org.eclipse.persistence.jpa.jpql.parser

Class ExpressionRegistry

java.lang.Object

org.eclipse.persistence.jpa.jpql.parser.ExpressionRegistry

public class ExpressionRegistry
extends java.lang.Object

This registry contains the necessary information used by Hermes parser. When parsing a JPQL query, the JPQLGrammar given to JPQLExpression will give access to this registry.

Provisional API: This interface is part of an interim API that is still under development and expected to change significantly before reaching stability. It is available at this early stage to solicit feedback from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken (repeatedly) as the API evolves.

Version:

2.5

See Also:

JPQLGrammar, ExpressionFactory, JPQLQueryBNF

Author:

Pascal Filion

Since:

2.4

Constructor Summary

Constructors

Constructor and Description
ExpressionRegistry() Creates the only instance of ExpressionRegistry.

Method Summary

Modifier and Type	Method and Description
void	addChildBNF(java.lang.String queryBNFId, java.lang.String childQueryBNFId) Adds to the given query BNF a child BNF.
void	addChildFactory(java.lang.String queryBNFId, java.lang.String childExpressionFactoryId) Adds to the given unique identifier of an ExpressionFactory to the given query BNF.
void	addIdentifier(java.lang.String expressionFactoryId, java.lang.String identifier) Adds the given JPQL identifier to this factory.
void	addIdentifiers(java.lang.String expressionFactoryId, java.lang.String... identifiers) Adds the given JPQL identifiers to this factory.
ExpressionFactory	expressionFactoryForIdentifier(java.lang.String identifier) Retrieves the ExpressionFactory that is responsible for creating the Expression object that represents the given JPQL identifier.
ExpressionFactory	getExpressionFactory(java.lang.String expressionFactoryId) Retrieves the registered ExpressionFactory that was registered for the given unique identifier.
IdentifierRole	getIdentifierRole(java.lang.String identifier) Retrieves the IdentifierRole of the given JPQL identifier.
java.util.Set<java.lang.String>	getIdentifiers() Returns the JPQL identifiers that are supported by the JPQL grammar.
java.lang.Iterable<java.lang.String>	getIdentifiers(java.lang.String queryBNFId) Retrieves the JPQL identifiers that are supported by the BNF rule with the given unique identifier.
JPAVersion	getIdentifierVersion(java.lang.String identifier) Retrieves the JPA version in which the identifier was first introduced.
JPQLQueryBNF	getQueryBNF(java.lang.String queryBNFId) Retrieves the BNF object that was registered for the given unique identifier.
protected void	initialize() Instantiates the only instance of various API used by the parser.
boolean	isIdentifier(java.lang.String text) Determines if the given word is a JPQL identifier.
void	registerBNF(JPQLQueryBNF queryBNF) Registers the given JPQLQueryBNF.
void	registerFactory(ExpressionFactory expressionFactory) Registers the given ExpressionFactory by storing it for all its identifiers.
void	registerIdentifierRole(java.lang.String identifier, IdentifierRole role) Registers the IdentifierRole for the given JPQL identifier.
void	registerIdentifierVersion(java.lang.String identifier, JPAVersion version) Registers the JPAVersion for which the given JPQL identifier was defined.
void	setFallbackBNFId(java.lang.String queryBNFId, java.lang.String fallbackBNFId) When parsing the query and no JPQLQueryBNFs can help to parse the query, then it will fall back on the given one.
void	setFallbackExpressionFactoryId(java.lang.String queryBNFId, java.lang.String fallbackExpressionFactoryId) Sets the unique identifier of the ExpressionFactory to use when the fall back BNF ID is not null.
void	setHandleCollection(java.lang.String queryBNFId, boolean handleCollection) Determines whether the Expression handles a collection of sub-expressions that are separated by commas.
void	setHandleNestedArray(java.lang.String queryBNFId, boolean handleNestedArray) Sets whether the BNF with the given ID supports nested array or not.
void	setHandleSubExpression(java.lang.String queryBNFId, boolean handleSubExpression) Sets whether the query BNF with the given ID handles parsing a sub-expression, i.e. parsing an expression encapsulated by parenthesis.
void	unregisterBNF(JPQLQueryBNF queryBNF) Unregisters the given JPQLQueryBNF.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionRegistry

public ExpressionRegistry()

Creates the only instance of ExpressionRegistry.

Method Detail

addChildBNF

public void addChildBNF(java.lang.String queryBNFId,
                        java.lang.String childQueryBNFId)

Adds to the given query BNF a child BNF.

