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

java.lang.Object
  org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
      org.eclipse.persistence.jpa.jpql.parser.AbstractSelectClause

All Implemented Interfaces:

Expression

Direct Known Subclasses:

SelectClause, SimpleSelectClause

public abstract class AbstractSelectClause
extends AbstractExpression

The SELECT clause denotes the query result. More than one value may be returned from the SELECT clause of a query. The SELECT clause may contain one or more of the following elements: a single range variable or identification variable that ranges over an entity abstract schema type, a single-valued path expression, an aggregate select expression, a constructor expression.

The DISTINCT keyword is used to specify that duplicate values must be eliminated from the query result. If DISTINCT is not specified, duplicate values are not eliminated. Stand-alone identification variables in the SELECT clause may optionally be qualified by the OBJECT operator. The SELECT clause must not use the OBJECT operator to qualify path expressions.

Version:

2.4.2

See Also:

SelectClause, SimpleSelectClause

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

protected

AbstractSelectClause(AbstractExpression parent) Creates a new SelectClause.

Method Summary

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.
CollectionExpression	buildCollectionExpression() Creates a new CollectionExpression that will wrap the single select item.
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	getActualDistinctIdentifier() Returns the actual DISTINCT identifier found in the string representation of the JPQL query, which has the actual case that was used.
java.lang.String	getActualIdentifier() Returns the actual SELECT identifier found in the string representation of the JPQL query, which has the actual case that was used.
Expression	getSelectExpression() Returns the Expression representing the select items.
boolean	hasDistinct() Determines whether the identifier DISTINCT was parsed or not.
boolean	hasSelectExpression() Determines whether the list of select items was parsed.
boolean	hasSpaceAfterDistinct() Determines whether a whitespace was parsed after DISTINCT.
boolean	hasSpaceAfterSelect() Determines whether a whitespace was parsed after SELECT.
protected void	parse(WordParser wordParser, boolean tolerant) Parses the query by starting at the current position, which is part of the given WordParser.
abstract java.lang.String	selectItemBNF() Returns the BNF for the list of select items to parse.
protected boolean	shouldSkipLiteral(AbstractExpression expression) When parsing an invalid or incomplete query, it is possible two literals would be parsed but in some cases, a CollectionExpression should not be created and the parsing should actually stop here.
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, toActualText, toParsedText, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.persistence.jpa.jpql.parser.Expression

accept, getQueryBNF

Constructor Detail

AbstractSelectClause

protected AbstractSelectClause(AbstractExpression parent)

Creates a new SelectClause.

Parameters:

parent - The parent of this expression

Method Detail

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

buildCollectionExpression

public CollectionExpression buildCollectionExpression()

Creates a new CollectionExpression that will wrap the single select item.

Returns:

The single select item represented by a temporary collection

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

getActualDistinctIdentifier

public final java.lang.String getActualDistinctIdentifier()

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

Returns:

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

Since:

2.4

getActualIdentifier

public final java.lang.String getActualIdentifier()

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

Returns:

The SELECT identifier that was actually parsed

getSelectExpression

public final Expression getSelectExpression()

Returns the Expression representing the select items.

Returns:

The expression representing the select items

hasDistinct

public final boolean hasDistinct()

Determines whether the identifier DISTINCT was parsed or not.

Returns:

true if the identifier DISTINCT was parsed; false otherwise

hasSelectExpression

public final boolean hasSelectExpression()

Determines whether the list of select items was parsed.

Returns:

true the list of select items was parsed; false otherwise

hasSpaceAfterDistinct

public final boolean hasSpaceAfterDistinct()

Determines whether a whitespace was parsed after DISTINCT.

Returns:

true if there was a whitespace after DISTINCT; false otherwise

hasSpaceAfterSelect

public final boolean hasSpaceAfterSelect()

Determines whether a whitespace was parsed after SELECT.

Returns:

true if there was a whitespace after SELECT; 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

selectItemBNF

public abstract java.lang.String selectItemBNF()

Returns the BNF for the list of select items to parse.

Returns:

The BNF for the list of select items to parse

shouldSkipLiteral

protected boolean shouldSkipLiteral(AbstractExpression expression)

When parsing an invalid or incomplete query, it is possible two literals would be parsed but in some cases, a CollectionExpression should not be created and the parsing should actually stop here. Example: BETWEEN 10 20, when parsing 20, it should not be parsed as part of the lower bound expression.

Overrides:

shouldSkipLiteral in class AbstractExpression

Parameters:

expression - The Expression that has just been parsed or null

Returns:

true

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