class Sprockets::DirectiveProcessor

The ‘DirectiveProcessor` is responsible for parsing and evaluating directive comments in a source file.

A directive comment starts with a comment prefix, followed by an “=”, then the directive name, then any arguments.

// JavaScript
//= require "foo"

# CoffeeScript
#= require "bar"

/* CSS
 *= require "baz"
 */

This makes it possible to disable or modify the processor to do whatever you’d like. You could add your own custom directives or invent your own directive syntax.

‘Environment#processors` includes `DirectiveProcessor` by default.

To remove the processor entirely:

env.unregister_processor('text/css', Sprockets::DirectiveProcessor)
env.unregister_processor('application/javascript', Sprockets::DirectiveProcessor)

Then inject your own preprocessor:

env.register_processor('text/css', MyProcessor)

Constants

DIRECTIVE_PATTERN

Directives are denoted by a ‘=` followed by the name, then argument list.

A few different styles are allowed:

// =require foo
//= require foo
//= require "foo"

Public Class Methods

call(input) click to toggle source
# File lib/sprockets/directive_processor.rb, line 56
def self.call(input)
  instance.call(input)
end
instance() click to toggle source
# File lib/sprockets/directive_processor.rb, line 51
def self.instance
  # Default to C comment styles
  @instance ||= new(comments: ["//", ["/*", "*/"]])
end
new(comments: []) click to toggle source
# File lib/sprockets/directive_processor.rb, line 60
def initialize(comments: [])
  @header_pattern = compile_header_pattern(Array(comments))
end

Public Instance Methods

_call(input) click to toggle source
# File lib/sprockets/directive_processor.rb, line 68
def _call(input)
  @environment  = input[:environment]
  @uri          = input[:uri]
  @filename     = input[:filename]
  @dirname      = File.dirname(@filename)
  # If loading a source map file like `application.js.map` resolve
  # dependencies using `.js` instead of `.js.map`
  @content_type = SourceMapProcessor.original_content_type(input[:content_type], error_when_not_found: false)
  @required     = Set.new(input[:metadata][:required])
  @stubbed      = Set.new(input[:metadata][:stubbed])
  @links        = Set.new(input[:metadata][:links])
  @dependencies = Set.new(input[:metadata][:dependencies])
  @to_link      = Set.new
  @to_load      = Set.new

  data, directives = process_source(input[:data])
  process_directives(directives)

  {
    data:         data,
    required:     @required,
    stubbed:      @stubbed,
    links:        @links,
    to_load:      @to_load,
    to_link:      @to_link,
    dependencies: @dependencies
  }
end
call(input) click to toggle source
# File lib/sprockets/directive_processor.rb, line 64
def call(input)
  dup._call(input)
end

Protected Instance Methods

compile_header_pattern(comments) click to toggle source

Directives will only be picked up if they are in the header of the source file. C style (/* */), JavaScript (//), and Ruby (#) comments are supported.

Directives in comments after the first non-whitespace line of code will not be processed.

# File lib/sprockets/directive_processor.rb, line 104
def compile_header_pattern(comments)
  re = comments.map { |c|
    case c
    when String
      "(?:#{Regexp.escape(c)}.*\\n?)+"
    when Array
      "(?:#{Regexp.escape(c[0])}(?m:.*?)#{Regexp.escape(c[1])})"
    else
      raise TypeError, "unknown comment type: #{c.class}"
    end
  }.join("|")
  Regexp.compile("\\A(?:(?m:\\s*)(?:#{re}))+")
end
extract_directives(header) click to toggle source

Returns an Array of directive structures. Each structure is an Array with the line number as the first element, the directive name as the second element, followed by any arguments.

