Package com.saxonica.xsltextn.pedigree

Class Pedigree

java.lang.Object
com.saxonica.xsltextn.pedigree.Pedigree
public class Pedigree extends Object
A Pedigree is transient information relating to a map or array indicating the route by which it was reached; it thus compensates for the absence of parent pointers in a JSON-like tree, by allowing the steps used to reach a map or array in such a structure to be retraced.

A map or array that has a Pedigree is represented by a PedigreeValue, which is a combination of the map/array and the Pedigree. The Pedigree holds a reference to the "container" PedigreeValue from which this map or array was reached, and the key or index value within that container.

Note that maps and arrays have no externally visible identity. It is not meaningful to ask whether the same map can be reached by two different routes, because there is no way to establish "sameness".

A map or array will have a Pedigree if it is found by downwards selection from a map or array that itself has a Pedigree, or if it was explicitly created with a Pedigree.

  • Field Details

    • PEDIGREE_ROOT

      public static final Pedigree PEDIGREE_ROOT
      An empty Pedigree: that is, the Pedigree of a map or array that was created as the root of a pedigree tree.

  • Constructor Details

    • Pedigree

      public Pedigree(PedigreeValue container, AtomicValue key)
      Create a pedigree for a map or array obtained by selection from a map, using a key value
      Parameters:
      container - the containing map
      key - the key value used to select an entry in the containing map

    • Pedigree

      public Pedigree(PedigreeValue container, int index)
      Create a pedigree for a map or array obtained by selection from an array, using an index value as a subscript into the array
      Parameters:
      container - the containing map
      index - the zero-based index value used to select a member of the containing array

  • Method Details

    • getContainer

      public PedigreeValue getContainer()
      Get the containing map or array
      Returns:
      the containing map or array

    • getIndex

      public int getIndex()
      Get the index if this item was obtained by selection from an array
      Returns:
      the zero-based index if this item was obtained by selection from an array, otherwise -1.

    • getKey

      public AtomicValue getKey()
      Get the key if this item was obtained by selection from a map
      Returns:
      the key if this item was obtained by selection from a map, otherwise null.

    • makePedigreeValue

      public GroundedValue makePedigreeValue(GroundedValue value)
      Make a map or array that combines a supplied map or array with this pedigree
      Parameters:
      value - the supplied value
      Returns:
      if the supplied value is a map or array, returns a map or array augmented with this pedigree. Otherwise, returns the supplied value unchanged.