Package nz.org.riskscape.engine.projection

Interface Projector

All Superinterfaces:
AutoCloseable, Function<Tuple,Tuple>, Realized
public interface Projector extends Function<Tuple,Tuple>, Realized

Realized Projection of one Struct to another. Exists so that a Projection's projection function can be associated with other metadata, such as the source and target Struct and a possible mapping of attributes from one to the other.

  • Method Details

    • identity

      static Projector identity(Struct type)

      Returns a 'noop' projector that does nothing other than pass the tuple along as-is

      Parameters:
      type - the type of tuple that comes in and out

    • join

      static String join(List<Struct.StructMember> members)

    • identityMapping

      static Map<List<Struct.StructMember>,List<Struct.StructMember>> identityMapping(Struct struct)

    • getProducedType

      Struct getProducedType()

      The exact Struct object that will be assigned to Tuples that emerge from this Projector

      Specified by:
      getProducedType in interface Realized

    • getProjectedType

      @Deprecated default Struct getProjectedType()
      Deprecated.
      use getProducedType

    • getSourceType

      Struct getSourceType()

      The exact Struct object that is expected to be seen by the Function.apply(java.lang.Object)

    • getDirectMapping

      default Map<List<Struct.StructMember>,List<Struct.StructMember>> getDirectMapping()
      Returns:
      a map that can be used to trace attributes from the target type (the key set) back to their source type (value set). Optional, as this is here to allow various optimisations to be applied to queries. Not implementing this method will prevent various optimisations for being possible.

    • getSpatialMetadataMapper

      default Optional<Function<SpatialMetadata,SpatialMetadata>> getSpatialMetadataMapper()

      An optional function used for transforming spatial metadata from source to target. If left out, spatial metadata is lost during projection. A default, fairly sane implementation exists that copies the CRS and picks the single geometry member that was found at the top level of the projectors projected type.

    • getDirectMappingStrings

      default Map<String,String> getDirectMappingStrings()
      Returns:
      a human-readable version of getDirectMapping(), useful for debug statements, test assertions etc