[[1, "require", "foo"], [2, "require", "bar"]]
# File lib/sprockets/directive_processor.rb, line 141
def extract_directives(header)
  processed_header = +""
  directives = []

  header.lines.each_with_index do |line, index|
    if directive = line[DIRECTIVE_PATTERN, 1]
      name, *args = Shellwords.shellwords(directive)
      if respond_to?("process_#{name}_directive", true)
        directives << [index + 1, name, *args]
        # Replace directive line with a clean break
        line = "\n"
      end
    end
    processed_header << line
  end

  processed_header.chomp!
  # Ensure header ends in a new line like before it was processed
  processed_header << "\n" if processed_header.length > 0 && header[-1] == "\n"

  return processed_header, directives
end
process_depend_on_asset_directive(path) click to toggle source

Allows you to state a dependency on an asset without including it.

This is used for caching purposes. Any changes that would invalidate the asset dependency will invalidate the cache of the source file.

Unlike ‘depend_on`, the path must be a requirable asset.

//= depend_on_asset "bar.js"
# File lib/sprockets/directive_processor.rb, line 284
def process_depend_on_asset_directive(path)
  to_load(resolve(path))
end
process_depend_on_directive(path) click to toggle source

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 will invalidate the cache of the source file.

This is useful if you are using ERB and File.read to pull in contents from another file.

//= depend_on "foo.png"
# File lib/sprockets/directive_processor.rb, line 269
def process_depend_on_directive(path)
  resolve(path)
end
process_depend_on_directory_directive(path = ".", accept = nil) click to toggle source

Allows you to state a dependency on a relative directory without including it.

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

This is useful if you are using ERB and File.read to pull in contents from multiple files in a directory.

//= depend_on_directory ./data
# File lib/sprockets/directive_processor.rb, line 300
def process_depend_on_directory_directive(path = ".", accept = nil)
  path = expand_relative_dirname(:depend_on_directory, path)
  accept = expand_accept_shorthand(accept)
  resolve_paths(*@environment.stat_directory_with_dependencies(path), accept: accept)
end
process_directives(directives) click to toggle source

Gathers comment directives in the source and processes them. Any directive method matching ‘process_*_directive` will automatically be available. This makes it easy to extend the processor.

To implement a custom directive called ‘require_glob`, subclass `Sprockets::DirectiveProcessor`, then add a method called `process_require_glob_directive`.

class DirectiveProcessor < Sprockets::DirectiveProcessor
  def process_require_glob_directive(glob)
    Dir["#{dirname}/#{glob}"].sort.each do |filename|
      require(filename)
    end
  end
end

Replace the current processor on the environment with your own:

env.unregister_processor('text/css', Sprockets::DirectiveProcessor)
env.register_processor('text/css', DirectiveProcessor)
# File lib/sprockets/directive_processor.rb, line 186
def process_directives(directives)
  directives.each do |line_number, name, *args|
    begin
      send("process_#{name}_directive", *args)
    rescue Exception => e
      e.set_backtrace(["#{@filename}:#{line_number}"] + e.backtrace)
      raise e
    end
  end
end
process_require_directive(path) click to toggle source

The ‘require` directive functions similar to Ruby’s own ‘require`. It provides a way to declare a dependency on a file in your path and ensures it’s only loaded once before the source file.

‘require` works with files in the environment path:

//= require "foo.js"

Extensions are optional. If your source file is “.js”, it assumes you are requiring another “.js”.

//= require "foo"

Relative paths work too. Use a leading ‘./` to denote a relative path:

//= require "./bar"
# File lib/sprockets/directive_processor.rb, line 215
def process_require_directive(path)
  @required << resolve(path, accept: @content_type, pipeline: :self)
end
process_require_directory_directive(path = ".") click to toggle source

‘require_directory` requires all the files inside a single directory. It’s similar to ‘path/*` since it does not follow nested directories.

//= require_directory "./javascripts"
# File lib/sprockets/directive_processor.rb, line 242
def process_require_directory_directive(path = ".")
  path = expand_relative_dirname(:require_directory, path)
  require_paths(*@environment.stat_directory_with_dependencies(path))
end
process_require_self_directive() click to toggle source

‘require_self` causes the body of the current file to be inserted before any subsequent `require` directives. Useful in CSS files, where it’s common for the index file to contain global styles that need to be defined before other dependencies are loaded.

