/lib/jammit/compressor.rb
http://github.com/documentcloud/jammit · Ruby · 266 lines · 177 code · 33 blank · 56 comment · 24 complexity · b49db26e8de4c2cf35f673a9ebccdc37 MD5 · raw file
- module Jammit
- # Uses the YUI Compressor or Closure Compiler to compress JavaScript.
- # Always uses YUI to compress CSS (Which means that Java must be installed.)
- # Also knows how to create a concatenated JST file.
- # If "embed_assets" is turned on, creates "mhtml" and "datauri" versions of
- # all stylesheets, with all enabled assets inlined into the css.
- class Compressor
- # Mapping from extension to mime-type of all embeddable assets.
- EMBED_MIME_TYPES = {
- '.png' => 'image/png',
- '.jpg' => 'image/jpeg',
- '.jpeg' => 'image/jpeg',
- '.gif' => 'image/gif',
- '.tif' => 'image/tiff',
- '.tiff' => 'image/tiff',
- '.ttf' => 'application/x-font-ttf',
- '.otf' => 'font/opentype',
- '.woff' => 'application/x-font-woff'
- }
- # Font extensions for which we allow embedding:
- EMBED_EXTS = EMBED_MIME_TYPES.keys
- EMBED_FONTS = ['.ttf', '.otf', '.woff']
- # (32k - padding) maximum length for data-uri assets (an IE8 limitation).
- MAX_IMAGE_SIZE = 32700
- # CSS asset-embedding regexes for URL rewriting.
- EMBED_DETECTOR = /url\(['"]?([^\s)]+\.[a-z]+)(\?\d+)?['"]?\)/
- EMBEDDABLE = /[\A\/]embed\//
- EMBED_REPLACER = /url\(__EMBED__(.+?)(\?\d+)?\)/
- # MHTML file constants.
- MHTML_START = "/*\r\nContent-Type: multipart/related; boundary=\"MHTML_MARK\"\r\n\r\n"
- MHTML_SEPARATOR = "--MHTML_MARK\r\n"
- MHTML_END = "\r\n--MHTML_MARK--\r\n*/\r\n"
- # JST file constants.
- JST_START = "(function(){"
- JST_END = "})();"
- JAVASCRIPT_COMPRESSORS = {
- :jsmin => Jammit.javascript_compressors.include?(:jsmin) ? Jammit::JsminCompressor : nil,
- :yui => Jammit.javascript_compressors.include?(:yui) ? YUI::JavaScriptCompressor : nil,
- :closure => Jammit.javascript_compressors.include?(:closure) ? Closure::Compiler : nil,
- :uglifier => Jammit.javascript_compressors.include?(:uglifier) ? Jammit::Uglifier : nil
- }
- CSS_COMPRESSORS = {
- :cssmin => Jammit.css_compressors.include?(:cssmin) ? Jammit::CssminCompressor : nil,
- :yui => Jammit.css_compressors.include?(:yui) ? YUI::CssCompressor : nil,
- :sass => Jammit.css_compressors.include?(:sass) ? Jammit::SassCompressor : nil
- }
- JAVASCRIPT_DEFAULT_OPTIONS = {
- :jsmin => {},
- :yui => {:munge => true},
- :closure => {},
- :uglifier => {:copyright => false}
- }
- # CSS compression can be provided with YUI Compressor or sass. JS
- # compression can be provided with YUI Compressor, Google Closure
- # Compiler or UglifyJS.
- def initialize
- if Jammit.javascript_compressors.include?(:yui) || Jammit.javascript_compressors.include?(:closure) || Jammit.css_compressors.include?(:yui)
- Jammit.check_java_version
- end
- css_flavor = Jammit.css_compressor || Jammit::DEFAULT_CSS_COMPRESSOR
- @css_compressor = CSS_COMPRESSORS[css_flavor].new(Jammit.css_compressor_options || {})
- js_flavor = Jammit.javascript_compressor || Jammit::DEFAULT_JAVASCRIPT_COMPRESSOR
- @options = JAVASCRIPT_DEFAULT_OPTIONS[js_flavor].merge(Jammit.compressor_options || {})
- @js_compressor = JAVASCRIPT_COMPRESSORS[js_flavor].new(@options)
- end
- # Concatenate together a list of JavaScript paths, and pass them through the
- # YUI Compressor (with munging enabled). JST can optionally be included.
