listiterator

A listiterator implements a forward iterator over the list type. A forward iterator is an iterator that can only be incremented. Invoking Advance on the iterator will position the iterator on the next element in the list. Elements in a list are identified by position. The positions have ordinals in the range 0 to Count -1. If there is no next element, the iterator will be positioned on the end of the list and IsEnd will be true.

Members

bool Reset

Positions the iterator to the start of the list. True is always returned.

bool Advance

The iterator is moved to the next item in the list, if one exists. True is returned if the iterator was advanced and False otherwise.

bool IsEnd

True if the iterator is at the end of the list.

string Value

Returns the element of the list under the iterator.

listiterator Clone

Returns a copy of the current listiterator. A copy has independent life and initially is over the same element as the source iterator.

Notes

Note

• If Advance returns False, IsEnd will be True.
• If IsEnd is True, then Value is undefined.

Examples

Sub ListIteratorTest
    /declare l list

    /echo 'Starting List Iterator Test'
    /echo 'Count of entries in List: ${l.Count}'

    | Add entries to the list.
    /echo 'Adding items to the list.

    /if (!${l.Append[One,Two,Three,Four,Five]}) {
        /echo 'List append failed.'
        /endmacro
    }

    /declare count int
    /varset count ${l.Count}
    /if (${count} != 5) {
        /echo 'List count is: ${count} and should be 5.'
        /endmacro
    }

    /echo 'Acquire an iterator to the start of the list.'

    | Get an iterator to the first element and output each
    | element in the list.
    /declare li listiterator
    /vardata li l.First

    /while (!${li.IsEnd}) {
        /echo ${li.Value}
        /if (${li.Advance}) {
            /echo 'Iterator advanced to next element.'
        } else {
            /echo 'Iterator not advanced. IsEnd: ${li.IsEnd}.'
            /endmacro
        }
    }

    | Test Reset and do it again.
    /echo 'Testing Reset.'

    /if (${li.Reset}) {
        /echo 'Iterator Reset.'
    } else {
        /echo 'Iterator could not be reset. IsEnd: ${li.IsEnd}.'
    }

    /while (!${li.IsEnd}) {
        /echo ${li.Value}
        /if (${li.Advance}) {
            /echo 'Iterator advanced to next element.'
        } else {
            /echo 'Iterator not advanced. IsEnd: ${li.IsEnd}.'
            /endmacro
        }
    }

    /echo 'Calling Find[Three] on the list.'

    | Acquire an iterator using Find to Three
    /vardata li l.Find[Three]

    /echo 'After Find[Three]: IsEnd: ${li.IsEnd}.'

    /while (!${li.IsEnd}) {
        /echo ${li.Value}
        /if (${li.Advance}) {
            /echo 'Iterator advanced to next element.'
        } else {
            /echo 'Iterator not advanced. IsEnd: ${li.IsEnd}.'
            /endmacro
        }
    }

    /echo 'Calling Find[Z] on the list.'

    | Acquire an iterator using Find to Z.
    /vardata li l.Find[Z]

    /if (${li.IsEnd}) {
        /echo 'IsEnd for Find[Z]: ${li.IsEnd}.'
    } else {
        /echo 'IsEnd is FALSE for Find[Z].'
        /endmacro
    }

    /echo 'Ending List Iterator Test'

    /return

This datatype is added by MQ2Collections.