Reapply the TemplateFinder first applied in [8669] then reverted in [8676]. Closes #10800 [lifofifo]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8683 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 165 insertions, 0 deletions

diff --git a/actionpack/lib/action_view/template_finder.rb b/actionpack/lib/action_view/template_finder.rb
new file mode 100644
index 0000000000..d88832ef7e
--- /dev/null
+++ b/actionpack/lib/action_view/template_finder.rb
@@ -0,0 +1,165 @@
+module ActionView #:nodoc:
+  class TemplateFinder #:nodoc:
+
+    class InvalidViewPath < StandardError #:nodoc:
+    end
+
+    cattr_reader :processed_view_paths
+    @@processed_view_paths = Hash.new {|hash, key| hash[key] = []}
+
+    cattr_reader :file_extension_cache
+    @@file_extension_cache = Hash.new {|hash, key|
+      hash[key] = Hash.new {|hash, key| hash[key] = []}
+    }
+
+    class << self #:nodoc:
+
+      # This method is not thread safe. Mutex should be used whenever this is accessed from an instance method
+      def process_view_paths(*view_paths)
+        view_paths.flatten.compact.each do |dir|
+          next if @@processed_view_paths.has_key?(dir)
+
+          @@processed_view_paths[dir] = []
+          Dir.glob("#{dir}/**/*").each do |file|
+            unless File.directory?(file)
+              @@processed_view_paths[dir] << file.split(dir).last.sub(/^\//, '')
+
+              # Build extension cache
+              extension = file.split(".").last
+              if template_handler_extensions.include?(extension)
+                key = file.split(dir).last.sub(/^\//, '').sub(/\.(\w+)$/, '')
+                @@file_extension_cache[dir][key] << extension
+              end
+            end
+          end
+        end
+      end
+
+      def update_extension_cache_for(extension)
+        @@processed_view_paths.keys.each do |dir|
+          Dir.glob("#{dir}/**/*.#{extension}").each do |file|
+            key = file.split(dir).last.sub(/^\//, '').sub(/\.(\w+)$/, '')
+            @@file_extension_cache[dir][key] << extension
+          end
+        end
+      end
+
+      def template_handler_extensions
+        ActionView::Base.template_handler_extensions
+      end
+
+      def reload!
+        view_paths = @@processed_view_paths.keys
+
+        @@processed_view_paths = Hash.new {|hash, key| hash[key] = []}
+        @@file_extension_cache = Hash.new {|hash, key|
+          hash[key] = Hash.new {|hash, key| hash[key] = []}
+        }
+
+        process_view_paths(view_paths)
+      end
+    end
+
+    attr_accessor :view_paths
+
+    def initialize(*args)
+      @template = args.shift
+
+      @view_paths = args.flatten
+      @view_paths = @view_paths.respond_to?(:find) ? @view_paths.dup : [*@view_paths].compact
+      check_view_paths(@view_paths)
+    end
+
+    def prepend_view_path(path)
+      @view_paths.unshift(*path)
+
+      self.class.process_view_paths(path)
+    end
+
+    def append_view_path(path)
+      @view_paths.push(*path)
+
+      self.class.process_view_paths(path)
+    end
+
+    def view_paths=(path)
+      @view_paths = path
+      self.class.process_view_paths(path)
+    end
+
+    def pick_template(template_path, extension)
+      file_name = "#{template_path}.#{extension}"
+      base_path = find_base_path_for(file_name)
+      base_path.blank? ? false : "#{base_path}/#{file_name}"
+    end
+    alias_method :template_exists?, :pick_template
+
+    def file_exists?(template_path)
+      # Clear the forward slash in the beginning if exists
+      template_path = template_path.sub(/^\//, '')
+
+      template_file_name, template_file_extension = path_and_extension(template_path)
+
+      if template_file_extension
+        template_exists?(template_file_name, template_file_extension)
+      else
+        template_exists?(template_file_name, pick_template_extension(template_path))
+      end
+    end
+
+    def find_base_path_for(template_file_name)
+      @view_paths.find { |path| @@processed_view_paths[path].include?(template_file_name) }
+    end
+
+    # Returns the view path that the full path resides in.
+    def extract_base_path_from(full_path)
+      @view_paths.find { |p| full_path[0..p.size - 1] == p }
+    end
+
+    # Gets the extension for an existing template with the given template_path.
+    # Returns the format with the extension if that template exists.
+    #
+    #   pick_template_extension('users/show')
+    #   # => 'html.erb'
+    #
+    #   pick_template_extension('users/legacy')
+    #   # => "rhtml"
+    #
+    def pick_template_extension(template_path)
+      find_template_extension_from_handler(template_path) || find_template_extension_from_first_render
+    end
+
+    def find_template_extension_from_handler(template_path)
+      formatted_template_path = "#{template_path}.#{@template.template_format}"
+
+      view_paths.each do |path|
+        if (extensions = @@file_extension_cache[path][formatted_template_path]).any?
+          return "#{@template.template_format}.#{extensions.first}"
+        elsif (extensions = @@file_extension_cache[path][template_path]).any?
+          return extensions.first.to_s
+        end
+      end
+      nil
+    end
+
+    # Splits the path and extension from the given template_path and returns as an array.
+    def path_and_extension(template_path)
+      template_path_without_extension = template_path.sub(/\.(\w+)$/, '')
+      [ template_path_without_extension, $1 ]
+    end
+
+    # Determine the template extension from the <tt>@first_render</tt> filename
+    def find_template_extension_from_first_render
+      File.basename(@template.first_render.to_s)[/^[^.]+\.(.+)$/, 1]
+    end
+
+    private
+
+    def check_view_paths(view_paths)
+      view_paths.each do |path|
+        raise(InvalidViewPath, "Unprocessed view path found in #{view_paths.inspect}") unless @@processed_view_paths.has_key?(path)
+      end
+    end
+
+  end
+end