A minimal implementation of Mustache in PHP. Supports escaped and HTML Variables, Comments, Sections and Inverted Section. Does not support Lists, Callbacks, Partials or Delimiter setting.

mini-mustache.php

<?php
/**
 * In Mustache syntax, values are represented by "tags".
 *
 * Tags are indicated by double braces (a.k.a. curly brackets): {{name}}
 *
 * To check if a value is available use a "section". A section is a tag that is
 * prefixed  with a pound `#` character. The closing tag is prefixed with a
 * slash `/`. For example, to only show "name" when it is available:
 *
 *     {{#name}}
 *         <p>{{name}}</p>
 *     {{/name}}
 *
 * To show content when a value is NOT available, use an inverted section. An
 * inverted section is a tag prefixed  with a caret `^`. The closing tag is
 * prefixed with a slash `/`. For example, to show content when "name" is not
 * available:
 *
 *     {{^name}}
 *         <p>No name available!</p>
 *     {{/name}}
 *
 * All values are HTML escaped by default. To have unescaped HTML, use triple
 * braces: {{{name}}}
 *
 * To add comments, prefix a tag with an exclamation mark `!` (comments may
 * contain newlines): {{! this is a comment }}
 *
 * @author Potherca <potherca@gmail.com>
 * @copyright 2016 Potherca
 * @license GPLv3+
 * @version 0.4.0
 *
 * @see https://gist.github.com/Potherca/94c0ba1449a2ee57aafddf961f3ebe5d/
 */

/**
 * A minimal implementation of Mustache in PHP.
 *
 * Supports escaped and HTML Variables, Comments, Sections and Inverted Section.
 * Does not support Lists, Callbacks, Partials or Delimiter setting.
 *
 * @param string $template
 * @param array $context
 *
 * @return string
 */
function mini_mustache($template, array $context = [])
{
    $pattern = '@({{)(?<SECTION_TYPE>#|\^)(?P<SECTION_NAME>[a-zA-Z\-\_\.]+)(}})(?P<SECTION_CONTENT>.*?)({{/\3}})@sm';

    $template = preg_replace_callback($pattern, function (array $matches) use ($context) {
        $result = '';
        $key = $matches['SECTION_NAME'];

        if ($matches['SECTION_TYPE'] === '^') {
            // Inverted Section, will be rendered if the key doesn't exist, is false, or is an empty list
            if (!array_key_exists($key, $context) || empty($context[$key])) {
                $result = $matches['SECTION_CONTENT'];
            }
        } elseif ($matches['SECTION_TYPE'] === '#') {
            // Section, will be rendered if the key exists and has a value of true or is an non-empty list
            if (array_key_exists($key, $context) && !empty($context[$key])) {
                $result = $matches['SECTION_CONTENT'];
            }
        } else {
            throw new \UnexpectedValueException('Unknown section type in template.');
        }
        return $result;
    }, $template);

    $pattern = '/{{\!\s?(?P<COMMENT>.+)\s?}}|{{{\s?(?P<HTML_RAW>[a-zA-Z\-\_\.]+)\s?}}}|{{\s?(?P<HTML_ENCODE>[a-zA-Z\-\_\.]+)\s?}}/m';

    return preg_replace_callback($pattern, function (array $matches) use ($context) {
        if ($matches['COMMENT'] !== '') {
            $result = '';
        } elseif ($matches['HTML_RAW'] !== '') {
            $encode = false;
            $key = $matches['HTML_RAW'];
        } elseif ($matches['HTML_ENCODE'] !== '') {
            $encode = true;
            $key = $matches['HTML_ENCODE'];
        } else {
            throw new \UnexpectedValueException('Unknown tag type in template.');
        }

        if (!isset($result) && isset($key)) {
            $result = $key;
            if (array_key_exists($key, $context)) {
                $result = $context[$key];

                if (isset($encode) && (bool) $encode === true) {
                    $result = htmlentities($result, ENT_HTML5 | ENT_QUOTES);
                }
            }
        }
        return $result;
    }, $template);
}

/*EOF*/