├── test
    ├── source
    │   └── _posts
    │   │   ├── 2011-01-16-post-3.textile
    │   │   ├── 2011-02-16-post-0.textile
    │   │   ├── 2011-08-16-post-1.textile
    │   │   ├── 2011-08-16-post-4.textile
    │   │   ├── 2011-08-16-post-5.textile
    │   │   ├── 2011-08-16-post-6.textile
    │   │   └── 2011-08-20-post-2.textile
    └── test_related_posts.rb
├── .gitignore
├── README.rdoc
├── LICENCE.rdoc
└── _plugins
    └── related_posts.rb


/test/source/_posts/2011-01-16-post-3.textile:
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/test/source/_posts/2011-08-16-post-4.textile:
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/test/source/_posts/2011-08-16-post-5.textile:
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/test/source/_posts/2011-08-16-post-6.textile:
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/test/source/_posts/2011-08-20-post-2.textile:
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/.gitignore:
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1 | # Ignore backup text files
2 | *~
3 | 
4 | # Ignore vi swap files
5 | *.swp
6 | 


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/README.rdoc:
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 1 | = related_posts
 2 | 
 3 | This is a {jekyll}[http://jekyllrb.com/] plugin that overrides the built in
 4 | related_posts function to calculate related posts based on a posts' tags.
 5 | 
 6 | == Installation
 7 | To register it as a plugin, copy <tt>_plugins/related_posts.rb</tt> to the
 8 | <tt>_plugins</tt> directory of your jekyll project.
 9 | 
10 | == How to use it
11 | The plugin replaces the functionality of <tt>site.related_posts</tt> so you
12 | can use it as follows:
13 |   {% for post in site.related_posts %}
14 |     <a href="{{ post.url }}">{{ post.title }}</a><br />
15 |   {% endfor %}
16 |  
17 | == Licence
18 | Copyright (c) 2011-2012, Lawrence Woodman
19 | This software is licensed under an MIT Licence.  Please see the file, LICENCE.rdoc, for details.
20 | 


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/LICENCE.rdoc:
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 1 | = The MIT Licence
 2 | 
 3 | Copyright (c) 2011-2012 Lawrence Woodman
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in
13 | all copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 | THE SOFTWARE.
22 | 


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/_plugins/related_posts.rb:
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 1 | require 'jekyll/post'
 2 | 
 3 | module RelatedPosts
 4 | 
 5 |   # Used to remove #related_posts so that it can be overridden
 6 |   def self.included(klass)
 7 |     klass.class_eval do
 8 |       remove_method :related_posts
 9 |     end
10 |   end
11 | 
12 |   # Calculate related posts.
13 |   #
14 |   # Returns [<Post>]
15 |   def related_posts(posts)
16 |     return [] unless posts.size > 1
17 |     highest_freq = Jekyll::Post.tag_freq(posts).values.max
18 |     related_scores = Hash.new(0)
19 |     posts.each do |post|
20 |       post.tags.each do |tag|
21 |         if self.tags.include?(tag) && post != self
22 |           cat_freq = Jekyll::Post.tag_freq(posts)[tag]
23 |           related_scores[post] += (1+highest_freq-cat_freq)
24 |         end
25 |       end
26 |     end
27 | 
28 |     Jekyll::Post.sort_related_posts(related_scores)
29 |   end
30 | 
31 |   module ClassMethods
32 |     # Calculate the frequency of each tag.
33 |     #
34 |     # Returns {tag => freq, tag => freq, ...}
35 |     def tag_freq(posts)
36 |       return @tag_freq if @tag_freq
37 |       @tag_freq = Hash.new(0)
38 |       posts.each do |post|
39 |         post.tags.each {|tag| @tag_freq[tag] += 1}
40 |       end
41 |       @tag_freq
42 |     end
43 | 
44 |     # Sort the related posts in order of their score and date
45 |     # and return just the posts
46 |     def sort_related_posts(related_scores)
47 |       related_scores.sort do |a,b|
48 |         if a[1] < b[1]
49 |           1
50 |         elsif a[1] > b[1]
51 |           -1
52 |         else
53 |           b[0].date <=> a[0].date
54 |         end
55 |       end.collect {|post,freq| post}
56 |     end
57 |   end
58 | 
59 | end
60 | 
61 | module Jekyll
62 |   class Post
63 |     include RelatedPosts
64 |     extend RelatedPosts::ClassMethods
65 |   end
66 | end
67 | 


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/test/test_related_posts.rb:
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 1 | require 'test/unit'
 2 | require 'minitest/mock'
 3 | require 'minitest/spec'
 4 | require 'jekyll'
 5 | require_relative '../_plugins/related_posts'
 6 | 
 7 | def createPost(site, id, date, tags)
 8 |   file_dir = File.expand_path(File.dirname(__FILE__))
 9 |   post = Jekyll::Post.new(
10 |     site, file_dir, 'source', "#{date}-post-#{id}.textile"
11 |   )
12 |   post.define_singleton_method(:id) {id}
13 |   post.define_singleton_method(:tags) {tags}
14 |   post
15 | end
16 | 
17 | describe Jekyll::Post do
18 |   before do
19 |     @site = MiniTest::Mock.new
20 |     @posts = []
21 |     @posts << createPost(@site, 0, "2011-02-16", ['Retro', 'Programming'])
22 |     @posts << createPost(@site, 1, "2011-08-16", ['Retro', 'Games'])
23 |     @posts << createPost(@site, 2, "2011-08-20", ['Programming', 'Ruby'])
24 |     @posts << createPost(@site, 3, "2011-01-16", ['Programming', 'C'])
25 |     @posts << createPost(@site, 4, "2011-08-16", ['Off-topic', 'Funny', 'Story'])
26 |     @posts << createPost(@site, 5, "2011-08-16", ['Programming', 'Games', 'C'])
27 |     @posts << createPost(@site, 6, "2011-08-16", ['Retro', 'C'])
28 |   end
29 | 
30 |   describe 'when given a post with nothing related' do
31 |     it 'must return an empty array' do
32 |       @posts[4].related_posts(@posts).must_equal []
33 |     end
34 |   end
35 | 
36 |   describe 'when given a post with more than one related post' do
37 |     it 'must return related posts in order of relationship strength and date' do
38 |       @posts[5].related_posts(@posts).must_equal [
39 |         @posts[1], @posts[3], @posts[6], @posts[2], @posts[0]
40 |       ]
41 |     end
42 | 
43 |     it 'must return posts of equal relationship score in date order' do
44 |       @posts[2].related_posts(@posts).must_equal [
45 |         @posts[5], @posts[0], @posts[3]
46 |       ]
47 |     end
48 |   end
49 | 
50 | end
51 | 


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