# Class ReplacementsFinder<T>

java.lang.Object
org.apache.commons.collections4.sequence.ReplacementsFinder<T>

Type Parameters:
  `T` - the type of the input to the visit operations.

All Implemented Interfaces:
  `CommandVisitor<T>`

public class ReplacementsFinder<T> extends Object implements CommandVisitor<T>
This class handles sequences of replacements resulting from a comparison.

The comparison of two objects sequences leads to the identification of common parts and parts which only belong to the first or to the second sequence. The common parts appear in the edit script in the form of keep commands, they can be considered as synchronization objects between the two sequences. These synchronization objects split the two sequences in synchronized sub-sequences. The first sequence can be transformed into the second one by replacing each synchronized sub-sequence of the first sequence by the corresponding sub-sequence of the second sequence. This is a synthetic way to see an `edit script`, replacing individual `delete`, `keep` and `insert` commands by fewer replacements acting on complete sub-sequences.

This class is devoted to perform this interpretation. It visits an `edit script` (because it implements the `CommandVisitor` interface) and calls a user-supplied handler implementing the `ReplacementsHandler` interface to process the sub-sequences.

Since:
  4.0
See Also:
  - `ReplacementsHandler`
  - `EditScript`
  - `SequencesComparator`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ReplacementsFinder(ReplacementsHandler<T> handler)`
  Simple constructor.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `visitDeleteCommand(T object)`
  Add an object to the pending deletions set.
  `void`
  `visitInsertCommand(T object)`
  Add an object to the pending insertions set.
  `void`
  `visitKeepCommand(T object)`
  Handle a synchronization object.

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

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

- ## Constructor Details

  - ### ReplacementsFinder

    public ReplacementsFinder(ReplacementsHandler<T> handler)
    Simple constructor. Creates a new instance of `ReplacementsFinder`.
    Parameters:
      `handler` - handler to call when synchronized sequences are found

- ## Method Details

  - ### visitDeleteCommand

    public void visitDeleteCommand(T object)
    Add an object to the pending deletions set.
    Specified by:
      `visitDeleteCommand` in interface `CommandVisitor<T>`
    Parameters:
      `object` - object to delete

  - ### visitInsertCommand

    public void visitInsertCommand(T object)
    Add an object to the pending insertions set.
    Specified by:
      `visitInsertCommand` in interface `CommandVisitor<T>`
    Parameters:
      `object` - object to insert

  - ### visitKeepCommand

    public void visitKeepCommand(T object)
    Handle a synchronization object.

    When a synchronization object is identified, the pending insertions and pending deletions sets are provided to the user handler as subsequences.

    Specified by:
      `visitKeepCommand` in interface `CommandVisitor<T>`
    Parameters:
      `object` - synchronization object detected