Package org.eclipse.persistence.jpa.jpql.parser

Class AsOfClause

java.lang.Object

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

org.eclipse.persistence.jpa.jpql.parser.AsOfClause

All Implemented Interfaces:

Expression

public final class AsOfClause
extends AbstractExpression

An AS OF clause is part of a flashback query, which provides ways to view past states of database objects, or to return database objects to a previous state, without using traditional point-in-time recovery.

Specify AS OF to retrieve the single version of the rows returned by the query at a particular change number (SCN) or timestamp. If you specify SCN, then the expression must evaluate to a number. If you specify TIMESTAMP, then the expression must evaluate to a timestamp value. Oracle Database returns rows as they existed at the specified system change number or time.

BNF: asof_clause ::= AS OF { SCN | TIMESTAMP } scalar_expression

Version:

2.5

Author:

Pascal Filion

Since:

2.5

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, AS_OF, ASC, AVG, BETWEEN, BIT_LENGTH, BOTH, CASE, CAST, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, COLUMN, CONCAT, CONNECT_BY, 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, FIRST, 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, LAST, 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, NULLS_FIRST, NULLS_LAST, OBJECT, OF, ON, OPERATOR, OR, ORDER_BY, ORDER_SIBLINGS_BY, OUTER, PLUS, POSITION, POSITIONAL_PARAMETER, QUOTE, REGEXP, SCN, SELECT, SET, SIZE, SOME, SQL, SQRT, START_WITH, SUBSTRING, SUM, TABLE, THEN, TIMESTAMP, TRAILING, TREAT, TRIM, TRUE, TYPE, UNION, UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE

Constructor Summary

Constructors

Constructor	Description
AsOfClause(AbstractExpression parent)	Creates a new AsOfClause.

Method Summary

Modifier and Type	Method	Description
void	accept(ExpressionVisitor visitor)	Visits this Expression by the given visitor.
void	acceptChildren(ExpressionVisitor visitor)	Visits the children of this Expression.
protected void	addChildrenTo(java.util.Collection<Expression> children)	Adds the children of this AbstractExpression to the given collection.
protected void	addOrderedChildrenTo(java.util.List<Expression> children)	Adds the children of this AbstractExpression to the given list.
JPQLQueryBNF	findQueryBNF(Expression expression)	Retrieves the JPQLQueryBNF that represents the fragment of this Expression that was used when parsing the given Expression.
java.lang.String	getActualIdentifier()	Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.
java.lang.String	getActualScnIdentifier()	Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.
java.lang.String	getActualTimestampIdentifier()	Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.
Expression	getExpression()	Returns the Expression representing the timestamp or change number.
JPQLQueryBNF	getQueryBNF()	Returns the BNF of this Expression.
boolean	hasExpression()	Determines whether the Expression representing the timestamp or change number was parsed or not.
boolean	hasScn()	Determines whether the identifier SCN was part of the query.
boolean	hasSpaceAfterCategory()	Determines whether a whitespace was found after either SCN or TIMESTAMP.
boolean	hasSpaceAfterIdentifier()	Determines whether a whitespace was found after AS OF.
boolean	hasTimestamp()	Determines whether the identifier TIMESTAMP was part of the query.
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, buildExpressionFromFallingBack, buildNullExpression, buildStringExpression, buildStringExpression, buildUnknownExpression, calculatePosition, children, findFallBackExpressionFactory, getExpressionFactory, getExpressionRegistry, getGrammar, getIdentifierVersion, getJPAVersion, getLength, getOffset, getParent, getQueryBNF, getRoot, getText, handleAggregate, handleCollection, isAncestor, isIdentifier, isNull, 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

AsOfClause

public AsOfClause(AbstractExpression parent)

Creates a new AsOfClause.

Parameters:

parent - The parent of this expression

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.

addChildrenTo

protected void addChildrenTo(java.util.Collection<Expression> children)

Adds the children of this AbstractExpression to the given collection.

Overrides:

addChildrenTo in class AbstractExpression

Parameters:

children - The collection used to store the children

addOrderedChildrenTo

protected void addOrderedChildrenTo(java.util.List<Expression> children)

Adds the children of this AbstractExpression to the given list.

Overrides:

addOrderedChildrenTo in class AbstractExpression

Parameters:

children - The list used to store the string representation of this AbstractExpression

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

getActualIdentifier

public java.lang.String getActualIdentifier()

Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.

Returns:

The AS OF identifier that was actually parsed

getActualScnIdentifier

public java.lang.String getActualScnIdentifier()

Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.

Returns:

The SCN identifier that was actually parsed, or an empty string if it was not parsed

getActualTimestampIdentifier

public java.lang.String getActualTimestampIdentifier()

Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.

Returns:

The TIMESTAMP identifier that was actually parsed, or an empty string if it was not parsed

getExpression

public Expression getExpression()

Returns the Expression representing the timestamp or change number.

Returns:

The Expression that was parsed representing the timestamp or change number

getQueryBNF

public JPQLQueryBNF getQueryBNF()

Returns the BNF of this Expression.

Returns:

The JPQLQueryBNF, which represents the grammar of this Expression

hasExpression

public boolean hasExpression()

Determines whether the Expression representing the timestamp or change number was parsed or not.

Returns:

true if the timestamp or change number was parsed; false otherwise

hasScn

public boolean hasScn()

Determines whether the identifier SCN was part of the query.

Returns:

true if the identifier SCN was parsed; false otherwise

hasSpaceAfterCategory

public boolean hasSpaceAfterCategory()

Determines whether a whitespace was found after either SCN or TIMESTAMP.

Returns:

true if there was a whitespace after SCN or TIMESTAMP; false otherwise

hasSpaceAfterIdentifier

public boolean hasSpaceAfterIdentifier()

Determines whether a whitespace was found after AS OF.

Returns:

true if there was a whitespace after AS OF; false otherwise

hasTimestamp

public boolean hasTimestamp()

Determines whether the identifier TIMESTAMP was part of the query.

Returns:

true if the identifier TIMESTAMP was parsed; false otherwise

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