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https://github.com/iwasrobbed/Down
Blazing fast Markdown / CommonMark rendering in Swift, built upon cmark.
https://github.com/iwasrobbed/Down
ast cmark commonmark html ios mac macos markdown parsing swift tvos
Last synced: about 2 months ago
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Blazing fast Markdown / CommonMark rendering in Swift, built upon cmark.
- Host: GitHub
- URL: https://github.com/iwasrobbed/Down
- Owner: johnxnguyen
- License: other
- Created: 2016-05-29T00:28:59.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2023-07-15T08:03:25.000Z (about 1 year ago)
- Last Synced: 2024-05-29T04:50:41.088Z (4 months ago)
- Topics: ast, cmark, commonmark, html, ios, mac, macos, markdown, parsing, swift, tvos
- Language: C
- Homepage:
- Size: 18.8 MB
- Stars: 2,200
- Watchers: 30
- Forks: 306
- Open Issues: 34
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
## Down
[](https://travis-ci.com/johnxnguyen/Down)
[](https://github.com/johnxnguyen/Down/blob/master/LICENSE)
[](https://cocoapods.org/pods/Down)
[](https://swift.org)
[](https://developer.apple.com/macos/)
[](https://developer.apple.com/ios/)
[](https://developer.apple.com/tvos/)
[](https://www.linux.org/)
[](https://codecov.io/gh/johnxnguyen/Down)
Blazing fast Markdown (CommonMark) rendering in Swift, built upon [cmark v0.29.0](https://github.com/commonmark/cmark).
Is your app using it? [Let us know!](mailto:[email protected])
If you're looking for `iwasrobbed/Down`, you found it! [Rob Phillips](https://github.com/iwasrobbed), the originator of this repository,
has transferred it to me as I will be the primary maintainer from now on. Thanks to Rob for bringing Down as far as it has come and for
entrusting me with its care.
All existing references to `iwasrobbed/Down` should redirect to this repository. However, It is recommended to update those urls to point
to this repository.
#### Maintainers
- [John Nguyen](https://github.com/johnxnguyen)
- [Rob Phillips](https://github.com/iwasrobbed)
- [Keaton Burleson](https://github.com/128keaton)
- [phoney](https://github.com/phoney)
- [Tony Arnold](https://github.com/tonyarnold)
- [Ken Harris](https://github.com/kengruven)
- [Chris Zielinski](https://github.com/chriszielinski)
- [Other contributors](https://github.com/johnxnguyen/Down/graphs/contributors) 🙌
### Installation
Note: Swift support is summarized in the table below.
|Swift Version|Tag|
| --- | --- |
| Swift 5.1 | >= 0.9.0 |
| Swift 5.0 | >= 0.8.1 |
| Swift 4 | >= 0.4.x |
| Swift 3 | 0.3.x |
now on the `master` branch and any tag >= 0.8.1 (Swift 4 is >= 0.4.x, Swift 3 is 0.3.x)
#### Quickly install using [CocoaPods](https://cocoapods.org):
```ruby
pod 'Down'
```
#### Install using [Carthage](https://github.com/Carthage/Carthage):
```
github "johnxnguyen/Down"
```
Due to limitations in Carthage regarding platform specification, you need to define the platform with Carthage.
e.g.
```carthage update --platform iOS```
#### Install using [Swift Package Manager](https://github.com/apple/swift-package-manager):
To add *Down* to your project, select `File → Swift Packages → Add Package Dependency` and enter the GitHub URL for *Down*.
See [Adding Package Dependencies to Your App](https://developer.apple.com/documentation/xcode/adding_package_dependencies_to_your_app) for detailed instructions.
#### Or manually install:
1. Clone this repository
2. Drag and drop the Down project into your workspace file, adding the framework in the embedded framework section
2. Build and run your app
4. ?
5. Profit
### Robust Performance
>[cmark](https://github.com/commonmark/cmark) can render a Markdown version of War and Peace in the blink of an eye (127 milliseconds on a ten year old laptop, vs. 100-400 milliseconds for an eye blink). In our [benchmarks](https://github.com/commonmark/cmark/blob/master/benchmarks.md), cmark is 10,000 times faster than the original Markdown.pl, and on par with the very fastest available Markdown processors.
> The library has been extensively fuzz-tested using [american fuzzy lop](http://lcamtuf.coredump.cx/afl). The test suite includes pathological cases that bring many other Markdown parsers to a crawl (for example, thousands-deep nested bracketed text or block quotes).
### Output Formats
* Web View (see DownView class)
* HTML
* XML
* LaTeX
* groff man
* CommonMark Markdown
* NSAttributedString
* AST (abstract syntax tree)
### View Rendering
The `DownView` class offers a very simple way to parse a UTF-8 encoded string with Markdown and convert it to a web view that can be added to any view:
```swift
let downView = try? DownView(frame: self.view.bounds, markdownString: "**Oh Hai**") {
// Optional callback for loading finished
}
// Now add to view or constrain w/ Autolayout
// Or you could optionally update the contents at some point:
try? downView?.update(markdownString: "## [Google](https://google.com)") {
// Optional callback for loading finished
}
```
Meta example of rendering this README:
### Parsing API
The `Down` struct has everything you need if you just want out-of-the-box setup for parsing and conversion.
