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require 'sinatra/base'
module Sinatra
# = Sinatra::LinkHeader
#
# <tt>Sinatra::LinkHeader</tt> adds a set of helper methods to generate link
# HTML tags and their corresponding Link HTTP headers.
#
# == Usage
#
# Once you had set up the helpers in your application (see below), you will
# be able to call the following methods from inside your route handlers,
# filters and templates:
#
# +prefetch+::
# Sets the Link HTTP headers and returns HTML tags to prefetch the given
# resources.
#
# +stylesheet+::
# Sets the Link HTTP headers and returns HTML tags to use the given
# stylesheets.
#
# +link+::
# Sets the Link HTTP headers and returns the corresponding HTML tags
# for the given resources.
#
# +link_headers+::
# Returns the corresponding HTML tags for the current Link HTTP headers.
#
# === Classic Application
#
# In a classic application simply require the helpers, and start using them:
#
# require "sinatra"
# require "sinatra/link_header"
#
# # The rest of your classic application code goes here...
#
# === Modular Application
#
# In a modular application you need to require the helpers, and then tell
# the application you will use them:
#
# require "sinatra/base"
# require "sinatra/link_header"
#
# class MyApp < Sinatra::Base
# helpers Sinatra::LinkHeader
#
# # The rest of your modular application code goes here...
# end
#
module LinkHeader
##
# Sets Link HTTP header and returns HTML tags for telling the browser to
# prefetch given resources (only supported by Opera and Firefox at the
# moment).
def prefetch(*urls)
link(:prefetch, *urls)
end
##
# Sets Link HTTP header and returns HTML tags for using stylesheets.
def stylesheet(*urls)
urls << {} unless urls.last.respond_to? :to_hash
urls.last[:type] ||= mime_type(:css)
link(:stylesheet, *urls)
end
##
# Sets Link HTTP header and returns corresponding HTML tags.
#
# Example:
#
# # Sets header:
# # Link: </foo>; rel="next"
# # Returns String:
# # '<link href="/foo" rel="next" />'
# link '/foo', :rel => :next
#
# # Multiple URLs
# link :stylesheet, '/a.css', '/b.css'
def link(*urls)
opts = urls.last.respond_to?(:to_hash) ? urls.pop : {}
opts[:rel] = urls.shift unless urls.first.respond_to? :to_str
options = opts.map { |k, v| " #{k}=#{v.to_s.inspect}" }
html_pattern = "<link href=\"%s\"#{options.join} />"
http_pattern = ['<%s>', *options].join ';'
link = (response['Link'] ||= '')
link = response['Link'] = +link
urls.map do |url|
link << "," unless link.empty?
link << (http_pattern % url)
html_pattern % url
end.join
end
##
# Takes the current value of th Link header(s) and generates HTML tags
# from it.
#
# Example:
#
# get '/' do
# # You can of course use fancy helpers like #link, #stylesheet
# # or #prefetch
# response["Link"] = '</foo>; rel="next"'
# haml :some_page
# end
#
# __END__
#
# @@ layout
# %head= link_headers
# %body= yield
def link_headers
yield if block_given?
return '' unless response.include? 'Link'
response['Link'].split(",").map do |line|
url, *opts = line.split(';').map(&:strip)
"<link href=\"#{url[1..-2]}\" #{opts.join ' '} />"
end.join
end
def self.registered(_base)
puts "WARNING: #{self} is a helpers module, not an extension."
end
end
helpers LinkHeader
end
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