egroupware/api/etemplate.php

611 lines
23 KiB
PHP

<?php
/**
* API: loading for web-components modified eTemplate from server
*
* Usage: /egroupware/api/etemplate.php/<app>/templates/default/<name>.xet
*
* @link https://www.egroupware.org
* @author Ralf Becker <rb@egroupware-org>
* @package api
* @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
*/
use EGroupware\Api;
// add et2- prefix to following widgets/tags, if NO <overlay legacy="true"
const ADD_ET2_PREFIX_REGEXP = '#<((/?)([vh]?box)|vfs-select)(/?|\s[^>]*)>#m';
const ADD_ET2_PREFIX_LAST_GROUP = 4;
// unconditional of legacy add et2- prefix to this widgets
const ADD_ET2_PREFIX_LEGACY_REGEXP = '#<((/?)(tabbox|description|searchbox|textbox|label|avatar|lavatar|image|appicon|colorpicker|checkbox|url(-email|-phone|-fax)?|vfs-mime|vfs-uid|vfs-gid|vfs-select|link|link-[a-z]+|favorites))(/?|\s[^>]*)>#m';
const ADD_ET2_PREFIX_LEGACY_LAST_GROUP = 5;
// switch evtl. set output-compression off, as we can't calculate a Content-Length header with transparent compression
ini_set('zlib.output_compression', 0);
$GLOBALS['egw_info'] = array(
'flags' => array(
'currentapp' => 'api',
'noheader' => true,
// miss-use session creation callback to send the template, in case we have no session
'autocreate_session_callback' => 'send_template',
'nocachecontrol' => true,
)
);
$start = microtime(true);
include dirname(__DIR__).'/header.inc.php';
send_template();
/**
* Give usage plus option error and exit
*
* @param string $prog
* @param string? $err
* @return void
*/
function usage($prog, $err=null)
{
error_log("Usage: $prog [(-i|--in-place)] <xet-file>\n");
error_log("\t convert <xet-file> to new syntax and output or replace it in-place.\n\n");
if ($err) error_log("$err\n\n");
exit;
}
function send_template()
{
$header_include = microtime(true);
if (PHP_SAPI === 'cli')
{
$in_place = false;
$args = $_SERVER['argv'];
$prog = array_shift($args);
while($args[0][0] === '-')
{
switch($arg = array_shift($args))
{
case '-i':
case '--in-place':
$in_place = true;
break;
default:
usage($prog, "Invalid argument '$arg'!");
}
if (count($args) !== 1)
{
usage($prog);
}
}
$fspath = array_shift($args);
if ($fspath[0] !== '/') $fspath = '/'.$fspath;
}
else
{
// release session, as we don't need it and it blocks parallel requests
$GLOBALS['egw']->session->commit_session();
header('Content-Type: application/xml; charset=UTF-8');
$fspath = $_SERVER['PATH_INFO'];
}
// check for customized template in VFS
list(, $app, , $template, $name) = explode('/', $fspath);
$path = Api\Etemplate::rel2path(Api\Etemplate::relPath($app . '.' . basename($name, '.xet'), $template));
if(empty($path) || !file_exists($path) || !is_readable($path))
{
if (PHP_SAPI === 'cli')
{
usage("Path '$path' NOT found!");
}
else
{
http_response_code(404);
}
exit;
}
$cache = $GLOBALS['egw_info']['server']['temp_dir'] . '/egw_cache/eT2-Cache-' .
