Front Matter

The most universal Front matter (yaml, json, neon, toml) parser and dumper for PHP. Front matter allows page-specific variables to be included at the top of a page.

Installation

This library can be installed via Composer:

composer require webuni/front-matter

Usage

This library can parse all form of front matter:

YAML (Neon)	TOML	Json
--- foo: bar --- # h1 paragraph	+++ foo = bar +++ # h1 paragraph	{ "foo": "bar" } # h1 paragraph

Parse an arbitrary string

<?php

$frontMatter = new \Webuni\FrontMatter\FrontMatter();

$document = $frontMatter->parse($string);

$data = $document->getData();
$content = $document->getContent();

Check if a string has front matter

<?php

$frontMatter = new \Webuni\FrontMatter\FrontMatter();

$hasFrontMatter = $frontMatter->exists($string);

Twig loader

If you want to store metadata about twig template, e.g.:

{#---
title: Hello world
menu: main
weight: 20
---#}
{% extend layout.html.twig %}
{% block content %}
Hello world!
{% endblock %}

you can use FrontMatterLoader, that decorates another Twig loader:

$frontMatter = \Webuni\FrontMatter\Twig\TwigCommentFrontMatter::create();
$loader = new \Twig\Loader\FilesystemLoader(['path/to/templates']);
$loader = new \Webuni\FrontMatter\Twig\FrontMatterLoader($frontMatter, $loader);

$twig = new \Twig\Environment($loader);
$content = $twig->render('template', []);
// rendered the valid twig template without front matter

It is possible to inject front matter to Twig template as variables:

// …
$converter = \Webuni\FrontMatter\Twig\DataToTwigConvertor::vars();
$loader = new \Webuni\FrontMatter\Twig\FrontMatterLoader($frontMatter, $loader, $converter);
// …

Loaded Twig template has this code:

{% set title = "Hello world" %}
{% set menu = "main" %}
{% set weight = 20 %}
{% line 5 %}
{% extend layout.html.twig %}
{% block content %}
Hello world!
{% endblock %}

Available converters:

Converter	Twig
`DataToTwigConvertor::nothing()`
`DataToTwigConvertor::vars()`	`{% set key1 = value1 %}`
`DataToTwigConvertor::vars(false)`	`{% set key1 = key1 is defined ? key1 : value1 %}`
`DataToTwigConvertor::var('name')`	`{% set name = {key1: value1, key2: value2} %}`
`DataToTwigConvertor::var('name', false)`	`{% set name = name is defined ? name : {key1: value1} %}`

Markdown

The most commonly used front matter is for markdown files:

---
layout: post
title: I Love Markdown
tags:
  - test
  - example
---

# Hello World!

This library can be used with league/commonmark:

$frontMatter = new \Webuni\FrontMatter\FrontMatter();
$extension = new \Webuni\FrontMatter\Markdown\FrontMatterLeagueCommonMarkExtension($frontMatter);

$converter = new \League\CommonMark\CommonMarkConverter([]);
$converter->getEnvironment()->addExtension($extension);
$html = $converter->convertToHtml('markdown'); // html without front matter

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Front matter