Twig macro for mapping a mime type to a font-awesome icon.

example_usage.html.twig

{% import 'Path:To:filemacros.html.twig' as file %}

<span class="fa {{ file.icon(attachment.file.mimeType) }}"> </span>

filemacros.html.twig

{% macro icon(mimeType) %}
	{% spaceless %}
		{% if mimeType == 'application/pdf' %}
			fa-file-pdf-o
		{% elseif mimeType in [
			'application/msword',
			'application/rtf',
			'application/x-rtf',
			'text/richtext'
		] %}
			fa-file-word-o
		{% elseif mimeType in [
			'application/mspowerpoint',
			'application/vnd.ms-powerpoint',
			'application/x-mspowerpoint'
		] %}
			fa-file-powerpoint-o
		{% elseif mimeType in [
			'application/excel',
			'application/x-excel',
			'application/x-msexcel',
			'application/vnd.ms-excel',
			'text/csv',
			'text/tab-separated-values'
		] %}
			fa-file-excel-o
		{% elseif mimeType in [
			'application/x-cpio',
			'application/x-shar',
			'application/x-tar',
			'application/gnutar',
			'application/x-bzip',
			'application/x-bzip2',
			'application/x-gzip',
			'multipart/x-gzip',
			'application/x-lzip',
			'application/x-lzma',
			'application/x-lzop',
			'application/x-xz',
			'application/x-compress',
			'application/x-7z-compressed',
			'application/x-ace-compressed',
			'application/vnd.android.package-archive',
			'application/x-compressed',
			'application/x-zip-compressed',
			'application/zip',
			'multipart/x-zip',
			'application/x-zip'
		] %}
			fa-file-archive-o
		{% elseif 'image/' in mimeType %}
			fa-file-image-o
		{% elseif 'audio/' in mimeType %}
			fa-file-audio-o
		{% elseif 'video/' in mimeType %}
			fa-file-video-o
		{% elseif 'text/' in mimeType %}
			fa-file-text-o
		{% else %}
			fa-file-o
		{% endif %}
	{% endspaceless %}
{% endmacro %}

{% macro bytesToSize(bytes) %}
	{% spaceless %}
		{% set kilobyte = 1024 %}
		{% set megabyte = kilobyte * 1024 %}
		{% set gigabyte = megabyte * 1024 %}
		{% set terabyte = gigabyte * 1024 %}

		{% if bytes < kilobyte %}
			{{ bytes ~ ' B' }}
		{% elseif bytes < megabyte %}
			{{ (bytes / kilobyte)|number_format(2, '.') ~ ' KB' }}
		{% elseif bytes < gigabyte %}
			{{ (bytes / megabyte)|number_format(2, '.') ~ ' MB' }}
		{% elseif bytes < terabyte %}
			{{ (bytes / gigabyte)|number_format(2, '.') ~ ' GB' }}
		{% else %}
			{{ (bytes / terabyte)|number_format(2, '.') ~ ' TB' }}
		{% endif %}
	{% endspaceless %}
{% endmacro %}

This just saved me like hours of work. Thanks!