Name

qipowl (pronounced as keep all)

Status: Minimum viable product

---

Introduction into techniques

Intro

The main idea of qipowl is to yield the power of DSL in Ruby. The whole input text is treated neither more nor less than DSL. That gives the user an ability to make virtually every term in input text the operating entity.

Principles

Qipowl is a Ruby parsing library. The parsing is done via DSL exactly as Ouroboros eats it’s own tail.

The whole input is treated as Ruby source code and executed respectively. To prevent collisions of input with built-in ruby methods, the ASCII symbols in the input are being translated into their fullwidth equivalents before execution (and back to ASCII after the parsing is done.)

Let’s say we have a string “Hello world” as input. It became ‘encoded’ into: “Ｈｅｌｌｏ ｗｏｒｌｄ”, executed as Ruby code (exactly as e. g. puts rand would) and finally ‘decoded’ back to ASCII. Whether the parser knows anything about ‘Ｈｅｌｌｏ’ or ‘ｗｏｒｌｄ’ it would be executed. Say, we have

def ｗｏｒｌｄ *args
  "ｂｒａｖｅ ｎｅｗ #{__callee__}"
end

thus the output will be:

# ⇒ Hello brave new world

More about may be found at project page.

Applications

Qipowl has a wide list of applications. The “markright”, descendant of “markup” and “markdown” is presented here.

Qipowl HTML uses extended unicode symbols to specify more clean and readable source files and (boom!) ruby DSL to interpret them. E.g. the data definitions look like:

▶ Data term — definition goes here

Headings:

§1 This is a second-level heading

Bold and emphasis:

The following ≡text≡ goes strong and this one is ≈emphasized≈.

Comments are possible as well:

✍ FIXME! 
Not to forget add this to parsing!
✍

etc.

Why?

Just because it’s 2013 all around. Unicode came already and those fancy symbols are easily mapped to the keyboard layouts. The brackets, used in old good Markdown are ugly, look at how they might be introduced:

I like Markdown¹http://daringfireball.net/projects/markdown/syntax

Markdown lacks a lot of modern features (properties of text).

Markdown does not provide a blanket set of marks, fully covering claims to markup language.

Parsing

Parsing is the most sexy part of Qipowl bowels, since it’s done almost without any external parsing; input files are the ruby scripts themselves. WTF? Let me explain.

Let we have an input file of the following structure:

§1 Qipowl

✍ FIXME 
include language reference here
✍

≡Qipowl≡ is the most exciting ruby DSL application example. As it
is stated in markdown reference:

〉 Readability, however, is emphasized above all else. 
A Markdown-formatted document should be publishable as-is, 
as plain text, without looking like it’s been marked up with 
tags or formatting instructions.
— http://daringfireball.net/projects/markdown/syntax

Now we simply give the source to ruby interpreter, which knowns, that §1 is in fact ruby function, which transforms that to any other syntax we want. To HTML, for instance.

Parsing problems

Not all the constructions may be passed to ruby script as is. There are four exceptions:

• blockquotes, which are in fact kinda documents inside documents, because they might be nested and they may include any other markup;
• images, videos, etc. which may be typed as the hyperlink only;
• anchors, abbrs etc., the elements which are not “symbol-text” formed. They rather are looking like “text-symbol-text” and unfortunately should be preparsed to supply correct ruby DSL;
• lists and data definitions, are to be surrounded with <ul>/<dd> tags;
• tables… Bah, I didn’t think most about tables yet. They are ugly.

Links

Links might be:

• anchors
  • Wiki says¹http://wikipedia.org
  • Wiki clone¹/wiki
  • — Wikipedia, http://wikipedia.org
    the latter may be found in quotations only.
• images
  • http://localhost/a.png
  • Best views of Hornsjø¹http://localhost/a.png
• videos
  • http://youtu.be/SAJ_TzLqy1U
  • http://www.youtube.com/watch?v=SAJ_TzLqy1U

Abbrs are looking (and processing) mostly like links, but now we may forget about them:

• abbrs
  • Wiki†Best online knowledge base ever†

Links are being parsed in the following manner:

• find the link in the input, according to simple pattern URI.regexp
• determine whether it is an image, video or link to page by downloading and analyzing the headers
• TODO copying the image to the host computer, providing the watermark with copyright and any other significant information
• TODO instead of previous two actions we might simply analyze it by extension e.g. if there is no internet connection available
• prepending the link with special character (understood by DSL)

After all is done, we yield smth like ⚐ http://localhost.a.png in place of http://localhost.a.png and ⚓ http://localhost/index.html in place of http://localhost/index.html

Examples

This chapter should be the last one, but who wants to read technical details without any clue of how they might be applied? So, here we go.

