FindNextItem (GenericNamedArraylist function): Difference between revisions

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m (match syntax table to diagram, couple of tags, lots of edits)
m (name required)
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<tr><th>Start</th>
<tr><th>Start</th>
<td>The <var class="term">number</var> of the item <b><i>after</i></b> which to begin the search. If the <var class="term">number</var> value of <var class="term">Start</var> is 2, item 3 is the first item considered. The value of <var class="term">Start</var> may be 0 through the number of items in the <var>NamedArraylist</var>. For a <var>NamedArraylist</var>of three items, <var class="term">number</var> may be 0, 1, 2, or 3.
<td>The <var class="term">number</var> of the item <b><i>after</i></b> which to begin the search. If the <var class="term">number</var> value of <var class="term">Start</var> is 2, item 3 is the first item considered. The value of <var class="term">Start</var> may be 0 through the number of items in the <var>NamedArraylist</var>. For a <var>NamedArraylist</var>of three items, <var class="term">number</var> may be 0, 1, 2, or 3.
<p>This is an optional argument, and it defaults to 0. If you specify a value, the parameter name <var class="term">number</var> is required.</p></td></tr>
<p>This is an optional, but <var>[[Methods#Named parameters|Name-Required]]</var>, argument which defaults to 0. If you specify a value, the parameter name <var class="term">number</var> is required.</p></td></tr>
</table>
</table>


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The following request contains two FindNextItem calls and one FindPreviousItem
The following request contains two FindNextItem calls and one FindPreviousItem
call, each with a class Variable as the function in the SelectionCriterion:
call, each with a class Variable as the function in the SelectionCriterion:
<p class="code">Begin
<p class="code">begin
class staff
  class staff
public
      public
  variable name is string len 20
        variable name is string len 20
  variable status is string len 8
        variable status is string len 8
  constructor newf(%a is string len 10, -
        constructor newf(%a is string len 10, -
    %b string len 8)
          %b string len 8)
  function myprint is longstring
        function myprint is longstring
end public
      end public
   
   
constructor newf(%a is string len 10, -
      constructor newf(%a is string len 10, -
  %b string len 8)
        %b string len 8)
  %this:name = %a
        %this:name = %a
  %this:status = %b
        %this:status = %b
end constructor
      end constructor
   
   
function myprint is longstring
      function myprint is longstring
  return %this:name with ' ' with %this:status
        return %this:name with ' ' with %this:status
  end function
      end function
end class
  end class
   
   
%stf is object staff
  %stf is object staff
%old is namedArraylist of object staff
  %old is namedArraylist of object staff
%old = new
  %old = new
%old('Jim') = newf('Red', 'employed')
  %old('Jim') = newf('Red', 'employed')
%old('Jed') = newf('Black', 'retired')
  %old('Jed') = newf('Black', 'retired')
%old('Jan') = newf('Green', 'employed')
  %old('Jan') = newf('Green', 'employed')
%old('Jud') = newf('Brown', 'retired')
  %old('Jud') = newf('Brown', 'retired')
%old('Jon') = newf('White', 'tired')
  %old('Jon') = newf('White', 'tired')
   
   
%stf = %old:findNextItem(Eq(status, 'employed'))
  %stf = %old:findNextItem(Eq(status, 'employed'))
print %stf:myprint
  print %stf:myprint
   
   
%stf = %old:findNextItem(Gt(name, 'Starks'))
  %stf = %old:findNextItem(Gt(name, 'Starks'))
print %stf:myprint
  print %stf:myprint
   
   
%stf = %old:findPreviousItem(AND(Lt(name, 'Starks'), -
  %stf = %old:findPreviousItem(AND(Lt(name, 'Starks'), -
                            Eq(status, 'employed')))
                              Eq(status, 'employed')))
print %stf:myprint
  print %stf:myprint
end
End
</p>
</p>



Revision as of 08:16, 3 March 2011

Next item that matches some selection criteria (FloatNamedArraylist, NamedArraylist, and UnicodeNamedArraylist classes)


FindNextItem searches "forward" in the NamedArraylist to find and return the next item that matches a specified criterion. The criterion is supplied by the SelectionCriterion object that is a required FindNextItem parameter. If no item satisfies the criterion, the request is cancelled and an ItemNotFound exception is thrown.

Syntax

%item = anyNal:FindNextItem( selectionCriterion, [Start= number]) Throws ItemNotFound

Syntax terms

%item A variable of the type of the items in the NamedArraylist to contain the item that is located by the search.
anyNal A NamedArraylist object.
selectionCriterion A SelectionCriterion object, which is a relational expression that is applied to a anyNal item values to determine whether the value satisfies the expression. The expression consists of a function, an operator, and a numeric or string value.

For example, GT(this, -11) is the criterion this > -11, where this is an identity function that simply returns the item's value. The first item tested by FindNextItem that satisfies this expression is the method's return value.

The function in the criterion is a method value (a method or class member name literal, or a method variable) for a method that operates on items of the type specified on the anyNal declaration and that returns a numeric or string value. This is described further in "Specifying a SelectionCriterion's parameters".

Start The number of the item after which to begin the search. If the number value of Start is 2, item 3 is the first item considered. The value of Start may be 0 through the number of items in the NamedArraylist. For a NamedArraylistof three items, number may be 0, 1, 2, or 3.

This is an optional, but Name-Required, argument which defaults to 0. If you specify a value, the parameter name number is required.

Usage notes

  • If the value of Start is greater than the number of items in the NamedArraylist, the request is cancelled. If the value of Start is equal to the number of items, the request is cancelled, but an ItemNotFound exception is thrown.
  • FindNextItem is available in "Sirius Mods" Version 7.6 and later.

Examples

  1. The following request contains two FindNextItem calls and one FindPreviousItem call, each with a class Variable as the function in the SelectionCriterion:

    begin class staff public variable name is string len 20 variable status is string len 8 constructor newf(%a is string len 10, - %b string len 8) function myprint is longstring end public constructor newf(%a is string len 10, - %b string len 8) %this:name = %a %this:status = %b end constructor function myprint is longstring return %this:name with ' ' with %this:status end function end class %stf is object staff %old is namedArraylist of object staff %old = new %old('Jim') = newf('Red', 'employed') %old('Jed') = newf('Black', 'retired') %old('Jan') = newf('Green', 'employed') %old('Jud') = newf('Brown', 'retired') %old('Jon') = newf('White', 'tired') %stf = %old:findNextItem(Eq(status, 'employed')) print %stf:myprint %stf = %old:findNextItem(Gt(name, 'Starks')) print %stf:myprint %stf = %old:findPreviousItem(AND(Lt(name, 'Starks'), - Eq(status, 'employed'))) print %stf:myprint end

    The result is:

    Green employed White tired Red employed

See also

  • FindPreviousItem is identical to FindNextItem except that it searches backward in the NamedArraylist.