com.saxonica.xsltextn.pedigree

Class Pedigree

java.lang.Object

com.saxonica.xsltextn.pedigree.Pedigree

public class Pedigree
extends java.lang.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 Summary

Fields

Modifier and Type	Field and Description
static 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 Summary

Constructors

Constructor and Description
Pedigree(PedigreeValue container, AtomicValue key) Create a pedigree for a map or array obtained by selection from a map, using a key value
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

Method Summary

Modifier and Type	Method and Description
PedigreeValue	getContainer() Get the containing map or array
int	getIndex() Get the index if this item was obtained by selection from an array
AtomicValue	getKey() Get the key if this item was obtained by selection from a map
GroundedValue<?>	makePedigreeValue(GroundedValue<?> value) Make a map or array that combines a supplied map or array with this pedigree

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

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 Detail

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 Detail

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.