# GitLab Markdown

This document is intended to be a comprehensive example of custom GitLab
Markdown usage. It will be parsed and then tested for accuracy. Let's get
started.

## Markdown

GitLab uses [Commonmark](https://git.io/fhDag) to parse all Markdown into
HTML.

It has some special features. Let's try 'em out!

### No Intra Emphasis

This string should have no emphasis: foo_bar_baz

### Tables

| Header   | Row  | Example |
| :------: | ---: | :------ |
| Foo      | Bar  | **Baz** |

### Fenced Code Blocks

```c
#include<stdio.h>

main()
{
    printf("Hello World");

}
```

```python
print "Hello, World!"
```

### Strikethrough

This text says this, ~~and this text doesn't~~.

### Superscript

This is my 1<sup>(st)</sup> time using superscript in Markdown. Now this is my
2<sup>(nd)</sup>.

Redcarpet supports this superscript syntax ( x^2 ).

### Subscript

This (C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>) is an example of subscripts in Markdown.

### Footnotes

This is footnote 1.[^f1]

A footnote with a `w` was failing.[^f2-w]

[^f1]: Footnote 1
[^f2-w]: Footnote with w

### Next step

After the Markdown has been turned into HTML, it gets passed through...

## HTML::Pipeline

### SanitizationFilter

GitLab uses <a href="http://git.io/vfW8a">HTML::Pipeline::SanitizationFilter</a>
to sanitize the generated HTML, stripping dangerous or unwanted tags.

Its default whitelist is pretty permissive. Check it:

<b>b tag</b> and <em>em tag</em>.

<code>code tag</code>

Press <kbd>s</kbd> to search.

<strike>Emoji</strike> Plain old images! <img src="http://www.emoji-cheat-sheet.com/graphics/emojis/smile.png" width="20" height="20" />

Here comes a line break:

<br />

And a horizontal rule:

<hr />

As permissive as it is, we've allowed even more stuff:

<span>span tag</span>

<details>
<summary>Summary lines are collapsible:</summary>
Hiding the details until expanded.
</details>

<a href="#" rel="bookmark">This is a link with a defined rel attribute, which should be removed</a>

<a href="javascript:alert('Hi')">This is a link trying to be sneaky. It gets its link removed entirely.</a>

### Escaping

The problem with SanitizationFilter is that it can be too aggressive.

| Input       | Expected         | Actual    |
| ----------- | ---------------- | --------- |
| `1 < 3 & 5` | 1 &lt; 3 &amp; 5 | 1 < 3 & 5 |
| `<foo>`     | &lt;foo&gt;      | <foo>     |

### Edge Cases

Markdown should be usable inside a link. Let's try!

- [_text_](#link-emphasis)
- [**text**](#link-strong)
- [`text`](#link-code)

### UploadLinkFilter

Linking to an upload in this project should work:
[Relative Upload Link](/uploads/e90decf88d8f96fe9e1389afc2e4a91f/test.jpg)
![Relative Upload Image](/uploads/e90decf88d8f96fe9e1389afc2e4a91f/test.jpg)

### RepositoryLinkFilter

Linking to a file relative to this project's repository should work.

[Relative Link](doc/README.md)
![Relative Image](app/assets/images/touch-icon-ipad.png)

### EmojiFilter

Because life would be :zzz: without Emoji, right? :rocket:

Get ready for the Emoji :bomb: : :+1: :-1: :ok_hand: :wave: :v: :raised_hand: :muscle:

### TableOfContentsFilter

All headers in this document should be linkable. Try it.

### AutolinkFilter

These are all plain text that should get turned into links:

- http://about.gitlab.com/
- https://google.com/
- ftp://ftp.us.debian.org/debian/
- smb://foo/bar/baz
- irc://irc.freenode.net/git
- http://localhost:3000

But it shouldn't autolink text inside certain tags:

- <code>http://code.gitlab.com/</code>
- <a>http://a.gitlab.com/</a>
- <kbd>http://kbd.gitlab.com/</kbd>

### ExternalLinkFilter

External links get a `rel="nofollow noreferrer"` and `target="_blank"` attributes:

- [Google](https://google.com/)
- [GitLab Root](<%= Gitlab.config.gitlab.url %>)

### Reference Filters (e.g., <%= issue.to_reference %>)

References should be parseable even inside _<%= merge_request.to_reference %>_ emphasis.

