org.apache.openjpa.kernel
Class ExpressionStoreQuery

java.lang.Object
  org.apache.openjpa.kernel.AbstractStoreQuery
      org.apache.openjpa.kernel.ExpressionStoreQuery

All Implemented Interfaces:

Serializable, QueryOperations, StoreQuery

Direct Known Subclasses:

JDBCStoreQuery

public class ExpressionStoreQuery
extends AbstractStoreQuery

Implementation of an expression-based query, which can handle String-based query expressions such as JPQL and JDOQL. This implementation is suitable for in-memory operation. Override the following methods to also support datastore operation:

• Override AbstractStoreQuery.supportsDataStoreExecution() to return true.
• Override executeQuery(org.apache.openjpa.kernel.StoreQuery.Executor, org.apache.openjpa.meta.ClassMetaData, org.apache.openjpa.meta.ClassMetaData[], boolean, org.apache.openjpa.kernel.exps.ExpressionFactory[], org.apache.openjpa.kernel.exps.QueryExpressions[], java.lang.Object[], org.apache.openjpa.kernel.StoreQuery.Range), executeDelete(org.apache.openjpa.kernel.StoreQuery.Executor, org.apache.openjpa.meta.ClassMetaData, org.apache.openjpa.meta.ClassMetaData[], boolean, org.apache.openjpa.kernel.exps.ExpressionFactory[], org.apache.openjpa.kernel.exps.QueryExpressions[], java.lang.Object[]), and executeUpdate(org.apache.openjpa.kernel.StoreQuery.Executor, org.apache.openjpa.meta.ClassMetaData, org.apache.openjpa.meta.ClassMetaData[], boolean, org.apache.openjpa.kernel.exps.ExpressionFactory[], org.apache.openjpa.kernel.exps.QueryExpressions[], java.lang.Object[]) to execute the query against the data store. Keep in mind that the parameters passed to this method might be in use by several threads in different query instances. Thus components like the expression factory must either be thread safe, or this method must synchronize on them.
• Override getDataStoreActions(org.apache.openjpa.meta.ClassMetaData, org.apache.openjpa.meta.ClassMetaData[], boolean, org.apache.openjpa.kernel.exps.ExpressionFactory[], org.apache.openjpa.kernel.exps.QueryExpressions[], java.lang.Object[], org.apache.openjpa.kernel.StoreQuery.Range) to return a representation of the actions that will be taken on the data store. For use in visual tools.
• Override getExpressionFactory(org.apache.openjpa.meta.ClassMetaData) to return a factory for creating expressions in the datastore's language. The factory must be cachable.

Author:

Abe White

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.openjpa.kernel.AbstractStoreQuery

AbstractStoreQuery.AbstractExecutor

Nested classes/interfaces inherited from interface org.apache.openjpa.kernel.StoreQuery

StoreQuery.Executor, StoreQuery.Range

Field Summary

Fields inherited from class org.apache.openjpa.kernel.AbstractStoreQuery

ctx

Fields inherited from interface org.apache.openjpa.kernel.StoreQuery

EMPTY_BOOLEANS, EMPTY_CLASSES, EMPTY_METAS, EMPTY_OBJECTS, EMPTY_PARAMS, EMPTY_STRINGS

Fields inherited from interface org.apache.openjpa.kernel.QueryOperations

OP_DELETE, OP_SELECT, OP_UPDATE

Constructor Summary

ExpressionStoreQuery(ExpressionParser parser)
Construct a query with a parser for the language.

