.. default-domain:: chpl

.. module:: EquivalenceClasses
   :synopsis: Provides an abstraction used to efficiently compute equivalence classes. An

EquivalenceClasses
==================
**Usage**

.. code-block:: chapel

   use EquivalenceClasses;


Provides an abstraction used to efficiently compute equivalence classes. An
equivalence class is a set where all elements of that set are equivalent to
each other. The `cmpType` is used to determine the equivalence class associated
with a `keyType`. For example, if the `keyType` is a hyperedge, the `cmpType`
is the set of vertices that are incident in it. Each equivalence class has what
is known as a `candidate`, which is an arbitrarily chosen leader for an equivalence
class, making it easy to select which `keyType` to keep based on duplicate `cmpType`.

.. class:: Equivalence

   .. attribute:: type keyType

   .. attribute:: type cmpType

   .. attribute:: var eqclassesDom: domain(cmpType)

   .. attribute:: var eqclasses: [eqclassesDom] keyType

   .. attribute:: var candidatesDom: domain(keyType)

   .. attribute:: var candidates: [candidatesDom] domain(keyType)

   .. method:: proc init(type keyType)

   .. method:: proc init(type keyType, type cmpType)

   .. itermethod:: iter getEquivalenceClasses(): keyType

   .. itermethod:: iter getEquivalenceClasses(param tag: iterKind): keyType

   .. itermethod:: iter getCandidates(key: keyType): keyType

   .. itermethod:: iter getCandidates(key: keyType, param tag: iterKind): keyType

   .. method:: proc add(key: keyType)

   .. method:: proc add(key: keyType, cmp: cmpType)

      
      Adds 'key' to an equivalence class, or making it the candidate
      if no current equivalence class exists. 
      

   .. method:: proc add(other: this.type )

      
      Adds another equivalence class to this one.
      

   .. method:: proc reduction()

   .. method:: proc readWriteThis(f)

.. class:: ReduceEQClass : ReduceScanOp

   .. attribute:: type keyType

   .. attribute:: type cmpType

   .. attribute:: var value: unmanaged keyTypeEquivalencecmpType

   .. method:: proc init(eq: unmanaged ?keyTypeEquivalence?cmpType)

   .. method:: proc init(type keyType, type cmpType)

   .. method:: proc identity

   .. method:: proc accumulate(x)

   .. method:: proc accumulateOntoState(ref state, x)

   .. method:: proc combine(x)

   .. method:: proc generate()

   .. method:: proc clone()

.. function:: proc main()