org.eclipse.incquery.runtime.matchers.context

Interface IQueryRuntimeContext

All Known Implementing Classes:

DynamicEMFQueryRuntimeContext, EMFQueryRuntimeContext

public interface IQueryRuntimeContext

Provides instance model information (relations corresponding to input keys) to query evaluator backends at runtime.

Author:

Bergmann Gabor

Method Summary

Modifier and Type	Method and Description
void	addUpdateListener(IInputKey key, Tuple seed, IQueryRuntimeContextListener listener) Subscribes for updates in the extensional relation identified by the input key, optionally seeded with the given tuple.
<V> V	coalesceTraversals(java.util.concurrent.Callable<V> callable) The given callable will be executed, and all model traversals will be delayed until the execution is done.
boolean	containsTuple(IInputKey key, Tuple seed) Simpler form of enumerateTuples(IInputKey, Tuple) in the case where all values of the tuples are bound by the seed.
int	countTuples(IInputKey key, Tuple seed) Returns the number of tuples in the extensional relation identified by the input key, optionally seeded with the given tuple.
void	ensureIndexed(IInputKey key) If the given (enumerable) input key is not yet indexed, the model will be traversed (after the end of the outermost coalescing block, see coalesceTraversals(Callable)) so that the index can be built.
java.lang.Iterable<Tuple>	enumerateTuples(IInputKey key, Tuple seed) Returns the tuples in the extensional relation identified by the input key, optionally seeded with the given tuple.
java.lang.Iterable<? extends java.lang.Object>	enumerateValues(IInputKey key, Tuple seed) Simpler form of enumerateTuples(IInputKey, Tuple) in the case where all values of the tuples are bound by the seed except for one.
IQueryMetaContext	getMetaContext() Provides metamodel-specific info independent of the runtime instance model.
boolean	isCoalescing()
boolean	isIndexed(IInputKey key)
void	removeUpdateListener(IInputKey key, Tuple seed, IQueryRuntimeContextListener listener) Unsubscribes from updates in the extensional relation identified by the input key, optionally seeded with the given tuple.
java.lang.Object	unwrapElement(java.lang.Object internalElement) Unwraps the internal representation of the element into its original form
Tuple	unwrapTuple(Tuple internalElements) Unwraps the tuple of internal representations of elements into their original forms
java.lang.Object	wrapElement(java.lang.Object externalElement) Wraps the external element into the internal representation that is to be used by the query backend
Tuple	wrapTuple(Tuple externalElements) Unwraps the tuple of elements into the internal representation that is to be used by the query backend

Method Detail

getMetaContext

IQueryMetaContext getMetaContext()

Provides metamodel-specific info independent of the runtime instance model.

coalesceTraversals

<V> V coalesceTraversals(java.util.concurrent.Callable<V> callable)
                  throws java.lang.reflect.InvocationTargetException

The given callable will be executed, and all model traversals will be delayed until the execution is done. If there are any outstanding information to be read from the model, a single coalesced model traversal will initialize the caches and deliver the notifications.

Calls may be nested. A single coalesced traversal will happen at the end of the outermost call.

Caution: results returned by the runtime context may be incomplete during the coalescing period, to be corrected by notifications sent during the final coalesced traversal. For example, if a certain input key is not cached yet, an empty relation may be reported during callable.call(); the cache will be constructed after the call terminates and notifications will deliver the entire content of the relation. Non-incremental query backends should therefore never enumerate input keys while coalesced (verify using isCoalescing()).

Parameters:

callable -

Throws:

java.lang.reflect.InvocationTargetException

isCoalescing

boolean isCoalescing()

Returns:

true iff currently within a coalescing section (i.e. within the callable of a call to coalesceTraversals(Callable)).

isIndexed

boolean isIndexed(IInputKey key)

Returns:

true iff the given input key is already indexed, and contents are available without costly model traversal.

ensureIndexed

void ensureIndexed(IInputKey key)

If the given (enumerable) input key is not yet indexed, the model will be traversed (after the end of the outermost coalescing block, see coalesceTraversals(Callable)) so that the index can be built.

