lib/picky/backends/file/json.rb in picky-3.1.0 vs lib/picky/backends/file/json.rb in picky-3.1.1

@@ -1,40 +1,81 @@
 module Picky
 
   module Backends
 
-    module File
+    class File
 
-      # Index files dumped in the JSON format.
+      # File-based index files dumped in the JSON format.
       #
       class JSON < Basic
 
-        # Uses the extension "json".
+        # The in-memory mapping hash, mapping
+        # a Symbol key to [length, offset] of
+        # the JSON data in the file.
         #
-        def extension
-          :json
+        attr_accessor :mapping
+
+        # See lib/picky/backends/file.rb for what this should return.
+        #
+        # 1. Gets the length and offset for the key.
+        # 2. Extracts and decodes the object from the file.
+        #
+        def [] key
+          length, offset = mapping[key]
+          return unless length
+          result = Yajl::Parser.parse IO.read(cache_path, length, offset)
+          result
         end
-        # Loads the index hash from json format.
+
+        # Clears the currently loaded index.
         #
-        def load
-          Yajl::Parser.parse ::File.open(cache_path, 'r'), symbolize_keys: true
+        # Note: This only clears the in-memory mapping,
+        #       but this is enough for the index to not exist
+        #       anymore, at least to the application.
+        #
+        def clear
+          self.mapping.clear
+        end
 
-          # Note: Circumvents the yajl symbolize utf-8 characters problem.
-          #
-          # Yajl::Parser.parse(::File.open(cache_path, 'r')).inject({}) do |hash, (k, v)|
-          #   hash[k.to_sym] = v
-          #   hash
-          # end
+        # Loads the mapping hash from json format.
+        #
+        def load
+          self.mapping = mapping_file.load
+          self
         end
+
         # Dumps the index hash in json format.
         #
+        # 1. Dump actual data.
+        # 2. Dumps mapping key => [length, offset].
+        #
         def dump hash
-          hash.dump_json cache_path
+          offset = 0
+          mapping = {}
+
+          ::File.open(cache_path, 'w:utf-8') do |out_file|
+            hash.each do |(key, object)|
+              encoded = Yajl::Encoder.encode object
+              length  = encoded.size
+              mapping[key] = [length, offset]
+              offset += length
+              out_file.write encoded
+            end
+          end
+
+          mapping_file.dump mapping
         end
+
         # A json file does not provide retrieve functionality.
         #
         def retrieve
           raise "Can't retrieve from JSON file. Use text file."
+        end
+
+        # Uses the extension "json".
+        #
+        def extension
+          :json
         end
 
       end
 
     end
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