Class: Sprockets::SourceMapProcessor

Inherits:
Object
  • Object
show all
Defined in:
lib/sprockets/source_map_processor.rb

Overview

The purpose of this class is to generate a source map file that can be read and understood by browsers.

When a file is passed in it will have a ‘application/js-sourcemap+json` or `application/css-sourcemap+json` mime type. The filename will be match the original asset. The original asset is loaded. As it gets processed by Sprockets it will acquire all information needed to build a source map file in the `asset.to_hash[:map]` key.

The output is an asset with a properly formatted source map file:

{
  "version": 3,
  "sources": ["foo.js"],
  "names":   [ ],
  "mappings": "AAAA,GAAIA"
}

Class Method Summary collapse

Class Method Details

.call(input) ⇒ Object 



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# File 'lib/sprockets/source_map_processor.rb', line 26

def self.call(input)
  links = Set.new(input[:metadata][:links])
  env = input[:environment]

  uri, _ = env.resolve!(input[:filename], accept: self.original_content_type(input[:content_type]))
  asset  = env.load(uri)
  map    = asset.metadata[:map]

  # TODO: Because of the default piplene hack we have to apply dependencies
  #       from compiled asset to the source map, otherwise the source map cache
  #       will never detect the changes from directives
  dependencies = Set.new(input[:metadata][:dependencies])
  dependencies.merge(asset.metadata[:dependencies])

  map["file"] = PathUtils.split_subpath(input[:load_path], input[:filename])
  sources = map["sections"] ? map["sections"].map { |s| s["map"]["sources"] }.flatten : map["sources"]

  sources.each do |source|
    source = PathUtils.join(File.dirname(map["file"]), source)
    uri, _ = env.resolve!(source)
    links << uri
  end

  json = JSON.generate(map)

  { data: json, links: links, dependencies: dependencies }
end

.original_content_type(source_map_content_type, error_when_not_found: true) ⇒ Object 



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# File 'lib/sprockets/source_map_processor.rb', line 54

def self.original_content_type(source_map_content_type, error_when_not_found: true)
  case source_map_content_type
  when "application/js-sourcemap+json"
    "application/javascript"
  when "application/css-sourcemap+json"
    "text/css"
  else
    fail(source_map_content_type) if error_when_not_found
    source_map_content_type
  end
end