Method Summary

protected Number	executeDelete(StoreQuery.Executor ex, ClassMetaData base, ClassMetaData[] types, boolean subclasses, ExpressionFactory[] facts, QueryExpressions[] parsed, Object[] params) Execute the given expression against the given candidate extent and delete the instances.
protected ResultObjectProvider	executeQuery(StoreQuery.Executor ex, ClassMetaData base, ClassMetaData[] types, boolean subclasses, ExpressionFactory[] facts, QueryExpressions[] parsed, Object[] params, StoreQuery.Range range) Execute the given expression against the given candidate extent.
protected Number	executeUpdate(StoreQuery.Executor ex, ClassMetaData base, ClassMetaData[] types, boolean subclasses, ExpressionFactory[] facts, QueryExpressions[] parsed, Object[] params) Execute the given expression against the given candidate extent and updates the instances.
protected String[]	getDataStoreActions(ClassMetaData base, ClassMetaData[] types, boolean subclasses, ExpressionFactory[] facts, QueryExpressions[] parsed, Object[] params, StoreQuery.Range range) Return the commands that will be sent to the datastore in order to execute the query, typically in the database's native language.
protected ExpressionFactory	getExpressionFactory(ClassMetaData type) Return an ExpressionFactory to use to create an expression to be executed against an extent.
FilterListener	getFilterListener(String tag) Return the standard filter listener for the given tag, or null.
protected ClassMetaData[]	getIndependentExpressionCandidates(ClassMetaData type, boolean subclasses) Return the assignable types for the given metadata whose expression trees must be compiled independently.
Resolver	getResolver() Resolver used in parsing.
void	invalidateCompilation() Invalidate any internal compilation state.
Object	newCompilation() Create a new compilation for this query.
StoreQuery.Executor	newDataStoreExecutor(ClassMetaData meta, boolean subs) Return an executor for datastore execution of this query.
StoreQuery.Executor	newInMemoryExecutor(ClassMetaData meta, boolean subs) Return an executor for in-memory execution of this query.
void	populateFromCompilation(Object comp) Populate internal data from compilation.
boolean	setQuery(Object query) Allow direct setting of parsed state for facades that do parsing.
boolean	supportsInMemoryExecution() True if this query supports in-memory execution, false if it can only run against the datastore.

Methods inherited from class org.apache.openjpa.kernel.AbstractStoreQuery

getAggregateListener, getContext, newCompilationKey, requiresCandidateType, requiresParameterDeclarations, setContext, supportsAbstractExecutors, supportsDataStoreExecution, supportsParameterDeclarations

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionStoreQuery

public ExpressionStoreQuery(ExpressionParser parser)

Construct a query with a parser for the language.

Method Detail

getResolver

public Resolver getResolver()

Resolver used in parsing.

setQuery

public boolean setQuery(Object query)

Allow direct setting of parsed state for facades that do parsing. The facade should call this method twice: once with the query string, and again with the parsed state.

Specified by:

setQuery in interface StoreQuery

Overrides:

setQuery in class AbstractStoreQuery

getFilterListener

public FilterListener getFilterListener(String tag)

Description copied from interface: StoreQuery

Return the standard filter listener for the given tag, or null.

Specified by:

getFilterListener in interface StoreQuery

Overrides:

getFilterListener in class AbstractStoreQuery

newCompilation

public Object newCompilation()

Description copied from interface: StoreQuery

Create a new compilation for this query. May be null.

Specified by:

newCompilation in interface StoreQuery

Overrides:

newCompilation in class AbstractStoreQuery

populateFromCompilation

public void populateFromCompilation(Object comp)

Description copied from interface: StoreQuery

Populate internal data from compilation.

Specified by:

populateFromCompilation in interface StoreQuery

Overrides:

populateFromCompilation in class AbstractStoreQuery

invalidateCompilation

public void invalidateCompilation()

Description copied from interface: StoreQuery

Invalidate any internal compilation state.

Specified by:

invalidateCompilation in interface StoreQuery

Overrides:

invalidateCompilation in class AbstractStoreQuery

supportsInMemoryExecution

public boolean supportsInMemoryExecution()

Description copied from interface: StoreQuery

True if this query supports in-memory execution, false if it can only run against the datastore.

Specified by:

supportsInMemoryExecution in interface StoreQuery

Overrides:

supportsInMemoryExecution in class AbstractStoreQuery

newInMemoryExecutor

public StoreQuery.Executor newInMemoryExecutor(ClassMetaData meta,
                                               boolean subs)

Description copied from interface: StoreQuery

Return an executor for in-memory execution of this query. Executors must be cachable and thread safe. If this class returns true from StoreQuery.supportsAbstractExecutors(), the given metadata will always be for the candidate class of this query, or possibly null if the candidate class is not itself persistence capable (like an interface or abstract base class). Otherwise, the given type will be a mapped class.