```swift
let down = Down(markdownString: "## [Down](https://github.com/johnxnguyen/Down)")
// Convert to HTML
let html = try? down.toHTML()
// "
Down
\n"
// Convert to XML
let xml = try? down.toXML()
// "\n\n\n \n \n Down\n \n \n\n"
// Convert to groff man
let man = try? down.toGroff()
// ".SS\nDown (https://github.com/johnxnguyen/Down)\n"
// Convert to LaTeX
let latex = try? down.toLaTeX()
// "\\subsection{\\href{https://github.com/johnxnguyen/Down}{Down}}\n"
// Convert to CommonMark Markdown
let commonMark = try? down.toCommonMark()
// "## [Down](https://github.com/johnxnguyen/Down)\n"
// Convert to an attributed string
let attributedString = try? down.toAttributedString()
// NSAttributedString representation of the rendered HTML;
// by default, uses a stylesheet that matches NSAttributedString's default font,
// but you can override this by passing in your own, using the 'stylesheet:' parameter.
// Convert to abstract syntax tree
let ast = try? down.toAST()
// Returns pointer to AST that you can manipulate
```
### Rendering Granularity
If you'd like more granularity for the output types you want to support, you can create your own struct conforming to at least one of the renderable protocols:
* DownHTMLRenderable
* DownXMLRenderable
* DownLaTeXRenderable
* DownGroffRenderable
* DownCommonMarkRenderable
* DownASTRenderable
* DownAttributedStringRenderable
Example:
```swift
public struct MarkdownToHTML: DownHTMLRenderable {
/**
A string containing CommonMark Markdown
*/
public var markdownString: String
/**
Initializes the container with a CommonMark Markdown string which can then be rendered as HTML using `toHTML()`
- parameter markdownString: A string containing CommonMark Markdown
- returns: An instance of Self
*/
@warn_unused_result
public init(markdownString: String) {
self.markdownString = markdownString
}
}
```
### Configuration of `DownView`
`DownView` can be configured with a custom bundle using your own HTML / CSS or to do things like supporting
Dynamic Type or custom fonts, etc. It's completely configurable.
This option can be found in [DownView's instantiation function](https://github.com/johnxnguyen/Down/blob/master/Source/Views/DownView.swift#L26).
##### Prevent zoom
The default implementation of the `DownView` allows for zooming in the rendered content. If you want to disable this, then you’ll need to instantiate the `DownView` with a custom bundle where the `viewport` in `index.html` has been assigned `user-scalable=no`. More info can be found [here](https://github.com/johnxnguyen/Down/pull/30).
### Options
Each protocol has options that will influence either rendering or parsing:
```swift
/**
Default options
*/
public static let `default` = DownOptions(rawValue: 0)
// MARK: - Rendering Options
/**
Include a `data-sourcepos` attribute on all block elements
*/
public static let sourcePos = DownOptions(rawValue: 1 << 1)
/**
Render `softbreak` elements as hard line breaks.
*/
public static let hardBreaks = DownOptions(rawValue: 1 << 2)
/**
Suppress raw HTML and unsafe links (`javascript:`, `vbscript:`,
`file:`, and `data:`, except for `image/png`, `image/gif`,
`image/jpeg`, or `image/webp` mime types). Raw HTML is replaced
by a placeholder HTML comment. Unsafe links are replaced by
empty strings. Note that this option is provided for backwards
compatibility, but safe mode is now the default.
*/
public static let safe = DownOptions(rawValue: 1 << 3)
/**
Allow raw HTML and unsafe links. Note that safe mode is now
the default, and the unsafe option must be used if rendering
of raw HTML and unsafe links is desired.
*/
public static let unsafe = DownOptions(rawValue: 1 << 17)
// MARK: - Parsing Options
/**
Normalize tree by consolidating adjacent text nodes.
*/
public static let normalize = DownOptions(rawValue: 1 << 4)
/**
Validate UTF-8 in the input before parsing, replacing illegal
sequences with the replacement character U+FFFD.
*/
public static let validateUTF8 = DownOptions(rawValue: 1 << 5)
/**
Convert straight quotes to curly, --- to em dashes, -- to en dashes.
*/
public static let smart = DownOptions(rawValue: 1 << 6)
/**
Combine smart typography with HTML rendering.
*/
public static let smartUnsaFe = DownOptions(rawValue: (1 << 17) + (1 << 6))
```
### Supports
Swift; iOS 9+, tvOS 9+, macOS 10.11+
### Markdown Specification
Down is built upon the [CommonMark](http://commonmark.org) specification.
### A little help from my friends
Please feel free to fork and create a pull request for bug fixes or improvements, being sure to maintain the general coding style, adding tests, and adding comments as necessary.
### Credit
This library is a wrapper around [cmark](https://github.com/commonmark/cmark), which is built upon the [CommonMark](http://commonmark.org) Markdown specification.
[cmark](https://github.com/commonmark/cmark) is Copyright (c) 2014, John MacFarlane. View [full license](https://github.com/commonmark/cmark/blob/master/COPYING).