Refactor hex output of BLOB data

lib/innodb.rb

@@ -18,6 +18,7 @@ def self.debug=(value)
 require "digest/crc32c"
 require "innodb/util/buffer_cursor"
 require "innodb/util/read_bits_at_offset"
+require "innodb/util/hex_format"
 
 require "innodb/version"
 require "innodb/stats"

lib/innodb/page/blob.rb

@@ -32,18 +32,6 @@ def blob_data
         end
       end
 
-      def dump_hex(string)
-        slice_size = 16
-        string.chars.each_slice(slice_size).each_with_index do |slice_bytes, slice_count|
-          puts "%08i  %-23s  %-23s  |%-16s|" % [
-            (slice_count * slice_size),
-            slice_bytes[0..8].map { |n| "%02x" % n.ord }.join(" "),
-            slice_bytes[8..16].map { |n| "%02x" % n.ord }.join(" "),
-            slice_bytes.join,
-          ]
-        end
-      end
-
       def each_region(&block)
         return enum_for(:each_region) unless block_given?
 
@@ -75,7 +63,7 @@ def dump
         puts
 
         puts "blob data:"
-        dump_hex(blob_data)
+        HexFormat.puts(blob_data)
         puts
 
         puts

lib/innodb/util/hex_format.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module HexFormat
+  LINE_SIZE = 16
+  GROUP_SIZE = 8
+  GROUP_FORMAT_LENGTH = ((LINE_SIZE.to_f / GROUP_SIZE).ceil * (GROUP_SIZE * 3))
+
+  def self.format_group(data)
+    data.map { |n| "%02x" % n.ord }.join(" ")
+  end
+
+  def self.format_groups(data, size)
+    data.each_slice(size).map { |g| format_group(g) }.join("  ")
+  end
+
+  def self.format_printable(data)
+    data.join.gsub(/[^[:print:]]/, ".")
+  end
+
+  def self.format_hex(data)
+    data.chars.each_slice(LINE_SIZE).each_with_index do |bytes, i|
+      yield format("%08i  %-#{GROUP_FORMAT_LENGTH}s  |%-#{LINE_SIZE}s|",
+                   (i * LINE_SIZE), format_groups(bytes, GROUP_SIZE), format_printable(bytes))
+    end
+
+    nil
+  end
+
+  def self.puts(data, io: $stdout)
+    format_hex(data) { |line| io.puts(line) }
+  end
+end