Conditional Fields Graph Implementation

conditionalField.php

<?php

class Node
{
    public $id;

    public function __construct($id)
    {
        $this->id = $id;
    }

    /**
     * Should show is the edge between different nodes and answers with an anonymous function
     * should the parent show the field passed in. The functions returns the field to be showed
     * if the function rules is true. This would get attached to an event listener at runtime
     * and be check when the event is fired.
     *
     * @param Node $field
     * @param mixed $rules | An anonymous function that returns true if the conditions are true
     *
     * @return Node|false
     */
    public function shouldShow(Node $field, $rules)
    {
        if ($rules()) {
            return $field;
        }
        return false;
    }
}


// We can have hard coded operators. This is a
function contains($fieldContents, $target) 
{
    if (strpos($fieldContents, $target)) {
        return true;
    } else {
        return false;
    }
}

$notContains = function ($fieldContents, $target) {
    return !contains($fieldContents, $target);
};

$A = new Node(1234);
$B = new Node(5678);
echo $A->shouldShow($B, contains('USA is my home country', 'USA'));
echo $A->shouldShow($B, $notContains('USA is my home', 'USA'));