feature: macro n:attr expands arrays

[dakujem]

When the first and only argument to n:attr macro is an array, expand it.

• bug fix? no
• new feature? yes
• BC break? yes, in a rare (and not really sensible) case

I opened another PR solving the same thing by adding a new macro here: #157

Motivation:
Suppose there is an array $attributes containing attributes for <meta> tag.

array (
  'content' => 'width=device-width, initial-scale=1',
  'name' => 'viewport',
  'http-equiv' => NULL,
  'scheme' => NULL,
)

The developer wants to achieve this HTML output:

<meta content="width=device-width, initial-scale=1" name="viewport">

However, using <meta n:attr="$meta"> the actual output is:

<meta 0="content:width=device-width, initial-scale=1 name:viewport">

The developer is currently forced to use workarounds, like:

{=Nette\Utils\Html::el('meta', $attributes)}

The solution:
The n:attr macro be changed to expand the input array in case that:

• the macro receives an array with only a single element
• the single element is an array itself

Code:

'$_tmp = %node.array; echo LR\Filters::htmlAttributes( isset($_tmp[0]) && is_array($_tmp[0]) && count($_tmp) === 1 ? $_tmp[0] : $_tmp);'

After the proposed change, the developer can use

<meta n:attr="$attributes">

with an expected result.

Caveat:
This change may actually lead to a changed behaviour if in an IMHO rare case someone actually wanted to output something like <tag 0="foo:bar"> passing the array directly to the macro like

<tag n:attr="['foo' => 'bar']">

Sidenote:
In this case, the macro is used for outputting metas:

<meta n:foreach="$metas as $meta" n:attr="$meta">

This approach is however very useful for many other cases during output generation.

[dg]

I think it is good idea to support <meta n:attr="$attributes">

[dakujem]

You can reopen the PR if you wish.

[TomasVotruba]

Thank you @dakujem