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require 'zlib'
module ActionView
# = Action View Asset URL Helpers
module Helpers
# This module provides methods for generating asset paths and
# urls.
#
# image_path("rails.png")
# # => "/assets/rails.png"
#
# image_url("rails.png")
# # => "http://www.example.com/assets/rails.png"
#
# === Using asset hosts
#
# By default, Rails links to these assets on the current host in the public
# folder, but you can direct Rails to link to assets from a dedicated asset
# server by setting <tt>ActionController::Base.asset_host</tt> in the application
# configuration, typically in <tt>config/environments/production.rb</tt>.
# For example, you'd define <tt>assets.example.com</tt> to be your asset
# host this way, inside the <tt>configure</tt> block of your environment-specific
# configuration files or <tt>config/application.rb</tt>:
#
# config.action_controller.asset_host = "assets.example.com"
#
# Helpers take that into account:
#
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# Browsers typically open at most two simultaneous connections to a single
# host, which means your assets often have to wait for other assets to finish
# downloading. You can alleviate this by using a <tt>%d</tt> wildcard in the
# +asset_host+. For example, "assets%d.example.com". If that wildcard is
# present Rails distributes asset requests among the corresponding four hosts
# "assets0.example.com", ..., "assets3.example.com". With this trick browsers
# will open eight simultaneous connections rather than two.
#
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets0.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# To do this, you can either setup four actual hosts, or you can use wildcard
# DNS to CNAME the wildcard to a single asset host. You can read more about
# setting up your DNS CNAME records from your ISP.
#
# Note: This is purely a browser performance optimization and is not meant
# for server load balancing. See http://www.die.net/musings/page_load_time/
# for background.
#
# Alternatively, you can exert more control over the asset host by setting
# +asset_host+ to a proc like this:
#
# ActionController::Base.asset_host = Proc.new { |source|
# "http://assets#{Digest::MD5.hexdigest(source).to_i(16) % 2 + 1}.example.com"
# }
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets1.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# The example above generates "http://assets1.example.com" and
# "http://assets2.example.com". This option is useful for example if
# you need fewer/more than four hosts, custom host names, etc.
#
# As you see the proc takes a +source+ parameter. That's a string with the
# absolute path of the asset, for example "/assets/rails.png".
#
# ActionController::Base.asset_host = Proc.new { |source|
# if source.ends_with?('.css')
# "http://stylesheets.example.com"
# else
# "http://assets.example.com"
# end
# }
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://stylesheets.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
# Alternatively you may ask for a second parameter +request+. That one is
# particularly useful for serving assets from an SSL-protected page. The
# example proc below disables asset hosting for HTTPS connections, while
# still sending assets for plain HTTP requests from asset hosts. If you don't
# have SSL certificates for each of the asset hosts this technique allows you
# to avoid warnings in the client about mixed media.
#
# config.action_controller.asset_host = Proc.new { |source, request|
# if request.ssl?
# "#{request.protocol}#{request.host_with_port}"
# else
# "#{request.protocol}assets.example.com"
# end
# }
#
# You can also implement a custom asset host object that responds to +call+
# and takes either one or two parameters just like the proc.
#
# config.action_controller.asset_host = AssetHostingWithMinimumSsl.new(
# "http://asset%d.example.com", "https://asset1.example.com"
# )
#
module AssetUrlHelper
URI_REGEXP = %r{^[-a-z]+://|^(?:cid|data):|^//}
# Computes the path to asset in public directory. If :type
# options is set, a file extension will be appended and scoped
# to the corresponding public directory.
#
# All other asset *_path helpers delegate through this method.
#
# asset_path "application.js" # => /application.js
# asset_path "application", type: :javascript # => /javascripts/application.js
# asset_path "application", type: :stylesheet # => /stylesheets/application.css
# asset_path "http://www.example.com/js/xmlhr.js" # => http://www.example.com/js/xmlhr.js
def asset_path(source, options = {})
source = source.to_s
return "" unless source.present?
