Extract Alignable

Author: kou

lib/flatbuffers/alignable.rb

@@ -0,0 +1,37 @@
+# Copyright 2026 Sutou Kouhei <kou@clear-code.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+require_relative "append_as_bytes"
+
+module FlatBuffers
+  module Alignable
+    using AppendAsBytes if const_defined?(:AppendAsBytes)
+
+    LARGEST_PADDING = "\x00" * 7
+
+    private
+    def compute_padding_size(size, alignment_byte)
+      size % alignment_byte
+    end
+
+    def pad!(data, padding_size)
+      return if padding_size.zero?
+      data.append_as_bytes(LARGEST_PADDING[0, padding_size])
+    end
+
+    def align!(data, alignment_byte)
+      pad!(data, compute_padding_size(data.bytesize, alignment_byte))
+    end
+  end
+end

lib/flatbuffers/serializer.rb

@@ -12,21 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+require_relative "alignable"
 require_relative "append_as_bytes"
 
 module FlatBuffers
   using AppendAsBytes if const_defined?(:AppendAsBytes)
 
   class Serializer
-    module Alignable
-      private
-      def align32!(data)
-        padding_size = data.bytesize % 4 # IO::Buffer.size_of(:s32)
-        return if padding_size.zero?
-        data.append_as_bytes("\x00" * padding_size)
-      end
-    end
-
     module Packable
       private
       def pack_value(base_type, value)
@@ -60,7 +52,6 @@ def pack_value(base_type, value)
           packed_value = [value.bytesize].pack("L<")
           packed_value.append_as_bytes(value)
           packed_value.append_as_bytes("\x00")
-          align32!(packed_value)
           packed_value
         when String
           klass = Object.const_get(base_type)
@@ -89,7 +80,7 @@ def add_field(field, value)
         packed_value = pack_value(field.base_type, value)
         @buffer.append_as_bytes(packed_value)
         unless field.padding.zero?
-          @buffer.append_as_bytes("\x00" * field.padding)
+          pad!(@buffer, field.padding)
         end
       end
 
@@ -243,7 +234,7 @@ def add_field(field, value)
       end
 
       def finish
-        align32!(@field_values)
+        align!(@field_values, View::OFFSET_SIZE)
         table_size = View::Table.compute_size(@field_values.bytesize)
 
         field_offset_base =