org.eclipse.persistence.jpa.jpql.parser

Class IdentificationVariable

java.lang.Object

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

org.eclipse.persistence.jpa.jpql.parser.IdentificationVariable

All Implemented Interfaces:

Expression

public final class IdentificationVariable
extends AbstractExpression

An identification variable is a valid identifier declared in the FROM clause of a query.

Requirements:

• All identification variables must be declared in the FROM clause. Identification variables cannot be declared in other clauses.
• An identification variable must not be a reserved identifier or have the same name as any entity in the same persistence unit.
• Identification variables are case insensitive.
• An identification variable evaluates to a value of the type of the expression used in declaring the variable.

An identification variable can range over an entity, embeddable, or basic abstract schema type. An identification variable designates an instance of an abstract schema type or an element of a collection of abstract schema type instances.

Note that for identification variables referring to an instance of an association or collection represented as a Map, the identification variable is of the abstract schema type of the map value.

An identification variable always designates a reference to a single value. It is declared in one of three ways:

• In a range variable declaration;
• In a join clause;
• In a collection member declaration.

The identification variable declarations are evaluated from left to right in the FROM clause, and an identification variable declaration can use the result of a preceding identification variable declaration of the query string.

All identification variables used in the SELECT, WHERE, ORDER BY, GROUP BY, or HAVING clause of a SELECT or DELETE statement must be declared in the FROM clause. The identification variables used in the WHERE clause of an UPDATE statement must be declared in the UPDATE clause.

An identification variable is scoped to the query (or subquery) in which it is defined and is also visible to any subqueries within that query scope that do not define an identification variable of the same name.

Version:

2.4

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, 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 and Description
IdentificationVariable(AbstractExpression parent, java.lang.String identificationVariable) Creates a new IdentificationVariable.
IdentificationVariable(AbstractExpression parent, java.lang.String identificationVariable, boolean virtual) Creates a new IdentificationVariable.

Method Summary

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.
protected void	addOrderedChildrenTo(java.util.List<Expression> children) Adds the children of this AbstractExpression to the given list.
JPQLQueryBNF	getQueryBNF() Returns the BNF of this Expression.
StateFieldPathExpression	getStateFieldPathExpression() Returns the actual representation of the parsed information.
java.lang.String	getText() Returns the encapsulated text of this AbstractExpression, which can be used in various ways, it can be a keyword, a literal, etc.
java.lang.String	getVariableName() Returns the identification variable, which has been changed to be upper case.
boolean	isVirtual() Determines whether this AbstractExpression is virtual, meaning it's not part of the query but is required for proper navigability.
protected void	parse(WordParser wordParser, boolean tolerant) Parses the query by starting at the current position, which is part of the given WordParser.
void	setVirtualIdentificationVariable(java.lang.String variableName) Sets a virtual identification variable because the abstract schema name was parsed without one.
java.lang.String	toParsedText() Returns a string representation of this Expression and its children.
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, buildExpressionFromFallingBack, buildNullExpression, buildStringExpression, buildStringExpression, buildUnknownExpression, calculatePosition, children, findFallBackExpressionFactory, findQueryBNF, getExpressionFactory, getExpressionRegistry, getGrammar, getIdentifierVersion, getJPAVersion, getLength, getOffset, getParent, getQueryBNF, getRoot, handleAggregate, handleCollection, isAncestor, isIdentifier, isNull, isParsingComplete, isTolerant, isUnknown, orderedChildren, parse, parseUsingExpressionFactory, populatePosition, rebuildActualText, rebuildParsedText, setParent, setText, shouldParseWithFactoryFirst, shouldSkipLiteral, toActualText, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

IdentificationVariable

public IdentificationVariable(AbstractExpression parent,
                              java.lang.String identificationVariable)

Creates a new IdentificationVariable.

Parameters:

parent - The parent of this expression

identificationVariable - The actual identification variable

IdentificationVariable

public IdentificationVariable(AbstractExpression parent,
                              java.lang.String identificationVariable,
                              boolean virtual)

Creates a new IdentificationVariable.

Parameters:

parent - The parent of this expression

identificationVariable - The actual identification variable

virtual - Determines whether this identification variable is virtual, meaning it's not part of the query but is required for proper navigability

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.

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

getQueryBNF

public JPQLQueryBNF getQueryBNF()

Returns the BNF of this Expression.

Returns:

The JPQLQueryBNF, which represents the grammar of this Expression

getStateFieldPathExpression

public StateFieldPathExpression getStateFieldPathExpression()

Returns the actual representation of the parsed information. This method should only be called if isVirtual() returns true. This is valid in an UPDATE and DELETE queries where the identification variable is not specified.

Returns:

The path expression that is qualified by the virtual identification variable

Throws:

java.lang.IllegalAccessError - If this expression does not have a virtual identification variable

getText

public java.lang.String getText()

Returns the encapsulated text of this AbstractExpression, which can be used in various ways, it can be a keyword, a literal, etc.

Overrides:

getText in class AbstractExpression

Returns:

Either the JPQL identifier for this AbstractExpression, the literal it encapsulates or an empty string

getVariableName

public java.lang.String getVariableName()

Returns the identification variable, which has been changed to be upper case.

Returns:

The uppercase version of the identification variable

Since:

2.4

isVirtual

public boolean isVirtual()

Determines whether this AbstractExpression is virtual, meaning it's not part of the query but is required for proper navigability.

Overrides:

isVirtual in class AbstractExpression

Returns:

true if this AbstractExpression was virtually created to fully qualify path expression; false if it was parsed

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

setVirtualIdentificationVariable

public void setVirtualIdentificationVariable(java.lang.String variableName)

Sets a virtual identification variable because the abstract schema name was parsed without one. This is valid in an UPDATE and DELETE queries. This internally transforms the what was thought to be an identification variable to a path expression.

Parameters:

variableName - The identification variable that was generated to identify the "root" object

toParsedText

public java.lang.String toParsedText()

Returns a string representation of this Expression and its children. The expression should contain whitespace even if the beautified version would not have any. For instance, "SELECT e " should be returned where Expression.toParsedText() would return "SELECT e".

Specified by:

toParsedText in interface Expression

Overrides:

toParsedText in class AbstractExpression

Returns:

The string representation of this Expression

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