Specified by:

newInMemoryExecutor in interface StoreQuery

Overrides:

newInMemoryExecutor in class AbstractStoreQuery

subs - whether to include dependent mapped subclasses in the results; independent subclasses should never be included

newDataStoreExecutor

public StoreQuery.Executor newDataStoreExecutor(ClassMetaData meta,
                                                boolean subs)

Description copied from interface: StoreQuery

Return an executor for datastore execution of this query. Executors must be cachable and thread safe. If this class returns true from StoreQuery.supportsAbstractExecutors(), the given metadata will always be for the candidate class of this query, or possibly null if the candidate class is not itself persistence capable (like an interface or abstract base class). Otherwise, the given type will be a mapped class.

Specified by:

newDataStoreExecutor in interface StoreQuery

Overrides:

newDataStoreExecutor in class AbstractStoreQuery

subs - whether to include dependent mapped subclasses in the results; independent subclasses should never be included

executeQuery

protected ResultObjectProvider executeQuery(StoreQuery.Executor ex,
                                            ClassMetaData base,
                                            ClassMetaData[] types,
                                            boolean subclasses,
                                            ExpressionFactory[] facts,
                                            QueryExpressions[] parsed,
                                            Object[] params,
                                            StoreQuery.Range range)

Execute the given expression against the given candidate extent.

Parameters:

ex - current executor

base - the base type the query should match

types - the independent candidate types

subclasses - true if subclasses should be included in the results

facts - the expression factory used to build the query for each base type

parsed - the parsed query values

params - parameter values, or empty array

range - result range

Returns:

a provider for matching objects

executeDelete

protected Number executeDelete(StoreQuery.Executor ex,
                               ClassMetaData base,
                               ClassMetaData[] types,
                               boolean subclasses,
                               ExpressionFactory[] facts,
                               QueryExpressions[] parsed,
                               Object[] params)

Execute the given expression against the given candidate extent and delete the instances.

Parameters:

ex - current executor

base - the base type the query should match

types - the independent candidate types

subclasses - true if subclasses should be included in the results

facts - the expression factory used to build the query for each base type

parsed - the parsed query values

params - parameter values, or empty array

Returns:

a number indicating the number of instances deleted, or null to execute the delete in memory

executeUpdate

protected Number executeUpdate(StoreQuery.Executor ex,
                               ClassMetaData base,
                               ClassMetaData[] types,
                               boolean subclasses,
                               ExpressionFactory[] facts,
                               QueryExpressions[] parsed,
                               Object[] params)

Execute the given expression against the given candidate extent and updates the instances.

Parameters:

ex - current executor

base - the base type the query should match

types - the independent candidate types

subclasses - true if subclasses should be included in the results

facts - the expression factory used to build the query for each base type

parsed - the parsed query values

params - parameter values, or empty array

Returns:

a number indicating the number of instances updated, or null to execute the update in memory.

getDataStoreActions

protected String[] getDataStoreActions(ClassMetaData base,
                                       ClassMetaData[] types,
                                       boolean subclasses,
                                       ExpressionFactory[] facts,
                                       QueryExpressions[] parsed,
                                       Object[] params,
                                       StoreQuery.Range range)

Return the commands that will be sent to the datastore in order to execute the query, typically in the database's native language.

Parameters:

base - the base type the query should match

types - the independent candidate types

subclasses - true if subclasses should be included in the results

facts - the expression factory used to build the query for each base type

parsed - the parsed query values

params - parameter values, or empty array

range - result range

Returns:

a textual description of the query to execute

getIndependentExpressionCandidates

protected ClassMetaData[] getIndependentExpressionCandidates(ClassMetaData type,
                                                             boolean subclasses)

Return the assignable types for the given metadata whose expression trees must be compiled independently.

getExpressionFactory

protected ExpressionFactory getExpressionFactory(ClassMetaData type)

Return an ExpressionFactory to use to create an expression to be executed against an extent. Each factory will be used to compile one filter only. The factory must be cachable.