Add a configuration file for unused

- https://github.com/joshuaclayton/unused
- All of the reported items are present because they are required for
  implementation or they are present because they are used by tools outside of
  mime-types itself (e.g., the mime-types-data tools).

Also remove .freeze methods on strings from all files because of the frozen
string magic comment.

3 files changed, 57 insertions, 19 deletions

diff --git a/.unused.yml b/.unused.yml
new file mode 100644
index 0000000..9cfe549
--- /dev/null
+++ b/.unused.yml
@@ -0,0 +1,39 @@
+---
+- name: Ruby
+  autoLowLikelihood:
+    - name: MIME::Types::Container implementation details
+      pathStartsWith: lib/mime/types/container.rb
+      allowedTerms:
+        - '[]='
+        - marshal_dump
+        - marshal_load
+        - to_hash
+    - name: MIME::Types::Columnar array parser
+      pathStartsWith: lib/mime/types/_columnar.rb
+      allowedTerms:
+        - arr
+        - extended
+    - name: MIME::Types::Logger close (required for implementation)
+      pathStartsWith: lib/mime/types/logger.rb
+      termEquals: close
+    - name: MIME::Type writers
+      pathStartsWith: lib/mime/type.rb
+      allowedTerms:
+        - content_type=
+        - extensions=
+    - name: MIME::Type dynamic calls
+      pathStartsWith: lib/mime/type.rb
+      termStartsWith: xref_url_for_
+    - name: MIME::Type object implementation
+      pathStartsWith: lib/mime/type.rb
+      allowedTerms:
+        - eql?
+        - to_str
+    - name: MIME::Types::Loader YAML loader (used by mime-types-data tools)
+      pathStartsWith: lib/mime/types/loader.rb
+      termEquals: load_yaml
+    - name: MIME::Types tests
+      pathStartsWith: test/
+      allowedTerms:
+        - around
+        - teardown
diff --git a/lib/mime/type.rb b/lib/mime/type.rb
index 61d20ab..11b8530 100644
--- a/lib/mime/type.rb
+++ b/lib/mime/type.rb
@@ -331,7 +331,7 @@ class MIME::Type
   # call-seq:
   #   text_plain.friendly         # => "Text File"
   #   text_plain.friendly('en')   # => "Text File"
-  def friendly(lang = 'en'.freeze)
+  def friendly(lang = 'en')
     @friendly ||= {}
 
     case lang
@@ -504,7 +504,7 @@ class MIME::Type
     # use with the I18n library.
     def i18n_key(content_type)
       simplify_matchdata(match(content_type), joiner: '.') { |e|
-        e.gsub!(I18N_RE, '-'.freeze)
+        e.gsub!(I18N_RE, '-')
       }
     end
 
@@ -521,12 +521,12 @@ class MIME::Type
 
     private
 
-    def simplify_matchdata(matchdata, remove_x = false, joiner: '/'.freeze)
+    def simplify_matchdata(matchdata, remove_x = false, joiner: '/')
       return nil unless matchdata
 
       matchdata.captures.map { |e|
         e.downcase!
-        e.sub!(%r{^x-}, ''.freeze) if remove_x
+        e.sub!(%r{^x-}, '') if remove_x
         yield e if block_given?
         e
       }.join(joiner)
@@ -551,23 +551,22 @@ class MIME::Type
   end
 
   def xref_url_for_rfc(value)
-    'http://www.iana.org/go/%s'.freeze % value
+    'http://www.iana.org/go/%s' % value
   end
 
   def xref_url_for_draft(value)
-    'http://www.iana.org/go/%s'.freeze % value.sub(/\ARFC/, 'draft')
+    'http://www.iana.org/go/%s' % value.sub(/\ARFC/, 'draft')
   end
 
   def xref_url_for_rfc_errata(value)
-    'http://www.rfc-editor.org/errata_search.php?eid=%s'.freeze % value
+    'http://www.rfc-editor.org/errata_search.php?eid=%s' % value
   end
 
   def xref_url_for_person(value)
-    'http://www.iana.org/assignments/media-types/media-types.xhtml#%s'.freeze %
-      value
+    'http://www.iana.org/assignments/media-types/media-types.xhtml#%s' % value
   end
 
   def xref_url_for_template(value)
-    'http://www.iana.org/assignments/media-types/%s'.freeze % value
+    'http://www.iana.org/assignments/media-types/%s' % value
   end
 end
diff --git a/lib/mime/types/_columnar.rb b/lib/mime/types/_columnar.rb
index 8c87267..8938f19 100644
--- a/lib/mime/types/_columnar.rb
+++ b/lib/mime/types/_columnar.rb
@@ -45,7 +45,7 @@ module MIME::Types::Columnar
       i = -1
       column = File.join(@__root__, "mime.#{name}.column")
 
-      IO.readlines(column, encoding: 'UTF-8'.freeze).each do |line|
+      IO.readlines(column, encoding: 'UTF-8').each do |line|
         line.chomp!
 
         if lookup
@@ -63,7 +63,7 @@ module MIME::Types::Columnar
   def load_encoding
     each_file_line('encoding') do |type, line|
       pool ||= {}
-      line.freeze
+      line
       type.instance_variable_set(:@encoding, (pool[line] ||= line))
     end
   end
@@ -108,11 +108,11 @@ module MIME::Types::Columnar
   end
 
   def dict(line, array: false)
-    if line == '-'.freeze
+    if line == '-'
       {}
     else
-      line.split('|'.freeze).each_with_object({}) { |l, h|
-        k, v = l.split('^'.freeze)
+      line.split('|').each_with_object({}) { |l, h|
+        k, v = l.split('^')
         v = nil if v.empty?
         h[k] = array ? Array(v) : v
       }
@@ -120,18 +120,18 @@ module MIME::Types::Columnar
   end
 
   def arr(line)
-    if line == '-'.freeze
+    if line == '-'
       []
     else
-      line.split('|'.freeze).flatten.compact.uniq
+      line.split('|').flatten.compact.uniq
     end
   end
 
   def opt(line)
-    line unless line == '-'.freeze
+    line unless line == '-'
   end
 
   def flag(line)
-    line == '1'.freeze ? true : false
+    line == '1' ? true : false
   end
 end