Fold

All Known Implementing Classes:

FoldLeftFn.FoldLeftFold, Sum.SumFold
```
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