middleman/middleman-core/lib/middleman-core/core_extensions/rendering.rb

# Shutup Tilt Warnings
# @private
class Tilt::Template
  def warn(*args)
    # Kernel.warn(*args)
  end
end

# Rendering extension
module Middleman
  module CoreExtensions
    module Rendering

      # Setup extension
      class << self

        # Once registered
        def registered(app)
          # Include methods
          app.send :include, InstanceMethods

          app.define_hook :before_render
          app.define_hook :after_render

          ::Tilt.mappings.delete('html') # WTF, Tilt?
          ::Tilt.mappings.delete('csv')

          require 'active_support/core_ext/string/output_safety'

          # Activate custom renderers
          require "middleman-core/renderers/erb"
          app.register Middleman::Renderers::ERb

          # CoffeeScript Support
          begin
            require "middleman-core/renderers/coffee_script"
            app.register Middleman::Renderers::CoffeeScript
          rescue LoadError
          end

          # Haml Support
          begin
            require "middleman-core/renderers/haml"
            app.register Middleman::Renderers::Haml
          rescue LoadError
          end

          # Sass Support
          begin
            require "middleman-core/renderers/sass"
            app.register Middleman::Renderers::Sass
          rescue LoadError
          end

          # Markdown Support
          require "middleman-core/renderers/markdown"
          app.register Middleman::Renderers::Markdown

          # Liquid Support
          begin
            require "middleman-core/renderers/liquid"
            app.register Middleman::Renderers::Liquid
          rescue LoadError
          end

          # Slim Support
          begin
            require "middleman-core/renderers/slim"
            app.register Middleman::Renderers::Slim
          rescue LoadError
          end

          # Less Support
          begin
            require "middleman-core/renderers/less"
            app.register Middleman::Renderers::Less
          rescue LoadError
          end

          # Stylus Support
          begin
            require "middleman-core/renderers/stylus"
            app.register Middleman::Renderers::Stylus
          rescue LoadError
          end

          # Clean up missing Tilt exts
          app.after_configuration do
            Tilt.mappings.each do |key, klasses|
              begin
                Tilt[".#{key}"]
              rescue LoadError, NameError
                Tilt.mappings.delete(key)
              end
            end
          end
        end

        alias :included :registered
      end

      # Custom error class for handling
      class TemplateNotFound < RuntimeError
      end

      # Rendering instance methods
      module InstanceMethods

        # Add or overwrite a default template extension
        #
        # @param [Hash] extension_map
        # @return [Hash]
        def template_extensions(extension_map=nil)
          @_template_extensions ||= {}
          @_template_extensions.merge!(extension_map) if extension_map
          @_template_extensions
        end

        # Render a template, with layout, given a path
        #
        # @param [String] path
        # @param [Hash] locs
        # @param [Hash] opts
        # @return [String]
        def render_template(path, locs={}, opts={}, blocks=[])
          # Detect the remdering engine from the extension
          extension = File.extname(path)
          engine = extension[1..-1].to_sym

          # Store last engine for later (could be inside nested renders)
          @current_engine, engine_was = engine, @current_engine
          if defined?(::I18n)
            old_locale = ::I18n.locale
            ::I18n.locale = opts[:lang] if opts[:lang]
          end

          # Use a dup of self as a context so that instance variables set within
          # the template don't persist for other templates.
          context = self.dup
          blocks.each do |block|
            context.instance_eval(&block)
          end

          # Store current locs/opts for later
          @current_locs = locs, @current_opts = opts

          # Keep rendering template until we've used up all extensions. This
          # handles cases like `style.css.sass.erb`
          content = nil
          while ::Tilt[path]
            begin
              opts[:template_body] = content if content
              content = render_individual_file(path, locs, opts, context)
              path = File.basename(path, File.extname(path))
            rescue LocalJumpError
              raise "Tried to render a layout (calls yield) at #{path} like it was a template. Non-default layouts need to be in #{source}/layouts."
            end
          end

          # Certain output file types don't use layouts
          needs_layout = !%w(.js .json .css .txt).include?(File.extname(path))

          # If we need a layout and have a layout, use it
          if needs_layout && layout_path = fetch_layout(engine, opts)
            content = render_individual_file(layout_path, locs, opts, context) { content }
          end

          # Return result
          content
        ensure
          # Pop all the saved variables from earlier as we may be returning to a
          # previous render (layouts, partials, nested layouts).
          ::I18n.locale = old_locale if defined?(::I18n)
          @current_engine = engine_was
          @content_blocks = nil
          @current_locs = nil
          @current_opts = nil
        end

