Merge pull request #11032 from strzalek/extract-actionview

Extract ActionView to separate directory

1 files changed, 326 insertions, 0 deletions

diff --git a/actionview/lib/action_view/template/resolver.rb b/actionview/lib/action_view/template/resolver.rb
new file mode 100644
index 0000000000..3304605c1a
--- /dev/null
+++ b/actionview/lib/action_view/template/resolver.rb
@@ -0,0 +1,326 @@
+require "pathname"
+require "active_support/core_ext/class"
+require "active_support/core_ext/class/attribute_accessors"
+require "action_view/template"
+require "thread"
+require "thread_safe"
+
+module ActionView
+  # = Action View Resolver
+  class Resolver
+    # Keeps all information about view path and builds virtual path.
+    class Path
+      attr_reader :name, :prefix, :partial, :virtual
+      alias_method :partial?, :partial
+
+      def self.build(name, prefix, partial)
+        virtual = ""
+        virtual << "#{prefix}/" unless prefix.empty?
+        virtual << (partial ? "_#{name}" : name)
+        new name, prefix, partial, virtual
+      end
+
+      def initialize(name, prefix, partial, virtual)
+        @name    = name
+        @prefix  = prefix
+        @partial = partial
+        @virtual = virtual
+      end
+
+      def to_str
+        @virtual
+      end
+      alias :to_s :to_str
+    end
+
+    # Threadsafe template cache
+    class Cache #:nodoc:
+      class SmallCache < ThreadSafe::Cache
+        def initialize(options = {})
+          super(options.merge(:initial_capacity => 2))
+        end
+      end
+
+      # preallocate all the default blocks for performance/memory consumption reasons
+      PARTIAL_BLOCK = lambda {|cache, partial| cache[partial] = SmallCache.new}
+      PREFIX_BLOCK  = lambda {|cache, prefix|  cache[prefix]  = SmallCache.new(&PARTIAL_BLOCK)}
+      NAME_BLOCK    = lambda {|cache, name|    cache[name]    = SmallCache.new(&PREFIX_BLOCK)}
+      KEY_BLOCK     = lambda {|cache, key|     cache[key]     = SmallCache.new(&NAME_BLOCK)}
+
+      # usually a majority of template look ups return nothing, use this canonical preallocated array to save memory
+      NO_TEMPLATES = [].freeze
+
+      def initialize
+        @data = SmallCache.new(&KEY_BLOCK)
+      end
+
+      # Cache the templates returned by the block
+      def cache(key, name, prefix, partial, locals)
+        if Resolver.caching?
+          @data[key][name][prefix][partial][locals] ||= canonical_no_templates(yield)
+        else
+          fresh_templates  = yield
+          cached_templates = @data[key][name][prefix][partial][locals]
+
+          if templates_have_changed?(cached_templates, fresh_templates)
+            @data[key][name][prefix][partial][locals] = canonical_no_templates(fresh_templates)
+          else
+            cached_templates || NO_TEMPLATES
+          end
+        end
+      end
+
+      def clear
+        @data.clear
+      end
+
+      private
+
+      def canonical_no_templates(templates)
+        templates.empty? ? NO_TEMPLATES : templates
+      end
+
+      def templates_have_changed?(cached_templates, fresh_templates)
+        # if either the old or new template list is empty, we don't need to (and can't)
+        # compare modification times, and instead just check whether the lists are different
+        if cached_templates.blank? || fresh_templates.blank?
+          return fresh_templates.blank? != cached_templates.blank?
+        end
+
+        cached_templates_max_updated_at = cached_templates.map(&:updated_at).max
+
+        # if a template has changed, it will be now be newer than all the cached templates
+        fresh_templates.any? { |t| t.updated_at > cached_templates_max_updated_at }
+      end
+    end
+
+    cattr_accessor :caching
+    self.caching = true
+
+    class << self
+      alias :caching? :caching
+    end
+
+    def initialize
+      @cache = Cache.new
+    end
+
+    def clear_cache
+      @cache.clear
+    end
+
+    # Normalizes the arguments and passes it on to find_templates.
