Introduce TemplateFinder to handle view paths and lookups. Closes #10800.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8669 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 178 insertions, 130 deletions

diff --git a/actionpack/lib/action_view/base.rb b/actionpack/lib/action_view/base.rb
index 34572e442d..bcc6d2ab37 100644
--- a/actionpack/lib/action_view/base.rb
+++ b/actionpack/lib/action_view/base.rb
@@ -150,9 +150,9 @@ module ActionView #:nodoc:
   class Base
     include ERB::Util
 
-    attr_reader   :first_render
+    attr_reader   :first_render, :finder
     attr_accessor :base_path, :assigns, :template_extension
-    attr_accessor :controller, :view_paths
+    attr_accessor :controller
 
     attr_reader :logger, :response, :headers
     attr_internal :cookies, :flash, :headers, :params, :request, :response, :session
@@ -204,12 +204,6 @@ module ActionView #:nodoc:
     @@template_args = {}
     # Count the number of inline templates
     @@inline_template_count = 0
-    # Maps template paths without extension to their file extension returned by pick_template_extension.
-    # If for a given path, path.ext1 and path.ext2 exist on the file system, the order of extensions
-    # used by pick_template_extension determines whether ext1 or ext2 will be stored.
-    @@cached_template_extension = {}
-    # Maps template paths / extensions to 
-    @@cached_base_paths = {}
 
     # Cache public asset paths
     cattr_reader :computed_public_paths
@@ -241,10 +235,11 @@ module ActionView #:nodoc:
     # return the rendered template as a string.
     def self.register_template_handler(extension, klass)
       @@template_handlers[extension.to_sym] = klass
+      TemplateFinder.update_extension_cache_for(extension.to_s)
     end
 
     def self.template_handler_extensions
-      @@template_handler_extensions ||= @@template_handlers.keys.map(&:to_s).sort
+      @@template_handlers.keys.map(&:to_s).sort
     end
 
     def self.register_default_template_handler(extension, klass)
@@ -265,11 +260,11 @@ module ActionView #:nodoc:
     register_template_handler :rxml, TemplateHandlers::Builder
 
     def initialize(view_paths = [], assigns_for_first_render = {}, controller = nil)#:nodoc:
-      @view_paths = view_paths.respond_to?(:find) ? view_paths.dup : [*view_paths].compact
       @assigns = assigns_for_first_render
       @assigns_added = nil
       @controller = controller
-      @logger = controller && controller.logger 
+      @logger = controller && controller.logger
+      @finder = TemplateFinder.new(self, view_paths)
     end
 
     # Renders the template present at <tt>template_path</tt>. If <tt>use_full_path</tt> is set to true, 
@@ -290,16 +285,16 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
       end
       
       @first_render ||= template_path
-      template_path_without_extension, template_extension = path_and_extension(template_path)
+      template_path_without_extension, template_extension = @finder.path_and_extension(template_path)
       if use_full_path
         if template_extension
-          template_file_name = full_template_path(template_path_without_extension, template_extension)
+          template_file_name = @finder.pick_template(template_path_without_extension, template_extension)
         else
-          template_extension = pick_template_extension(template_path).to_s
+          template_extension = @finder.pick_template_extension(template_path).to_s
           unless template_extension
-            raise ActionViewError, "No template found for #{template_path} in #{view_paths.inspect}"
+            raise ActionViewError, "No template found for #{template_path} in #{@finder.view_paths.inspect}"
           end
-          template_file_name = full_template_path(template_path, template_extension)
+          template_file_name = @finder.pick_template(template_path, template_extension)
           template_extension = template_extension.gsub(/^.+\./, '') # strip off any formats
         end
       else
@@ -309,7 +304,7 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
       template_source = nil # Don't read the source until we know that it is required
 
       if template_file_name.blank?
-        raise ActionViewError, "Couldn't find template file for #{template_path} in #{view_paths.inspect}"
+        raise ActionViewError, "Couldn't find template file for #{template_path} in #{@finder.view_paths.inspect}"
       end
 
       begin
@@ -319,7 +314,8 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
           e.sub_template_of(template_file_name)
           raise e
         else
-          raise TemplateError.new(find_base_path_for("#{template_path_without_extension}.#{template_extension}") || view_paths.first, template_file_name, @assigns, template_source, e)
+          raise TemplateError.new(@finder.find_base_path_for("#{template_path_without_extension}.#{template_extension}") ||
+                @finder.view_paths.first, template_file_name, @assigns, template_source, e)
         end
       end
     end
@@ -371,45 +367,6 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
       end
     end
 
