Cover the same whitespace in both ArgumentKeys character maps

REMOVE_CHARACTERS uses [[:space:]], so it strips a tab and a newline.
REPLACE_MAP listed only a plain space, so it left them in the key:

  remove  "a\tb"  # => "ab"
  replace "a\tb"  # => "a\tb"    tab survives into the key

A raw tab or newline in a cache key breaks the Memcached protocol.

REPLACE_MAP now covers tab, newline, carriage return, form feed, and vertical
tab. It is also a Hash rather than an array of pairs, so #cache_key makes one
gsub pass over the string instead of 13.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: John Bolliger

lib/active_remote/cached/argument_keys.rb

@@ -6,21 +6,29 @@ class ArgumentKeys
       attr_reader :arguments, :argument_string, :options
 
       REMOVE_CHARACTERS = /[[:space:]+=><{}\[\];:\-,]/
-      REPLACE_MAP = [
-        [' ', 'SP'],
-        ['+', 'PL'],
-        ['=', 'EQ'],
-        ['>', 'GT'],
-        ['<', 'LT'],
-        ['{', 'LB'],
-        ['}', 'RB'],
-        ['[', 'LB2'],
-        [']', 'RB2'],
-        [';', 'SC'],
-        [':', 'CO'],
-        ['-', 'DA'],
-        [',', 'COM']
-      ].freeze
+      # Covers the same characters as REMOVE_CHARACTERS. A tab or a newline
+      # left in a key breaks the Memcached protocol.
+      REPLACE_MAP = {
+        ' ' => 'SP',
+        "\t" => 'TB',
+        "\n" => 'NL',
+        "\r" => 'CR',
+        "\f" => 'FF',
+        "\v" => 'VT',
+        '+' => 'PL',
+        '=' => 'EQ',
+        '>' => 'GT',
+        '<' => 'LT',
+        '{' => 'LB',
+        '}' => 'RB',
+        '[' => 'LB2',
+        ']' => 'RB2',
+        ';' => 'SC',
+        ':' => 'CO',
+        '-' => 'DA',
+        ',' => 'COM'
+      }.freeze
+      REPLACE_CHARACTERS = ::Regexp.union(REPLACE_MAP.keys)
 
       # The separators below are absent from both REMOVE_CHARACTERS and
       # REPLACE_MAP, so they survive either option. escape_value/1 escapes them
@@ -64,9 +72,8 @@ def cache_key
         return @argument_string.gsub(REMOVE_CHARACTERS, '') if remove_characters?
         return @argument_string unless replace_characters?
 
-        REPLACE_MAP.inject(@argument_string) do |key, (character, replacement)|
-          key.gsub(character, replacement)
-        end
+        # One pass, rather than one gsub for each entry in the map.
+        @argument_string.gsub(REPLACE_CHARACTERS, REPLACE_MAP)
       end
 
       def to_s

spec/active_remote/cached/argument_keys_spec.rb

@@ -25,6 +25,32 @@
     expect(::ActiveRemote::Cached::ArgumentKeys.new('hello {}', options).cache_key).to eq('helloSPLBRB')
   end
 
+  it 'replaces a tab when :active_remote_cached_replace_characters' do
+    options = { :active_remote_cached_replace_characters => true }
+    expect(::ActiveRemote::Cached::ArgumentKeys.new("a\tb", options).cache_key).to eq('aTBb')
+  end
+
+  it 'replaces a newline when :active_remote_cached_replace_characters' do
+    options = { :active_remote_cached_replace_characters => true }
+    expect(::ActiveRemote::Cached::ArgumentKeys.new("a\nb", options).cache_key).to eq('aNLb')
+  end
+
+  # REMOVE_CHARACTERS uses [[:space:]], so both options must cover the same
+  # whitespace. A raw tab or newline in a key breaks the Memcached protocol.
+  it 'leaves no whitespace in the key under either option' do
+    argument = "a b\tc\nd\re\ff\vg"
+
+    removed = ::ActiveRemote::Cached::ArgumentKeys.new(
+      argument, :active_remote_cached_remove_characters => true
+    ).cache_key
+    replaced = ::ActiveRemote::Cached::ArgumentKeys.new(
+      argument, :active_remote_cached_replace_characters => true
+    ).cache_key
+
+    expect(removed).not_to match(/[[:space:]]/)
+    expect(replaced).not_to match(/[[:space:]]/)
+  end
+
   it 'joins multiple arguments into one key' do
     expect(::ActiveRemote::Cached::ArgumentKeys.new('hello', 'world', {}).cache_key).to eq('helloworld')
   end