non_rdf_source.rb in rdf-ldp-0.8.0

- old
+ new

@@ -1,44 +1,60 @@
+require 'rdf/ldp/storage_adapters/file_storage_adapter'
+
 module RDF::LDP
   ##
   # A NonRDFSource describes a `Resource` whose response body is a format other
-  # than an RDF serialization. The persistent state of the resource, as 
-  # represented by the body, is persisted to an IO stream provided by a 
+  # than an RDF serialization. The persistent state of the resource, as
+  # represented by the body, is persisted to an IO stream provided by a
   # `RDF::LDP::NonRDFSource::StorageAdapter` given by `#storage`.
   #
   # In addition to the properties stored by the `RDF::LDP::Resource#metagraph`,
-  # `NonRDFSource`s also store a content type (format). 
+  # `NonRDFSource`s also store a content type (format).
   #
-  # When a `NonRDFSource` is created, it also creates an `RDFSource` which 
+  # When a `NonRDFSource` is created, it also creates an `RDFSource` which
   # describes it. This resource is created at the URI in `#description_uri`,
-  # the resource itself is returned by `#description`. 
+  # the resource itself is returned by `#description`.
   #
   # @see RDF::LDP::Resource
   # @see http://www.w3.org/TR/ldp/#dfn-linked-data-platform-non-rdf-source for
   #   a definition of NonRDFSource in LDP
   class NonRDFSource < Resource
+    attr_reader :storage
+
+    # Use the default filesystem-based storage adapter
+    DEFAULT_ADAPTER = RDF::LDP::NonRDFSource::FileStorageAdapter
+
     # Use DC elements format
-    FORMAT_TERM = RDF::Vocab::DC11.format
-    DESCRIBED_BY_TERM = RDF::URI('http://www.w3.org/2007/05/powder-s#describedby')
-    
+    FORMAT_TERM = RDF::Vocab::DC11.format.freeze
+
     ##
-    # @return [RDF::URI] uri with lexical representation 
+    # @param [storage_adapter] a class implementing the StorageAdapter interface
+    #
+    # @see RDF::LDP::Resource#initialize
+    def initialize(subject_uri, data = RDF::Repository.new, storage_adapter = DEFAULT_ADAPTER)
+      data ||= RDF::Repository.new # allows explict `nil` pass
+      @storage = storage_adapter.new(self)
+      super(subject_uri, data)
+    end
+
+    ##
+    # @return [RDF::URI] uri with lexical representation
     #   'http://www.w3.org/ns/ldp#NonRDFSource'
     #
     # @see http://www.w3.org/TR/ldp/#dfn-linked-data-platform-non-rdf-source
-    def self.to_uri 
+    def self.to_uri
       RDF::Vocab::LDP.NonRDFSource
     end
 
     ##
     # @return [Boolean] whether this is an ldp:NonRDFSource
     def non_rdf_source?
       true
     end
 
     ##
-    # @param [IO, File] input  input (usually from a Rack env's 
+    # @param [IO, File] input  input (usually from a Rack env's
     #   `rack.input` key) that will be read into the NonRDFSource
     # @param [#to_s] c_type  a MIME content_type used as a content type
     #   for the created NonRDFSource
     #
     # @raise [RDF::LDP::RequestError] when saving the NonRDFSource
@@ -50,11 +66,11 @@
       storage.io { |io| IO.copy_stream(input, io) }
       super
       self.content_type = c_type
 
       RDFSource.new(description_uri, @data)
-        .create(StringIO.new, 'application/n-triples')
+               .create(StringIO.new, 'application/n-triples')
 
       self
     end
 
     ##
@@ -65,17 +81,17 @@
       self.content_type = c_type
       self
     end
 
     ##
-    # Deletes the LDP-NR contents from the storage medium and marks the 
+    # Deletes the LDP-NR contents from the storage medium and marks the
     # resource as destroyed.
     #
     # @see RDF::LDP::Resource#destroy
     def destroy
-      storage.delete
       super
+      storage.delete
     end
 
     ##
     # @raise [RDF::LDP::NotFound] if the describedby resource doesn't exist
     #
@@ -89,52 +105,46 @@
     def description_uri
       subject_uri / '.well-known' / 'desc'
     end
 
     ##
-    # @return [StorageAdapter] the storage adapter for this LDP-NR
-    def storage
-      @storage_adapter ||= StorageAdapter.new(self)
-    end
-    
-    ##
     # Sets the MIME type for the resource in `metagraph`.
     #
     # @param [String] a string representing the content type for this LDP-NR.
     #   This SHOULD be a regisered MIME type.
     #
-    # @return [StorageAdapter] the content type 
+    # @return [StorageAdapter] the content type
     def content_type=(content_type)
       metagraph.delete([subject_uri, FORMAT_TERM])
-      metagraph << 
-        RDF::Statement(subject_uri, RDF::Vocab::DC11.format, content_type)
+      metagraph <<
+        RDF::Statement(subject_uri, FORMAT_TERM, content_type)
     end
-    
+
     ##
-    # @return [StorageAdapter] this resource's content type 
+    # @return [StorageAdapter] this resource's content type
     def content_type
       format_triple = metagraph.first([subject_uri, FORMAT_TERM, :format])
       format_triple.nil? ? nil : format_triple.object.object
     end
 