+    def find_all(name, prefix=nil, partial=false, details={}, key=nil, locals=[])
+      cached(key, [name, prefix, partial], details, locals) do
+        find_templates(name, prefix, partial, details)
+      end
+    end
+
+  private
+
+    delegate :caching?, to: :class
+
+    # This is what child classes implement. No defaults are needed
+    # because Resolver guarantees that the arguments are present and
+    # normalized.
+    def find_templates(name, prefix, partial, details)
+      raise NotImplementedError, "Subclasses must implement a find_templates(name, prefix, partial, details) method"
+    end
+
+    # Helpers that builds a path. Useful for building virtual paths.
+    def build_path(name, prefix, partial)
+      Path.build(name, prefix, partial)
+    end
+
+    # Handles templates caching. If a key is given and caching is on
+    # always check the cache before hitting the resolver. Otherwise,
+    # it always hits the resolver but if the key is present, check if the
+    # resolver is fresher before returning it.
+    def cached(key, path_info, details, locals) #:nodoc:
+      name, prefix, partial = path_info
+      locals = locals.map { |x| x.to_s }.sort!
+
+      if key
+        @cache.cache(key, name, prefix, partial, locals) do
+          decorate(yield, path_info, details, locals)
+        end
+      else
+        decorate(yield, path_info, details, locals)
+      end
+    end
+
+    # Ensures all the resolver information is set in the template.
+    def decorate(templates, path_info, details, locals) #:nodoc:
+      cached = nil
+      templates.each do |t|
+        t.locals         = locals
+        t.formats        = details[:formats] || [:html] if t.formats.empty?
+        t.virtual_path ||= (cached ||= build_path(*path_info))
+      end
+    end
+  end
+
+  # An abstract class that implements a Resolver with path semantics.
+  class PathResolver < Resolver #:nodoc:
+    EXTENSIONS = [:locale, :formats, :handlers]
+    DEFAULT_PATTERN = ":prefix/:action{.:locale,}{.:formats,}{.:handlers,}"
+
+    def initialize(pattern=nil)
+      @pattern = pattern || DEFAULT_PATTERN
+      super()
+    end
+
+    private
+
+    def find_templates(name, prefix, partial, details)
+      path = Path.build(name, prefix, partial)
+      query(path, details, details[:formats])
+    end
+
+    def query(path, details, formats)
+      query = build_query(path, details)
+
+      # deals with case-insensitive file systems.
+      sanitizer = Hash.new { |h,dir| h[dir] = Dir["#{dir}/*"] }
+
+      template_paths = Dir[query].reject { |filename|
+        File.directory?(filename) ||
+          !sanitizer[File.dirname(filename)].include?(filename)
+      }
+
+      template_paths.map { |template|
+        handler, format = extract_handler_and_format(template, formats)
+        contents = File.binread template
+
+        Template.new(contents, File.expand_path(template), handler,
+          :virtual_path => path.virtual,
+          :format       => format,
+          :updated_at   => mtime(template))
+      }
+    end
+
+    # Helper for building query glob string based on resolver's pattern.
+    def build_query(path, details)
+      query = @pattern.dup
+
+      prefix = path.prefix.empty? ? "" : "#{escape_entry(path.prefix)}\\1"
+      query.gsub!(/\:prefix(\/)?/, prefix)
+
+      partial = escape_entry(path.partial? ? "_#{path.name}" : path.name)
+      query.gsub!(/\:action/, partial)
+
+      details.each do |ext, variants|
+        query.gsub!(/\:#{ext}/, "{#{variants.compact.uniq.join(',')}}")
+      end
+
+      File.expand_path(query, @path)
+    end
+
+    def escape_entry(entry)
+      entry.gsub(/[*?{}\[\]]/, '\\\\\\&')
+    end
+
+    # Returns the file mtime from the filesystem.
