# Package org.eclipse.viatra.query.runtime.matchers.psystem.queries

- Interface Summary
  Interface | Description
  --- | ---
  PQuery | Internal representation of a query / graph pattern (using a constraint system formalism), to be interpreted by a query evaluator (`IQueryBackend`).
  PQueryHeader | Represents header information (metainfo) about a query.

- Class Summary
  Class | Description
  --- | ---
  BasePQuery | Default implementation of PQuery.
  PDisjunction | A disjunction is a set of bodies representing separate conditions.
  PParameter | A descriptor for declared PQuery parameters.
  PProblem | Represents an error that was detected while the `PQuery` object was built from a source.
  PQueries | Utility class for using PQueries in functional/streaming collection operations effectively

- Enum Summary
  Enum | Description
  --- | ---
  PParameterDirection | Values of this enum describe a constraint to the calling of patterns regarding its parameters.
  PQuery.PQueryStatus |
  PVisibility |

- Exception Summary
  Exception | Description
  --- | ---
  QueryInitializationException | Represent an exception that occurred while initializing the specification of a query.