HTML Pagination Generator

Question

I have created a function that helps me generate pagination really easily but I am concerned about its performance mainly.

The function accepts 2 parameters:

1. A list of items (has meaning in the framework I'm using) which contains information about the state of pagination itself and state of the storage layer - more precisely:

   • page the current page
   • perpage how many items are being shown per page
   • total the total amount of items in storage.

2. Parameter name - allows to customize the query string parameter key, which is by default named page - http://example.com/news?page=1.

---

public function paginationControls(BaseList $list, $parameter = 'page') {
 if (!isset($list->pagination)) {
 return 'Error: List has not been supplied with pagination details.';
 }
 // if total results are less than the results displayed on each page
 // then do not render controls
 if ($list->pagination->perpage >= $list->pagination->total) {
 return null;
 }
 // Keep track of current query string parameters
 $query = trim(preg_replace('/' . $parameter . '\=\d+\&?/', '', $_SERVER['QUERY_STRING']), '&');
 if (strlen($query)) {
 $query .= '&';
 }
 $query .= $parameter . '=';
 $makeanchor = function($page, $current = false) use ($query) {
 if ($current) {
 $url = '#';
 $class = 'pagination anchor current';
 } else {
 $url = '?' . $query . $page;
 $class = 'pagination anchor';
 }
 return $this->a($url, $page + 1, null, ['class' => $class]);
 };
 $page = $list->pagination->page;
 $pages = ceil($list->pagination->total / $list->pagination->perpage);
 // If page is greater than 3 then display link to first page
 $output = $page > 3 ? ($makeanchor(0) . ' ... ') : '';
 // Add controls for 3 pages before current page
 $tmp = '';
 for ($i = 1; $i <= 3 && $page - $i >= 0; $i++) {
 $tmp = $makeanchor($page - $i) . $tmp;
 }
 // Add current page indicator
 $output .= $tmp . $makeanchor($page, true);
 // Add controls for 3 pages after current page
 for ($i = 1; $i <= 3 && $page + $i + 1 <= $pages; $i++) {
 $output .= $makeanchor($page + $i);
 }
 // If there are more than 3 pages after the current page
 // Then add control for last page
 if ($page + $i < $pages) {
 $output .= ' ... ' . $makeanchor($pages - 1);
 }
 return $output;
}

And here are the respective helper functions

public function a($url, $text = null, $target = null, array $attributes = array()) {
 $attributes['href'] = $url;
 if ($target !== null) {
 $attributes['target'] = $target;
 }
 if ($text === null) {
 $text = $attributes['href'];
 }
 return '<a' . $this->parseAttributes($attributes) . '>' . html($text) . '</a>';
}
private function parseAttributes($attributes) {
 $string = '';
 foreach ($attributes as $attribute => $value) {
 $string .= ' ' . html($attribute) . '="' . html($value) . '"';
 }
 return $string;
}

In a class far, far away

function html($string, $flag = ENT_QUOTES, $encoding = 'UTF-8') {
 return htmlspecialchars($string, $flag, $encoding);
}

I'm mainly interested in optimizing this function in terms of performance, it would be very much appreciated if someone more experienced than me can have a say on this.

• coderodde: I like your code, eww, you sexy lady!

Answer 1

Your code looks clean. The suggested changes below mainly focuses on reducing it a bit, so IMO improving its readability.
But I'm not quite sure it'll also improve performance as you said you're interested to: I only hope some light gain could come from having suppressed your $makeanchor() function.

Changes I propose affect only your main paginationControl() function:

public function paginationControls(BaseList $list, $parameter = 'page') {
 if (!isset($list->pagination)) {
 return 'Error: List has not been supplied with pagination details.';
 }
 // if total results are less than the results displayed on each page
 // then do not render controls
 if ($list->pagination->perpage >= $list->pagination->total) {
 return null;
 }
 // Keep track of current query string parameters
 $query = preg_replace('/' . $parameter . '\=\d+\&?/', '', $_SERVER['QUERY_STRING']);
 if ($query) {
 $query .= '&';
 }
 $query .= $parameter . '=';
 $page = $list->pagination->page;
 $pages = ceil($list->pagination->total / $list->pagination->perpage);
 // Prepare link to first page, if needed
 if ($page > 3) {
 $pageSet['1...'] = FALSE;
 }
 // Prepare link to 3 pages before + current + 3 pages after
 for ($i = $page - 3; $i <= $page + 3; $i++) {
 if ($i AND $i <= $pages) {
 $pageSet[$i] = ($i == $page);
 }
 }
 // Prepare link to last page, if needed
 if ($i < $pages) {
 $pageSet['...' . $pages] = FALSE;
 }
 // Build output
 $output = NULL;
 $classes = 'pagination anchor';
 foreach ($pageSet as $pageNo => $current) {
 $output .= $this->a(
 ($current ? '#' : '?' . $query . $pageNo),
 $pageNo,
 NULL,
 ($classes . ($current ? 'current' : NULL))
 );
 }
 return $output;
}

Apart from the way to build pagination, you'll notice that:

• I dropped trim(..., '&') from your $query = ..., since "&" has already suppressed by preg_replace(); otherwise it sounds like you suspect the whole query to abusively include an ending "&"
• at the just next line, I dropped strlen() from if ($query), which is enough (and may be slightly faster, but it is only cosmetic)