com.espertech.esper.epl.rettype

Class EPTypeHelper

java.lang.Object

com.espertech.esper.epl.rettype.EPTypeHelper

public class EPTypeHelper
extends Object

Carries return type information related to the return values returned by expressions.

Use factory methods to initialize return type information according to the return values that your expression is going to provide.

1. Use collectionOfEvents(com.espertech.esper.client.EventType) to indicate that the expression returns a collection of events.
2. Use singleEvent(com.espertech.esper.client.EventType) to indicate that the expression returns a single event.
3. Use collectionOfSingleValue(Class) to indicate that the expression returns a collection of single values. A single value can be any object including null.
4. Use array(Class) to indicate that the expression returns an array of single values. A single value can be any object including null.
5. Use singleValue(Class) to indicate that the expression returns a single value. A single value can be any object including null. Such expression results cannot be used as input to enumeration methods, for example.

Constructor Summary

Constructors

Constructor and Description
EPTypeHelper()

Method Summary

Modifier and Type	Method and Description
static EPType	array(Class arrayComponentType) Indicate that the expression return type is an array of a given component type.
static EPType	collectionOfEvents(EventType eventTypeOfCollectionEvents) Indicate that the expression return type is a collection of a given type of events.
static EPType	collectionOfSingleValue(Class collectionComponentType) Indicate that the expression return type is a collection of a given component type.
static EPType	fromMethod(Method method) Interrogate the provided method and determine whether it returns single-value, array of single-value or collection of single-value and their component type.
static Class	getClassMultiValued(EPType type)
static Class	getClassSingleValued(EPType type)
static Class	getCodegenReturnType(EPType theType)
static EventType	getEventType(EPType epType)
static EventType	getEventTypeMultiValued(EPType type)
static EventType	getEventTypeSingleValued(EPType type)
static Class	getNormalizedClass(EPType theType)
static boolean	isCarryEvent(EPType epType)
static EPType	nullValue()
static EPType	optionalFromEnumerationExpr(int statementId, EventAdapterService eventAdapterService, ExprNode exprNode)
static Class	optionalIsComponentTypeColl(EPType type)
static EventType	optionalIsEventTypeColl(EPType type)
static EventType	optionalIsEventTypeSingle(EPType type)
static EPType	singleEvent(EventType eventTypeOfSingleEvent) Indicate that the expression return type is single event of a given event type.
static EPType	singleValue(Class singleValueType) Indicate that the expression return type is a single (non-enumerable) value of the given type.
static String	toTypeDescriptive(EPType epType) Returns a nice text detailing the expression result type.

Methods inherited from class java.lang.Object

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

Constructor Detail

EPTypeHelper

public EPTypeHelper()

Method Detail

getEventTypeSingleValued

public static EventType getEventTypeSingleValued(EPType type)

getEventTypeMultiValued

public static EventType getEventTypeMultiValued(EPType type)

getClassMultiValued

public static Class getClassMultiValued(EPType type)

getClassSingleValued

public static Class getClassSingleValued(EPType type)

isCarryEvent

public static boolean isCarryEvent(EPType epType)

getEventType

public static EventType getEventType(EPType epType)

array

public static EPType array(Class arrayComponentType)

Indicate that the expression return type is an array of a given component type.

Parameters:

arrayComponentType - array component type

Returns:

array of single value expression result type

singleValue

public static EPType singleValue(Class singleValueType)

Indicate that the expression return type is a single (non-enumerable) value of the given type. The expression can still return an array or collection or events however since the engine would not know the type of such objects and may not use runtime reflection it may not allow certain operations on expression results.

Parameters:

singleValueType - type of single value returned, or null to indicate that the expression always returns null

Returns:

single-value expression result type

nullValue

public static EPType nullValue()

collectionOfSingleValue

public static EPType collectionOfSingleValue(Class collectionComponentType)

Indicate that the expression return type is a collection of a given component type.

Parameters:

collectionComponentType - collection component type

Returns:

collection of single value expression result type

collectionOfEvents

public static EPType collectionOfEvents(EventType eventTypeOfCollectionEvents)

Indicate that the expression return type is a collection of a given type of events.

Parameters:

eventTypeOfCollectionEvents - the event type of the events that are part of the collection

Returns:

collection of events expression result type

singleEvent

public static EPType singleEvent(EventType eventTypeOfSingleEvent)

Indicate that the expression return type is single event of a given event type.

Parameters:

eventTypeOfSingleEvent - the event type of the event returned

Returns:

single-event expression result type

fromMethod

public static EPType fromMethod(Method method)

Interrogate the provided method and determine whether it returns single-value, array of single-value or collection of single-value and their component type.

Parameters:

method - the class methods

Returns:

expression return type

toTypeDescriptive

public static String toTypeDescriptive(EPType epType)

Returns a nice text detailing the expression result type.

Parameters:

epType - type

Returns:

descriptive text

getNormalizedClass

public static Class getNormalizedClass(EPType theType)

getCodegenReturnType

public static Class getCodegenReturnType(EPType theType)

optionalFromEnumerationExpr

public static EPType optionalFromEnumerationExpr(int statementId,
                                                 EventAdapterService eventAdapterService,
                                                 ExprNode exprNode)
                                          throws ExprValidationException

Throws:

ExprValidationException

optionalIsEventTypeColl

public static EventType optionalIsEventTypeColl(EPType type)

optionalIsComponentTypeColl

public static Class optionalIsComponentTypeColl(EPType type)

optionalIsEventTypeSingle

public static EventType optionalIsEventTypeSingle(EPType type)