     ##
-    # @return [#each] the response body. This is normally the StorageAdapter's 
+    # @return [#each] the response body. This is normally the StorageAdapter's
     #   IO object in read and binary mode.
-    # 
+    #
     # @raise [RDF::LDP::RequestError] when the request fails
     def to_response
       (exists? && !destroyed?) ? storage.io : []
     end
 
-    private 
+    private
 
     ##
     # Process & generate response for PUT requsets.
-    def put(status, headers, env)
-      raise PreconditionFailed.new('Etag invalid') if 
-        env.has_key?('HTTP_IF_MATCH') && !match?(env['HTTP_IF_MATCH'])
-      
+    def put(_status, headers, env)
+      raise(PreconditionFailed, 'Etag invalid') if
+        env.key?('HTTP_IF_MATCH') && !match?(env['HTTP_IF_MATCH'])
+
       if exists?
         update(env['rack.input'], env['CONTENT_TYPE'])
         headers = update_headers(headers)
         [200, headers, self]
       else
@@ -150,107 +160,8 @@
       super
     end
 
     def link_headers
       super << "<#{description_uri}>;rel=\"describedBy\""
-    end
-
-    ##
-    # StorageAdapters bundle the logic for mapping a `NonRDFSource` to a 
-    # specific IO stream. Implementations must conform to a minimal interface:
-    #
-    #  - `#initailize` must accept a `resource` parameter. The input should be 
-    #     a `NonRDFSource` (LDP-NR).
-    #  - `#io` must yield and return a IO object in binary mode that represents 
-    #    the current state of the LDP-NR.
-    #    - If a block is passed to `#io`, the implementation MUST allow return a
-    #      writable IO object and that anything written to the stream while 
-    #      yielding is synced with the source in a thread-safe manner.
-    #    - Clients not passing a block to `#io` SHOULD call `#close` on the 
-    #      object after reading it. 
-    #    - If the `#io` object responds to `#to_path` it MUST give the location
-    #      of a file whose contents are identical the IO object's. This supports
-    #      Rack's response body interface.
-    #  - `#delete` remove the contents from the corresponding storage. This MAY
-    #      be a no-op if is undesirable or impossible to delete the contents 
-    #      from the storage medium.
-    #
-    # @see http://www.rubydoc.info/github/rack/rack/master/file/SPEC#The_Body 
-    #   for details about `#to_path` in Rack response bodies.
-    #
-    # @example reading from a `StorageAdapter`
-    #   storage = StorageAdapter.new(an_nr_source)
-    #   storage.io.read # => [string contents of `an_nr_source`]
-    #
-    # @example writing to a `StorageAdapter`
-    #   storage = StorageAdapter.new(an_nr_source)
-    #   storage.io { |io| io.write('moomin') }
-    #
-    # Beyond this interface, implementations are permitted to behave as desired.
-    # They may, for instance, reject undesirable content or alter the graph (or 
-    # metagraph) of the resource. They should throw appropriate `RDF::LDP` 
-    # errors when failing to allow the middleware to handle response codes and 
-    # messages.
-    #
-    # The base storage adapter class provides a simple File storage 
-    # implementation.
-    #
-    # @todo check thread saftey on write for base implementation 
-    class StorageAdapter
-      STORAGE_PATH = '.storage'.freeze
-
-      ##
-      # Initializes the storage adapter.
-      #
-      # @param [NonRDFSource] resource
-      def initialize(resource)
-        @resource = resource
-      end
-      
-      ##
-      # Gives an IO object which represents the current state of @resource.
-      # Opens the file for read-write (mode: r+), if it already exists; 
-      # otherwise, creates the file and opens it for read-write (mode: w+).
-      #
-      # @yield [IO] yields a read-writable object conforming to the Ruby IO 
-      #   interface for storage. The IO object will be closed when the block 
-      #   ends.
-      #
-      # @return [IO] an object conforming to the Ruby IO interface
-      def io(&block)
-        FileUtils.mkdir_p(path_dir) unless Dir.exists?(path_dir)
-        FileUtils.touch(path) unless file_exists?
-
-        File.open(path, 'r+b', &block)
-      end
-      
-      ##
-      # @return [Boolean] 1 if the file has been deleted, otherwise false
-      def delete
-        return false unless File.exists?(path)
-        File.delete(path) 
-      end
-
-      private 
-
-      ##
-      # @return [Boolean]
-      def file_exists?
-        File.exists?(path)
-      end
-
-      ##
-      # Build the path to the file on disk.
-      # @return [String]
-      def path
-        File.join(STORAGE_PATH, @resource.subject_uri.path)
-      end
-
-      ##
-      # Build the path to the file's directory on disk
-      # @return [String]
-      def path_dir
-        File.split(path).first
-      end
     end
   end
 end