<?php

function coalesce($value, $empty) { return isset($value) ? $value : $empty; }

function starts_with($str, $prefix)

{

	return substr($str, 0, strlen($prefix)) === $prefix;

}

function ends_with($str, $suffix)

{

	return substr($str, -strlen($suffix)) === $suffix;

}

function rm_prefix($prefix, $str)

{

	return starts_with($str, $prefix) ? substr($str, strlen($prefix)) : $str;

}

function rm_suffix($suffix, $str)

{

	return ends_with($str, $suffix) ?

		substr($str, 0, strlen($str) - strlen($suffix)) : $str;

}

function ensure_prefix($prefix, $str)

{

	return starts_with($str, $prefix) ? $str : $prefix.$str;

}

function ensure_suffix($suffix, $str)

{

	return ends_with($str, $suffix) ? $str : $str.$suffix;

}

class Path

{

	public $head;

	public $tail;

	function Path($head, $tail="")

	{

		$this->head = $head;

		$this->tail = $tail;

	}

}

function partition($str, $delim)

{

	$delim_idx = strpos($str, $delim);

	return $delim_idx !== false ? new Path(substr($str, 0, $delim_idx),

		substr($str, $delim_idx+strlen($delim))) : new Path($str);

}

function array_non_empty($array)

{

	foreach ($array as $key => $value)

		if (!isset($value) || $value === "") unset($array[$key]);

	return $array;

}

function join_non_empty($delim, $array)

{

	return implode($delim, array_non_empty($array));

}

function parse_dot_path($path) { return partition($path, "."); }

function parse_mixed_path($path)

{

	preg_match('/^([\w-]*)(.*)$/', $path, $path);

	return new Path($path[1], rm_prefix(".", $path[2]));

}

function strip_url($url) { return rm_suffix("#", $url); }

?>