org.apache.sysds.hops.rewrite

## Class RewriteRemoveDanglingParentReferences

- java.lang.Object
- - org.apache.sysds.hops.rewrite.HopRewriteRule
  - - org.apache.sysds.hops.rewrite.RewriteRemoveDanglingParentReferences

-     public class RewriteRemoveDanglingParentReferences
      extends HopRewriteRule

  This rewrite is a general-purpose cleanup pass that removes any dangling parent references in one pass through the hop DAG. These dangling references could have been introduced by rewrites that remove operators but miss a proper cleanup.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `RewriteRemoveDanglingParentReferences()`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Hop` | `rewriteHopDAG(Hop root, ProgramRewriteStatus state)` Handle a predicate hop DAG with exactly one root.
    `ArrayList<Hop>` | `rewriteHopDAGs(ArrayList<Hop> roots, ProgramRewriteStatus state)` Handle a generic (last-level) hop DAG with multiple roots.

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### RewriteRemoveDanglingParentReferences

          public RewriteRemoveDanglingParentReferences()

  - ### Method Detail

    - #### rewriteHopDAGs

          public ArrayList<Hop> rewriteHopDAGs(ArrayList<Hop> roots,
                                               ProgramRewriteStatus state)

      Description copied from class: `HopRewriteRule`
      Handle a generic (last-level) hop DAG with multiple roots.
      Specified by:
        `rewriteHopDAGs` in class `HopRewriteRule`
      Parameters:
        `roots` - high-level operator roots
        `state` - program rewrite status
      Returns:
        list of high-level operators

    - #### rewriteHopDAG

          public Hop rewriteHopDAG(Hop root,
                                   ProgramRewriteStatus state)

      Description copied from class: `HopRewriteRule`
      Handle a predicate hop DAG with exactly one root.
      Specified by:
        `rewriteHopDAG` in class `HopRewriteRule`
      Parameters:
        `root` - high-level operator root
        `state` - program rewrite status
      Returns:
        high-level operator

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