Package net.sf.saxon.expr.instruct

## Class BlockIterator

- java.lang.Object
- - net.sf.saxon.expr.instruct.BlockIterator

- All Implemented Interfaces:
    `java.io.Closeable`, `java.lang.AutoCloseable`, `SequenceIterator`

      public class BlockIterator
      extends java.lang.Object
      implements SequenceIterator

  Iterate over the instructions in a sequence of instructions (or an XPath comma expression), concatenating the result of each instruction into a single combined sequence.

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator

      `SequenceIterator.Property`

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `BlockIterator​(Operand[] operanda, XPathContext context)` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `close()` | Close the iterator.
    `Item` | `next()` | Get the next item in the sequence.

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

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

    - ### Methods inherited from interface net.sf.saxon.om.SequenceIterator

      `forEachOrFail, getProperties, materialize`

- - ### Constructor Detail

    - #### BlockIterator

          public BlockIterator​(Operand[] operanda,
                               XPathContext context)

  - ### Method Detail

    - #### next

          public Item next()
                    throws XPathException

      Get the next item in the sequence.
      Specified by:
        `next` in interface `SequenceIterator`
      Returns:
        the next item, or null if there are no more items.
      Throws:
        `XPathException` - if an error occurs retrieving the next item

    - #### close

          public void close()

      Description copied from interface: `SequenceIterator`
      Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

      For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.

      Closing an iterator is important when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.

      Specified by:
        `close` in interface `java.lang.AutoCloseable`
      Specified by:
        `close` in interface `java.io.Closeable`
      Specified by:
        `close` in interface `SequenceIterator`