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

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.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.

Since:

2.3

Version:

2.3

Author:

Pascal Filion

Field Summary

private StateFieldPathExpression	stateFieldPathExpression The virtual state field path expression having
private boolean	virtual Determines whether this identification variable is virtual, meaning it's not part of the query but is required for proper navigability.

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

Constructor Summary

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

void	accept(ExpressionVisitor visitor) Visits this Expression by the given visitor.
void	acceptChildren(ExpressionVisitor visitor) Visits the children of this Expression.
(package private) void	addOrderedChildrenTo(java.util.List<StringExpression> children) Adds the StringExpressions representing this Expression.
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.
boolean	isVirtual() Determines whether this identification variable is virtual, meaning it's not part of the query but is required for proper navigability.
(package private) void	parse(WordParser wordParser, boolean tolerant) Parses the query by starting at the current position, which is part of the given WordParser.
(package private) 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 StringExpression and its children.
(package private) void	toParsedText(java.lang.StringBuilder writer, boolean includeVirtual) Generates a string representation of this Expression.

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

addChildrenTo, buildExpressionFromFallingBack, buildNullExpression, buildStringExpression, buildStringExpression, buildUnknownExpression, children, expressionFactory, expressionFactoryForIdentifier, findQueryBNF, getChildren, getJPAVersion, getParent, getRoot, handleAggregate, identifierRole, identifiers, identifiers, identifierVersion, isAncestor, isIdentifier, isNull, isParsingComplete, isTolerant, isUnknown, orderedChildren, parse, parseSingleExpression, populatePosition, queryBNF, readdLeadingSpaces, 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

Field Detail

stateFieldPathExpression

private StateFieldPathExpression stateFieldPathExpression

The virtual state field path expression having

virtual

private boolean virtual

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

Constructor Detail

IdentificationVariable

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

Creates a new IdentificationVariable.

Parameters:

parent - The parent of this expression

identificationVariable - The actual identification variable

IdentificationVariable

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 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.

addOrderedChildrenTo

void addOrderedChildrenTo(java.util.List<StringExpression> children)

Adds the StringExpressions representing this Expression.

Overrides:

addOrderedChildrenTo in class AbstractExpression

Parameters:

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

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:

The full text of this expression or a keyword, or only what this expression encapsulates

isVirtual

public boolean isVirtual()

Determines whether this identification variable 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 identification variable was virtually created to fully qualify path expression; false if it was parsed

parse

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

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 abstract schema name

toParsedText

public java.lang.String toParsedText()

Returns a string representation of this StringExpression 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#toText() would return "SELECT e".

Specified by:

toParsedText in interface Expression

Overrides:

toParsedText in class AbstractExpression

Returns:

The string representation of this StringExpression

toParsedText

void toParsedText(java.lang.StringBuilder writer,
                  boolean includeVirtual)

Generates a string representation of this Expression.

Specified by:

toParsedText in class AbstractExpression

Parameters:

writer - The buffer used to append this Expression's string representation

includeVirtual - Determines whether to include any characters that are considered virtual, i.e. that was parsed when the query is incomplete and is needed for functionality like content assist

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