Reduce complexity of do_parse

Author: aaronkison

lib/json_sequence/parser.rb

@@ -18,35 +18,31 @@ def parse(chunk, &block)
     # Takes a String buffer to parse and returns String containing any
     # text remaining to parse when more data is available.
     def do_parse(buffer)
-      records = buffer.split(RS, -1) # -1 stops suppression of trailing null fields
-
-      records.each_with_index do |record, i|
-        # RFC7464 2.1 Multiple consecutive RS octets do not denote empty
-        # sequence elements between them and can be ignored.
-        next if record == ''
-
-        is_last_record = i == records.size - 1
-
-        # Try to decode the record
-        begin
-          value = MultiJson.load(record)
-          if truncated?(record, value)
-            return record if is_last_record
-
-            yield JsonSequence::Result::MaybeTruncated.new(value)
-          else
-            yield JsonSequence::Result::Json.new(value)
-          end
-        rescue MultiJson::ParseError => err
-          return record if is_last_record
-
-          yield JsonSequence::Result::ParseError.new(record, err)
-        end
-      end
+      # RFC7464 2.1 Multiple consecutive RS octets do not denote empty
+      # sequence elements between them and can be ignored.
+      records = buffer.split(RS).reject(&:empty?)
+
+      # Every record except the last is guaranteed to be completed
+      records[0...-1].each { |record| yield decode_record(record) }
+
+      last_result = decode_record(records.last)
+
+      # If we have an incomplete record and run out of valid json early, return it to the buffer
+      return records.last if !buffer.end_with?(RS) && partial_result?(last_result)
+      yield last_result
 
       ''
     end
 
+    def decode_record(record)
+      value = MultiJson.load(record)
+      return JsonSequence::Result::MaybeTruncated.new(value) if truncated?(record, value)
+
+      JsonSequence::Result::Json.new(value)
+    rescue MultiJson::ParseError => e
+      JsonSequence::Result::ParseError.new(record, e)
+    end
+
     def truncated?(record, value)
       case value
       when Numeric, TrueClass, FalseClass, NilClass
@@ -57,5 +53,9 @@ def truncated?(record, value)
         false
       end
     end
+
+    def partial_result?(result)
+      !result.is_a?(JsonSequence::Result::Json)
+    end
   end
 end

lib/json_sequence/version.rb

@@ -1,3 +1,3 @@
 module JsonSequence
-  VERSION = "0.2.0"
+  VERSION = "0.2.1"
 end

spec/json_sequence/parser_spec.rb

@@ -66,6 +66,15 @@
     )
   end
 
+  it 'process records when ending with a RS token' do
+    expect { |b| parser.parse(%|\x1E123\x0A\x1E|, &b) }.to yield_successive_args(
+      JsonSequence::Result::Json.new(123),
+    )
+    expect { |b| parser.parse(%|123\x0A|, &b) }.to yield_successive_args(
+      JsonSequence::Result::Json.new(123),
+    )
+  end
+
   it 'parses formatted json' do
     expect { |b| parser.parse(%|\x1E{"some": "json",\n"more": 1,\n"even more": []}\x0A|, &b) }.to yield_successive_args(
       JsonSequence::Result::Json.new('some' => 'json', 'more' => 1, 'even more' => [])