$GLOBALS['egw_info']['server']['install_id'] . '-' . str_replace('/', '-', $_SERVER['PATH_INFO']) . '-' . filemtime($path);
if (PHP_SAPI !== 'cli' && file_exists($cache) && filemtime($cache) > max(filemtime($path), filemtime(__FILE__)) &&
($str = file_get_contents($cache)) !== false)
{
$cache_read = microtime(true);
}
elseif(($str = file_get_contents($path)) !== false)
{
// replace single quote enclosing attribute values with double quotes
$str = preg_replace_callback("#([a-z_-]+)='([^']*)'([ />])#i", static function($matches){
return $matches[1].'="'.str_replace('"', '&quot;', $matches[2]).'"'.$matches[3];
}, $str);
// fix <menulist...><menupopup type="select-*"/></menulist> --> <select type="select-*" .../>
$str = preg_replace('#<menulist([^>]*)>[\r\n\s]*(<!--[^>]+-->[\r\n\s]*)?<menupopup([^>]+>)[\r\n\s]*</menulist>#', '$2<select$1$3', $str);
$str = preg_replace('#<menupopup([^>]*)>#', '<select$1>', $str);
// fix legacy options, so new client-side has not to deal with them
$str = preg_replace_callback('#<([^- />]+)(-[^ ]+)?[^>]* (options="([^"]+)")[ />]#', static function ($matches) {
// take care of (static) type attribute, if used
if (preg_match('/ type="([a-z-]+)"/', $matches[0], $type))
{
str_replace('<' . $matches[1] . $matches[2], '<' . $type[1], $matches[0]);
str_replace($type[0], '', $matches[0]);
list($matches[1], $matches[2]) = explode('-', $type[1], 2);
if (!empty($matches[2])) $matches[2] = '-'.$matches[2];
}
static $legacy_options = array(
// use "ignore" to ignore further comma-sep. values, otherwise they are all in last attribute
'select' => 'empty_label,ignore',
'select-account' => 'empty_label,account_type,ignore',
'select-number' => 'empty_label,min,max,interval,suffix',
'select-cat' => 'empty_label,global_categories,ignore,application,parentCat,owner',
'box' => ',cellpadding,cellspacing,keep',
'hbox' => 'cellpadding,cellspacing,keep',
'vbox' => 'cellpadding,cellspacing,keep',
'groupbox' => 'cellpadding,cellspacing,keep',
'checkbox' => 'selected_value,unselected_value,ro_true,ro_false',
'radio' => 'set_value,ro_true,ro_false',
'customfields' => 'type_filter,private,fields',
'date' => 'data_format,ignore',
// Legacy option "mode" was never implemented in et2
'description' => 'bold-italic,link,activate_links,label_for,link_target,link_popup_size,link_title',
'button' => 'image,ro_image',
'buttononly' => 'image,ro_image',
'link' => 'app',
'link-entry' => 'only_app,application_list',
'nextmatch-filterheader' => 'empty_label',
// disable legacy-options conversation for nm-customfilter as it breaks infolog and addressbook index templates
//'nextmatch-customfilter' => 'widget_type,widget_options',
'nextmatch-accountfilter' => 'empty_label,account_type,ignore',
);
// prefer more specific type-subtype over just type
$names = $legacy_options[$matches[1] . $matches[2]] ?? $legacy_options[trim($matches[1])] ?? null;
if (isset($names))
{
$names = explode(',', $names);
$values = Api\Etemplate\Widget::csv_split($matches[4], count($names));
if (count($values) < count($names))
{
$values = array_merge($values, array_fill(count($values), count($names) - count($values), ''));
}
$attrs = array_diff(array_combine($names, $values), ['', null]);
unset($attrs['ignore']);
// fix select options can be either multiple or empty_label
if ($matches[1] === 'select' && !empty($attrs['empty_label']) && (int)$attrs['empty_label'] > 0)
{
$attrs['multiple'] = (int)$attrs['empty_label'];
unset($matches['empty_label']);
}
$options = '';
foreach ($attrs as $attr => $value)
{
$options .= $attr . '="' . $value . '" ';
}
return str_replace($matches[3], $options, $matches[0]);
}
return $matches[0];
}, $str);
// Change details title --> summary (This can currently not kope with nested details like in smallpart.curse.xet
$str = preg_replace_callback('#<details([^>]*?)>(.*?)</details>#su', static function ($matches)
{
$attrs = parseAttrs($matches[1]);
if (isset($attrs['title']) && !isset($attrs['summary']))
{
$attrs['summary'] = $attrs['title'];
unset($attrs['title']);
}
return "<et2-details" . stringAttrs($attrs) . '>' . $matches[2] . "</et2-details>";
}, $str);
// Change splitter dockside -> primary + vertical
$str = preg_replace_callback('#<split([^>]*?)>(.*?)</split>#su', static function ($matches)
{
$tag = 'et2-split';
$attrs = parseAttrs($matches[1]);
$attrs['vertical'] = $attrs['orientation'] === 'h' ? "true" : "false";
if (str_contains($attrs['dock_side'], 'top') || str_contains($attrs['dock_side'], 'left'))
{
$attrs['primary'] = "end";
}