Parameters:

queryBNFId - The unique identifier of the parent BNF to add a child BNF

childQueryBNFId - The unique identifier of the child to add to the parent BNF

Throws:

java.lang.NullPointerException - The JPQLQueryBNF identified by the given ID does not exist

addChildFactory

public void addChildFactory(java.lang.String queryBNFId,
                            java.lang.String childExpressionFactoryId)

Adds to the given unique identifier of an ExpressionFactory to the given query BNF.

Parameters:

queryBNFId - The unique identifier of the parent BNF

childExpressionFactoryId - The unique identifier of the ExpressionFactory to add to the given query BNF

Throws:

java.lang.NullPointerException - The JPQLQueryBNF identified by the given ID does not exist

addIdentifier

public void addIdentifier(java.lang.String expressionFactoryId,
                          java.lang.String identifier)

Adds the given JPQL identifier to this factory.

Parameters:

expressionFactoryId - The unique identifier of the ExpressionFactory to add more JPQL identifiers

identifier - The JPQL identifier this factory will parse

addIdentifiers

public void addIdentifiers(java.lang.String expressionFactoryId,
                           java.lang.String... identifiers)

Adds the given JPQL identifiers to this factory.

Parameters:

expressionFactoryId - The unique identifier of the ExpressionFactory to add more JPQL identifiers

identifiers - The JPQL identifiers this factory will parse

expressionFactoryForIdentifier

public ExpressionFactory expressionFactoryForIdentifier(java.lang.String identifier)

Retrieves the ExpressionFactory that is responsible for creating the Expression object that represents the given JPQL identifier.

Parameters:

identifier - The JPQL identifier for which its factory is searched

Returns:

Either the ExpressionFactory that creates the Expression or null if none was found

getExpressionFactory

public ExpressionFactory getExpressionFactory(java.lang.String expressionFactoryId)

Retrieves the registered ExpressionFactory that was registered for the given unique identifier.

Parameters:

expressionFactoryId - The unique identifier of the ExpressionFactory to retrieve

Returns:

The ExpressionFactory mapped with the given unique identifier

getIdentifierRole

public IdentifierRole getIdentifierRole(java.lang.String identifier)

Retrieves the IdentifierRole of the given JPQL identifier. A role helps to describe the purpose of the identifier in a JPQL query.

Parameters:

identifier - The JPQL identifier for which its role is returned

Returns:

The IdentifierRole of the given JPQL identifier

getIdentifiers

public java.util.Set<java.lang.String> getIdentifiers()

Returns the JPQL identifiers that are supported by the JPQL grammar.

Returns:

The supported JPQL identifiers

getIdentifiers

public java.lang.Iterable<java.lang.String> getIdentifiers(java.lang.String queryBNFId)

Retrieves the JPQL identifiers that are supported by the BNF rule with the given unique identifier. The JPQL identifiers are retrieved by scanning the ExpressionFactory registered with the BNF rule and its child BNF rules.

Returns:

The list of JPQL identifiers that are supported by a BNF rule

getIdentifierVersion

public JPAVersion getIdentifierVersion(java.lang.String identifier)

Retrieves the JPA version in which the identifier was first introduced.

Returns:

The version in which the identifier was introduced

getQueryBNF

public JPQLQueryBNF getQueryBNF(java.lang.String queryBNFId)

Retrieves the BNF object that was registered for the given unique identifier.

Parameters:

queryBNFId - The unique identifier of the JPQLQueryBNF to retrieve

Returns:

The JPQLQueryBNF representing a section of the grammar

initialize

protected void initialize()

Instantiates the only instance of various API used by the parser.

isIdentifier

public boolean isIdentifier(java.lang.String text)

Determines if the given word is a JPQL identifier. The check is case insensitive.

Parameters:

text - The string value to test if it's a JPQL identifier based on what is registered with this ExpressionRegistry

Returns:

true if the word is an identifier, false otherwise

registerBNF

public void registerBNF(JPQLQueryBNF queryBNF)

Registers the given JPQLQueryBNF. The BNF will be registered using its unique identifier.

Parameters:

queryBNF - The JPQLQueryBNF to store

Throws:

java.lang.NullPointerException - The JPQLQueryBNF cannot be null

registerFactory

public void registerFactory(ExpressionFactory expressionFactory)

Registers the given ExpressionFactory by storing it for all its identifiers.

Parameters:

expressionFactory - The ExpressionFactory to store

Throws:

java.lang.NullPointerException - The ExpressionFactory cannot be null

registerIdentifierRole

public void registerIdentifierRole(java.lang.String identifier,
                                   IdentifierRole role)

Registers the IdentifierRole for the given JPQL identifier.