Postcondition: After invoking this method, isIndexed(IInputKey) for the same key will be guaranteed to return true as soon as isCoalescing() first returns false.

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

countTuples

int countTuples(IInputKey key,
                Tuple seed)

Returns the number of tuples in the extensional relation identified by the input key, optionally seeded with the given tuple.

Parameters:

key - an input key

seed - can be null or a tuple with matching arity; if non-null, only those tuples in the model are counted that match the seed at positions where the seed is non-null.

Returns:

the number of tuples in the model for the given key and seed

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

enumerateTuples

java.lang.Iterable<Tuple> enumerateTuples(IInputKey key,
                                          Tuple seed)

Returns the tuples in the extensional relation identified by the input key, optionally seeded with the given tuple.

Parameters:

key - an input key

seed - can be null or a tuple with matching arity; if non-null, only those tuples in the model are enumerated that match the seed at positions where the seed is non-null.

Returns:

the tuples in the model for the given key and seed

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

enumerateValues

java.lang.Iterable<? extends java.lang.Object> enumerateValues(IInputKey key,
                                                               Tuple seed)

Simpler form of enumerateTuples(IInputKey, Tuple) in the case where all values of the tuples are bound by the seed except for one.

Selects the tuples in the extensional relation identified by the input key, optionally seeded with the given tuple, and then returns the single value from each tuple which corresponds to the only null value in the seed.

Parameters:

key - an input key

seed - can be null (if key is unary) or a tuple with matching arity; if non-null, only those tuples in the model are enumerated that match the seed at positions where the seed is non-null; the seed is null at exactly one position.

Returns:

the objects in the model for the given key and seed

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

containsTuple

boolean containsTuple(IInputKey key,
                      Tuple seed)

Simpler form of enumerateTuples(IInputKey, Tuple) in the case where all values of the tuples are bound by the seed.

Returns whether the given tuple is in the extensional relation identified by the input key.

Note: this call works for non-enumerable input keys as well.

Parameters:

key - an input key

seed - a tuple with matching arity, consisting of non-null elements (null can be used in the 0-ary case).

Returns:

true iff the seed tuple is contained in the relation

addUpdateListener

void addUpdateListener(IInputKey key,
                       Tuple seed,
                       IQueryRuntimeContextListener listener)

Subscribes for updates in the extensional relation identified by the input key, optionally seeded with the given tuple.

This should be called after invoking

Parameters:

key - an input key

seed - can be null or a tuple with matching arity; if non-null, only those updates in the model are notified about that match the seed at positions where the seed is non-null.

listener - will be notified of future changes

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

removeUpdateListener

void removeUpdateListener(IInputKey key,
                          Tuple seed,
                          IQueryRuntimeContextListener listener)

Unsubscribes from updates in the extensional relation identified by the input key, optionally seeded with the given tuple.

Parameters:

key - an input key

seed - can be null or a tuple with matching arity; if non-null, only those updates in the model are notified about that match the seed at positions where the seed is non-null.

listener - will no longer be notified of future changes

Precondition: the given key is enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

Throws:

java.lang.IllegalArgumentException - if key is not enumerable, see IQueryMetaContext.isEnumerable(IInputKey).

wrapElement

java.lang.Object wrapElement(java.lang.Object externalElement)

Wraps the external element into the internal representation that is to be used by the query backend

model element -> internal object.

null must be mapped to null.

unwrapElement

java.lang.Object unwrapElement(java.lang.Object internalElement)

Unwraps the internal representation of the element into its original form

internal object -> model element

null must be mapped to null.

wrapTuple

Tuple wrapTuple(Tuple externalElements)

Unwraps the tuple of elements into the internal representation that is to be used by the query backend

model elements -> internal objects

null must be mapped to null.

unwrapTuple

Tuple unwrapTuple(Tuple internalElements)

Unwraps the tuple of internal representations of elements into their original forms

internal objects -> model elements

null must be mapped to null.