The Eclipse EMF Query component facilitates the process of search and retrieval of model elements of interest in a flexible yet controlled and structured manner. Provides API support for the basic EObject based Condition objects that are used to formulate queries for EMF models.
The query component provides the following classes/interfaces to support queries.
- The IEObjectSource interface provides the search scope elements to be used in a query.
- The SELECT class implements a template-function that does the iteration over model elements and applies the search condition on each; it collects the resulting elements into a QueryResultSet object and returns it to the caller.
- The FROM class represents the elements to search. It is responsible of providing an appropriate iterator for the elements in the search space.
- The WHERE class applies the search conditions over the elements in the search set.
- The UPDATE class passes the elements who satisfy the search condition to a caller-supplied modification function. It collects the modified elements into a QueryResultSet object and returns it to the caller.
- The QueryResultSet class represents the set of elements returned by a given query.
- The EObjectCondition class is the abstract parent of all conditions that deal with model-elements (i.e., EObjects). It incorporates the services of a PruneHandler in order to answers whether or not to prune the element tree at a specific element and thus ignore its children.
- The ConditionPolicy class is used to allow the user to decide how to apply a given condition on a collection of a model-element EAttributes or EReferences values. Supports both the: exists (ANY) and for-all (ALL) semantics.
- The EObjectStructuralFeatureValueCondition class is the parent class for conditions that are responsible for checking the values held in model-elements attributes or references.