How can I read a string into a Ruby dictionary? - ruby

Question

I currently want to replace my Wordpress-Blog by a Jekyll-Blog. To do so, I have to find an alternative to WordPress caption tags:
[caption id="attachment_76716" align="aligncenter" width="500"]<img src="http://martin-thoma.com/wp-content/uploads/2013/11/WER-calculation.png" alt="WER calculation" width="500" height="494" class="size-full wp-image-76716" /> WER calculation[/caption]
I thought it would be nice, if I could use them like that in my posts:
{% caption align="aligncenter" width="500" alt="WER calculation" text="WER calculation" url="../images/2013/11/WER-calculation.png" %}
While it should get rendered to:
<div style="width: 510px" class="wp-caption aligncenter">
<a href="../images/2013/11/WER-calculation.png">
<img src="../images/2013/11/WER-calculation.png" alt="WER calculation" width="500" height="494" class="size-full">
</a>
<p class="wp-caption-text">WER calculation</p>
</div>
So I've written some python code that does the replacement (once) and I wanted to write a Ruby / Liquid / Jekyll plugin that does the rendering. But I don't know how to read
align="aligncenter" width="500" alt="WER calculation" text="WER calculation" url="../images/2013/11/WER-calculation.png"
into a ruby dictionary (they seem to be called "Hash"?).
Here is my plugin:
# Title: Caption tag
# Author: Martin Thoma, http://martin-thoma.com
module Jekyll
class CaptionTag < Liquid::Tag
def initialize(tag_name, text, tokens)
super
#text = text
#tokens = tokens
end
def render(context)
#hash = Hash.new
#array = #text.split(" ")
#array.each do |element|
key, value = element.split("=")
#hash[key] = value
end
#"#{#text} #{#tokens}"
"<div style=\"width: #{#hash['width']}px\" class=\"#{#hash['alignment']}\">" +
"<a href=\"../images/#{#hash['url']}\">" +
"<img src=\"../images/#{#hash['url']}\" alt=\"#{#hash['text']}\" width=\"#{#hash['width']}\" height=\"#{#hash['height']}\" class=\"#{#hash['class']}\">" +
"</a>" +
"<p class=\"wp-caption-text\">#{#hash['text']}</p>" +
"</div>"
end
end
end
Liquid::Template.register_tag('caption', Jekyll::CaptionTag)
In Python, I would use the CSV module and set delimiter to space and quotechar to ". But I'm new to Ruby.
I've just seen that Ruby also has a CSV-module. But it doesn't work, as the quoting isn't correct. So I need some html-parsing.
A Python solution
def parse(text):
splitpoints = []
# parse
isOpen = False
for i, char in enumerate(text):
if char == '"':
isOpen = not isOpen
if char == " " and not isOpen:
splitpoints.append(i)
# build data structure
dictionary = {}
last = 0
for i in splitpoints:
key, value = text[last:i].split('=')
last = i+1
dictionary[key] = value[1:-1] # remove delimiter
return dictionary
print(parse('align="aligncenter" width="500" alt="WER calculation" text="WER calculation" url="../images/2013/11/WER-calculation.png"'))

Answer 1

If you set row separator to space, column separator to '=' and quote char to '"', you can easily parse your string into Hash with Ruby's CSV class:
require 'csv'
def parse_attrs(input)
options = { col_sep: '=', row_sep: ' ', quote_char: '"' }
csv = CSV.new input, options
csv.each_with_object({}) do |row, attrs|
attr, value = row
value ||= true
attrs[attr] = value
end
end
Example:
irb(main):031:0> input = 'align="aligncenter" width="500" alt="WER calculation" text="WER calculation" url="../images/2013/11/WER-calculation.png" required'
=> "align=\"aligncenter\" width=\"500\" alt=\"WER calculation\" text=\"WER calculation\" url=\"../images/2013/11/WER-calculation.png\""
irb(main):032:0> parse_attrs input
=> {"align"=>"aligncenter", "width"=>"500", "alt"=>"WER calculation", "text"=>"WER calculation", "url"=>"../images/2013/11/WER-calculation.png"}