#### UserReferenceFilter

- All: @all
- User: <%= user.to_reference %>
- Group: <%= group.to_reference %>
- Ignores invalid: <%= User.reference_prefix %>fake_user
- Ignored in code: `<%= user.to_reference %>`
- Ignored in links: [Link to <%= user.to_reference %>](#user-link)
- Ignored when backslash escaped: \<%= user.to_reference %>
- Ignored when backslash escaped: \<%= group.to_reference %>
- Link to user by reference: [User](<%= user.to_reference %>)

#### IssueReferenceFilter

- Issue: <%= issue.to_reference %>
- Issue in another project: <%= xissue.to_reference(project) %>
- Ignored in code: `<%= issue.to_reference %>`
- Ignored in links: [Link to <%= issue.to_reference %>](#issue-link)
- Ignored when backslash escaped: \<%= issue.to_reference %>
- Issue by URL: <%= urls.project_issue_url(issue.project, issue) %>
- Link to issue by reference: [Issue](<%= issue.to_reference %>)
- Link to issue by URL: [Issue](<%= urls.project_issue_url(issue.project, issue) %>)

#### MergeRequestReferenceFilter

- Merge request: <%= merge_request.to_reference %>
- Merge request in another project: <%= xmerge_request.to_reference(project) %>
- Ignored in code: `<%= merge_request.to_reference %>`
- Ignored in links: [Link to <%= merge_request.to_reference %>](#merge-request-link)
- Ignored when backslash escaped: \<%= merge_request.to_reference %>
- Merge request by URL: <%= urls.project_merge_request_url(merge_request.project, merge_request) %>
- Link to merge request by reference: [Merge request](<%= merge_request.to_reference %>)
- Link to merge request by URL: [Merge request](<%= urls.project_merge_request_url(merge_request.project, merge_request) %>)

#### SnippetReferenceFilter

- Snippet: <%= snippet.to_reference %>
- Snippet in another project: <%= xsnippet.to_reference(project) %>
- Ignored in code: `<%= snippet.to_reference %>`
- Ignored in links: [Link to <%= snippet.to_reference %>](#snippet-link)
- Ignored when backslash escaped: \<%= snippet.to_reference %>
- Snippet by URL: <%= urls.project_snippet_url(snippet.project, snippet) %>
- Link to snippet by reference: [Snippet](<%= snippet.to_reference %>)
- Link to snippet by URL: [Snippet](<%= urls.project_snippet_url(snippet.project, snippet) %>)

#### CommitRangeReferenceFilter

- Range: <%= commit_range.to_reference %>
- Range in another project: <%= xcommit_range.to_reference(project) %>
- Ignored in code: `<%= commit_range.to_reference %>`
- Ignored in links: [Link to <%= commit_range.to_reference %>](#commit-range-link)
- Range by URL: <%= urls.project_compare_url(commit_range.project, commit_range.to_param) %>
- Link to range by reference: [Range](<%= commit_range.to_reference %>)
- Link to range by URL: [Range](<%= urls.project_compare_url(commit_range.project, commit_range.to_param) %>)

#### CommitReferenceFilter

- Commit: <%= commit.to_reference %>
- Commit in another project: <%= xcommit.to_reference(project) %>
- Ignored in code: `<%= commit.to_reference %>`
- Ignored in links: [Link to <%= commit.to_reference %>](#commit-link)
- Commit by URL: <%= urls.project_commit_url(commit.project, commit) %>
- Link to commit by reference: [Commit](<%= commit.to_reference %>)
- Link to commit by URL: [Commit](<%= urls.project_commit_url(commit.project, commit) %>)

#### LabelReferenceFilter

- Label by ID: <%= simple_label.to_reference %>
- Label by name: <%= Label.reference_prefix %><%= simple_label.name %>
- Label by name in quotes: <%= label.to_reference(format: :name) %>
- Ignored in code: `<%= simple_label.to_reference %>`
- Ignored in links: [Link to <%= simple_label.to_reference %>](#label-link)
- Ignored when backslash escaped: \<%= simple_label.to_reference %>
- Link to label by reference: [Label](<%= label.to_reference %>)