        # Sinatra/Padrino compatible render method signature referenced by some view
        # helpers. Especially partials.
        #
        # @param [String, Symbol] engine
        # @param [String, Symbol] data
        # @param [Hash] options
        # @return [String]
        def render(engine, data, options={}, &block)
          data = data.to_s

          locals = options[:locals]

          found_partial = false
          engine        = nil

          # If the path is known to the sitemap
          if resource = sitemap.find_resource_by_path(current_path)
            current_dir = File.dirname(resource.source_file)
            engine = File.extname(resource.source_file)[1..-1].to_sym

            # Look for partials relative to the current path
            relative_dir = File.join(current_dir.sub(%r{^#{self.source_dir}/?}, ""), data)

            # Try to use the current engine first
            found_partial, found_engine = resolve_template(relative_dir, :preferred_engine => engine, :try_without_underscore => true)

            # Fall back to any engine available
            if !found_partial
              found_partial, found_engine = resolve_template(relative_dir, :try_without_underscore => true)
            end
          end

          # Look in the partials_dir for the partial with the current engine
          partials_path = File.join(config[:partials_dir], data)
          if !found_partial && !engine.nil?
            found_partial, found_engine = resolve_template(partials_path, :preferred_engine => engine, :try_without_underscore => true)
          end

          # Look in the root with any engine
          if !found_partial
            found_partial, found_engine = resolve_template(partials_path, :try_without_underscore => true)
          end

          # Render the partial if found, otherwide throw exception
          if found_partial
            render_individual_file(found_partial, locals, options, self, &block)
          else
            raise ::Middleman::CoreExtensions::Rendering::TemplateNotFound, "Could not locate partial: #{data}"
          end
        end

        # Render an on-disk file. Used for everything, including layouts.
        #
        # @param [String, Symbol] path
        # @param [Hash] locs
        # @param [Hash] opts
        # @param [Class] context
        # @return [String]
        def render_individual_file(path, locs = {}, opts = {}, context = self, &block)
          path = path.to_s

          # Save current buffer for later
          @_out_buf, _buf_was = "", @_out_buf

          # Read from disk or cache the contents of the file
          body = if opts[:template_body]
            opts.delete(:template_body)
          else
            template_data_for_file(path)
          end

          # Merge per-extension options from config
          extension = File.extname(path)
          options = opts.dup.merge(options_for_ext(extension))
          options[:outvar] ||= '@_out_buf'
          options.delete(:layout)

          # Overwrite with frontmatter options
          options = options.deep_merge(options[:renderer_options]) if options[:renderer_options]

          template_class = Tilt[path]
          # Allow hooks to manipulate the template before render
          self.class.callbacks_for_hook(:before_render).each do |callback|
            newbody = callback.call(body, path, locs, template_class)
            body = newbody if newbody # Allow the callback to return nil to skip it
          end

          # Read compiled template from disk or cache
          template = cache.fetch(:compiled_template, extension, options, body) do
           ::Tilt.new(path, 1, options) { body }
          end

          # Render using Tilt
          content = template.render(context, locs, &block)

          # Allow hooks to manipulate the result after render
          self.class.callbacks_for_hook(:after_render).each do |callback|
            content = callback.call(content, path, locs, template_class)
          end

          output = ::ActiveSupport::SafeBuffer.new
          output.safe_concat content
          output
        ensure
          # Reset stored buffer
          @_out_buf = _buf_was
        end

        # Get the template data from a path
        # @param [String] path
        # @return [String]
        def template_data_for_file(path)
          File.read(File.expand_path(path, source_dir))
        end

        # Get a hash of configuration options for a given file extension, from
        # config.rb
        #
        # @param [String] ext
        # @return [Hash]
        def options_for_ext(ext)
          # Read options for extension from config/Tilt or cache
          cache.fetch(:options_for_ext, ext) do
            options = {}

            # Find all the engines which handle this extension in tilt. Look for
            # config variables of that name and merge it
            extension_class = ::Tilt[ext]
            ::Tilt.mappings.each do |mapping_ext, engines|
              next unless engines.include? extension_class
              engine_options = config[mapping_ext.to_sym] || {}
              options.merge!(engine_options)
            end

            options
          end
        end

        # Find a layout for a given engine
        #
        # @param [Symbol] engine
        # @param [Hash] opts
        # @return [String]
        def fetch_layout(engine, opts)
          # The layout name comes from either the system default or the options
          local_layout = opts.has_key?(:layout) ? opts[:layout] : config[:layout]
          return false unless local_layout