-    # Gets the full template path with base path for the given template_path and extension.
-    #
-    #   full_template_path('users/show', 'html.erb')
-    #   # => '~/rails/app/views/users/show.html.erb
-    #
-    def full_template_path(template_path, extension)
-      if @@cache_template_extensions
-        (@@cached_base_paths[template_path] ||= {})[extension.to_s] ||= find_full_template_path(template_path, extension)
-      else
-        find_full_template_path(template_path, extension)
-      end
-    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)#:nodoc:
-      if @@cache_template_extensions
-        (@@cached_template_extension[template_path] ||= {})[template_format] ||= find_template_extension_for(template_path)
-      else
-        find_template_extension_for(template_path)
-      end
-    end
-
-    def file_exists?(template_path)#:nodoc:
-      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
-
     # Returns true is the file may be rendered implicitly.
     def file_public?(template_path)#:nodoc:
       template_path.split('/').last[0,1] != '_'
@@ -422,83 +379,12 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
       @template_format = format.blank? ? :html : format.to_sym
     end
 
-    # Adds a view_path to the front of the view_paths array.
-    # This change affects the current request only.
-    #
-    #   @template.prepend_view_path("views/default")
-    #   @template.prepend_view_path(["views/default", "views/custom"])
-    #
-    def prepend_view_path(path)
-      @view_paths.unshift(*path)
-    end
-    
-    # Adds a view_path to the end of the view_paths array.
-    # This change affects the current request only.
-    #
-    #   @template.append_view_path("views/default")
-    #   @template.append_view_path(["views/default", "views/custom"])
-    #
-    def append_view_path(path)
-      @view_paths.push(*path)
-    end
-
     private
       def wrap_content_for_layout(content)
         original_content_for_layout = @content_for_layout
         @content_for_layout = content
         returning(yield) { @content_for_layout = original_content_for_layout }
       end
-  
-      def find_full_template_path(template_path, extension)
-        file_name = "#{template_path}.#{extension}"
-        base_path = find_base_path_for(file_name)
-        base_path.blank? ? "" : "#{base_path}/#{file_name}"
-      end
-
-      # Asserts the existence of a template.
-      def template_exists?(template_path, extension)
-        file_path = full_template_path(template_path, extension)
-        !file_path.blank? && @@method_names.has_key?(file_path) || File.exist?(file_path)
-      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, $1 ]
-      end
-      
-      # Returns the view path that contains the given relative template path.
-      def find_base_path_for(template_file_name)
-        view_paths.find { |p| File.file?(File.join(p, template_file_name)) }
-      end
-
-      # Returns the view path that the full path resides in.
-      def extract_base_path_from(full_path)
-        view_paths.find { |p| full_path[0..p.size - 1] == p }
-      end
-
-      # Determines the template's file extension, such as rhtml, rxml, or rjs.
-      def find_template_extension_for(template_path)
-        find_template_extension_from_handler(template_path, true) ||
-        find_template_extension_from_handler(template_path) ||
-        find_template_extension_from_first_render()
-      end
-
-      def find_template_extension_from_handler(template_path, formatted = nil)
-        checked_template_path = formatted ? "#{template_path}.#{template_format}" : template_path
-
-        self.class.template_handler_extensions.each do |extension|
-          if template_exists?(checked_template_path, extension)
-            return formatted ? "#{template_format}.#{extension}" : extension.to_s
-          end
-        end
-        nil
-      end
-      
-      # Determine the template extension from the <tt>@first_render</tt> filename
-      def find_template_extension_from_first_render
-        File.basename(@first_render.to_s)[/^[^.]+\.(.+)$/, 1]
-      end
 
       # This method reads a template file.
       def read_template_file(template_path, extension)
@@ -603,7 +489,8 @@ If you are rendering a subtemplate, you must now use controller-like partial syn
             logger.debug "Backtrace: #{e.backtrace.join("\n")}"
           end
 
-          raise TemplateError.new(extract_base_path_from(file_name) || view_paths.first, file_name || template, @assigns, template, e)
+          raise TemplateError.new(@finder.extract_base_path_from(file_name) ||
+                @finder.view_paths.first, file_name || template, @assigns, template, e)
         end
 
         @@compile_time[render_symbol] = Time.now
diff --git a/actionpack/lib/action_view/helpers/cache_helper.rb b/actionpack/lib/action_view/helpers/cache_helper.rb
index ea505adfa7..aa85b9fb40 100644
--- a/actionpack/lib/action_view/helpers/cache_helper.rb
+++ b/actionpack/lib/action_view/helpers/cache_helper.rb
@@ -32,7 +32,7 @@ module ActionView
       #      <i>Topics listed alphabetically</i>
       #    <% end %>
       def cache(name = {}, options = nil, &block)
-        template_extension = find_template_extension_for(first_render)[/\.?(\w+)$/, 1].to_sym
+        template_extension = @finder.pick_template_extension(first_render)[/\.?(\w+)$/, 1].to_sym
         handler = Base.handler_class_for_extension(template_extension)
         handler.new(@controller).cache_fragment(block, name, options)
       end
diff --git a/actionpack/lib/action_view/template_finder.rb b/actionpack/lib/action_view/template_finder.rb
new file mode 100644
index 0000000000..3d7acec33c
--- /dev/null
+++ b/actionpack/lib/action_view/template_finder.rb
@@ -0,0 +1,161 @@
+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)
+      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