elseif (str_contains($attrs['dock_side'], 'bottom') || str_contains($attrs['dock_side'], 'right'))
{
$attrs['primary'] = "start";
}
unset($attrs['dock_side']);
return "<$tag" . stringAttrs($attrs) . '>' . $matches[2] . "</$tag>";
}, $str);
// modify <(image|description) expose_view="true" --> <et2-*-expose
$str = preg_replace('/<(image|description)\s([^><]*)expose_view="true"\s([^><]*)\\/>/',
'<et2-$1-expose $2 $3></et2-$1-expose>', $str);
// fix <textbox multiline="true" or rows="..." --> <et2-textarea .../>
$str = preg_replace('#<textbox(.*?)\smultiline="true"(.*?)/>#', '<et2-textarea$1$2></et2-textarea>', $str);
$str = preg_replace('#<textbox(.*?\srows="\d+".*?)/>#', '<et2-textarea$1></et2-textarea>', $str);
// fix <(textbox|int(eger)?|float|passwd) precision="int(eger)?|float|passwd" .../> --> <et2-number precision=.../>, <et2-password .../> or <et2-textbox .../>
$str = preg_replace_callback('#<(textbox|int(eger)?|float|number|passwd).*?\s(type="(int(eger)?|float|passwd)")?.*?(/|></textbox)>#',
static function ($matches)
{
if ($matches[1] === 'passwd' || $matches['4'] === 'passwd')
{
return '<et2-password'.str_replace('type="passwd"', '',
substr($matches[0], 1+strlen($matches[1]), -strlen($matches[6])-1)).'></et2-password>';
}
if ($matches[1] === 'textbox' && !in_array($matches[4], ['float', 'int', 'integer'], true))
{
return '<et2-'.substr($matches[0], 1, -strlen($matches[6])-1).'></et2-textbox>'; // regular textbox --> nothing to do
}
$type = $matches[1] === 'float' || $matches[4] === 'float' ? 'float' : 'int';
$tag = str_replace('<' . $matches[1], '<et2-number', substr($matches[0], 0, -2));
if (!empty($matches[3])) $tag = str_replace($matches[3], '', $tag);
if ($type !== 'float') $tag .= ' precision="0"';
return $tag . '></et2-number>';
}, $str);
// replace just description, as they often contain >, like label="> %s"
$str = preg_replace('#<description\s*/>#', '<et2-description></et2-description>', $str);
$str = preg_replace('#<description\s(.*?")\s*/>#s', '<et2-description $1></et2-description>', $str);
// modify <(vfs-mime|link-string|link-list) --> <et2-*
$str = preg_replace_callback(ADD_ET2_PREFIX_LEGACY_REGEXP, static function (array $matches) {
return '<' . $matches[2] . 'et2-' . $matches[3] .
// web-components must not be self-closing (no "<et2-button .../>", but "<et2-button ...></et2-button>")
(substr($matches[ADD_ET2_PREFIX_LEGACY_LAST_GROUP], -1) === '/' ? substr($matches[ADD_ET2_PREFIX_LEGACY_LAST_GROUP], 0, -1) .
'></et2-' . $matches[3] : $matches[ADD_ET2_PREFIX_LEGACY_LAST_GROUP]) . '>';
}, $str);
// change link attribute only_app to et2-link attribute app and map r/o link-entry to link
$str = preg_replace_callback('#<et2-link(-[a-z]+)?([^>]*?)></et2-link(-[a-z]+)?>#su', static function ($matches)
{
$tag = 'et2-link'.$matches[1];
$attrs = parseAttrs($matches[2]);
if ($tag === 'et2-link-entry' && !empty($attrs['readonly']) || $tag === 'et2-link')
{
$tag = 'et2-link';
$attrs['app'] = $attrs['app'] ?? $attrs['only_app'];
unset($attrs['only_app'], $attrs['readonly']);
}
return "<$tag" . stringAttrs($attrs) . "></$tag>";
}, $str);
// handling of select and taglist widget, incl. removing of type attribute
$str = preg_replace_callback('#<(select|taglist|listbox)(-[^ ]+)? ([^>]+?)(/|>(.*?)</(select|taglist|listbox))>#s', static function (array $matches)
{
$attrs = parseAttrs($matches[3]);
// ignore tags for select-country, it was never used to get multiple countries
if (isset($attrs['tags']) && ($attrs['type'] === 'select-country' || str_starts_with($matches[0], '<select-country')))
{
unset($attrs['tags']);
}
// set multiple for old tags attribute or taglist without maxSelection="1"
if (isset($attrs['tags']) || $matches['1'] === 'taglist' && (empty($attrs['maxSelection']) || $attrs['maxSelection'] > 1))
{
$attrs['multiple'] = 'true';
unset($attrs['tags']);
}
// converting taglist to et2-select
if($matches['1'] === 'taglist')
{
// taglist had allowFreeEntries and enableEditMode with a default of true, while et2-select has it with a default of false
if(!$matches[2] && !isset($attrs['allowFreeEntries']) && (empty($matches[5]) || !preg_match('#</?option(\s[^>]+|/)>#', $matches[5])))
{
$attrs['allowFreeEntries'] = 'true';
if(!isset($attrs['editModeEnabled']))
{
$attrs['editModeEnabled'] = 'true';
}
}
// only set (default) searchUrl for regular taglist or taglist-email, or if a non-empty autocomplete_url was given
if (empty($matches['2']) || $matches[2] === '-email' || !empty($attrs['autocomplete_url']))
{
$attrs['searchUrl'] = $attrs['autocomplete_url'] ?? 'EGroupware\\Api\\Etemplate\\Widget\\Taglist::'.
