handle -unix, -dos, -mac special encoding suffixes

lib/live_ast/reader.rb

@@ -12,7 +12,15 @@ def self.read(file)
       # magic comment overrides BOM
       encoding = contents[MAGIC_COMMENT, 1] || utf8 || "US-ASCII"
 
-      contents.force_encoding(encoding)
+      contents.force_encoding(strip_special(encoding))
+    end
+
+    def self.strip_special(encoding)
+      if encoding =~ /\Autf8-mac\Z/i
+        "UTF8-MAC"
+      else
+        encoding.sub(/-(unix|dos|mac)\Z/i, "")
+      end
     end
   end
 end

test/encoding_test.rb

@@ -5,6 +5,10 @@ class AllEncodingTest < RegularTest
     default US-ASCII
     usascii US-ASCII
     utf8 UTF-8
+    utf8unix UTF-8
+    utf8mac UTF-8
+    utf8mac_alt UTF8-MAC
+    utf8dos UTF-8
     utf8bom UTF-8
     utf8bom_only UTF-8
     usascii_with_utf8bom US-ASCII

test/encoding_test/utf8dos.rb

@@ -0,0 +1,6 @@
+# -*- coding: utf-8-dos -*-
+module EncodingTest
+  def utf8dos_string
+    "大きな箱とねこ。"
+  end
+end

test/encoding_test/utf8mac.rb

@@ -0,0 +1,6 @@
+# -*- coding: utf-8-mac -*-
+module EncodingTest
+  def utf8mac_string
+    "大きな箱とねこ。"
+  end
+end

test/encoding_test/utf8mac_alt.rb

@@ -0,0 +1,6 @@
+# -*- coding: utf8-mac -*-
+module EncodingTest
+  def utf8mac_alt_string
+    "大きな箱とねこ。"
+  end
+end

test/encoding_test/utf8unix.rb

@@ -0,0 +1,6 @@
+# -*- coding: utf-8-unix -*-
+module EncodingTest
+  def utf8unix_string
+    "大きな箱とねこ。"
+  end
+end