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

Class AbstractJPQLGrammar

java.lang.Object
org.eclipse.persistence.jpa.jpql.parser.AbstractJPQLGrammar
All Implemented Interfaces:
JPQLGrammar
Direct Known Subclasses:
EclipseLinkJPQLGrammar1, EclipseLinkJPQLGrammar2_0, EclipseLinkJPQLGrammar2_1, EclipseLinkJPQLGrammar2_2, EclipseLinkJPQLGrammar2_3, EclipseLinkJPQLGrammar2_4, EclipseLinkJPQLGrammar2_5, EclipseLinkJPQLGrammar2_6, JPQLGrammar1_0, JPQLGrammar2_0, JPQLGrammar2_1
public abstract class AbstractJPQLGrammar extends Object implements JPQLGrammar

The abstract definition of a JPQLGrammar. The grammar defines how a JPQL query is parsed, which is based on the BNF defined for that grammar.

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
Author:
Pascal Filion

  • Constructor Details

    • AbstractJPQLGrammar

      protected AbstractJPQLGrammar()
      Creates a new AbstractJPQLGrammar.

    • AbstractJPQLGrammar

      protected AbstractJPQLGrammar(AbstractJPQLGrammar jpqlGrammar)
      Creates a new AbstractJPQLGrammar.
      Parameters:
      jpqlGrammar - The JPQLGrammar to extend with the content of this one without instantiating the base JPQLGrammar

  • Method Details

    • addChildBNF

      public void addChildBNF(String queryBNFId, 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

    • addChildFactory

      public void addChildFactory(String queryBNFId, 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

    • addIdentifier

      public void addIdentifier(String expressionFactoryId, 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(String expressionFactoryId, 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

    • buildBaseGrammar

      protected abstract JPQLGrammar buildBaseGrammar()
      Creates the base JPQLGrammar this one extends, if one exists.

      IMPORTANT: The singleton instance of any JPQLGrammar (for example JPQLGrammar1_0.instance() cannot be used, the API does not support extending it, a new instance has to be created.

      Returns:
      The base JPQLGrammar or null if there is no base grammar

    • buildExpressionRegistry

      protected ExpressionRegistry buildExpressionRegistry()
      Creates a new ExpressionRegistry that will be used to store the definition of the JPQL grammar. This method is invoked if buildBaseGrammar() returns null.
      Returns:
      The registry of JPQLQueryBNFs, ExpressionFactories and the JPQL identifiers

    • getBaseGrammar

      public JPQLGrammar getBaseGrammar()
      Creates the base JPQLGrammar this one extends.
      Returns:
      The base JPQLGrammar or null if this is the base grammar

    • getExpressionRegistry

      public ExpressionRegistry getExpressionRegistry()
      Description copied from interface: JPQLGrammar
      Returns the registry containing the JPQLQueryBNFs and the ExpressionFactories that are used to properly parse a JPQL query.
      Specified by:
      getExpressionRegistry in interface JPQLGrammar
      Returns:
      The registry containing the information related to the JPQL grammar

    • initialize

      protected void initialize()
      Initializes this JPQL grammar.

    • initializeBNFs

      protected abstract void initializeBNFs()
      Registers the JPQL query BNFs defining the JPQL grammar.

    • initializeExpressionFactories

      protected abstract void initializeExpressionFactories()
      Registers the ExpressionFactories required to properly parse JPQL queries. An ExpressionFactory is responsible to create an Expression object that represents a portion of the JPQL query.

    • initializeIdentifiers

      protected abstract void initializeIdentifiers()
      Registers the JPQL identifiers support by this JPQLGrammar. The registration involves registering the JPAVersion and the IdentifierRole.

    • registerBNF

      protected void registerBNF(JPQLQueryBNF queryBNF)
      Registers the given JPQLQueryBNF. The BNF will be registered using its unique identifier.
      Parameters:
      queryBNF - The JPQLQueryBNF to store

    • registerFactory

      protected void registerFactory(ExpressionFactory expressionFactory)
      Registers the given ExpressionFactory by storing it for all its identifiers.
      Parameters:
      expressionFactory - The ExpressionFactory to store

    • registerIdentifierRole

      protected void registerIdentifierRole(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

    • registerIdentifierVersion

      protected void registerIdentifierVersion(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

    • setFallbackBNFId

      public void setFallbackBNFId(String queryBNFId, 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

    • setFallbackExpressionFactoryId

      public void setFallbackExpressionFactoryId(String queryBNFId, 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

    • setHandleCollection

      public void setHandleCollection(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(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

    • setHandleSubExpression

      public void setHandleSubExpression(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)