($matches[2] === '-email' ? 'ajax_email' : 'ajax_search');
if (isset($attrs['autocomplete_params']))
{
$attrs['searchOptions'] = $attrs['autocomplete_params'];
}
}
unset($attrs['autocomplete_url'], $attrs['autocomplete_params']);
if (isset($attrs['maxSelection']) && $attrs['maxSelection'] === '1')
{
unset($attrs['multiple'], $attrs['maxSelection']);
}
}
// no multiple="toggle" or expand_multiple_rows="N" currently, thought Shoelace's select multiple="true" is relative close
// until we find something better, just switch to multiple="true"
if (isset($attrs['multiple']) && $attrs['multiple'] === 'toggle' || !empty($attrs['expand_multiple_rows']))
{
$attrs['multiple'] = 'true';
unset($attrs['expand_multiple_rows']);
}
// <select rows="N" (to show N rows) previously also switched multiple on
if (!empty($attrs['rows']) && (int)$attrs['rows'] > 1)
{
$attrs['multiple'] = true;
}
else
{
unset($attrs['rows']);
}
// automatic convert empty_label for multiple=true to a placeholder
if (!empty($attrs['empty_label']) && !empty($attrs['multiple']))
{
$attrs['placeholder'] = $attrs['empty_label'];
unset($attrs['empty_label']);
}
// type attribute need to go in widget type <select type="select-account" --> <et2-select-account
if (empty($matches[2]) && isset($attrs['type']))
{
$matches[2] = preg_replace('/^(select|taglist)/', '', $attrs['type']);
unset($attrs['type']);
}
return '<et2-select' . $matches[2] . stringAttrs($attrs) . '>'.$matches[5].'</et2-select' . $matches[2] . '>';
}, $str);
// use et2-email instead of et2-select-email
$str = preg_replace('#<et2-select-email\s(.*?")\s*></et2-select-email>#s', '<et2-email $1></et2-email>', $str);
// nextmatch headers
$str = preg_replace_callback('#<(nextmatch-)([^ ]+)(header|filter) ([^>]+?)/>#s', static function (array $matches)
{
$attrs = parseAttrs($matches[4]);
if ($matches[2] === 'custom')
{
$attrs['widget_type'] = $attrs['type'];
}
if(!$matches[2] || in_array($matches[2], ['sort']) || ($matches[2] == "custom" && empty($attrs['widget_type'])))
{
return $matches[0];
}
// No longer needed & type causes problems
unset($attrs['type'], $attrs['tags']);
if($matches[2] === 'taglist')
{
$matches[2] = "filter";
}
return '<et2-nextmatch-header-' . $matches[2] . stringAttrs($attrs) . '/>';
}, $str);
// fix <(button|buttononly|timestamper).../> --> <et2-(button|image|button-timestamp) (noSubmit="true")?.../>
$str = preg_replace_callback('#<(button|buttononly|timestamper|button-timestamp|dropdown_button)\s(.*?)(/|></(button|buttononly|timestamper|button-timestamp|dropdown_button))>#s', function ($matches) use ($name)
{
$tag = 'et2-button';
$attrs = parseAttrs($matches[2]);
switch ($matches[1])
{
case 'buttononly': // replace buttononly tag with noSubmit="true" attribute
$attrs['noSubmit'] = 'true';
break;
case 'timestamper':
case 'button-timestamp':