return source if source =~ URI_REGEXP
tail, source = source[/([\?#].+)$/], source.sub(/([\?#].+)$/, '')
if extname = compute_asset_extname(source, options)
source = "#{source}#{extname}"
end
if source[0] != ?/
source = compute_asset_path(source, options)
end
relative_url_root = (defined?(config.relative_url_root) && config.relative_url_root) ||
(respond_to?(:request) && request.try(:script_name))
if relative_url_root
source = "#{relative_url_root}#{source}" unless source.starts_with?("#{relative_url_root}/")
end
if host = compute_asset_host(source, options)
source = "#{host}#{source}"
end
"#{source}#{tail}"
end
alias_method :path_to_asset, :asset_path # aliased to avoid conflicts with a asset_path named route
# Computes the full URL to a asset in the public directory. This
# will use +asset_path+ internally, so most of their behaviors
# will be the same.
def asset_url(source, options = {})
path_to_asset(source, options.merge(:protocol => :request))
end
alias_method :url_to_asset, :asset_url # aliased to avoid conflicts with an asset_url named route
ASSET_EXTENSIONS = {
javascript: '.js',
stylesheet: '.css'
}
# Compute extname to append to asset path. Returns nil if
# nothing should be added.
def compute_asset_extname(source, options = {})
return if options[:extname] == false
extname = options[:extname] || ASSET_EXTENSIONS[options[:type]]
extname if extname && File.extname(source) != extname
end
# Maps asset types to public directory.
ASSET_PUBLIC_DIRECTORIES = {
audio: '/audios',
font: '/fonts',
image: '/images',
javascript: '/javascripts',
stylesheet: '/stylesheets',
video: '/videos'
}
# Computes asset path to public directory. Plugins and
# extensions can override this method to point to custom assets
# or generate digested paths or query strings.
def compute_asset_path(source, options = {})
dir = ASSET_PUBLIC_DIRECTORIES[options[:type]] || ""
File.join(dir, source)
end
# Pick an asset host for this source. Returns +nil+ if no host is set,
# the host if no wildcard is set, the host interpolated with the
# numbers 0-3 if it contains <tt>%d</tt> (the number is the source hash mod 4),
# or the value returned from invoking call on an object responding to call
# (proc or otherwise).
def compute_asset_host(source = "", options = {})
request = self.request if respond_to?(:request)
host = config.asset_host if defined? config.asset_host
host ||= request.base_url if request && options[:protocol] == :request
return unless host
if host.respond_to?(:call)
arity = host.respond_to?(:arity) ? host.arity : host.method(:call).arity
args = [source]
args << request if request && (arity > 1 || arity < 0)
host = host.call(*args)
elsif host =~ /%d/
host = host % (Zlib.crc32(source) % 4)
end
if host =~ URI_REGEXP
host
else
protocol = options[:protocol] || config.default_asset_host_protocol || (request ? :request : :relative)
case protocol
when :relative
"//#{host}"
when :request
"#{request.protocol}#{host}"
else
"#{protocol}://#{host}"
end
end
end
# Computes the path to a javascript asset in the public javascripts directory.
# If the +source+ filename has no extension, .js will be appended (except for explicit URIs)
# Full paths from the document root will be passed through.
# Used internally by javascript_include_tag to build the script path.
#
# javascript_path "xmlhr" # => /javascripts/xmlhr.js
# javascript_path "dir/xmlhr.js" # => /javascripts/dir/xmlhr.js
# javascript_path "/dir/xmlhr" # => /dir/xmlhr.js
# javascript_path "http://www.example.com/js/xmlhr" # => http://www.example.com/js/xmlhr
# javascript_path "http://www.example.com/js/xmlhr.js" # => http://www.example.com/js/xmlhr.js
def javascript_path(source, options = {})
path_to_asset(source, {type: :javascript}.merge!(options))
end
alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with a javascript_path named route
# Computes the full URL to a javascript asset in the public javascripts directory.
# This will use +javascript_path+ internally, so most of their behaviors will be the same.
def javascript_url(source, options = {})
url_to_asset(source, {type: :javascript}.merge!(options))
end
alias_method :url_to_javascript, :javascript_url # aliased to avoid conflicts with a javascript_url named route
# Computes the path to a stylesheet asset in the public stylesheets directory.
# If the +source+ filename has no extension, <tt>.css</tt> will be appended (except for explicit URIs).
# Full paths from the document root will be passed through.
# Used internally by +stylesheet_link_tag+ to build the stylesheet path.
#
# stylesheet_path "style" # => /stylesheets/style.css
# stylesheet_path "dir/style.css" # => /stylesheets/dir/style.css
# stylesheet_path "/dir/style.css" # => /dir/style.css
# stylesheet_path "http://www.example.com/css/style" # => http://www.example.com/css/style
# stylesheet_path "http://www.example.com/css/style.css" # => http://www.example.com/css/style.css
def stylesheet_path(source, options = {})
path_to_asset(source, {type: :stylesheet}.merge!(options))
end
alias_method :path_to_stylesheet, :stylesheet_path # aliased to avoid conflicts with a stylesheet_path named route