Parameters:

identifier - The JPQL identifier to register its role within a JPQL query

role - The role of the given JPQL identifier

Throws:

java.lang.NullPointerException - The JPQL identifier and the IdentifierRole cannot be null

registerIdentifierVersion

public void registerIdentifierVersion(java.lang.String identifier,
                                      JPAVersion version)

Registers the JPAVersion for which the given JPQL identifier was defined.

Parameters:

identifier - The JPQL identifier to register in which version it was added to the grammar

version - The version when the JPQL identifier was added to the grammar

Throws:

java.lang.NullPointerException - The JPQL identifier and the JPAVersion cannot be null

setFallbackBNFId

public void setFallbackBNFId(java.lang.String queryBNFId,
                             java.lang.String fallbackBNFId)

When parsing the query and no JPQLQueryBNFs can help to parse the query, then it will fall back on the given one.

Parameters:

queryBNFId - The unique identifier of the BNF to modify its fallback BNF unique identifier

fallbackBNFId - The unique identifier of the JPQLQueryBNF to use in the last resort

Throws:

java.lang.NullPointerException - The JPQLQueryBNF identified by the given ID does not exist

setFallbackExpressionFactoryId

public void setFallbackExpressionFactoryId(java.lang.String queryBNFId,
                                           java.lang.String fallbackExpressionFactoryId)

Sets the unique identifier of the ExpressionFactory to use when the fall back BNF ID is not null. This will be used to parse a portion of the query when the registered expression factories cannot parse it.

Note: This method is only called if JPQLQueryBNF. getFallbackBNFId() does not return null.

Parameters:

queryBNFId - The unique identifier of the BNF to modify its fallback expression factory unique identifier

Throws:

java.lang.NullPointerException - The JPQLQueryBNF identified by the given ID does not exist

setHandleCollection

public void setHandleCollection(java.lang.String queryBNFId,
                                boolean handleCollection)

Determines whether the Expression handles a collection of sub-expressions that are separated by commas.

Parameters:

queryBNFId - The unique identifier of the JPQLQueryBNF

handleCollection - true if the sub-expression to parse might have several sub-expressions separated by commas; false otherwise

setHandleNestedArray

public void setHandleNestedArray(java.lang.String queryBNFId,
                                 boolean handleNestedArray)

Sets whether the BNF with the given ID supports nested array or not. A nested array is a sub- expression with its child being a collection expression: (item_1, item_2, ..., item_n).

Parameters:

queryBNFId - The unique identifier of the JPQLQueryBNF

handleNestedArray - true if the expression represented by this BNF can be a nested array; false otherwise

Since:

2.5

setHandleSubExpression

public void setHandleSubExpression(java.lang.String queryBNFId,
                                   boolean handleSubExpression)

Sets whether the query BNF with the given ID handles parsing a sub-expression, i.e. parsing an expression encapsulated by parenthesis. Which in fact would be handled by the fallback ExpressionFactory. The default behavior is to not handle it.

A good example for using this option is when an Expression cannot use any ExpressionFactory for creating a child object, parsing will use the fallback ExpressionFactory, if one was specified. So when this is set to true, the fallback ExpressionFactory will be immediately invoked.

Let's say we want to parse "SELECT e FROM (SELECT a FROM Address a) e", FromClause cannot use a factory for parsing the entity name (that's what usually the FROM clause has) so it uses the fallback factory to create IdentificationVariableDeclaration. Then IdentificationVariableDeclaration also cannot use any factory to create its child object so it uses the fallback factory to create RangeVariableDeclaration. By changing the status of for handling the sub-expression for the BNFs for those objects, then a subquery can be created by RangeVariableDeclaration.

FromClause
  |- IdentificationVariableDeclaration
       |- RangeVariableDeclaration
            |- SubExpression(subquery)

In order to get this working, the following would have to be done into the grammar:

 public class MyJPQLGrammar extends AbstractJPQLGrammar {
   @Override
   protected void initializeBNFs() {
      setHandleSubExpression(InternalFromClauseBNF.ID,                true);
      setHandleSubExpression(InternalSimpleFromClauseBNF.ID,          true);
      setHandleSubExpression(IdentificationVariableDeclarationBNF.ID, true);
      setHandleSubExpression(RangeVariableDeclarationBNF.ID,          true);
   }
 }

Parameters:

queryBNFId - The unique identifier of the JPQLQueryBNF

handleSubExpression - true to let the creation of a sub-expression be created by the fallback ExpressionFactory registered with this BNF; false otherwise (which is the default value)

unregisterBNF

public void unregisterBNF(JPQLQueryBNF queryBNF)

Unregisters the given JPQLQueryBNF.

Parameters:

queryBNF - The JPQLQueryBNF to unregister

Throws:

java.lang.NullPointerException - The JPQLQueryBNF cannot be null