- def compress_js(paths)
- if (jst_paths = paths.grep(Jammit.template_extension_matcher)).empty?
- js = concatenate(paths)
- else
- js = concatenate(paths - jst_paths) + compile_jst(jst_paths)
- end
- Jammit.compress_assets ? @js_compressor.compress(js) : js
- end
- # Concatenate and compress a list of CSS stylesheets. When compressing a
- # :datauri or :mhtml variant, post-processes the result to embed
- # referenced assets.
- def compress_css(paths, variant=nil, asset_url=nil)
- @asset_contents = {}
- css = concatenate_and_tag_assets(paths, variant)
- css = @css_compressor.compress(css) if Jammit.compress_assets
- case variant
- when nil then return css
- when :datauri then return with_data_uris(css)
- when :mhtml then return with_mhtml(css, asset_url)
- else raise PackageNotFound, "\"#{variant}\" is not a valid stylesheet variant"
- end
- end
- # Compiles a single JST file by writing out a javascript that adds
- # template properties to a top-level template namespace object. Adds a
- # JST-compilation function to the top of the package, unless you've
- # specified your own preferred function, or turned it off.
- # JST templates are named with the basename of their file.
- def compile_jst(paths)
- namespace = Jammit.template_namespace
- paths = paths.grep(Jammit.template_extension_matcher).sort
- base_path = find_base_path(paths)
- compiled = paths.map do |path|
- contents = read_binary_file(path)
- contents = contents.gsub(/\r?\n/, "\\n").gsub("'", '\\\\\'')
- name = template_name(path, base_path)
- "#{namespace}['#{name}'] = #{Jammit.template_function}('#{contents}');"
- end
- compiler = Jammit.include_jst_script ? read_binary_file(DEFAULT_JST_SCRIPT) : '';
- setup_namespace = "#{namespace} = #{namespace} || {};"
- [JST_START, setup_namespace, compiler, compiled, JST_END].flatten.join("\n")
- end
- private
- # Given a set of paths, find a common prefix path.
- def find_base_path(paths)
- return nil if paths.length <= 1
- paths.sort!
- first = paths.first.split('/')
- last = paths.last.split('/')
- i = 0
- while first[i] == last[i] && i <= first.length
- i += 1
- end
- res = first.slice(0, i).join('/')
- res.empty? ? nil : res
- end
- # Determine the name of a JS template. If there's a common base path, use
- # the namespaced prefix. Otherwise, simply use the filename.
- def template_name(path, base_path)
- return File.basename(path, ".#{Jammit.template_extension}") unless base_path
- path.gsub(/\A#{Regexp.escape(base_path)}\/(.*)\.#{Jammit.template_extension}\Z/, '\1')
- end
- # In order to support embedded assets from relative paths, we need to
- # expand the paths before contatenating the CSS together and losing the
- # location of the original stylesheet path. Validate the assets while we're
- # at it.
- def concatenate_and_tag_assets(paths, variant=nil)
- stylesheets = [paths].flatten.map do |css_path|
- contents = read_binary_file(css_path)
- contents.gsub(EMBED_DETECTOR) do |url|
- ipath, cpath = Pathname.new($1), Pathname.new(File.expand_path(css_path))
- is_url = URI.parse($1).absolute?
- is_url ? url : "url(#{construct_asset_path(ipath, cpath, variant)})"
- end
- end
- stylesheets.join("\n")
- end
- # Re-write all enabled asset URLs in a stylesheet with their corresponding
- # Data-URI Base-64 encoded asset contents.
- def with_data_uris(css)
- css.gsub(EMBED_REPLACER) do |url|
- "url(\"data:#{mime_type($1)};charset=utf-8;base64,#{encoded_contents($1)}\")"
- end
- end
- # Re-write all enabled asset URLs in a stylesheet with the MHTML equivalent.
