Package net.sf.saxon.functions

## Interface Fold

- All Known Implementing Classes:
    `FoldLeftFn.FoldLeftFold`

      public interface Fold

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `boolean` | `isFinished()` | Ask whether the computation has completed.
    `void` | `processItem​(Item item)` | Process one item in the input sequence, returning a new copy of the working data
    `Sequence` | `result()` | Compute the final result of the function, when all the input has been processed

- - ### Method Detail

    - #### processItem

          void processItem​(Item item)
                    throws XPathException

      Process one item in the input sequence, returning a new copy of the working data
      Parameters:
        `item` - the item to be processed from the input sequence
      Throws:
        `XPathException` - if a dynamic error occurs

    - #### isFinished

          boolean isFinished()

      Ask whether the computation has completed. A function that can deliver its final result without reading the whole input should return true; this will be followed by a call on result() to deliver the final result.
      Returns:
        true if the result of the function is now available even though not all items in the sequence have been processed

    - #### result

          Sequence result()
                   throws XPathException

      Compute the final result of the function, when all the input has been processed
      Returns:
        the result of the function
      Throws:
        `XPathException` - if a dynamic error occurs