/*= require "reset"
 *= require_self
 *= require_tree .
 */
# File lib/sprockets/directive_processor.rb, line 229
def process_require_self_directive
  if @required.include?(@uri)
    raise ArgumentError, "require_self can only be called once per source file"
  end
  @required << @uri
end
process_require_tree_directive(path = ".") click to toggle source

‘require_tree` requires all the nested files in a directory. Its glob equivalent is `path/*/`.

//= require_tree "./public"
# File lib/sprockets/directive_processor.rb, line 252
def process_require_tree_directive(path = ".")
  path = expand_relative_dirname(:require_tree, path)
  require_paths(*@environment.stat_sorted_tree_with_dependencies(path))
end
process_source(source) click to toggle source
# File lib/sprockets/directive_processor.rb, line 118
def process_source(source)
  header = source[@header_pattern, 0] || ""
  body   = $' || source

  header, directives = extract_directives(header)

  data = +""
  data.force_encoding(body.encoding)
  data << header unless header.empty?
  data << body
  # Ensure body ends in a new line
  data << "\n" if data.length > 0 && data[-1] != "\n"

  return data, directives
end
process_stub_directive(path) click to toggle source

Allows dependency to be excluded from the asset bundle.

The ‘path` must be a valid asset and may or may not already be part of the bundle. Once stubbed, it is blacklisted and can’t be brought back by any other ‘require`.

//= stub "jquery"
# File lib/sprockets/directive_processor.rb, line 314
def process_stub_directive(path)
  @stubbed << resolve(path, accept: @content_type, pipeline: :self)
end

Private Instance Methods

expand_accept_shorthand(accept) click to toggle source
# File lib/sprockets/directive_processor.rb, line 365
def expand_accept_shorthand(accept)
  if accept.nil?
    nil
  elsif accept.include?("/")
    accept
  elsif accept.start_with?(".")
    @environment.mime_exts[accept]
  else
    @environment.mime_exts[".#{accept}"]
  end
end
expand_relative_dirname(directive, path) click to toggle source
# File lib/sprockets/directive_processor.rb, line 399
def expand_relative_dirname(directive, path)
  if @environment.relative_path?(path)
    path = File.expand_path(path, @dirname)
    stat = @environment.stat(path)

    if stat && stat.directory?
      path
    else
      raise ArgumentError, "#{directive} argument must be a directory"
    end
  else
    # The path must be relative and start with a `./`.
    raise ArgumentError, "#{directive} argument must be a relative path"
  end
end
require_paths(paths, deps) click to toggle source
# File lib/sprockets/directive_processor.rb, line 377
def require_paths(paths, deps)
  resolve_paths(paths, deps, accept: @content_type, pipeline: :self) do |uri|
    @required << uri
  end
end
resolve(path, **kargs) click to toggle source
# File lib/sprockets/directive_processor.rb, line 420
def resolve(path, **kargs)
  # Prevent absolute paths in directives
  if @environment.absolute_path?(path)
    raise FileOutsidePaths, "can't require absolute file: #{path}"
  end

  kargs[:base_path] = @dirname
  uri, deps = @environment.resolve!(path, **kargs)
  @dependencies.merge(deps)
  uri
end
resolve_paths(paths, deps, **kargs) { |uri| ... } click to toggle source
# File lib/sprockets/directive_processor.rb, line 389
def resolve_paths(paths, deps, **kargs)
  @dependencies.merge(deps)
  paths.each do |subpath, stat|
    next if subpath == @filename || stat.directory?
    uri, deps = @environment.resolve(subpath, **kargs)
    @dependencies.merge(deps)
    yield uri if uri && block_given?
  end
end
to_load(uri) click to toggle source
# File lib/sprockets/directive_processor.rb, line 415
def to_load(uri)
  @to_load << uri
  uri
end