- # The newlines ("\r\n") in the following method are critical. Without them
- # your MHTML will look identical, but won't work.
- def with_mhtml(css, asset_url)
- paths, index = {}, 0
- css = css.gsub(EMBED_REPLACER) do |url|
- i = paths[$1] ||= "#{index += 1}-#{File.basename($1)}"
- "url(mhtml:#{asset_url}!#{i})"
- end
- mhtml = paths.sort.map do |path, identifier|
- mime, contents = mime_type(path), encoded_contents(path)
- [MHTML_SEPARATOR, "Content-Location: #{identifier}\r\n", "Content-Type: #{mime}\r\n", "Content-Transfer-Encoding: base64\r\n\r\n", contents, "\r\n"]
- end
- [MHTML_START, mhtml, MHTML_END, css].flatten.join('')
- end
- # Return a rewritten asset URL for a new stylesheet -- the asset should
- # be tagged for embedding if embeddable, and referenced at the correct level
- # if relative.
- def construct_asset_path(asset_path, css_path, variant)
- public_path = absolute_path(asset_path, css_path)
- return "__EMBED__#{public_path}" if embeddable?(public_path, variant)
- source = asset_path.absolute? || ! Jammit.rewrite_relative_paths ? asset_path.to_s : relative_path(public_path)
- rewrite_asset_path(source, public_path)
- end
- # Get the site-absolute public path for an asset file path that may or may
- # not be relative, given the path of the stylesheet that contains it.
- def absolute_path(asset_pathname, css_pathname)
- (asset_pathname.absolute? ?
- Pathname.new(File.join(Jammit.public_root, asset_pathname)) :
- css_pathname.dirname + asset_pathname).cleanpath
- end
- # CSS assets that are referenced by relative paths, and are *not* being
- # embedded, must be rewritten relative to the newly-merged stylesheet path.
- def relative_path(absolute_path)
- File.join('../', absolute_path.sub(Jammit.public_root, ''))
- end
- # Similar to the AssetTagHelper's method of the same name, this will
- # append the RAILS_ASSET_ID cache-buster to URLs, if it's defined.
- def rewrite_asset_path(path, file_path)
- asset_id = rails_asset_id(file_path)
- (!asset_id || asset_id == '') ? path : "#{path}?#{asset_id}"
- end
- # Similar to the AssetTagHelper's method of the same name, this will
- # determine the correct asset id for a file.
- def rails_asset_id(path)
- asset_id = ENV["RAILS_ASSET_ID"]
- return asset_id if asset_id
- File.exists?(path) ? File.mtime(path).to_i.to_s : ''
- end
- # An asset is valid for embedding if it exists, is less than 32K, and is
- # stored somewhere inside of a folder named "embed". IE does not support
- # Data-URIs larger than 32K, and you probably shouldn't be embedding assets
- # that large in any case. Because we need to check the base64 length here,
- # save it so that we don't have to compute it again later.
- def embeddable?(asset_path, variant)
- font = EMBED_FONTS.include?(asset_path.extname)
- return false unless variant
- return false unless asset_path.to_s.match(EMBEDDABLE) && asset_path.exist?
- return false unless EMBED_EXTS.include?(asset_path.extname)
- return false unless font || encoded_contents(asset_path).length < MAX_IMAGE_SIZE
- return false if font && variant == :mhtml
- return true
- end
- # Return the Base64-encoded contents of an asset on a single line.
- def encoded_contents(asset_path)
- return @asset_contents[asset_path] if @asset_contents[asset_path]
- data = read_binary_file(asset_path)
- @asset_contents[asset_path] = Base64.encode64(data).gsub(/\n/, '')
- end
- # Grab the mime-type of an asset, by filename.
- def mime_type(asset_path)
- EMBED_MIME_TYPES[File.extname(asset_path)]
- end
- # Concatenate together a list of asset files.
- def concatenate(paths)
- [paths].flatten.map {|p| read_binary_file(p) }.join("\n")
- end
- # `File.read`, but in "binary" mode.
- def read_binary_file(path)
- File.open(path, 'rb:UTF-8') {|f| f.read }
- end
- end
- end