$tag .= '-timestamp';
$attrs['background_image'] = 'true';
break;
case 'dropdown_button':
$tag = 'et2-dropdown-button';
break;
}
// novalidation --> noValidation
if (!empty($attrs['novalidation']) && in_array($attrs['novalidation'], ['true', '1'], true))
{
unset($attrs['novalidation']);
$attrs['noValidation'] = 'true';
}
// replace not set background_image attribute with et2-button-icon tag, if not in NM / lists
if (!empty($attrs['image']) && (empty($attrs['background_image']) || $attrs['background_image'] === 'false') &&
empty($attrs['label']) && !preg_match('/^(index|list)/', $name))
{
$tag = 'et2-button-icon';
}
unset($attrs['background_image']);
return "<$tag" . stringAttrs($attrs) . '></' . $tag . '>';
}, $str);
$str = preg_replace('#<time_or_date\s([^>]+)/>#', '<et2-date-time-today $1></et2-date-time-today>', $str);
$str = preg_replace_callback('#<date(-time[^\s]*|-duration|-since)?\s([^>]+)/>#', static function($matches)
{
if ($matches[1] === '-time_today') $matches[1] = '-time-today';
return "<et2-date$matches[1] $matches[2]></et2-date$matches[1]>";
}, $str);
// replace <tree(-cat)? multiple="..." with <et2-tree(-cat)(-multiple) and fix attributes
$str = preg_replace_callback('#<tree(-cat)?\s(.*?)\s*/>#s', static function (array $matches)
{
$tag = 'et2-tree'.($matches[1] ?? '');
$attrs = parseAttrs($matches[2]);
if (!empty($attrs['multiple']) && $attrs['multiple'] !== 'false' ||
!empty($attrs['options']) && (int)$attrs['options'] > 1)
{
$tag .= '-multiple';
}
// fix renamed attrs, thought regular under_score to camelCase happens later
if (!empty($attrs['parent_node'])) $attrs['parentId'] = $attrs['parent_node'];
unset($attrs['multiple'], $attrs['options'], $attrs['parent_node']);
return "<$tag" . stringAttrs($attrs) . "></$tag>";
}, $str);
if ($template === 'mobile')
{
}
// ^^^^^^^^^^^^^^^^ above widgets get transformed independent of legacy="true" set in overlay ^^^^^^^^^^^^^^^^^^
// eTemplate marked as legacy --> replace only some widgets (eg. requiring jQueryUI) with web-components
if (!preg_match('/<overlay[^>]* legacy="true"/', $str))
{
$str = preg_replace_callback(ADD_ET2_PREFIX_REGEXP, static function (array $matches) {
return '<' . $matches[2] . 'et2-' . $matches[3] .
// web-components must not be self-closing (no "<et2-button .../>", but "<et2-button ...></et2-button>")
(substr($matches[ADD_ET2_PREFIX_LAST_GROUP], -1) === '/' ? substr($matches[ADD_ET2_PREFIX_LAST_GROUP], 0, -1) .
'></et2-' . $matches[3] : $matches[ADD_ET2_PREFIX_LAST_GROUP]) . '>';
}, $str);
}
// change all attribute-names of new et2-* widgets to camelCase, and other attribute modifications for all web-components
$str = preg_replace_callback('#<(et2|records)-([a-z-]+)\s(.*?")\s*/?>#s', static function(array $matches)
{
$attrs = parseAttrs($matches[3]);
// fix deprecated attributes: needed, blur, ...
