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context.rb
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context.rb
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require 'base64'
require 'rack/utils'
require 'sprockets/errors'
require 'sprockets/utils'
require 'pathname'
require 'set'
module Sprockets
# `Context` provides helper methods to all `Template` 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.
class Context
attr_reader :environment, :pathname
attr_reader :_required_paths, :_stubbed_assets
attr_reader :_dependency_paths, :_dependency_assets
attr_writer :__LINE__
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
# 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`.
def root_path
environment.paths.detect { |path| pathname.to_s[path] }
end
# Returns logical path without any file extensions.
#
# 'app/javascripts/application.js'
# # => 'application'
#
def logical_path
@logical_path.chomp(File.extname(@logical_path))
end
# Returns content type of file
#
# 'application/javascript'
# 'text/css'
#
def content_type
environment.content_type_of(pathname)
end
# 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"
#
def resolve(path, options = {}, &block)
pathname = Pathname.new(path)
attributes = environment.attributes_for(pathname)
if pathname.absolute?
if environment.stat(pathname)
pathname
else
raise FileNotFound, "couldn't find file '#{pathname}'"
end
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}.merge(options), &block)
end
end
# `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.
def depend_on(path)
@_dependency_paths << resolve(path).to_s
nil
end
# `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.
def depend_on_asset(path)
filename = resolve(path).to_s
@_dependency_assets << filename
nil
end
# `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" %>
#
def require_asset(path)
pathname = resolve(path, content_type: :self)
depend_on_asset(pathname)
@_required_paths << pathname.to_s
nil
end
# `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.
def stub_asset(path)
@_stubbed_assets << resolve(path, content_type: :self).to_s
nil
end
# Tests if target path is able to be safely required into the
# current concatenation.
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
# 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" %>
#
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
# 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' %>')
#
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
# Expands logical path to full url to asset.
#
# NOTE: This helper is currently not implemented and should be
# customized by the application. Though, in the future, some
# basics implemention may be provided with different methods that
# are required to be overridden.
def asset_path(path, options = {})
message = <<-EOS
Custom asset_path helper is not implemented
Extend your environment context with a custom method.
environment.context_class.class_eval do
def asset_path(path, options = {})
end
end
EOS
raise NotImplementedError, message
end
# Expand logical image asset path.
def image_path(path)
asset_path(path, type: :image)
end
# Expand logical video asset path.
def video_path(path)
asset_path(path, type: :video)
end
# Expand logical audio asset path.
def audio_path(path)
asset_path(path, type: :audio)
end
# Expand logical font asset path.
def font_path(path)
asset_path(path, type: :font)
end
# Expand logical javascript asset path.
def javascript_path(path)
asset_path(path, type: :javascript)
end
# Expand logical stylesheet asset path.
def stylesheet_path(path)
asset_path(path, type: :stylesheet)
end
private
# Annotates exception backtrace with the original template that
# the exception was raised in.
def annotate_exception!(exception)
location = pathname.to_s
location << ":#{@__LINE__}" if @__LINE__
exception.extend(Sprockets::EngineError)
exception.sprockets_annotation = " (in #{location})"
end
def logger
environment.logger
end
end
end