Add to the second position of a Fluid array - typo3

Question

Currently I have this code that wraps every 2 items with <li></li>
<f:for each="{modules}" as="module" iteration="loop">
<f:cycle values="{0: 1, 1: 0}" as="header">
<li>
</f:cycle>
...stuff here...
<f:cycle values="{0: 0, 1: 1}" as="footer">
</li>
</f:cycle>
</f:for>
Lets say {modules} = [A,B,C,D] and output is something like this:
<li>AB</li>
<li>CD</li>
What I need to do is add custom html to the second position. So my desired output is:
<li>AX</li>
<li>BC</li>
<li>D</li>
How can I do this?

Answer 1

To your updated question I would say, you may want to solve this issue with your own Helper class before adding modules to the View through the Controller.
It is however possible to build it simple in the template:
Here is the documentation about the for ViewHelper.
For simplicity I would do the following:
<f:for each="{modules}" as="module" iteration="loop">
<f:if condition="{loop.isFirst}">
<f:then>
<li>
{module}
##extra_code##
</li>
</f:then>
<f:else>
<f:if condition="{loop.isEven}">
<li>
</f:if>
...stuff here...
<f:if condition="{loop.isOdd} || {loop.isLast}">
</li>
</f:if>
</f:else>
</f:if>
</f:for>
Note: The first element will be "odd" because isOdd takes the current interation (based on "cycle"), which starts with 1.
For the first element there is your own block. You can take the first module and write your own code. It will run only once.
From the second element to the last it will use the 2 element in one li logic. Here is only one interesting thing, that we need take isOdd OR isLast to always close the last li, even if you have an even number of elements.

Answer 2

You can do this like below.
<f:for each="{modules}" as="module" iteration="iteration">
<f:if condition="{iteration.isFirst}">
<f:then>
<li>
</f:then>
<f:else>
<f:if condition="{iteration.index}%2">
<f:then></f:then>
<f:else><li></f:else>
</f:if>
</f:else>
</f:if>
<!--
Here Your Content
-->
<f:if condition="{iteration.isLast}">
<f:then>
</li>
</f:then>
<f:else>
<f:if condition="{iteration.cycle}%2">
<f:then></f:then>
<f:else></li></f:else>
</f:if>
</f:else>
</f:if>
</f:for>