static $deprecated = [
'needed' => 'required',
'blur' => 'placeholder',
];
foreach($attrs as $name => $value)
{
if (isset($deprecated[$name]))
{
unset($attrs[$name]);
$attrs[$name = $deprecated[$name]] = $value;
}
if (count($parts = preg_split('/[_-]/', $name)) > 1)
{
if ($name === 'parent_node') $parts[1] = 'Id'; // we can not use DOM property parentNode --> parentId
$attrs[array_shift($parts).implode('', array_map('ucfirst', $parts))] = $value;
unset($attrs[$name]);
}
}
// remove no longer necessary et2_fullWidth class, it's the default now anyway
if (isset($attrs['class']) && empty($attrs['class'] = trim(preg_replace('/(^| )et2_fullWidth( |$)/', ' ', $attrs['class']))))
{
unset($attrs['class']);
}
// Drop all (old) size attributes of input like fields, if it's not shoelace size format: small, medium or large
if (preg_match('/^<et2-(textbox|number|int|float|password|url|vfs-|input)/', $matches[0]) &&
isset($attrs['size']) && !in_array($attrs['size'], ['small', 'medium', 'large']))
{
unset($attrs['size']);
}
return str_replace($matches[3], stringAttrs($attrs).(substr($matches[3], -1) === '/' ? '/' : ''), $matches[0]);
}, $str);
$processing = microtime(true);
if (isset($cache) && (file_exists($cache_dir = dirname($cache)) || mkdir($cache_dir, 0755, true) || is_dir($cache_dir)))
{
file_put_contents($cache, $str);
}
}
// stop here for not existing file or path-traversal for both file and cache here
if(empty($str) || strpos($path, '..') !== false)
{
if (PHP_SAPI === 'cli')
{
usage("Path '$path' NOT found!");
}
else
{
http_response_code(404);
}
exit;
}
// remove old CSV Id
$str = trim(str_replace("<!-- \$Id$ -->\n", '', $str))."\n";
// replace DTD
$str = preg_replace('/^<!DOCTYPE.*>$/m',
'<!DOCTYPE overlay PUBLIC "-//EGroupware GmbH//eTemplate 2.0//EN" "https://www.egroupware.org/etemplate2.0.dtd">', $str);
// cli just echos or updates the file
if (PHP_SAPI === 'cli')
{
if (!$in_place)
{
echo $str;
}
elseif (!is_writable($path) ||
!rename($path, dirname($path).'/'.basename($path, '.xet').'.old.xet') ||
file_put_contents($path, $str) !== strlen($str))
{
error_log("Error writing file '$path'!\n");
}
exit;
}
// headers to allow caching, egw_framework specifies etag on url to force reload, even with Expires header
Api\Session::cache_control(86400); // cache for one day
$etag = '"' . md5($str) . '"';
Header('ETag: ' . $etag);
// if servers send a If-None-Match header, response with 304 Not Modified, if etag matches
if(isset($_SERVER['HTTP_IF_NONE_MATCH']) && $_SERVER['HTTP_IF_NONE_MATCH'] === $etag)
{
header("HTTP/1.1 304 Not Modified");
exit;
}
// we run our own gzip compression, to set a correct Content-Length of the encoded content
if(function_exists('gzencode') && in_array('gzip', explode(',', $_SERVER['HTTP_ACCEPT_ENCODING']), true))
{
$gzip_start = microtime(true);
$str = gzencode($str);
header('Content-Encoding: gzip');
$gziping = microtime(true) - $gzip_start;
}
header('X-Timing: header-include=' . number_format($header_include - $GLOBALS['start'], 3) .
(empty($processing) ? ', cache-read=' . number_format($cache_read - $header_include, 3) :
', processing=' . number_format($processing - $header_include, 3)) .
(!empty($gziping) ? ', gziping=' . number_format($gziping, 3) : '') .
', total=' . number_format(microtime(true) - $GLOBALS['start'], 3)
);
// Content-Length header is important, otherwise browsers dont cache!
Header('Content-Length: ' . bytes($str));
echo $str;
exit; // stop further processing eg. redirect to login
}
/**
* Parse attributes in an array
*
* @param string $str
* @return array
*/
function parseAttrs($str)
{
if (empty($str) || !trim($str))
{
return [];
}
if (!preg_match_all('/(^|\s)([a-z\d_-]+)="([^"]*)"/i', $str, $attrs, PREG_PATTERN_ORDER))
{
throw new Exception("Can NOT parse attributes from '$str'");
}
return array_combine($attrs[2], $attrs[3]);
}
/**
* Combine attribute array into a string
*
* If there are attributes the returned string is prefixed with a single space, otherwise an empty string is returned.
*
* @param array $attrs
* @return string
*/
function stringAttrs(array $attrs)
{
if (!$attrs)
{
return '';
}
return ' '.implode(' ', array_map(static function ($name, $value) {
return $name . '="' . $value . '"';
}, array_keys($attrs), $attrs));
}