#### MilestoneReferenceFilter

- Milestone by ID: <%= simple_milestone.to_reference %>
- Milestone by name: <%= Milestone.reference_prefix %><%= simple_milestone.name %>
- Milestone by name in quotes: <%= milestone.to_reference(format: :name) %>
- Milestone in another project: <%= xmilestone.to_reference(project) %>
- Ignored in code: `<%= simple_milestone.to_reference %>`
- Ignored in links: [Link to <%= simple_milestone.to_reference %>](#milestone-link)
- Ignored when backslash escaped: \<%= simple_milestone.to_reference %>
- Milestone by URL: <%= urls.milestone_url(milestone) %>
- Link to milestone by URL: [Milestone](<%= milestone.to_reference %>)
- Group milestone by name: <%= Milestone.reference_prefix %><%= group_milestone.name %>
- Group milestone by name in quotes: <%= group_milestone.to_reference(format: :name) %>
- Group milestone by URL is ignore: <%= urls.milestone_url(group_milestone) %>

##### AlertReferenceFilter
- Alert: <%= alert.to_reference %>
- Alert in another project: <%= xalert.to_reference(project) %>
- Ignored in code: `<%= alert.to_reference %>`
- Ignored in links: [Link to <%= alert.to_reference %>](#alert-link)
- Ignored when backslash escaped: \<%= alert.to_reference %>
- Alert by URL: <%= alert.details_url %>
- Link to alert by reference: [Alert](<%= alert.to_reference %>)
- Link to alert by URL: [Alert](<%= alert.details_url %>)

### Task Lists

- [ ] Incomplete task 1
- [x] Complete task 1
- [~] Inapplicable task 1
- [ ] Incomplete task 2
  - [ ] Incomplete sub-task 1
  - [ ] Incomplete sub-task 2
  - [~] Inapplicable sub-task 1
  - [x] Complete sub-task 1
- [X] Complete task 2

### Math

- Dollar math: $a^2 + b^2 = c^2$
- Dollar math and snippet reference: $d^2 + e^2 = f^2$ and <%= snippet.to_reference %>
- Dollar math and snippet in another project: <%= xsnippet.to_reference(project) %> and $g^2 + h^2 = i^2$
- Not dollar math: $20,000 and $30,000
- Dollar-backtick math: $`j^2 + k^2 = l^2`$
- Dollar display math: $$m^2 + n^2 = o^2$$
- Dollar display math and snippet reference: $$p^2 + q^2 = r^2$$ and <%= snippet.to_reference %>
- Dollar math and snippet in another project: <%= xsnippet.to_reference(project) %> and $$s^2 + t^2 = u^2$$
- Display math using a block

  ```math
  v^2 + w^2 = x^2
  ```

### Gollum Tags

- [[linked-resource]]
- [[link-text|linked-resource]]
- [[http://example.com]]
- [[link-text|http://example.com/pdfs/gollum.pdf]]
- [[images/example.jpg]]
- [[http://example.com/images/example.jpg]]

### Inline Diffs

With inline diffs tags you can display {+ additions +} or [- deletions -].

The wrapping tags can be either curly braces or square brackets [+ additions +] or {- deletions -}.

Examples:

```
- {+ additions +}
- [+ additions +]
- {- deletions -}
- [- deletions -]
```

However the wrapping tags cannot be mixed as such:

```
- {+ additions +]
- [+ additions +}
- {- deletions -]
- [- deletions -}
```

### Videos

![My Video](/assets/videos/gitlab-demo.mp4)

### Audio

![My Audio Clip](/assets/audio/gitlab-demo.wav)

### Colors

`#F00`
`#F00A`
`#FF0000`
`#FF0000AA`
`RGB(0,255,0)`
`RGB(0%,100%,0%)`
`RGBA(0,255,0,0.7)`
`HSL(540,70%,50%)`
`HSLA(540,70%,50%,0.7)`

### Mermaid

> If this is not rendered correctly, see
https://gitlab.com/gitlab-org/gitlab-foss/blob/master/doc/user/markdown.md#mermaid

It is possible to generate diagrams and flowcharts from text using [Mermaid][mermaid].

In order to generate a diagram or flowchart, you should write your text inside the `mermaid` block.

Example:

    ```mermaid
    graph TD;
      A-->B;
      A-->C;
      B-->D;
      C-->D;
    ```

Becomes:

```mermaid
graph TD;
  A-->B;
  A-->C;
  B-->D;
  C-->D;
```

For details see the [Mermaid official page][mermaid].

[mermaid]: https://mermaidjs.github.io/ "Mermaid website"

### PLantUML

```plantuml
Bob -> Sara : Hello
```

### Kroki

```nomnoml
[Pirate|eyeCount: Int|raid();pillage()|
  [beard]--[parrot]
  [beard]-:>[foul mouth]
]
```

### Image Attributes

![Sized Image](app/assets/images/touch-icon-ipad.png){width=75% height=100}