+    def mtime(p)
+      File.mtime(p)
+    end
+
+    # Extract handler and formats from path. If a format cannot be a found neither
+    # from the path, or the handler, we should return the array of formats given
+    # to the resolver.
+    def extract_handler_and_format(path, default_formats)
+      pieces = File.basename(path).split(".")
+      pieces.shift
+
+      extension = pieces.pop
+      unless extension
+        message = "The file #{path} did not specify a template handler. The default is currently ERB, " \
+                  "but will change to RAW in the future."
+        ActiveSupport::Deprecation.warn message
+      end
+
+      handler = Template.handler_for_extension(extension)
+      format  = pieces.last && Template::Types[pieces.last]
+      [handler, format]
+    end
+  end
+
+  # A resolver that loads files from the filesystem. It allows setting your own
+  # resolving pattern. Such pattern can be a glob string supported by some variables.
+  #
+  # ==== Examples
+  #
+  # Default pattern, loads views the same way as previous versions of rails, eg. when you're
+  # looking for `users/new` it will produce query glob: `users/new{.{en},}{.{html,js},}{.{erb,haml},}`
+  #
+  #   FileSystemResolver.new("/path/to/views", ":prefix/:action{.:locale,}{.:formats,}{.:handlers,}")
+  #
+  # This one allows you to keep files with different formats in separate subdirectories,
+  # eg. `users/new.html` will be loaded from `users/html/new.erb` or `users/new.html.erb`,
+  # `users/new.js` from `users/js/new.erb` or `users/new.js.erb`, etc.
+  #
+  #   FileSystemResolver.new("/path/to/views", ":prefix/{:formats/,}:action{.:locale,}{.:formats,}{.:handlers,}")
+  #
+  # If you don't specify a pattern then the default will be used.
+  #
+  # In order to use any of the customized resolvers above in a Rails application, you just need
+  # to configure ActionController::Base.view_paths in an initializer, for example:
+  #
+  #   ActionController::Base.view_paths = FileSystemResolver.new(
+  #     Rails.root.join("app/views"),
+  #     ":prefix{/:locale}/:action{.:formats,}{.:handlers,}"
+  #   )
+  #
+  # ==== Pattern format and variables
+  #
+  # Pattern has to be a valid glob string, and it allows you to use the
+  # following variables:
+  #
+  # * <tt>:prefix</tt> - usually the controller path
+  # * <tt>:action</tt> - name of the action
+  # * <tt>:locale</tt> - possible locale versions
+  # * <tt>:formats</tt> - possible request formats (for example html, json, xml...)
+  # * <tt>:handlers</tt> - possible handlers (for example erb, haml, builder...)
+  #
+  class FileSystemResolver < PathResolver
+    def initialize(path, pattern=nil)
+      raise ArgumentError, "path already is a Resolver class" if path.is_a?(Resolver)
+      super(pattern)
+      @path = File.expand_path(path)
+    end
+
+    def to_s
+      @path.to_s
+    end
+    alias :to_path :to_s
+
+    def eql?(resolver)
+      self.class.equal?(resolver.class) && to_path == resolver.to_path
+    end
+    alias :== :eql?
+  end
+
+  # An Optimized resolver for Rails' most common case.
+  class OptimizedFileSystemResolver < FileSystemResolver #:nodoc:
+    def build_query(path, details)
+      exts = EXTENSIONS.map { |ext| details[ext] }
+      query = escape_entry(File.join(@path, path))
+
+      query + exts.map { |ext|
+        "{#{ext.compact.uniq.map { |e| ".#{e}," }.join}}"
+      }.join
+    end
+  end
+
+  # The same as FileSystemResolver but does not allow templates to store
+  # a virtual path since it is invalid for such resolvers.
+  class FallbackFileSystemResolver < FileSystemResolver #:nodoc:
+    def self.instances
+      [new(""), new("/")]
+    end
+
+    def decorate(*)
+      super.each { |t| t.virtual_path = nil }
+    end
+  end
+end