# Computes the full URL to a stylesheet asset in the public stylesheets directory.
# This will use +stylesheet_path+ internally, so most of their behaviors will be the same.
def stylesheet_url(source, options = {})
url_to_asset(source, {type: :stylesheet}.merge!(options))
end
alias_method :url_to_stylesheet, :stylesheet_url # aliased to avoid conflicts with a stylesheet_url named route
# Computes the path to an image asset.
# Full paths from the document root will be passed through.
# Used internally by +image_tag+ to build the image path:
#
# image_path("edit") # => "/assets/edit"
# image_path("edit.png") # => "/assets/edit.png"
# image_path("icons/edit.png") # => "/assets/icons/edit.png"
# image_path("/icons/edit.png") # => "/icons/edit.png"
# image_path("http://www.example.com/img/edit.png") # => "http://www.example.com/img/edit.png"
#
# If you have images as application resources this method may conflict with their named routes.
# The alias +path_to_image+ is provided to avoid that. Rails uses the alias internally, and
# plugin authors are encouraged to do so.
def image_path(source, options = {})
path_to_asset(source, {type: :image}.merge!(options))
end
alias_method :path_to_image, :image_path # aliased to avoid conflicts with an image_path named route
# Computes the full URL to an image asset.
# This will use +image_path+ internally, so most of their behaviors will be the same.
def image_url(source, options = {})
url_to_asset(source, {type: :image}.merge!(options))
end
alias_method :url_to_image, :image_url # aliased to avoid conflicts with an image_url named route
# Computes the path to a video asset in the public videos directory.
# Full paths from the document root will be passed through.
# Used internally by +video_tag+ to build the video path.
#
# video_path("hd") # => /videos/hd
# video_path("hd.avi") # => /videos/hd.avi
# video_path("trailers/hd.avi") # => /videos/trailers/hd.avi
# video_path("/trailers/hd.avi") # => /trailers/hd.avi
# video_path("http://www.example.com/vid/hd.avi") # => http://www.example.com/vid/hd.avi
def video_path(source, options = {})
path_to_asset(source, {type: :video}.merge!(options))
end
alias_method :path_to_video, :video_path # aliased to avoid conflicts with a video_path named route
# Computes the full URL to a video asset in the public videos directory.
# This will use +video_path+ internally, so most of their behaviors will be the same.
def video_url(source, options = {})
url_to_asset(source, {type: :video}.merge!(options))
end
alias_method :url_to_video, :video_url # aliased to avoid conflicts with an video_url named route
# Computes the path to an audio asset in the public audios directory.
# Full paths from the document root will be passed through.
# Used internally by +audio_tag+ to build the audio path.
#
# audio_path("horse") # => /audios/horse
# audio_path("horse.wav") # => /audios/horse.wav
# audio_path("sounds/horse.wav") # => /audios/sounds/horse.wav
# audio_path("/sounds/horse.wav") # => /sounds/horse.wav
# audio_path("http://www.example.com/sounds/horse.wav") # => http://www.example.com/sounds/horse.wav
def audio_path(source, options = {})
path_to_asset(source, {type: :audio}.merge!(options))
end
alias_method :path_to_audio, :audio_path # aliased to avoid conflicts with an audio_path named route
# Computes the full URL to an audio asset in the public audios directory.
# This will use +audio_path+ internally, so most of their behaviors will be the same.
def audio_url(source, options = {})
url_to_asset(source, {type: :audio}.merge!(options))
end
alias_method :url_to_audio, :audio_url # aliased to avoid conflicts with an audio_url named route
# Computes the path to a font asset.
# Full paths from the document root will be passed through.
#
# font_path("font") # => /assets/font
# font_path("font.ttf") # => /assets/font.ttf
# font_path("dir/font.ttf") # => /assets/dir/font.ttf
# font_path("/dir/font.ttf") # => /dir/font.ttf
# font_path("http://www.example.com/dir/font.ttf") # => http://www.example.com/dir/font.ttf
def font_path(source, options = {})
path_to_asset(source, {type: :font}.merge!(options))
end
alias_method :path_to_font, :font_path # aliased to avoid conflicts with an font_path named route
# Computes the full URL to a font asset.
# This will use +font_path+ internally, so most of their behaviors will be the same.
def font_url(source, options = {})
url_to_asset(source, {type: :font}.merge!(options))
end
alias_method :url_to_font, :font_url # aliased to avoid conflicts with an font_url named route
end
end
end
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