blog/plugins/pagination.rb

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4.0 KiB
Ruby
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module Jekyll
class Pagination < Generator
# This generator is safe from arbitrary code execution.
safe true
# Generate paginated pages if necessary.
#
# site - The Site.
#
# Returns nothing.
def generate(site)
site.pages.dup.each do |page|
paginate(site, page) if Pager.pagination_enabled?(site.config, page)
end
end
# Paginates the blog's posts. Renders the index.html file into paginated
# directories, e.g.: page2/index.html, page3/index.html, etc and adds more
# site-wide data.
#
# site - The Site.
# page - The index.html Page that requires pagination.
#
# {"paginator" => { "page" => <Number>,
# "per_page" => <Number>,
# "posts" => [<Post>],
# "total_posts" => <Number>,
# "total_pages" => <Number>,
# "previous_page" => <Number>,
# "next_page" => <Number> }}
def paginate(site, page)
all_posts = site.site_payload['site']['posts']
pages = Pager.calculate_pages(all_posts, site.config['paginate'].to_i)
page_dir = page.destination('').sub(/\/[^\/]+$/, '')
page_dir_config = site.config['pagination_dir']
dir = ((page_dir_config || page_dir) + '/').sub(/^\/+/, '')
(1..pages).each do |num_page|
pager = Pager.new(site.config, num_page, all_posts, pages, page_dir+'/', '/'+dir)
if num_page > 1
newpage = Page.new(site, site.source, page_dir, page.name)
newpage.pager = pager
newpage.dir = File.join(page.dir, "#{dir}page/#{num_page}")
site.pages << newpage
else
page.pager = pager
end
end
end
end
class Pager
attr_reader :page, :per_page, :posts, :total_posts, :total_pages, :previous_page, :next_page
# Calculate the number of pages.
#
# all_posts - The Array of all Posts.
# per_page - The Integer of entries per page.
#
# Returns the Integer number of pages.
def self.calculate_pages(all_posts, per_page)
(all_posts.size.to_f / per_page.to_i).ceil
end
# Determine if pagination is enabled for a given file.
#
# config - The configuration Hash.
# file - The String filename of the file.
#
# Returns true if pagination is enabled, false otherwise.
def self.pagination_enabled?(config, file)
file.name == 'index.html' && !config['paginate'].nil? && file.content =~ /paginator\./
end
# Initialize a new Pager.
#
# config - The Hash configuration of the site.
# page - The Integer page number.
# all_posts - The Array of all the site's Posts.
# num_pages - The Integer number of pages or nil if you'd like the number
# of pages calculated.
def initialize(config, page, all_posts, num_pages = nil, index_dir, pagination_dir)
@page = page
@per_page = config['paginate'].to_i
@page_dir = pagination_dir + 'page/'
@total_pages = num_pages || Pager.calculate_pages(all_posts, @per_page)
@previous_page = nil
if @page > @total_pages
raise RuntimeError, "page number can't be greater than total pages: #{@page} > #{@total_pages}"
end
init = (@page - 1) * @per_page
offset = (init + @per_page - 1) >= all_posts.size ? all_posts.size : (init + @per_page - 1)
@total_posts = all_posts.size
@posts = all_posts[init..offset]
@previous_page = @page != 1 ? @page_dir + (@page - 1).to_s + '/' : nil
@previous_page = index_dir if @page - 1 == 1
@next_page = @page != @total_pages ? @page_dir + (@page + 1).to_s + '/' : nil
end
# Convert this Pager's data to a Hash suitable for use by Liquid.
#
# Returns the Hash representation of this Pager.
def to_liquid
{
'page' => page,
'per_page' => per_page,
'posts' => posts,
'total_posts' => total_posts,
'total_pages' => total_pages,
'previous_page' => previous_page,
'next_page' => next_page
}
end
end
end