          # Look for engine-specific options
          engine_options = respond_to?(engine) ? send(engine) : {}

          # The engine for the layout can be set in options, engine_options or passed
          # into this method
          layout_engine = if opts.has_key?(:layout_engine)
            opts[:layout_engine]
          elsif engine_options.has_key?(:layout_engine)
            engine_options[:layout_engine]
          else
            engine
          end

          # Automatic mode
          if local_layout == :_auto_layout
            # Look for :layout of any extension
            # If found, use it. If not, continue
            locate_layout(:layout, layout_engine) || false
          else
            # Look for specific layout
            # If found, use it. If not, error.
            if layout_path = locate_layout(local_layout, layout_engine)
              layout_path
            else
              raise ::Middleman::CoreExtensions::Rendering::TemplateNotFound, "Could not locate layout: #{local_layout}"
            end
          end
        end

        # Find a layout on-disk, optionally using a specific engine
        # @param [String] name
        # @param [Symbol] preferred_engine
        # @return [String]
        def locate_layout(name, preferred_engine=nil)
          # Whether we've found the layout
          layout_path = false

          # If we prefer a specific engine
          if !preferred_engine.nil?
            # Check root
            layout_path, layout_engine = resolve_template(name, :preferred_engine => preferred_engine)

            # Check layouts folder
            if !layout_path
              layout_path, layout_engine = resolve_template(File.join("layouts", name.to_s), :preferred_engine => preferred_engine)
            end
          end

          # Check root, no preference
          if !layout_path
            layout_path, layout_engine = resolve_template(name)
          end

          # Check layouts folder, no preference
          if !layout_path
            layout_path, layout_engine = resolve_template(File.join("layouts", name.to_s))
          end

          # Return the path
          layout_path
        end

        # Allow layouts to be wrapped in the contents of other layouts
        # @param [String, Symbol] layout_name
        # @return [void]
        def wrap_layout(layout_name, &block)
          # Save current buffer for later
          @_out_buf, _buf_was = "", @_out_buf

          layout_path = locate_layout(layout_name, current_engine)

          extension = File.extname(layout_path)
          engine = extension[1..-1].to_sym

          # Store last engine for later (could be inside nested renders)
          @current_engine, engine_was = engine, @current_engine

          begin
            content = if block_given?
              capture_html(&block)
            else
              ""
            end
          ensure
            # Reset stored buffer
            @_out_buf = _buf_was
          end

          concat_safe_content render_individual_file(layout_path, @current_locs || {}, @current_opts || {}, self) { content }
        ensure
          @current_engine = engine_was
        end

        # The currently rendering engine
        # @return [Symbol, nil]
        def current_engine
          @current_engine ||= nil
        end

        # Find a template on disk given a output path
        # @param [String] request_path
        # @param [Hash] options
        # @return [Array<String, Symbol>, Boolean]
        def resolve_template(request_path, options={})
          # Find the path by searching or using the cache
          request_path = request_path.to_s
          cache.fetch(:resolve_template, request_path, options) do
            relative_path = Util.strip_leading_slash(request_path)
            on_disk_path  = File.expand_path(relative_path, self.source_dir)

            # By default, any engine will do
            preferred_engine = "*"

            # Unless we're specifically looking for a preferred engine
            if options.has_key?(:preferred_engine)
              extension_class = ::Tilt[options[:preferred_engine]]
              matched_exts = []

              # Get a list of extensions for a preferred engine
              # TODO: Cache this
              ::Tilt.mappings.each do |ext, engines|
                next unless engines.include? extension_class
                matched_exts << ext
              end

              # Change the glob to only look for the matched extensions
              if matched_exts.length > 0
                preferred_engine = "{" + matched_exts.join(",") + "}"
              else
                return false
              end
            end

            # Look for files that match
            path_with_ext = on_disk_path + "." + preferred_engine

            found_path = Dir[path_with_ext].find do |path|
              ::Tilt[path]
            end

            if !found_path && options[:try_without_underscore] &&
              path_no_underscore = path_with_ext.
                sub(relative_path, relative_path.sub(/^_/, "").
                sub(/\/_/, "/"))
              found_path = Dir[path_no_underscore].find do |path|
                ::Tilt[path]
              end
            end

            # If we found one, return it and the found engine
            if found_path || (File.exists?(on_disk_path) && !File.directory?(on_disk_path))
              engine = found_path ? File.extname(found_path)[1..-1].to_sym : nil
              [ found_path || on_disk_path, engine ]
            else
              false
            end
          end
        end
      end
    end
  end
end