIdentifierVersion, getJPAVersion, getLength, getOffset, getParent, getQueryBNF, getRoot, getText, handleAggregate, handleCollection, isAncestor, isIdentifier, isParsingComplete, isTolerant, isUnknown, isVirtual, orderedChildren, parse, parseUsingExpressionFactory, populatePosition, rebuildActualText, rebuildParsedText, setParent, setText, shouldParseWithFactoryFirst, shouldSkipLiteral, toActualText, toParsedText, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

NullExpression

public NullExpression(AbstractExpression parent)
Creates a new NullExpression.

Parameters:
parent - The parent of this NullExpression
Method Detail

accept

public void accept(ExpressionVisitor visitor)
Visits this Expression by the given visitor.

Parameters:
visitor - The ExpressionVisitor 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() is called.

This does not traverse the Expression sub-hierarchy, use a 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(Expression expression)
Retrieves the JPQLQueryBNF that represents the fragment of this Expression that was used when parsing the given Expression.

Specified by:
findQueryBNF in interface Expression
Overrides:
findQueryBNF in class AbstractExpression
Parameters:
expression - The Expression that is a descendant of this one
Returns:
The JPQLQueryBNF that was used to parse the given expression

getQueryBNF

public JPQLQueryBNF getQueryBNF()
Returns the BNF of this Expression.

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.

Overrides:
isNull in class AbstractExpression
Returns:
false by default

parse

protected void parse(WordParser wordParser,
                     boolean tolerant)
Parses the query by starting at the current position, which is part of the given WordParser.

Specified by:
parse in class AbstractExpression
Parameters:
wordParser - The text to parse based on the current position of the cursor
tolerant - Determines whether the parsing system should be tolerant, meaning if it should try to parse invalid or incomplete queries

toParsedText

protected void toParsedText(java.lang.StringBuilder writer,
                            boolean actual)
Generates a string representation of this Expression, including its children, if it has any.

Specified by:
toParsedText in class AbstractExpression
Parameters:
writer - The buffer used to append this Expression's string representation
actual - Determines whether the string representation should represent what was parsed, i.e. include any "virtual" whitespace (such as ending whitespace) and the actual case of the JPQL identifiers

EclipseLink 2.4.2, build 'v20130514-5956486' API Reference