Shipping with: Markright

Right is looking right past up and down, right? qipowl comes with built-in markright parser, which is superset of markdown.

qipowl markright utilizes UTF-8 heavily. The standard markup (here and further: qipowl markup, or qp) lays on unicode characters instead of legacy asterisks and underscores in markdown. It brings the better readability to plain text before it’s processed with qipowl and allows more readable DSL for processing. For instance, the input:

§3 Emphasized text

There are four standard modifiers for emphasizing text:
▶ “≡” — bold
▶ “≈” — italic
▶ “↓” — small
▶ “λ” — code

The formers are to surround the target text piece.
This text contains:
• ≡bold≡,
• ≈italics≈,
• ↓small↓ 
• and even some λcodeλ.

will be processed as:

<h3>Emphasized text</h3>
<p class='dropcap'>There are four standard modifiers for emphasizing text:</p>
<dl><dt>“≡”</dt><dd>bold</dd>
<dt>“≈”</dt><dd>italic</dd>
<dt>“↓”</dt><dd>small</dd>
<dt>“λ”</dt><dd>code</dd></dl>
<p class='dropcap'>The formers are to surround the target text piece.
This text contains:</p>
<ul><li><strong>bold</strong>,</li>
<li><em>italics</em>,</li>
<li><small>small</small></li>
<li>and even some <code>code</code>.</li></ul>

The valuable subset of HTML5 is implemented directly, plus the user may eventually extend the list of understandable tags.

The markup-specific symbols, like “▶” and “•” in the previous example may be mapped to keyboard (see typo file within data directory of the project.

Internals

qipowl markup implementation consists of two parts: markup definition (kinda yaml file) and markup processor. The latter derives from base processor implementation Qipowl::Bowler.

Markup definition

qipowl understands six types of ‘operators’:

• flush
• block
• magnet
• grip
• regular
• self

:flush

The operators in this group are executed immediately and do not break the control flow. Technically, they are simply being substituted with their representation.

:flush
  :⏎ : :br

means that “⏎” anywhere in text will be substituted with “<br>”

:block

This group contains operators, which are driving the blocks. Such a block should start with the operator and ends with it. Operator may receive an additional parameter, located on the same string as the opening operator.

:block
  :Λ : :pre

means that the following block:

Λ ruby
  @mapping[:block].each { |tag, htmltag|
    break if tag < :inplace
  }
Λ

is to be left intouch (except of html is escaped inside) and surrounded with pre tags:

<pre class='ruby'>
  @mapping[:block].each { |tag, htmltag|
    break if tag &lt; :inplace
  }
</pre>

This operator is the only one which preserves the line breaks.

:magnet

Almost the same as :inplace but does not require closing match. Operates on the following text piece until the space. E.g.

:magnet
  :☎ : :span†phone

will produce

<span class='phone'>☎ +1(987)5554321</span>

for the markup:

☎ +1(987)5554321

:grip

Acts mostly like :block but inside one text block (text blocks are likely paragraphs, delimited with double carriage returns.) Requires closing element. Inplace operators are of highest priority and may overlap.

:grip
  :≡ : :strong

will convert

That is ≡bold≡ text.

into

That is <strong>bold</strong> text.

:regular

Those are not require closings, since they are operated on the rest of the text. Support nesting by prepending tags with non-breakable space:

:regular
  :• : li

The following syntax

• Line item 1
 • Nested li 1
 • Nested li 2
• Line item 2

will produce:

<ul><li>Line item 1</li>
<ul><li>Nested li 1</li>
<li>Nested li 2</li></ul>
<li>Line item 2</li></ul>

Extending

Extending qipowl is as easy as writing a couple of strings in YAML format. Let’s take a look at additional rules file for markdown support:

:synsugar :
  # Code blocks, 4+ spaces indent
  '(?x-mi:(\R)((?:(?:\R)+(?:\s{4,}|\t).*)+\R)(?=\R))' : "\\1\nΛ auto\\2Λ\n"
  # Pictures
  '!\[(.*?)\]\((.*?)\)' :  '⚓\2 \1⚓'
  # Links
  '\[(.*?)\]\((.*?)\)' :  '⚓\2 \1⚓'
  # Blockquotes
  '^\s*>' : '〉'
  '^\s*>\s*>' : '〉 〉'
  '^\s*\*\s*\*' : '〉 •'
  '^\s+\*' : '• •'


:inplace : 
  :'__' : :strong
  :'**' : :strong
  :'_' : :em
  :'*' : :em
  :'`' : :code

Bold, italic, code, images, links, blockquotes (including nesteds) are now supported by qipowl. Let any one of you who is not delighted with, be the first to throw a stone at me.

Need custom support for github-flavored markdown strikethrough? Oneliner inside an :inplace section of custom rules came on scene:

  :'~~' :strike

Sophisticated extending

Whether one needs more sophisticated rules, she is to write her own descendant of Bowler class, implementing DSL herself. E.g. Html markup uses the following DSL for handling video links to YouTube:

 # Handler for Youtube video
 # @param [Array] args the words, gained since last call to {#harvest}
 # @return [Nil] nil
 def ✇ *args
   id, *rest = args.flatten
   harvest nil, orphan(rest.join(SEPARATOR)) unless rest.vacant?
   harvest __callee__, "<iframe width='560' height='315' 
           src='http://www.youtube.com/embed/#{id}' 
           frameborder='0' allowfullscreen></iframe>"
 end

Here we harvest the previously gained words (rest) and transform copy-pasted link to video into embedded frame with video content as by YouTube.

Installation

Add this line to your application's Gemfile:

gem 'qipowl'

And then execute:

$ bundle

Or install it yourself as:

$ gem install qipowl

Usage

require 'qipowl'
…
result =  Qipowl.parse text # qipowl markup _and_ markdown

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request