class Sprockets::Context

`Context` provides helper methods to all `Tilt` processors. They are typically accessed by ERB templates. You can mix in custom helpers by injecting them into `Environment#context_class`. Do not mix them into `Context` directly.

environment.context_class.class_eval do
  include MyHelper
  def asset_url; end
end

<%= asset_url "foo.png" %>

The `Context` also collects dependencies declared by assets. See `DirectiveProcessor` for an example of this.

Attributes

__LINE__[W]
_dependency_assets[R]
_dependency_paths[R]
_required_paths[R]
_stubbed_assets[R]
environment[R]
pathname[R]

Public Class Methods

new(environment, logical_path, pathname) click to toggle source
# File lib/sprockets/context.rb, line 29
def initialize(environment, logical_path, pathname)
  @environment  = environment
  @logical_path = logical_path
  @pathname     = pathname
  @__LINE__     = nil

  @_required_paths    = []
  @_stubbed_assets    = Set.new
  @_dependency_paths  = Set.new
  @_dependency_assets = Set.new([pathname.to_s])
end

Public Instance Methods

asset_data_uri(path) click to toggle source

Returns a Base64-encoded `data:` URI with the contents of the asset at the specified path, and marks that path as a dependency of the current file.

Use `asset_data_uri` from ERB with CSS or JavaScript assets:

#logo { background: url(<%= asset_data_uri 'logo.png' %>) }

$('<img>').attr('src', '<%= asset_data_uri 'avatar.jpg' %>')
# File lib/sprockets/context.rb, line 213
def asset_data_uri(path)
  depend_on_asset(path)
  asset  = environment.find_asset(path)
  base64 = Base64.encode64(asset.to_s).gsub(/\s+/, "")
  "data:#{asset.content_type};base64,#{Rack::Utils.escape(base64)}"
end
asset_requirable?(path) click to toggle source

Tests if target path is able to be safely required into the current concatenation.

# File lib/sprockets/context.rb, line 158
def asset_requirable?(path)
  pathname = resolve(path)
  content_type = environment.content_type_of(pathname)
  stat = environment.stat(path)
  return false unless stat && stat.file?
  self.content_type.nil? || self.content_type == content_type
end
content_type() click to toggle source

Returns content type of file

'application/javascript'
'text/css'
# File lib/sprockets/context.rb, line 64
def content_type
  environment.content_type_of(pathname)
end
depend_on(path) click to toggle source

`depend_on` allows you to state a dependency on a file without including it.

This is used for caching purposes. Any changes made to the dependency file with invalidate the cache of the source file.

# File lib/sprockets/context.rb, line 114
def depend_on(path)
  @_dependency_paths << resolve(path).to_s
  nil
end
depend_on_asset(path) click to toggle source

`depend_on_asset` allows you to state an asset dependency without including it.

This is used for caching purposes. Any changes that would invalidate the dependency asset will invalidate the source file. Unlike `depend_on`, this will include recursively include the target asset's dependencies.

# File lib/sprockets/context.rb, line 126
def depend_on_asset(path)
  filename = resolve(path).to_s
  @_dependency_assets << filename
  nil
end
evaluate(path, options = {}) click to toggle source

Reads `path` and runs processors on the file.

This allows you to capture the result of an asset and include it directly in another.

<%= evaluate "bar.js" %>
# File lib/sprockets/context.rb, line 173
def evaluate(path, options = {})
  pathname   = resolve(path)
  attributes = environment.attributes_for(pathname)
  processors = options[:processors] || attributes.processors

  if options[:data]
    result = options[:data]
  else
    if environment.respond_to?(:default_external_encoding)
      mime_type = environment.mime_types(pathname.extname)
      encoding  = environment.encoding_for_mime_type(mime_type)
      result    = Sprockets::Utils.read_unicode(pathname, encoding)
    else
      result = Sprockets::Utils.read_unicode(pathname)
    end
  end

  processors.each do |processor|
    begin
      template = processor.new(pathname.to_s) { result }
      result = template.render(self, {})
    rescue Exception => e
      annotate_exception! e
      raise
    end
  end

  result
end
logical_path() click to toggle source

Returns logical path without any file extensions.

'app/javascripts/application.js'
# => 'application'
# File lib/sprockets/context.rb, line 55
def logical_path
  @logical_path[/^([^.]+)/, 0]
end
require_asset(path) click to toggle source

`require_asset` declares `path` as a dependency of the file. The dependency will be inserted before the file and will only be included once.

If ERB processing is enabled, you can use it to dynamically require assets.

<%= require_asset "#{framework}.js" %>
# File lib/sprockets/context.rb, line 141
def require_asset(path)
  pathname = resolve(path, :content_type => :self)
  depend_on_asset(pathname)
  @_required_paths << pathname.to_s
  nil
end
resolve(path, options = {}, &block) click to toggle source

Given a logical path, `resolve` will find and return the fully expanded path. Relative paths will also be resolved. An optional `:content_type` restriction can be supplied to restrict the search.

resolve("foo.js")
# => "/path/to/app/javascripts/foo.js"

resolve("./bar.js")
# => "/path/to/app/javascripts/bar.js"
# File lib/sprockets/context.rb, line 79
def resolve(path, options = {}, &block)
  pathname   = Pathname.new(path)
  attributes = environment.attributes_for(pathname)

  if pathname.absolute?
    pathname

  elsif content_type = options[:content_type]
    content_type = self.content_type if content_type == :self

    if attributes.format_extension
      if content_type != attributes.content_type
        raise ContentTypeMismatch, "#{path} is " +
          "'#{attributes.content_type}', not '#{content_type}'"
      end
    end

    resolve(path) do |candidate|
      if self.content_type == environment.content_type_of(candidate)
        return candidate
      end
    end

    raise FileNotFound, "couldn't find file '#{path}'"
  else
    environment.resolve(path, :base_path => self.pathname.dirname, &block)
  end
end
root_path() click to toggle source

Returns the environment path that contains the file.

If `app/javascripts` and `app/stylesheets` are in your path, and current file is `app/javascripts/foo/bar.js`, `root_path` would return `app/javascripts`.

# File lib/sprockets/context.rb, line 46
def root_path
  environment.paths.detect { |path| pathname.to_s[path] }
end
stub_asset(path) click to toggle source

`stub_asset` blacklists `path` from being included in the bundle. `path` must be an asset which may or may not already be included in the bundle.

# File lib/sprockets/context.rb, line 151
def stub_asset(path)
  @_stubbed_assets << resolve(path, :content_type => :self).to_s
  nil
end

Private Instance Methods

annotate_exception!(exception) click to toggle source

Annotates exception backtrace with the original template that the exception was raised in.

# File lib/sprockets/context.rb, line 223
def annotate_exception!(exception)
  location = pathname.to_s
  location << ":#{@__LINE__}" if @__LINE__

  exception.extend(Sprockets::EngineError)
  exception.sprockets_annotation = "  (in #{location})"
end
logger() click to toggle source
# File lib/sprockets/context.rb, line 231
def logger
  environment.logger
end